Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(F...Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(FNP)were investigated on the fresh leachate AD process.Firstly,a simple hydrothermal method was used to prepare FNP,then introduced into the UASB reactor to evaluate its AD efficiency.Results showed that the inclusion of FNP could shorten the lag phase by 10 days compared to the control group.Furthermore,cumulative methane production in the FNP group was enhanced by 20.11%.Mechanistic studies suggested that hydrogenotrophic methanogenesis in the FNP group was more pronounced due to the influence of key enzymes(i.e.,dehydrogenase and coenzyme F420).Microbial community analysis demonstrated that FNP could enhance the abundance of Methanosarcina,Proteobacteria,Sytrophomonas,and Limnobacter,which might elevate enzyme activity involved in methane production.These findings suggest that FNP might mediate interspecies electron transfer among these microorganisms,which is essential for efficient leachate treatment.展开更多
To reveal the relative contribution of the components, Fe, Mn oxides or organic materials（OMs） in the surficial sediments（SSs）, and the natural surface coating samples（NSCSs） to adsorbing atrazine（AT）, a selec...To reveal the relative contribution of the components, Fe, Mn oxides or organic materials（OMs） in the surficial sediments（SSs）, and the natural surface coating samples（NSCSs） to adsorbing atrazine（AT）, a selective chemical extraction technique was employed, to remove the different components, and the adsorption characteristics of AT on the SSs and the NSCSs were investigated. The observed adsorptions of AT on the original and extracted SSs and NSCSs were analyzed by nonlinear least squares fitting（NLSF） to estimate the relative contribution of the components. The results showed that the maximum adsorption of AT on the NSCSs was greater than that in the SSs, before and after extraction treatments, implying that the NSCSs were more dominant than the SSs for organic pollutant adsorption. It was also found that the Fe oxides, OMs, and residues in SSs（NSCSs） facilitated the adsorption of AT, but Mn oxides directly or indirectly restrained the interaction of AT with SSs（NSCSs） particles. The contribution of the Fe oxides to AT adsorption was more than that of OMs; the greatest contribution to AT adsorption on a molar basis was from the Fe oxides in the nonresidual fractions, indicating that the Fe oxides played an important role in controlling the environmental behavior of AT in an aquatic environment.展开更多
Artificial neural network（ANN） and full factorial design assisted atrazine（AT） multiple regression adsorption model（AT-MRAM） were developed to analyze the adsorption capability of the main components in the surf...Artificial neural network（ANN） and full factorial design assisted atrazine（AT） multiple regression adsorption model（AT-MRAM） were developed to analyze the adsorption capability of the main components in the surficial sediments（SSs）. Artificial neural network was used to build a model（the determination coefficient square r2 is 0.9977） to describe the process of atrazine adsorption onto SSs, and then to predict responses of the full factorial design. Based on the results of the full factorial design, the interactions of the main components in SSs on AT adsorption were investigated through the analysis of variance（ANOVA）, F-test and t-test. The adsorption capability of the main components in SSs for AT was calculated via a multiple regression adsorption model（MRAM）. The results show that the greatest contribution to the adsorption of AT on a molar basis was attributed to Fe/Mn（–1.993 μmol/mol）. Organic materials（OMs） and Fe oxides in SSs are the important adsorption sites for AT, and the adsorption capabilities are 1.944 and 0.418 μmol/mol, respectively. The interaction among the non-residual components（Fe, Mn oxides and OMs） in SSs interferes in the adsorption of AT that shouldn’t be neglected, revealing the significant contribution of the interaction among non-residual components to controlling the behavior of AT in aquatic environments.展开更多
