The earthworm-based vermiremediation facilitated with benign chemicals such as nano zero-valent iron(nZVI)is a promising approach for the remediation of a variety of soil contaminants including cyanotoxins.As themost ...The earthworm-based vermiremediation facilitated with benign chemicals such as nano zero-valent iron(nZVI)is a promising approach for the remediation of a variety of soil contaminants including cyanotoxins.As themost toxic cyanotoxin,microcystin-LR(MC-LR)enter soil via runoff,irrigated surface water and sewage,and the application of cyanobacterial biofertilizers as part of the sustainable agricultural practice.Earthworms in such remediation systems must sustain the potential risk from both nZVI and MC-LR.In the present study,earthworms(Eisenia fetida)were exposed up to 14 days to MC-LR and nZVI(individually and inmixture),and the toxicity was investigated at both the organismal andmetabolic levels,including growth,tissue damage,oxidative stress,metabolic response and gut microbiota.Results showed that co-exposure of MC-LR and nZVI is less potent to earthworms than that of separate exposure.Histological observations in the co-exposure group revealed only minor epidermal brokenness,and KEGG enrichment analysis showed that co-exposure induced earthworms to regulate glutathione biosynthesis for detoxification and reduced adverse effects from MC-LR.The combined use of nZVI promoted the growth and reproduction of soil and earthworm gut bacteria(e.g.,Sphingobacterium and Acinetobacter)responsible for the degradation of MC-LR,whichmight explain the observed antagonism between nZVI and MC-LR in earthworm microcosm.Our study suggests the beneficial use of nZVI to detoxify pollutants in earthworm-based vermiremediation systems where freshwater containing cyanobacterial blooms is frequently used to irrigate soil and supply water for the growth and metabolism of earthworms.展开更多
Graphene Oxide(GO),nanoscale Zero-Valent Iron(nZVI)and GO-modified nZVI(GO-nZVI)composite materials were prepared by the Hummer and polyphenol reduction method,respectively,and Scanning Electron Microscope(SEM)and X-r...Graphene Oxide(GO),nanoscale Zero-Valent Iron(nZVI)and GO-modified nZVI(GO-nZVI)composite materials were prepared by the Hummer and polyphenol reduction method,respectively,and Scanning Electron Microscope(SEM)and X-ray Diffraction(XRD)were used to characterize the morphology and phase composition of these materials.A series of batch experiments were then conducted to inves-tigate the performance and influencing factors of GO-nZVI activating peroxydisulfate(SPS)for the degra-dation of 1,2,3-trichloropropane(TCP).Finally,an in-situ oxidation reaction zone was created by GO-nZVI-activated SPS in a one-dimensional simulated system to study the remediation of TCP contamination under different aquifer conditions.The results showed that the GO-nZVI composite exhibited a porous,fluffy structure,with spherical nZVI particles loaded onto the surface and folds of the GO sheets.Compared with unmodified nZVI particles,the GO-nZVI composite significantly enhanced the removal efficiency of TCP by activated SPS,achieving a removal rate of 67.2%within an hour-78.2%higher than that of the unmodi-fied system.The SPS dosage and the C/Fe ratio in GO-nZVI were found to significantly affect the degradation efficiency of TCP.The removal rate of TCP increased with higher SPS concentration,and a 10%carbon addition,yielded the best activation effect.The one-dimensional simulation results indicated that the removal rate of TCP ranged from 30.1%to 73.3%under different conditions.A larger medium particle size and higher concentrations of reactants(SPS and GO-nZVI)improved pollutant degradation efficiency,increasing TCP removal by 62.1%,23.8%,and 3.7%,respectively.In contrast,a higher groundwater flow velocity was not conducive to the removal of pollutants,with the TCP removal rate decreasing by approxi-mately 41.9%.展开更多
Antimony(Sb)contamination in paddy fields can lead to its accumulation in rice grains,posing a threat to food safety.To address this issue,the combined use of zero-valent iron(ZVI)and biochar(BC)were applied to decrea...Antimony(Sb)contamination in paddy fields can lead to its accumulation in rice grains,posing a threat to food safety.To address this issue,the combined use of zero-valent iron(ZVI)and biochar(BC)were applied to decrease the uptake of Sb in Sb-polluted soils,and their effects on Sb uptake from soil to rice grains were investigated.Our results showed that the combination treatment of 0.05%ZVI and 0.095%BC resulted in a significant decrease(42.8%)in Sb accumulation in rice grains that was comparably more efficient than that by 0.05%ZVI(decrease of 15.8%Sb accumulation)or 0.095%BC(decrease of 12.7%Sb accumulation)alone,demonstrating the synergistic effect of ZVI and BC on mitigating Sb uptake by rice plants.ZVI presence resulted in the formation of iron oxides in the soil and on root surfaces,and the S^(2-)/S_(2)^(2-)ascent also increased by 58.7%on day 75 compared with that of the control,facilitating the reduction of Sb(Ⅴ)to less mobile Sb(Ⅲ),thereby decreasing Sb accumulation in rice plants.BC initially increased themobility of Sb owing to its alkaline nature,whereas the electron shuttle properties of BC contributed to a decrease in Sbmobility.The abundance of the arsenite-reducing gene arrA ultimately increased by 203.2% on day 120 compared with the initial phase on day 5,and BC caused a remarkable increase in arrA gene abundance.This study revealed the synergistic mechanisms by combining ZVI and BC to mitigate Sb uptake by rice,which may be useful for the sustainable remediation of contaminated rice paddies.展开更多
Sulfamethoxazole(SMX)contamination in farmland disrupts soil micro-ecological functions,posing a risk to soil health and productivity.Sulfidated zero-valent iron(SZVI),a promising green material known for its good rea...Sulfamethoxazole(SMX)contamination in farmland disrupts soil micro-ecological functions,posing a risk to soil health and productivity.Sulfidated zero-valent iron(SZVI),a promising green material known for its good reactivity,had been used for soil remediation.However,existing studies often overlooked the effects of particle size and sulfur content on the long-term performance of SZVI and its impact on soil micro-ecological safety.This study employed polysulfide-modified nano,micro-nano,and micron-sized SZVI to investigate how particle size and sulfur content influenced the reactivity and durability,as well as the iron oxide forms and microbial community of soil during the SMX remediation.The results demonstrated that micro-nano sized SZVI(nm-SZVI)exhibited prolonged reactivity,achieving 83.12%-99.91%SMX removal over 30 days and maintaining higher levels of soil amorphous and reactive ferrous iron.Although sulfidation improved reactivity,excessive sulfur content reduced removal efficiency and accelerated the conversion to soil crystalline iron forms.Compared to nanoparticles,nm-SZVI fostered microbial diversity and balanced functional bacteria for electron transfer,organic matter utilization,and nutrient cycling.However,the elevated sulfur content in SZVI inhibited the stability of the microbial network.Finally,it was found that SMX underwent isoxazole reduction cleavage and oxidative removal pathways,reducing ecological toxicity.This study provided a new insight into the rational design of SZVI to achieve long-term pollutant removal and ensuring the health and stability of the microbial community by regulating particle size and sulfur content in soil remediation.展开更多