Due to its high efficiency,Fe(Ⅱ)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants.A lot of chemical Fe sludge alongwith various refractory polluta...Due to its high efficiency,Fe(Ⅱ)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants.A lot of chemical Fe sludge alongwith various refractory pollutantswas concomitantly produced,whichmay cause secondary environmental problemswithout proper disposal.We here innovatively proposed an effective method of achieving zero Fe sludge,reusing Fe resources(Fe recovery=100%)and advancing organics removal(final TOC removal>70%)simultaneously,based on the in situ formation of magnetic Ca-Fe layered double hydroxide(Fe_(3)O_(4)@CaFe-LDH)nano-material.Cations(Ca^(2+)and Fe^(3+))concentration(≥30 mmol/L)and their molar ratio(Ca:Fe≥1.75)were crucial to the success of the method.Extrinsic nano Fe_(3)O_(4)was designed to be involved in the Fe(Ⅱ)-catalytic wastewater treatment process,and was modified by oxidation intermediates/products(especially those with COO-structure),which promoted the co-precipitation of Ca^(2+)(originated from Ca(OH)_(2)added after oxidation process)and byproduced Fe^(3+)cations on its surface to in situ generate core-shell Fe_(3)O_(4)@CaFe-LDH.The oxidation products were further removed during Fe_(3)O_(4)@CaFe-LDH material formation via intercalation and adsorption.Thismethodwas applicable to many kinds of organicwastewater,such as bisphenol A,methyl orange,humics,and biogas slurry.The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs.This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(Ⅱ)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials.展开更多
Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect ...Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect of ionic strength （0-1 000 mmol kg-1） adjusted by NaCl or CaCl2 on adsorption of Bt toxin by a lateritic red soil, a paddy soil and these soils after chemical removal of organic-bound or free Fe and Al oxides, as well as by pure minerals （goethite, hematite and gibbsite） which are widespread in these soils, were studied. The results indicated that when the supporting electrolyte was NaCl, the adsorption of Bt toxin by the lateritic red soil and paddy soil increased rapidly until the ionic strength reached 250 mmol kg-1 and then gradually slowed down with the increase of ionic strength; while in ease the supporting electrolyte was CaCl2, the adsorption of Bt toxin enhanced significantly at low ionic strength （〈 10 mmol kg-1） and then decreased as the ionic strength increased. The adsorption of Bt toxin by the tested minerals and soils after the removal of organic-bound or free Fe and Al oxides also increased with increasing ionic strength controlled by NaCl. Removing organic-bound Fe and Al oxides obviously increased the adsorption of Bt toxin in the tested soils. Differently, removing free Fe and Al oxides increased the Bt adsorption by the paddy soil, but decreased the adsorption by the lateritic red soil. The study indicated that the varieties of ionic strength and the presence of Ve and Al oxides affected the adsorption of Bt toxin by the soils, which would contribute to the further understanding of the fate of Bt toxin in the soil environment and provide references for the ecological risk assessment of transgenic Bt plants.展开更多
Antimony（Sb）, which can be toxic at relatively low concentrations, may co-exist with Mn（Ⅱ）and/or Fe（Ⅱ） in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption ...Antimony（Sb）, which can be toxic at relatively low concentrations, may co-exist with Mn（Ⅱ）and/or Fe（Ⅱ） in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption pathways of Sb（Ⅲ and V） species in the presence of Mn（Ⅱ） and Mn-oxidizing bacteria, with or without Fe（Ⅱ）. Batch experiments were conducted to determine the oxidation and adsorption characteristics of Sb species in the presence of biogenic Mn oxides（BMOs）, which were formed in-situ via the oxidation of Mn（Ⅱ） by a Mn-oxidizing bacterium（Pseudomonas sp. QJX-1）. Results indicated that Sb（Ⅲ） ions could be oxidized to Sb（V） ions by BMO, but only Sb（V） originating from Sb（Ⅲ） oxidation was adsorbed effectively by BMO. Introduced Fe（Ⅱ） was chemically oxidized to Fe OOH, the precipitates of which mixed with BMO to form a new compound, biogenic Fe–Mn oxides（BFMO）. The BMO part of the BFMO mainly oxidized and the Fe OOH of the BFMO mainly adsorbed the Sb species. In aquatic solutions containing both As（Ⅲ） and Sb（Ⅲ）, the BFMO that formed in-situ preferentially oxidized Sb over As but adsorbed As more efficiently. Chemical analysis and reverse transcription real-time polymerase chain reaction revealed that the presence of Fe（Ⅱ）, As（Ⅲ） and Sb（Ⅲ） accelerated the oxidation of Mn（Ⅱ） but inhibited the activity of Mn-oxidizing bacteria. These results provide significant insights into the biogeochemical pathways of Sb, Mn（Ⅱ） in aquatic ecosystems, with or without Fe（Ⅱ）.展开更多