Recently,using anaerobic hydrolysis of waste activated sludge (WAS) to recover volatile fatty acids (VFAs) as carbon sources for denitrification has been widely studied,and the key is to solve the problem of improving...Recently,using anaerobic hydrolysis of waste activated sludge (WAS) to recover volatile fatty acids (VFAs) as carbon sources for denitrification has been widely studied,and the key is to solve the problem of improving the solubility and bioavailability of WAS organic matter.Considering the energy consumption and chemical cost,this paper used low-dose nanozero-valent iron (NZVI) coupled with low-intensity ultrasonication (US) to pretreat WAS,and explored the effects of different treatment sequences on the fragmentation of WAS flocs particles,the dissolution of organic matter,and the subsequent biofermentation conversion process.The results showed low-dose NZVI synchronized with low-intensity US (NZVIUS)worked best for WAS anaerobic fermentation.Compared with 2062 mg/L in control group,soluble chemical oxygen demand (SCOD) after NZVIUS treatment reached up to 2786 mg/L during the fermentation cycle,and the initial release rate of SCOD increased by 69%.The VFAs production was elevated from 1522 to 1940 mg COD/L.NZVIUS pretreatment promoted the solubilization of attached organic matter,manifested by the fragmentation of WAS flocs and cell lysis.At the same time,proteins and carbohydrates in the extracellular polymeric substances (EPS) had different types of migration and transformation,and transfer of EPS can contribute 35.6% to SCOD.Moreover,adding NZVI promoted PO_(4)^(3-)-P recovery in the fermentation supernatant by 22.3% more than in day 4 control.This study demonstrated that the NZVIUS pretreatment method can effectively improve the production of VFAs by WAS anaerobic fermentation,meeting the practical needs of wastewater plants.展开更多
Nano zero-valent iron(nZVI)is widely used in soil remediation due to its high reactivity.However,the easy agglomeration,poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its a...Nano zero-valent iron(nZVI)is widely used in soil remediation due to its high reactivity.However,the easy agglomeration,poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its application scale in Cr-contaminated soil remediation,especially in high concentration of Cr-contaminated soil.Herein,we found that the carboxymethyl cellulose on nZVI particles could increase the zeta potential value of soil and change the phase of nZVI.Along with the presence of biochar,97.0%and 96.6%Cr immobilization efficiency through CMC-nZVI/BC were respectively achieved in high and low concentrations of Cr-contaminated soils after 90-days remediation.In addition,the immobilization efficiency of Cr(VI)only decreased by 5.1%through CMC-nZVI/BC treatment after 10 weeks aging in air,attributing to the strong antioxidation ability.As for the surrounding Crcontaminated groundwater,the Cr(VI)removal capacity of CMC-nZVI/BC was evaluated under different reaction conditions through column experiments and COMSOL Multiphysics.CMC-nZVI/BC could efficiently remove 85%of Cr(VI)in about 400 hr when the initial Cr(VI)concentration was 40 mg/L and the flow rate was 0.5 mL/min.This study demonstrates that uniformly dispersed CMC-nZVI/BC has an excellent remediation effect on different concentrations of Cr-contaminated soils.展开更多
The MXenes,a new class of two-dimensional layered materials,have found extensive applications in water treatment for its excellent thermal stability,electrical conductivity,and excellent adsorption ability.Sulfidized ...The MXenes,a new class of two-dimensional layered materials,have found extensive applications in water treatment for its excellent thermal stability,electrical conductivity,and excellent adsorption ability.Sulfidized nano zero-valent iron(S-nZVI)is a good reducing agent,however,the practical application of S-nZVI is currently restricted due to the tendency of nano materials to agglomerate.Herein,MXenes use as a support and in situ loading S-nZVI on it to prepare a new material(S-nZVI/Ti_(3)C_(2)T_(x)),and applied it to U(VI)removal in water treatment.The microscopic characterization proves that S-nZVI on Ti_(3)C_(2)T_(x) has good dispersion and effectively alleviates agglomeration.Batch experiments shown that SnZVI/Ti_(3)C_(2)T_(x) has a very good effect on U(VI)removal,and themaximumadsorption capacity reaches 674.4mg/g under the aerobic condition at pH=6.0.The pseudo-second-order kinetic model and the Langmuir isotherm model were found to be more appropriate for describing the adsorption behavior.This indicates that the removal process is a single molecular layer chemisorption.Moreover,the S-nZVI/Ti_(3)C_(2)T_(x) maintained a removal efficiency of over 85%for U(VI)even after being reused five times,demonstrating its excellent reusability.It is worth noting that the material can remove 79.8%of 50 mg/L of U(VI)in simulated seawater,indicating that S-nZVI/Ti_(3)C_(2)T_(x) possessed an excellent uranium extraction performance from seawater.Experimental results and XPS analysis showed that U(VI)was removed by adsorption,reduction and co-precipitation.Moreover,S-nZVI/Ti_(3)C_(2)T_(x) was a lowtoxicitymaterial to Hyriopsis cumingii.Therefore,S-nZVI/Ti_(3)C_(2)T_(x) was expected to be a candidate as adsorbent with great potential in removal of uranium from wastewater and seawater.展开更多
Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-c...Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were investigated.The addition of ZVI to the flooding process was more conducive to Cd immobilization.Less potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe minerals.Moreover,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd immobilization.Additionally,the addition of ZVI before flooding played a vital role in Cd retention after soil drainage.In contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil surfaces.The findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.展开更多
Anaerobic digestion has been defined as a competitive approach to facilitate the recycling of corn stalks.However,few studies have focused on the role of direct interspecies electron transfer(DIET)pathway in the acidi...Anaerobic digestion has been defined as a competitive approach to facilitate the recycling of corn stalks.However,few studies have focused on the role of direct interspecies electron transfer(DIET)pathway in the acidification stage under the addition of different particle sizes of zero-valent iron(ZVI).In this study,three types of ZVI,namely iron filings,iron powder and nanoscale iron,were investigated,respectively,to enhance its high-value conversion.Variations in volatile fatty acids(VFAs)and methane(CH4)production associated with the underlyingmechanisms were emphatically determined.Results indicated that the addition of ZVI could increase the concentration of VFAs,with the most outstanding performance observed with the use of nanoscale iron.Importantly,the conversion of propionic acid to acetic acid was driven by adding ZVI with no between-group differences in acidizing phase.Conversely,the substrate was more fully utilized when supplied with iron powder compared with other groups in methanogenic phase,thereby displaying the maximumCH4 yield with a value of 263.1 mL/(g total solids(TS)).However,adding nanoscale iron could signally shorten the digestion time(T80),saving 7 days in comparison to the group of iron powder.展开更多
Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing...Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications.Herein,this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water.Firstly,Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion.The morphological,structural,and compositional evolution of(modified-)nZVI under different environmental conditions,assisted with microscopic and spectroscopic evidence,is then summarized.Afterwards,common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water.Specifically,stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed,emphasizing their capabilities in studying the dynamic iron corrosion processes.Finally,in the future,more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties.We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.展开更多
Industries such as non-ferrous metal smelting discharge billions of gallons of highly toxic heavy metal wastewater(HMW)worldwide annually,posing a severe challenge to conventional wastewater treatment plants and harmi...Industries such as non-ferrous metal smelting discharge billions of gallons of highly toxic heavy metal wastewater(HMW)worldwide annually,posing a severe challenge to conventional wastewater treatment plants and harming the environment.HMW is traditionally treated via chemical precipitation using lime,caustic,or sulfide,but the effluents do not meet the increasingly stringent discharge standards.This issue has spurred an increase in research and the development of innovative treatment technologies,among which those using nanoparticles receive particular interest.Among such initiatives,treatment using nanoscale zero-valent iron(nZVI)is one of the best developed.While nZVI is already well known for its site-remediation use,this perspective highlights its application in HMW treatment with metal recovery.We demonstrate several advantages of nZVI in this wastewater application,including its multifunctionality in sequestrating a wide array of metal(loid)s(>30 species);its capability to capture and enrich metal(loid)s at low concentrations(with a removal capacity reaching 500 mg·g^(-1)nZVI);and its operational convenience due to its unique hydrodynamics.All these advantages are attributable to nZVI’s diminutive nanoparticle size and/or its unique iron chemistry.We also present the first engineering practice of this application,which has treated millions of cubic meters of HMW and recovered tons of valuable metals(e.g.,Cu and Au).It is concluded that nZVI is a potent reagent for treating HMW and that nZVI technology provides an eco-solution to this toxic waste.展开更多
To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes,amino acids were used to modify nanoscale zero-valent iron(AA@Fe^(0)),which were applied in the Fenton-like deg...To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes,amino acids were used to modify nanoscale zero-valent iron(AA@Fe^(0)),which were applied in the Fenton-like degradation of organic solvents(tributyl phosphate and n-dodecane,named TBP and DD).Twelve amino acids,i.e.,glycine(Gly),alanine(Ala),leucine(Leu),proline(Pro),phenylalanine(Phe),methionine(Met),cysteine(Cys),asparagine(Asn),serine(Ser),glutamic acid(Glu),lysine(Lys)and arginine(Arg),were selected and calculated by density functional theory(DFT).The optimized structure,charge distribution,the highest occupied molecular orbital(HOMO),the lowest unoccupied molecular orbital(LUMO),interaction region indicator(IRI)isosurface map and adsorption energy of AA@Fe^(0),AA@Fe^(0)-TBP and AA@Fe^(0)-DD were studied,which indicated that Fe is more likely to approach and charge transfer with-COO and-NH_(3) on theα-carbon of amino acids.There is strong attraction between Fe and–COO,and Van der Waals force between Fe and-NH_(3),respectively.In the interaction of AA@Fe^(0)with TBP and DD,Van der Waal force plays an important role.AA@Fe^(0)was synthesized in laboratory and characterized to investigate physicochemical properties.In Fenton-like degradation of organic solvents,the change of COD in water phase during the degradation process as well as the volume of the organic phase after the reaction were investigated.The results of calculations combined with experiments showed that Ser-modified Fe^(0)performed the best in these amino acids,with 98%removal of organic solvents.A possible catalytic mechanism was proposed in which amino acids acted a linking role between Fe and organic solvents,activating H_(2)O_(2)to generate hydroxyl radicals for the degradation of organic solvents.展开更多
Sulfidation of zero-valent iron(ZVI)has attracted broad attention in recent years for improving the sequestration of contaminants from water.However,sulfidated ZVI(S-ZVI)is mostly synthesized in the aqueous phase,whic...Sulfidation of zero-valent iron(ZVI)has attracted broad attention in recent years for improving the sequestration of contaminants from water.However,sulfidated ZVI(S-ZVI)is mostly synthesized in the aqueous phase,which usually causes the formation of a thick iron oxide layer on the ZVI surface and hinders the efficient electron transfer to the contaminants.In this study,an alcohothermal strategy was employed for S-ZVI synthesis by the one-step reaction of iron powder with elemental sulfur.It is found that ferrous sulfide(FeS)with high purity and fine crystallization was formed on the ZVI surface,which is extremely favorable for electron transfer.Cr(Ⅵ)removal experiments confirm that the rate constant of SZVI synthesized by the alcohothermal method was 267.1-and 5.4-fold higher than those of un-sulfidated ZVI and aqueous-phase synthesized S-ZVI,respectively.Systematic characterizations proved that Cr(Ⅵ)was reduced and co-precipitated on S-ZVI in the form of a Fe(Ⅲ)/Cr(Ⅲ)/Cr(Ⅵ)composite,suggesting its environmental benignancy.展开更多
Nitrobenzene has been considered as a significant groundwater contaminant due to its wide usage in explosives, insecticides, herbicides, pharmaceuticals and dyes. Nitrobenzene is of environmental concern because of it...Nitrobenzene has been considered as a significant groundwater contaminant due to its wide usage in explosives, insecticides, herbicides, pharmaceuticals and dyes. Nitrobenzene is of environmental concern because of its toxicity. In the presence of zero-valent iron （ZVI）, reduction of the nitro group is the dominant transformation process for nitrobenzene. A series of experiments were carried out to investigate the kinetics of nitrobenzene reduction by ZVI and the effects of pH and ZVI particle size on nitrobenzene removal in groundwater. The results indicated that nitrobenzene could be reduced to aniline by ZVI; the reduction of nitrobenzene by ZVI followed a pseudo first-order kinetics; the observed nitrobenzene reduction rate constant （k obs ） was 0.0006 min^-1 and the half-life of nitrobenzene （t 1/2 ） was 115.5 min; the mass balance achieved 87.5% for nitrobenzene reduction by the 1 mm ZVI particle and the final removal efficiency was 80.98%. In addition, the pH and ZVI particle size were found to exhibit significant influences on the nitrobenzene reduction. The observed nitrobenzene reduction rate constant linearly decreased with increase pH and the data fitted on polynomial regression equation for the observed nitrobenzene reduction rate constant and ZVI particle size. Therefore, use of ZVI based permeable reactive barrier technology to remedy nitrobenzene contaminated groundwater was feasible.展开更多