A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron micro...A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron microscope（TEM）, and H2-temperature-programmed reduction（H2-TPR） techniques. The gas–solid reactions between these oxides and methane for syngas generation as well as the catalytic performance for selective oxidation of carbon deposition in O2-enriched atmosphere were investigated in detail. The results show that the samples with the presence of Fe2O3show much higher activity for methane oxidation compared with the Ce0.7Zr0.3O2solid solution,while the CeO2-contained samples represent higher CO selectively in methane oxidation than the Fe2O3/Al2O3sample. This suggests that the iron species should be the active sites for methane activation, and the cerium oxides provide the oxygen source for the selective oxidation of the activated methane to syngas during the reaction between methane and Fe2O3/Ce0.7Zr0.3O2. For the oxidation process of the carbon deposition, the CeO2-containing samples show much higher CO selectivity than the Fe2O3/Al2O3sample, which indicates that the cerium species should play a very important role in catalyzing the carbon selective oxidation to CO. The presence of the Ce–Zr–O solid solution could induce the growth direction of the carbonfilament, resulting in a loose contact between the carbon filament and the catalyst. This results in abundant exposed active sites for catalyzing carbon oxidation, strongly improving the oxidation rate of the carbon deposition over this sample. In addition, the Fe2O3/Ce0.7Zr0.3O2also represents much higher selectivity（ca. 97 %） for the conversion of carbon to CO than the Fe2O3/CeO2sample, which can be attributed to the higher concentration of reduced cerium sites on this sample. The increase of the Zr content in the Fe2O3/Ce1-xZrxO2samples could improve the reactivity of the materials for methane oxidation, but it also reduces the selectivity for CO formation.展开更多
Bimetallic oxides composites have received an increasing attention as promising adsorbents for aqueous phosphate (P) removal in recent years. In this study, a novel magnetic composite MZLCO was prepared by hybridizing...Bimetallic oxides composites have received an increasing attention as promising adsorbents for aqueous phosphate (P) removal in recent years. In this study, a novel magnetic composite MZLCO was prepared by hybridizing amorphous Zr-La (carbonate) oxides (ZLCO) with nano-FeOthrough a one-pot solvothermal method for efficient phosphate adsorption. Our optimum sample of MZLCO-45 exhibited a high Langmuir maximum adsorption capacity of 96.16 mg P/g and performed well even at low phosphate concentration. The phosphate adsorption kinetics by MZLCO-45 fitted well with the pseudo-second-order model, and the adsorption capacity could reach 79% of the ultimate value within the first 60 min. The phosphate adsorption process was highly p H-dependent, and MZLCO-45 performed well over a wide p H range of 2.0-8.0. Moreover, MZLCO-45 showed a strong selectivity to phosphate in the presence of competing ions (Cl^(-), NO_(3)^(-), SO_(4)^(2-), HCO_(3)^(-), Ca^(2+), and Mg^(2+)) and a good reusability using the eluent of Na OH/Na Cl mixture, then 64% adsorption capacity remained after ten recycles. The initial 2.0 mg P/L in municipal wastewater and surface water could be efficiently reduced to below 0.1mg P/L by 0.07 g/L MZLCO-45, and the phosphate removal efficiencies were 95.7% and 96.21%, respectively. Phosphate adsorption mechanisms by MZLCO-45 could be attributed to electrostatic attraction and the inner-sphere complexation via ligand exchange forming Zr/La-O-P, -OH and CO_(3)^(2-)groups on MZLCO-45 surface played important roles in the ligand exchange process. The existence of oxygen vacancies could accelerate the phosphate absorption rate of the MZLCO-45 composites.展开更多
Iron(Fe)minerals are commonly used to remove phosphorus(P)from waste streams,producing P-loaded Fe(Ⅲ)oxides or Fe(Ⅱ)phosphate minerals(e.g.,vivianite).These minerals may be used as fertilizers to enhance P circulari...Iron(Fe)minerals are commonly used to remove phosphorus(P)from waste streams,producing P-loaded Fe(Ⅲ)oxides or Fe(Ⅱ)phosphate minerals(e.g.,vivianite).These minerals may be used as fertilizers to enhance P circularity if solubilized in soil.Here,we tested the P fertilizer value of recycled Fe phosphates(FePs)in a pot trial and in an incubation experiment,hypothesizing that P release from FePs is possible under Fe(Ⅲ)-reducing conditions.First,a pot trial was set up with rice(Oryza sativa)in all combinations of soil flooding or not,three P-deficient soils(acid,neutral,and calcareous),and six FePs(three Fe(Ⅲ)Ps and three Fe(Ⅱ)Ps)referenced to triple superphosphate(TSP)or zero amendments.Shoot P uptake responded to TSP application in all