In this study, bimetallic nanoscale zero-valent iron particles（nZVI）, including copper/nanoscale zero-valent iron particles（Cu/nZVI） and nickel/nanoscale zero-valent iron particles（Ni/nZVI）, were synthesized by ...In this study, bimetallic nanoscale zero-valent iron particles（nZVI）, including copper/nanoscale zero-valent iron particles（Cu/nZVI） and nickel/nanoscale zero-valent iron particles（Ni/nZVI）, were synthesized by one-step liquid-phase reduction and applied for oxytetracycline（OTC） removal. The effects of contact time and initial p H on the removal efficiency were studied. The as-prepared nanoscale particles were characterized by scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and X-ray diffraction（XRD）. Finally, the degradation mechanisms of OTC utilizing the as-prepared nanoparticles were investigated by using X-ray photoelectron spectroscopy（XPS） and mass spectrometry（MS）. Cu/n ZVI presented remarkable ability for OTC degradation and removed71.44% of OTC（100 mg/L） in 4 hr, while only 62.34% and 31.05% of OTC was degraded by Ni/nZVI and nZVI respectively. XPS and MS analysis suggested that OTC was broken down to form small molecules by ·OH radicals generated from the corrosion of Fe0. Cu/nZVI and Ni/n ZVI have been proved to have potential as materials for application in OTC removal because of their significant degradation ability toward OTC.展开更多
Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（...Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,Fourier-transform infrared（FTIR） spectroscopy and Brunauer–Emmett–Teller（BET） analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr（Ⅵ） removal performance. The results showed that the Cr（Ⅵ） removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG（10.00%） and ZⅥ（29.80%）. Furthermore, the removal rate of Cr（Ⅵ） by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr（Ⅵ） removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr（Ⅵ） via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy（XPS） was used to analyze the mechanisms of Cr（Ⅵ） removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr（Ⅵ） was immobilized via the formation of Cr（III） hydroxide and Cr（III）–Fe（III）hydroxide/oxyhydroxide on the surface of EG-ZⅥ.展开更多
Sulfide-modified nanoscale zero-valent iron(S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles(NPs) easily agglomerate and have poor contact with organic contaminant...Sulfide-modified nanoscale zero-valent iron(S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles(NPs) easily agglomerate and have poor contact with organic contaminants.Herein, we propose a new S-nZVI/graphene aerogel(S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene(TCE) from water.Three-dimensional porous graphene aerogel(GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs.The TCE removal rates of Fe S, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2 hr, respectively.Furthermore, TCE was completely removed within 50 min by S-nZVI/GA.The TCE removal rate increased with increasing p H and temperature, and TCE removal followed the pseudo-first-order kinetic model.The results demonstrate the great potential of S-nZVI/GA composite as a low-cost,easily separated and superior monolithic adsorbent for removal of organic pollutants.展开更多
In this study, a novel nanoscale zero-valent iron（n ZVI） composite material was successfully synthesized using a low-cost natural clay, ＂Hangjin 2~#clay＂（HJ clay） as the support and tested for the decolorization...In this study, a novel nanoscale zero-valent iron（n ZVI） composite material was successfully synthesized using a low-cost natural clay, ＂Hangjin 2~#clay＂（HJ clay） as the support and tested for the decolorization of the azo dye Methyl Orange（MO） in aqueous solution by n ZVI particles. According to the characterization and MO decolorization experiments, the sample with 5：1 HJ clay-supported n ZVI（HJ/n ZVI） mass ratio（HJ-n ZVI5） showed the best dispersion and reactivity and the highest MO decolorization efficiency. With the same equivalent Fe0 dosage, the HJ-n ZVI1 and HJ-n ZVI5 samples demonstrated a synergetic effect for the decolorization of MO： their decolorization efficiencies were much higher than that achieved by physical mixing of HJ clay and n ZVIs, or the sum of HJ clay and n ZVIs alone. The synergetic effect was primarily due to the improved dispersion and more effective utilization of the n ZVI particles on/in the composite materials. Higher decolorization efficiency of MO was obtained at larger HJ-n ZVI dosage, higher temperature and under N2 atmosphere, while the MO initial concentration and p H were negatively correlated to the efficiency. HJ clay not only works as a carrier for n ZVI nanoparticles, but also contributes to the decolorization through an ＂adsorption-enhanced reduction＂ mechanism. The high efficiency of HJ-n ZVI for decontamination gives it great potential for use in a variety of remediation applications.展开更多
Zero-valent iron amended biochar(ZVIB)has been proposed as a promising material in immobilizing heavy metals in paddy fields.In this study,the impacts of p H of ZVIB(p H 6.3 and p H 9.7)and watering management techniq...Zero-valent iron amended biochar(ZVIB)has been proposed as a promising material in immobilizing heavy metals in paddy fields.In this study,the impacts of p H of ZVIB(p H 6.3 and p H 9.7)and watering management techniques(watering amount in the order of CON(control,5/72)>3/72>1-3/72>3/100>1/72,with 5/72,for example,representing irrigation given to 5 cm above soil surface in 72 hr regular interval)on As and Cd bioavailability for rice and its grain yield(Yield BR)were investigated in a pot experiment.Brown rice As(As BR)content was irrelative to the watering treatments,while significantly decreased(>50%)with the addition of both ZVIB materials.The diminutions of brown rice Cd(Cd BR)content as well as the Yield BR were highly dependent on both the soil amendment materials’p H and watering amount.Among all the watering treatments,3/72 treatment(15%less irrigation water than the CON)with ZVIB 6.3 amendment was the optimum fit for simultaneous reduction of As BR(50%)and Cd BR contents(19%)as well as for significant increment(12%)of the Yield BR.Although high pH(9.7)ZVIB application could also efficiently decrease As and Cd contents in brown rice,it might risk grain yield lost if appropriate(e.g.3/72 in our study)watering management technique was not chosen.Therefore,ZVIB would be an environmentally friendly option as an amendment material with proper selection of watering management technique to utilize As and Cd co-contaminated arable soils safely for paddy cultivation.展开更多
Some problems including low treatment capacity,agglomeration and clogging phenomena,and short working life,limit the application of pre-treatment methods involving zero-valent iron （ZVI）.In this article,ZVI was froz...Some problems including low treatment capacity,agglomeration and clogging phenomena,and short working life,limit the application of pre-treatment methods involving zero-valent iron （ZVI）.In this article,ZVI was frozen in an amorphous state through a melt-spinning technique,and the decolorization effect of amorphous ZVI on Acid Orange II solution was investigated under varied conditions of experimental variables such as reaction temperature,ribbon dosage,and initial pH.Batch experiments suggested that the decolorization rate was enhanced with the increase of reaction temperature and ribbon dosage,but decreased with increasing initial solution pH.Kinetic analyses indicated that the decolorization process followed a first order exponential kinetic model,and the surface-normalized decolorization rate could reach 2.09 L/（m^2 ·min） at room temperature,which was about ten times larger than any previously reported under similar conditions.Recycling experiments also proved that the ribbons could be reused at least four times without obvious decay of decolorization rate and efficiency.This study suggests a tremendous application potential for amorphous ZVI in remediation of groundwater or wastewater contaminated with azo dyes.展开更多
基金supported by the National Natural Science Foundation of China(No.21777139)the National Key Research and Development Program of China(No.2017YFA0207003).
文摘The earthworm-based vermiremediation facilitated with benign chemicals such as nano zero-valent iron(nZVI)is a promising approach for the remediation of a variety of soil contaminants including cyanotoxins.As themost toxic cyanotoxin,microcystin-LR(MC-LR)enter soil via runoff,irrigated surface water and sewage,and the application of cyanobacterial biofertilizers as part of the sustainable agricultural practice.Earthworms in such remediation systems must sustain the potential risk from both nZVI and MC-LR.In the present study,earthworms(Eisenia fetida)were exposed up to 14 days to MC-LR and nZVI(individually and inmixture),and the toxicity was investigated at both the organismal andmetabolic levels,including growth,tissue damage,oxidative stress,metabolic response and gut microbiota.Results showed that co-exposure of MC-LR and nZVI is less potent to earthworms than that of separate exposure.Histological observations in the co-exposure group revealed only minor epidermal brokenness,and KEGG enrichment analysis showed that co-exposure induced earthworms to regulate glutathione biosynthesis for detoxification and reduced adverse effects from MC-LR.The combined use of nZVI promoted the growth and reproduction of soil and earthworm gut bacteria(e.g.,Sphingobacterium and Acinetobacter)responsible for the degradation of MC-LR,whichmight explain the observed antagonism between nZVI and MC-LR in earthworm microcosm.Our study suggests the beneficial use of nZVI to detoxify pollutants in earthworm-based vermiremediation systems where freshwater containing cyanobacterial blooms is frequently used to irrigate soil and supply water for the growth and metabolism of earthworms.
基金financially supported by the Basal Research Fund of Chinese Academy of Geological Sciences(NO.SK202318)the Natural Science Foundation of Xiamen,China(No.3502Z20227309)the Natural Science Foundation of Fujian Province of China(NO.2023J01227).
文摘Graphene Oxide(GO),nanoscale Zero-Valent Iron(nZVI)and GO-modified nZVI(GO-nZVI)composite materials were prepared by the Hummer and polyphenol reduction method,respectively,and Scanning Electron Microscope(SEM)and X-ray Diffraction(XRD)were used to characterize the morphology and phase composition of these materials.A series of batch experiments were then conducted to inves-tigate the performance and influencing factors of GO-nZVI activating peroxydisulfate(SPS)for the degra-dation of 1,2,3-trichloropropane(TCP).Finally,an in-situ oxidation reaction zone was created by GO-nZVI-activated SPS in a one-dimensional simulated system to study the remediation of TCP contamination under different aquifer conditions.The results showed that the GO-nZVI composite exhibited a porous,fluffy structure,with spherical nZVI particles loaded onto the surface and folds of the GO sheets.Compared with unmodified nZVI particles,the GO-nZVI composite significantly enhanced the removal efficiency of TCP by activated SPS,achieving a removal rate of 67.2%within an hour-78.2%higher than that of the unmodi-fied system.The SPS dosage and the C/Fe ratio in GO-nZVI were found to significantly affect the degradation efficiency of TCP.The removal rate of TCP increased with higher SPS concentration,and a 10%carbon addition,yielded the best activation effect.The one-dimensional simulation results indicated that the removal rate of TCP ranged from 30.1%to 73.3%under different conditions.A larger medium particle size and higher concentrations of reactants(SPS and GO-nZVI)improved pollutant degradation efficiency,increasing TCP removal by 62.1%,23.8%,and 3.7%,respectively.In contrast,a higher groundwater flow velocity was not conducive to the removal of pollutants,with the TCP removal rate decreasing by approxi-mately 41.9%.
基金financially supported by the National Natural Science Foundation of China(Nos.42030702,42307014,and 42077354)the Guangdong Foundation for Program of Science and Technology Research(No.2020B1212060048)+7 种基金the China Postdoctoral Science Foundation(No.2022M720847)the GDAS’Project of Science and Technology Development(Nos.2023GDASZH-2023010103,and 2020GDASYL-20200104017)the open competition program of top ten critical priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(No.2022SDZG08)Research Project of Hunan Provincial Department of Education(No.21C0788)National Key Technology R&D Program of China(No.2022YFD1700804)Guangdong Province Key Field R&D Project(No.2023B0202010027)Guangzhou Science and Technology Plan Project(No.2023B03J1286)the research platformwas also supported by Guangdong Science and Technology Infrastructure development(No.2019B121201004).
文摘Antimony(Sb)contamination in paddy fields can lead to its accumulation in rice grains,posing a threat to food safety.To address this issue,the combined use of zero-valent iron(ZVI)and biochar(BC)were applied to decrease the uptake of Sb in Sb-polluted soils,and their effects on Sb uptake from soil to rice grains were investigated.Our results showed that the combination treatment of 0.05%ZVI and 0.095%BC resulted in a significant decrease(42.8%)in Sb accumulation in rice grains that was comparably more efficient than that by 0.05%ZVI(decrease of 15.8%Sb accumulation)or 0.095%BC(decrease of 12.7%Sb accumulation)alone,demonstrating the synergistic effect of ZVI and BC on mitigating Sb uptake by rice plants.ZVI presence resulted in the formation of iron oxides in the soil and on root surfaces,and the S^(2-)/S_(2)^(2-)ascent also increased by 58.7%on day 75 compared with that of the control,facilitating the reduction of Sb(Ⅴ)to less mobile Sb(Ⅲ),thereby decreasing Sb accumulation in rice plants.BC initially increased themobility of Sb owing to its alkaline nature,whereas the electron shuttle properties of BC contributed to a decrease in Sbmobility.The abundance of the arsenite-reducing gene arrA ultimately increased by 203.2% on day 120 compared with the initial phase on day 5,and BC caused a remarkable increase in arrA gene abundance.This study revealed the synergistic mechanisms by combining ZVI and BC to mitigate Sb uptake by rice,which may be useful for the sustainable remediation of contaminated rice paddies.
基金supported by the National Natural Science Foundation of China(No.22478226)Shandong Provincial Natural Science Foundation(Nos.ZR2023JQ022 and ZR2024QE165)+1 种基金the Postdoctoral Fellowship Program of CPSF(No.GZC20240917)Taishan Scholars Project of Shandong Province(No.tstp20230604)。
文摘Sulfamethoxazole(SMX)contamination in farmland disrupts soil micro-ecological functions,posing a risk to soil health and productivity.Sulfidated zero-valent iron(SZVI),a promising green material known for its good reactivity,had been used for soil remediation.However,existing studies often overlooked the effects of particle size and sulfur content on the long-term performance of SZVI and its impact on soil micro-ecological safety.This study employed polysulfide-modified nano,micro-nano,and micron-sized SZVI to investigate how particle size and sulfur content influenced the reactivity and durability,as well as the iron oxide forms and microbial community of soil during the SMX remediation.The results demonstrated that micro-nano sized SZVI(nm-SZVI)exhibited prolonged reactivity,achieving 83.12%-99.91%SMX removal over 30 days and maintaining higher levels of soil amorphous and reactive ferrous iron.Although sulfidation improved reactivity,excessive sulfur content reduced removal efficiency and accelerated the conversion to soil crystalline iron forms.Compared to nanoparticles,nm-SZVI fostered microbial diversity and balanced functional bacteria for electron transfer,organic matter utilization,and nutrient cycling.However,the elevated sulfur content in SZVI inhibited the stability of the microbial network.Finally,it was found that SMX underwent isoxazole reduction cleavage and oxidative removal pathways,reducing ecological toxicity.This study provided a new insight into the rational design of SZVI to achieve long-term pollutant removal and ensuring the health and stability of the microbial community by regulating particle size and sulfur content in soil remediation.