treatments but only marginally to FePs.The redox potential did not decrease to-200 mV by flooding for a brief period(13 d)during the pot trial.A longer incubation experiment(60 d)was performed,including a treatment of glutamate addition to stimulate reductive conditions,and P availability was assessed with CaCl_(2)extraction of soils.Glutamate addition and/or longer incubation lowered soil redox potential to<-100 mV.On the longer term,Fe(Ⅲ)minerals released P,and adequate P was reached in the calcareous soil and in the neutral soil amended with Fe(Ⅲ)P-sludge.It can be concluded that prolonged soil flooding and organic matter addition can enhance the P fertilizer efficiency of FePs.Additionally,application of FeP in powder form may enhance P availability.展开更多
The adsorption of phosphate onto ferrihydrite(FH) and two FH-humic acid(HA) complexes, obtained by co-precipitating FH with low(FH-HA1) and relatively high amounts of humic acid(FH-HA2), was studied through kinetics a...The adsorption of phosphate onto ferrihydrite(FH) and two FH-humic acid(HA) complexes, obtained by co-precipitating FH with low(FH-HA1) and relatively high amounts of humic acid(FH-HA2), was studied through kinetics and isotherm experiments to determine the differences in phosphate adsorption between FH-HA complexes and FH and to reveal the mechanisms of phosphate adsorption onto two soil compositions. The isoelectric point(IEP) and the specific surface area(SSA) of the mineral decreased as the particle porosity of the mineral increased, which corresponded to an increase in the amount of organic carbon. The adsorption capacity of phosphate was higher on FH than on FH-HA1 and FH-HA2 at the scale of micromoles per kilogram. The initial adsorption rate and adsorption affinity of phosphate decreased with an increase in the amount of HA in the mineral. The sensitivity of phosphate adsorption to the change in the pH was greater for FH than for FH-HA complexes. Ionic strength did not affect the adsorption of phosphate onto FH and FH-HA1 at a lower p H, and the increase in the ionic strength promoted phosphate adsorption at a higher p H.However, for the FH-HA2 complex, the increase in the ionic strength inhibited the adsorption of phosphate onto FH-HA2 at a lower p H and increased the adsorption at a higher pH.展开更多
The types, contents and morphologies of crystalline Fe oxides and their relations to phosphate adsorptionon the clay fractions in soils with variable charge in southern China were investigated by means of XRD, TEM,EMA...The types, contents and morphologies of crystalline Fe oxides and their relations to phosphate adsorptionon the clay fractions in soils with variable charge in southern China were investigated by means of XRD, TEM,EMA and chemical analysis methods.Results indicated that the types and contents of crystalline Fe oxidesvaried with the soils examined. The dominant crystalline Fe oxide was hematite in the latosols and goethitesin the red soils.In yellow-brown soils, the only crystalline Fe oxide was goethite.The difference between Aldand Alo came mainly from the Al substituting for Fe in the pe oxides. The crystal morphology of goethiteappeared mainly as subrounded flat or iso-dimensional rather than acicular particles. Hematites occurredin plates of various thickness. Their MCDa/MCDc ratios in the latosols and red soils were generally above1.5 and below 1.5, respectively. The MCD values of goethites and hematites were 15-25nm and 20-35nm,and their specific surface areas were 80-120m￣2/g and 35-75m￣2/g, respectively.The goethite crystals weregenerally smaller. Variations of the total amounts of crystalline Fe oxi es in clay fractions were not related tophosphate adsorption. The types, contents and morphologies of crystalline Fe oxides in the soils remarkablyaffected phosphate adsorption characteristics of the soils. The phosphate adsorption of goethite was muchgreater than that of hematite. The higher the MCD /MCDc rotio of hematite, the lower the phosphateadsorption.展开更多
Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We h...Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We hypothesized that Fe(oxyhydr)oxide(FeOOH)minerals precipitated in situ from indigenous Fe in groundwater may immobilize As,providing a solution for safely using As-contaminated groundwater in irrigation.To confirm this hypothesis and identify the controlling mechanisms,we comprehensively evaluated the transport,speciation changes,and immobilization of As and Fe in agricultural canals irrigated using As-contaminated groundwater.The efficiently removed As and Fe in the canals accumulated in shallow sediment rather than subsurface sediment.Linear combination fitting(LCF)analysis of X-ray absorption near edge spectroscopy(XANES)indicated that As(Ⅴ)was the dominant As species,followed by As(Ⅲ),and therewas no FeAsO_(4) precipitate.Sequential extraction revealed higher contents of amorphous FeOOH and associated As in shallower sediment than in the subsurface layer.Stoichiometric molar ratio calculations,SEM-EDS,FTIR,and fluorescence spectroscopy collectively demonstrated that the microbial reductive dissolution of amorphous FeOOH proceeded via reactive dissolved organic matter(DOM)consumption in subsurface anoxic porewater environment facilitating high labile As,whereas in surface sediment,the in situ-generated amorphous FeOOH was stable and strongly inhibited As release via adsorption.In summary,groundwater Fe^(2+)can efficiently precipitate in benthic surface sediment as abundant amorphous FeOOH,which immobilizes most of the dissolved As,protecting agricultural soil from contamination.This field research supports the critical roles of the phase and reactivity of in situ-generated FeOOH in As immobilization and provides new insight into the sustainable use of contaminated water.展开更多
As the fundamental unit of soil,aggregates exhibit significant variations in their abilities to adsorb and desorb trace elements,depending on their size.Batch experiments were conducted to investigate the characterist...As the fundamental unit of soil,aggregates exhibit significant variations in their abilities to adsorb and desorb trace elements,depending on their size.Batch experiments were conducted to investigate the characteristics of adsorption and desorption of cadmium(Cd),copper(Cu),and lead(Pb)on and from soil aggregate fractions from three layers of a calcareous soil profile in Changxing County,Zhejiang Prvince,China.The results showed that both Langmuir and Freundlich models successfully described the isothermal adsorption processes of single Cd,Cu,and Pb on different soil aggregates.Additionally,aggregates from the bottom soil layer showed the highest maximum adsorption capacity and required the lowest energy for Cd,Cu,and Pb adsorption compared to aggregates from upper soil layers.The physicochemical properties of soil aggregates were found to govern the adsorption and desorption processes of heavy metals rather than the aggregate size,wherein the contents of iron/aluminum oxides and organic matter were the most crucial influencing factors.Cadmium displayed higher mobility than Cu and Pb in different soil aggregates,and the maximum adsorption capacities of the metal ions followed the order of Pb>Cu>Cd,while their desorption rates followed the order of Cd>Cu>Pb.Additionally,the<0.053 mm microaggregates presented the lowest desorption rates for Cd,Cu,and Pb compared to other soil aggregate fractions in each soil layer.Furthermore,the orthogonal experiment results demonstrated that the competitive adsorption between metals occurred on soil aggregates in the ternary heavy metal system,but only the desorption of Pb was significantly affected by the coexistence of Cd and Cu.展开更多
The binding of metallic contaminants （Pb, Cd, and Zn） and As on soil constituents was studied on four highly contaxninated alluvial soil profiles from the mining/smelting district of Pribram （Czech Republic） using...The binding of metallic contaminants （Pb, Cd, and Zn） and As on soil constituents was studied on four highly contaxninated alluvial soil profiles from the mining/smelting district of Pribram （Czech Republic） using a combination of mineralogical and chemical methods. Sequential extraction analysis （SEA） was supplemented by mineralogical investigation of both bulk samples and heavy mineral fractions using X-ray diffraction analysis （XRD） and scanning electron microscopy with an energy dispersive X-ray spectrometer （SEM/EDS）. The mineralogy of Fe and Mn oxides was studied by voltammetry of microparticles （VMP） and diffuse reflectance spectrometry （DRS）. Zinc and Pb were predominantly bound in the reducible fraction attributed to Fe oxides and Mn oxides （mainly birnessite, Na4Mn14O27.9H2O）, which were detected in soils by XRD and SEM/EDS. In contrast, Cd was the most mobile contaminant and was predominantly present in the exchangeable fraction. Arsenic was bound to the residual and reducible fractions （corresponding to Fe oxides or to unidentified Fe-Pb arsenates）. SEM/EDS observations indicate the predominant affinity of Pb for Mn oxides, and to a lesser extent, for Fe oxides. Thus, a more suitable SEA procedure should be used for these mining-affected soils to distinguish between the contaminant fraction bound to Mn oxides and Fe oxides.展开更多