基金supported by Sichuan Environmental Protection Industry Group Co.,Ltd.,China(No.2021-CNSW-A01).
文摘Recently,using anaerobic hydrolysis of waste activated sludge (WAS) to recover volatile fatty acids (VFAs) as carbon sources for denitrification has been widely studied,and the key is to solve the problem of improving the solubility and bioavailability of WAS organic matter.Considering the energy consumption and chemical cost,this paper used low-dose nanozero-valent iron (NZVI) coupled with low-intensity ultrasonication (US) to pretreat WAS,and explored the effects of different treatment sequences on the fragmentation of WAS flocs particles,the dissolution of organic matter,and the subsequent biofermentation conversion process.The results showed low-dose NZVI synchronized with low-intensity US (NZVIUS)worked best for WAS anaerobic fermentation.Compared with 2062 mg/L in control group,soluble chemical oxygen demand (SCOD) after NZVIUS treatment reached up to 2786 mg/L during the fermentation cycle,and the initial release rate of SCOD increased by 69%.The VFAs production was elevated from 1522 to 1940 mg COD/L.NZVIUS pretreatment promoted the solubilization of attached organic matter,manifested by the fragmentation of WAS flocs and cell lysis.At the same time,proteins and carbohydrates in the extracellular polymeric substances (EPS) had different types of migration and transformation,and transfer of EPS can contribute 35.6% to SCOD.Moreover,adding NZVI promoted PO_(4)^(3-)-P recovery in the fermentation supernatant by 22.3% more than in day 4 control.This study demonstrated that the NZVIUS pretreatment method can effectively improve the production of VFAs by WAS anaerobic fermentation,meeting the practical needs of wastewater plants.
基金supported by the National Key Research and Development Program of China(No.2020YFC1808701)the Fundamental Research Funds for the Central Universities(No.buctrc202232).
文摘Nano zero-valent iron(nZVI)is widely used in soil remediation due to its high reactivity.However,the easy agglomeration,poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its application scale in Cr-contaminated soil remediation,especially in high concentration of Cr-contaminated soil.Herein,we found that the carboxymethyl cellulose on nZVI particles could increase the zeta potential value of soil and change the phase of nZVI.Along with the presence of biochar,97.0%and 96.6%Cr immobilization efficiency through CMC-nZVI/BC were respectively achieved in high and low concentrations of Cr-contaminated soils after 90-days remediation.In addition,the immobilization efficiency of Cr(VI)only decreased by 5.1%through CMC-nZVI/BC treatment after 10 weeks aging in air,attributing to the strong antioxidation ability.As for the surrounding Crcontaminated groundwater,the Cr(VI)removal capacity of CMC-nZVI/BC was evaluated under different reaction conditions through column experiments and COMSOL Multiphysics.CMC-nZVI/BC could efficiently remove 85%of Cr(VI)in about 400 hr when the initial Cr(VI)concentration was 40 mg/L and the flow rate was 0.5 mL/min.This study demonstrates that uniformly dispersed CMC-nZVI/BC has an excellent remediation effect on different concentrations of Cr-contaminated soils.
基金supported by the National Natural Science Foundation of China(No.42277063)the Postdoctoral Research Foundation of China(No.2021M702886)+1 种基金the Leading Innovative Talents cultivation Project of Changzhou City(No.CQ20230096)the Research Initiation Project of Changzhou University.
文摘The MXenes,a new class of two-dimensional layered materials,have found extensive applications in water treatment for its excellent thermal stability,electrical conductivity,and excellent adsorption ability.Sulfidized nano zero-valent iron(S-nZVI)is a good reducing agent,however,the practical application of S-nZVI is currently restricted due to the tendency of nano materials to agglomerate.Herein,MXenes use as a support and in situ loading S-nZVI on it to prepare a new material(S-nZVI/Ti_(3)C_(2)T_(x)),and applied it to U(VI)removal in water treatment.The microscopic characterization proves that S-nZVI on Ti_(3)C_(2)T_(x) has good dispersion and effectively alleviates agglomeration.Batch experiments shown that SnZVI/Ti_(3)C_(2)T_(x) has a very good effect on U(VI)removal,and themaximumadsorption capacity reaches 674.4mg/g under the aerobic condition at pH=6.0.The pseudo-second-order kinetic model and the Langmuir isotherm model were found to be more appropriate for describing the adsorption behavior.This indicates that the removal process is a single molecular layer chemisorption.Moreover,the S-nZVI/Ti_(3)C_(2)T_(x) maintained a removal efficiency of over 85%for U(VI)even after being reused five times,demonstrating its excellent reusability.It is worth noting that the material can remove 79.8%of 50 mg/L of U(VI)in simulated seawater,indicating that S-nZVI/Ti_(3)C_(2)T_(x) possessed an excellent uranium extraction performance from seawater.Experimental results and XPS analysis showed that U(VI)was removed by adsorption,reduction and co-precipitation.Moreover,S-nZVI/Ti_(3)C_(2)T_(x) was a lowtoxicitymaterial to Hyriopsis cumingii.Therefore,S-nZVI/Ti_(3)C_(2)T_(x) was expected to be a candidate as adsorbent with great potential in removal of uranium from wastewater and seawater.
基金supported by the National Natural Science Foundation of China(Nos.42277034 and 42207249)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110904)+1 种基金the Guangdong Academy of Sciences(GDAS)Project of Science and Technology Development(No.2022GDASZH-2022010105)the Guangdong Foundation for Program of Science and Technology Research(No.2020B1212060048)。
文摘Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were investigated.The addition of ZVI to the flooding process was more conducive to Cd immobilization.Less potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe minerals.Moreover,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd immobilization.Additionally,the addition of ZVI before flooding played a vital role in Cd retention after soil drainage.In contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil surfaces.The findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.
基金supported by the Fundamental Research Funds for the Central Universities of China(No.B220202066)the Natural Science Foundation of Jiangsu Province(No.BK20200527)the Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse(No.2021EPC05).
文摘Anaerobic digestion has been defined as a competitive approach to facilitate the recycling of corn stalks.However,few studies have focused on the role of direct interspecies electron transfer(DIET)pathway in the acidification stage under the addition of different particle sizes of zero-valent iron(ZVI).In this study,three types of ZVI,namely iron filings,iron powder and nanoscale iron,were investigated,respectively,to enhance its high-value conversion.Variations in volatile fatty acids(VFAs)and methane(CH4)production associated with the underlyingmechanisms were emphatically determined.Results indicated that the addition of ZVI could increase the concentration of VFAs,with the most outstanding performance observed with the use of nanoscale iron.Importantly,the conversion of propionic acid to acetic acid was driven by adding ZVI with no between-group differences in acidizing phase.Conversely,the substrate was more fully utilized when supplied with iron powder compared with other groups in methanogenic phase,thereby displaying the maximumCH4 yield with a value of 263.1 mL/(g total solids(TS)).However,adding nanoscale iron could signally shorten the digestion time(T80),saving 7 days in comparison to the group of iron powder.
基金supported by the National Natural Science Foundation of China (No.52200184)the Fundamental Research Funds for Central Universities (No.12060096014)。
文摘Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications.Herein,this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water.Firstly,Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion.The morphological,structural,and compositional evolution of(modified-)nZVI under different environmental conditions,assisted with microscopic and spectroscopic evidence,is then summarized.Afterwards,common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water.Specifically,stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed,emphasizing their capabilities in studying the dynamic iron corrosion processes.Finally,in the future,more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties.We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.
基金supported by the National Natural Science Foundation of China(21876131)the National Key Research and Development Program of China(2022YFC3702101)the Foundation of State Key Laboratory of Pollution Control and Resource Reuse of China(PCRRY).
文摘Industries such as non-ferrous metal smelting discharge billions of gallons of highly toxic heavy metal wastewater(HMW)worldwide annually,posing a severe challenge to conventional wastewater treatment plants and harming the environment.HMW is traditionally treated via chemical precipitation using lime,caustic,or sulfide,but the effluents do not meet the increasingly stringent discharge standards.This issue has spurred an increase in research and the development of innovative treatment technologies,among which those using nanoparticles receive particular interest.Among such initiatives,treatment using nanoscale zero-valent iron(nZVI)is one of the best developed.While nZVI is already well known for its site-remediation use,this perspective highlights its application in HMW treatment with metal recovery.We demonstrate several advantages of nZVI in this wastewater application,including its multifunctionality in sequestrating a wide array of metal(loid)s(>30 species);its capability to capture and enrich metal(loid)s at low concentrations(with a removal capacity reaching 500 mg·g^(-1)nZVI);and its operational convenience due to its unique hydrodynamics.All these advantages are attributable to nZVI’s diminutive nanoparticle size and/or its unique iron chemistry.We also present the first engineering practice of this application,which has treated millions of cubic meters of HMW and recovered tons of valuable metals(e.g.,Cu and Au).It is concluded that nZVI is a potent reagent for treating HMW and that nZVI technology provides an eco-solution to this toxic waste.
基金supported by the National Natural Science Foundation of China (No.22176067)。
文摘To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes,amino acids were used to modify nanoscale zero-valent iron(AA@Fe^(0)),which were applied in the Fenton-like degradation of organic solvents(tributyl phosphate and n-dodecane,named TBP and DD).Twelve amino acids,i.e.,glycine(Gly),alanine(Ala),leucine(Leu),proline(Pro),phenylalanine(Phe),methionine(Met),cysteine(Cys),asparagine(Asn),serine(Ser),glutamic acid(Glu),lysine(Lys)and arginine(Arg),were selected and calculated by density functional theory(DFT).The optimized structure,charge distribution,the highest occupied molecular orbital(HOMO),the lowest unoccupied molecular orbital(LUMO),interaction region indicator(IRI)isosurface map and adsorption energy of AA@Fe^(0),AA@Fe^(0)-TBP and AA@Fe^(0)-DD were studied,which indicated that Fe is more likely to approach and charge transfer with-COO and-NH_(3) on theα-carbon of amino acids.There is strong attraction between Fe and–COO,and Van der Waals force between Fe and-NH_(3),respectively.In the interaction of AA@Fe^(0)with TBP and DD,Van der Waal force plays an important role.AA@Fe^(0)was synthesized in laboratory and characterized to investigate physicochemical properties.In Fenton-like degradation of organic solvents,the change of COD in water phase during the degradation process as well as the volume of the organic phase after the reaction were investigated.The results of calculations combined with experiments showed that Ser-modified Fe^(0)performed the best in these amino acids,with 98%removal of organic solvents.A possible catalytic mechanism was proposed in which amino acids acted a linking role between Fe and organic solvents,activating H_(2)O_(2)to generate hydroxyl radicals for the degradation of organic solvents.
基金the National Key Research and Development Program of China(No.2019YFC1806203)for financial support。
文摘Sulfidation of zero-valent iron(ZVI)has attracted broad attention in recent years for improving the sequestration of contaminants from water.However,sulfidated ZVI(S-ZVI)is mostly synthesized in the aqueous phase,which usually causes the formation of a thick iron oxide layer on the ZVI surface and hinders the efficient electron transfer to the contaminants.In this study,an alcohothermal strategy was employed for S-ZVI synthesis by the one-step reaction of iron powder with elemental sulfur.It is found that ferrous sulfide(FeS)with high purity and fine crystallization was formed on the ZVI surface,which is extremely favorable for electron transfer.Cr(Ⅵ)removal experiments confirm that the rate constant of SZVI synthesized by the alcohothermal method was 267.1-and 5.4-fold higher than those of un-sulfidated ZVI and aqueous-phase synthesized S-ZVI,respectively.Systematic characterizations proved that Cr(Ⅵ)was reduced and co-precipitated on S-ZVI in the form of a Fe(Ⅲ)/Cr(Ⅲ)/Cr(Ⅵ)composite,suggesting its environmental benignancy.
基金supported by the National High Technology Research and Development Program(863) of China(No.2007AA06A410)the Water Pollution Control and Management Project(No.2008ZX07207-007-05)the National Natural Science Foundation of China(No.40802055)
文摘Nitrobenzene has been considered as a significant groundwater contaminant due to its wide usage in explosives, insecticides, herbicides, pharmaceuticals and dyes. Nitrobenzene is of environmental concern because of its toxicity. In the presence of zero-valent iron （ZVI）, reduction of the nitro group is the dominant transformation process for nitrobenzene. A series of experiments were carried out to investigate the kinetics of nitrobenzene reduction by ZVI and the effects of pH and ZVI particle size on nitrobenzene removal in groundwater. The results indicated that nitrobenzene could be reduced to aniline by ZVI; the reduction of nitrobenzene by ZVI followed a pseudo first-order kinetics; the observed nitrobenzene reduction rate constant （k obs ） was 0.0006 min^-1 and the half-life of nitrobenzene （t 1/2 ） was 115.5 min; the mass balance achieved 87.5% for nitrobenzene reduction by the 1 mm ZVI particle and the final removal efficiency was 80.98%. In addition, the pH and ZVI particle size were found to exhibit significant influences on the nitrobenzene reduction. The observed nitrobenzene reduction rate constant linearly decreased with increase pH and the data fitted on polynomial regression equation for the observed nitrobenzene reduction rate constant and ZVI particle size. Therefore, use of ZVI based permeable reactive barrier technology to remedy nitrobenzene contaminated groundwater was feasible.
基金supported by grants from Tai Shan Scholar Foundation(No.ts 201511003)
文摘In this study, bimetallic nanoscale zero-valent iron particles（nZVI）, including copper/nanoscale zero-valent iron particles（Cu/nZVI） and nickel/nanoscale zero-valent iron particles（Ni/nZVI）, were synthesized by one-step liquid-phase reduction and applied for oxytetracycline（OTC） removal. The effects of contact time and initial p H on the removal efficiency were studied. The as-prepared nanoscale particles were characterized by scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and X-ray diffraction（XRD）. Finally, the degradation mechanisms of OTC utilizing the as-prepared nanoparticles were investigated by using X-ray photoelectron spectroscopy（XPS） and mass spectrometry（MS）. Cu/n ZVI presented remarkable ability for OTC degradation and removed71.44% of OTC（100 mg/L） in 4 hr, while only 62.34% and 31.05% of OTC was degraded by Ni/nZVI and nZVI respectively. XPS and MS analysis suggested that OTC was broken down to form small molecules by ·OH radicals generated from the corrosion of Fe0. Cu/nZVI and Ni/n ZVI have been proved to have potential as materials for application in OTC removal because of their significant degradation ability toward OTC.
基金supported by the National Key Research and Development Program of China(No.2017YFD0801503)the Fundamental Research Funds for the Central Universities(No.PYVZ1703)the Higher Education and High-quality and World-class Universities(PY201606)
文摘Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,Fourier-transform infrared（FTIR） spectroscopy and Brunauer–Emmett–Teller（BET） analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr（Ⅵ） removal performance. The results showed that the Cr（Ⅵ） removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG（10.00%） and ZⅥ（29.80%）. Furthermore, the removal rate of Cr（Ⅵ） by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr（Ⅵ） removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr（Ⅵ） via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy（XPS） was used to analyze the mechanisms of Cr（Ⅵ） removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr（Ⅵ） was immobilized via the formation of Cr（III） hydroxide and Cr（III）–Fe（III）hydroxide/oxyhydroxide on the surface of EG-ZⅥ.
基金financially supported by the National Natural Science Foundation of China (No.51408101)the Key Research and Development (R&D) Program from the Department of Science and Technology of Sichuan Province (No.2018FZ0011).
文摘Sulfide-modified nanoscale zero-valent iron(S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles(NPs) easily agglomerate and have poor contact with organic contaminants.Herein, we propose a new S-nZVI/graphene aerogel(S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene(TCE) from water.Three-dimensional porous graphene aerogel(GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs.The TCE removal rates of Fe S, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2 hr, respectively.Furthermore, TCE was completely removed within 50 min by S-nZVI/GA.The TCE removal rate increased with increasing p H and temperature, and TCE removal followed the pseudo-first-order kinetic model.The results demonstrate the great potential of S-nZVI/GA composite as a low-cost,easily separated and superior monolithic adsorbent for removal of organic pollutants.
基金support provided by the National Key Technology R&D Program(no.2012BAJ21B04)the financial support from the China Scholarship Council(CSC)for one year as a visiting scholar at Stevens Institute of Technology
文摘In this study, a novel nanoscale zero-valent iron（n ZVI） composite material was successfully synthesized using a low-cost natural clay, ＂Hangjin 2~#clay＂（HJ clay） as the support and tested for the decolorization of the azo dye Methyl Orange（MO） in aqueous solution by n ZVI particles. According to the characterization and MO decolorization experiments, the sample with 5：1 HJ clay-supported n ZVI（HJ/n ZVI） mass ratio（HJ-n ZVI5） showed the best dispersion and reactivity and the highest MO decolorization efficiency. With the same equivalent Fe0 dosage, the HJ-n ZVI1 and HJ-n ZVI5 samples demonstrated a synergetic effect for the decolorization of MO： their decolorization efficiencies were much higher than that achieved by physical mixing of HJ clay and n ZVIs, or the sum of HJ clay and n ZVIs alone. The synergetic effect was primarily due to the improved dispersion and more effective utilization of the n ZVI particles on/in the composite materials. Higher decolorization efficiency of MO was obtained at larger HJ-n ZVI dosage, higher temperature and under N2 atmosphere, while the MO initial concentration and p H were negatively correlated to the efficiency. HJ clay not only works as a carrier for n ZVI nanoparticles, but also contributes to the decolorization through an ＂adsorption-enhanced reduction＂ mechanism. The high efficiency of HJ-n ZVI for decontamination gives it great potential for use in a variety of remediation applications.
基金the National Key Research and Development Program of China(No.2017YFD0801003)。
文摘Zero-valent iron amended biochar(ZVIB)has been proposed as a promising material in immobilizing heavy metals in paddy fields.In this study,the impacts of p H of ZVIB(p H 6.3 and p H 9.7)and watering management techniques(watering amount in the order of CON(control,5/72)>3/72>1-3/72>3/100>1/72,with 5/72,for example,representing irrigation given to 5 cm above soil surface in 72 hr regular interval)on As and Cd bioavailability for rice and its grain yield(Yield BR)were investigated in a pot experiment.Brown rice As(As BR)content was irrelative to the watering treatments,while significantly decreased(>50%)with the addition of both ZVIB materials.The diminutions of brown rice Cd(Cd BR)content as well as the Yield BR were highly dependent on both the soil amendment materials’p H and watering amount.Among all the watering treatments,3/72 treatment(15%less irrigation water than the CON)with ZVIB 6.3 amendment was the optimum fit for simultaneous reduction of As BR(50%)and Cd BR contents(19%)as well as for significant increment(12%)of the Yield BR.Although high pH(9.7)ZVIB application could also efficiently decrease As and Cd contents in brown rice,it might risk grain yield lost if appropriate(e.g.3/72 in our study)watering management technique was not chosen.Therefore,ZVIB would be an environmentally friendly option as an amendment material with proper selection of watering management technique to utilize As and Cd co-contaminated arable soils safely for paddy cultivation.
基金the financial support from the Ministry of Science and Technology of China(No. 2011CB606301)the National Natural Science Foundation of China (No. 50825402,51101156)
文摘Some problems including low treatment capacity,agglomeration and clogging phenomena,and short working life,limit the application of pre-treatment methods involving zero-valent iron （ZVI）.In this article,ZVI was frozen in an amorphous state through a melt-spinning technique,and the decolorization effect of amorphous ZVI on Acid Orange II solution was investigated under varied conditions of experimental variables such as reaction temperature,ribbon dosage,and initial pH.Batch experiments suggested that the decolorization rate was enhanced with the increase of reaction temperature and ribbon dosage,but decreased with increasing initial solution pH.Kinetic analyses indicated that the decolorization process followed a first order exponential kinetic model,and the surface-normalized decolorization rate could reach 2.09 L/（m^2 ·min） at room temperature,which was about ten times larger than any previously reported under similar conditions.Recycling experiments also proved that the ribbons could be reused at least four times without obvious decay of decolorization rate and efficiency.This study suggests a tremendous application potential for amorphous ZVI in remediation of groundwater or wastewater contaminated with azo dyes.