A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge...A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge disintegration can destroy the sludge structure and cell wall, so as change the sludge floc structure and moisture distribution, thus affecting the dewatering performance of sludge. In this article, the disintegration methods were ultrasound treatment, K2 Fe O4oxidation and KMn O4 oxidation. The degree of disintegration（DDCOD）, sludge moisture distribution and the final water content of sludge cake after centrifuging were measured. Results showed that three disintegration methods were all effective, and K2 Fe O4oxidation was more efficient than KMn O4 oxidation. The content of free water increased obviously with K2 Fe O4and KMn O4 oxidations, while it decreased with ultrasound treatment. The changes of free water and interstitial water were in the opposite trend. The content of bounding water decreased with K2 Fe O4oxidation, and increased slightly with KMn O4 oxidation, while it increased obviously with ultrasound treatment. The water content of sludge cake after centrifuging decreased with K2 Fe O4oxidation, and did not changed with KMn O4 oxidation, but increased obviously with ultrasound treatment. In summary, ultrasound treatment deteriorated the sludge dewaterability, while K2 Fe O4and KMn O4 oxidation improved the sludge dewaterability.展开更多
A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO)sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As)and cadmium (Cd) in water.The maximum As(Ⅲ)...A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO)sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As)and cadmium (Cd) in water.The maximum As(Ⅲ) and Cd(Ⅱ) adsorption capacities of 1%CaSFMBO were 156.25 mg/g and 107.53 mg/g respectively in single-adsorption systems.The adsorption of As and Cd by the Ca-SFMBO sorbent was pH-dependent at values from 1 to 7,with an optimal adsorption pH of 6.In the dual-adsorbate system,the presence of Cd(Ⅱ) at low concentrations enhanced As(Ⅲ) adsorption by 33.3%,while the adsorption of As(Ⅲ) was inhibited with the increase of Cd(Ⅱ) concentration.Moreover,the addition of As(Ⅲ) increased the adsorption capacity for Cd(Ⅱ) up to two-fold.Through analysis by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR),it was inferred that the mechanism for the co-adsorption of Cd(Ⅱ) and As(Ⅲ) included both competitive and synergistic effects,which resulted from the formation of ternary complexes.The results indicate that the Ca-SFMBO material developed here could be used for the simultaneous removal of As(Ⅲ) and Cd(Ⅱ) from contaminated water.展开更多
Addition of clay-rich subsoil to sandy soil results in heterogeneous soil with clay peds （2-mm） or finely ground （〈 2 mm） clay soil （FG）, which may affect the nutrient availability. The aim of this study was to...Addition of clay-rich subsoil to sandy soil results in heterogeneous soil with clay peds （2-mm） or finely ground （〈 2 mm） clay soil （FG）, which may affect the nutrient availability. The aim of this study was to assess the effect of clay soil particle size （FG or peds） and properties on nutrient availability and organic C binding in sandy soil after addition of residues with low （young kikuyu grass, KG） or high （faba bean, FB） C/N ratio. Two clay soils with high and low smectite percentage, clay and exchangeable Fe and A1 were added to a sandy soil at a rate of 20% （weight/weight） either as FG or peds. Over 45 d, available N and P as well as microbial biomass N and P concentrations and cumulative respiration were greater in soils with residues of KG than FB. For soils with KG residues, clay addition increased available N and initial microbial biomass C and N concentrations, but decreased cumulative respiration and P availability compared to sandy soil without clay. Differences in measured parameters between clay type and size were inconsistent and varied with time except the increase in total organic C in the 〈 53 μm fraction during the experiment, which was greater for soils with FG than with peds. We concluded that the high exchangeable Fe and A1 concentrations in the low-smectite clay soil can compensate a lower clay concentration and proportion of smectite with respect to binding of organic matter and nutrients.展开更多
Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The e...Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The experimental results demonstrated that Fe?Mn binary oxide(FMBO)was the most suitable adsorbent for the separation.Under a wide pH(6.9?11.3)region,more than80%W removal efficiency and less than3%Mo loss could be obtained.In addition,the Fe?Mn binary oxide adsorbent can be regenerated by treating with3mol/L NaOH,and the W adsorption efficiency was retained after five adsorption?desorption?regeneration cycles.All these indicate that the Fe?Mn binary oxides have the potential for the separation of W from molybdate solution.展开更多
An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the mag...An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the magnetism, conductivity and biocompatibility of the Fe3O4-RGO nanosheets, the nanocomposites could be facilely adhered to the electrode surface by magnetically controllable assembling and beneficial to achieve the direct redox reactions and electrocatalytic behaviors of GOx immobilized into the nanocomposites. The biosensor exhibited good electrocatalytic activity, high sensitivity and stability. The current response is linear over glucose concentration ranging from 0.05 to 1.5 m M with a low detection limit of0.15 μM. Meanwhile, validation of the applicability of the biosensor was carried out by determining glucose in serum samples. The proposed protocol is simple, inexpensive and convenient, which shows great potential in biosensing application.展开更多
A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polyprop...A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polypropylene separator(Celgard 2400)close to the sulfur cathode.The special nanotubes are in-situ catalyzed by Fe3C nanoparticles.They could entrap lithium polysulfides(Li PSs)to restrain the shuttle effect and reduce the loss of active material.The battery with the modified separator and sulfur cathode shows an excellent cycle performance.It has a high rate performance,580.5 mAh/g at the high current rate of 4 C relative to 1075 mAh/g at 0.1 C.It also has an initial discharge capacity of 774.8 m Ah/g measured at 0.5 C and remains 721.8 mAh/g after 100 cycles with a high capacity retention of 93.2%.The outstanding performances are notable in recently reports with modified separator.展开更多
基金supported by the National Key Research and Development Program of China(No.2019YFC0408500)the Scientific Research Project of China State Construction Engineering Corporation Limited(CSCEC-2022-K-(36))the Scientific Research Project of CSCEC AECOM Consultants Corporation Limited(XBSZKY2216).
文摘Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(FNP)were investigated on the fresh leachate AD process.Firstly,a simple hydrothermal method was used to prepare FNP,then introduced into the UASB reactor to evaluate its AD efficiency.Results showed that the inclusion of FNP could shorten the lag phase by 10 days compared to the control group.Furthermore,cumulative methane production in the FNP group was enhanced by 20.11%.Mechanistic studies suggested that hydrogenotrophic methanogenesis in the FNP group was more pronounced due to the influence of key enzymes(i.e.,dehydrogenase and coenzyme F420).Microbial community analysis demonstrated that FNP could enhance the abundance of Methanosarcina,Proteobacteria,Sytrophomonas,and Limnobacter,which might elevate enzyme activity involved in methane production.These findings suggest that FNP might mediate interspecies electron transfer among these microorganisms,which is essential for efficient leachate treatment.
基金Supported by the National Natural Science Foundation of China(No.50879025)the Scientific Start-up Fund from North China Electric Power University, China(No.X60218)the National Basic Research Program of China(No.2004CB3418501).
文摘To reveal the relative contribution of the components, Fe, Mn oxides or organic materials（OMs） in the surficial sediments（SSs）, and the natural surface coating samples（NSCSs） to adsorbing atrazine（AT）, a selective chemical extraction technique was employed, to remove the different components, and the adsorption characteristics of AT on the SSs and the NSCSs were investigated. The observed adsorptions of AT on the original and extracted SSs and NSCSs were analyzed by nonlinear least squares fitting（NLSF） to estimate the relative contribution of the components. The results showed that the maximum adsorption of AT on the NSCSs was greater than that in the SSs, before and after extraction treatments, implying that the NSCSs were more dominant than the SSs for organic pollutant adsorption. It was also found that the Fe oxides, OMs, and residues in SSs（NSCSs） facilitated the adsorption of AT, but Mn oxides directly or indirectly restrained the interaction of AT with SSs（NSCSs） particles. The contribution of the Fe oxides to AT adsorption was more than that of OMs; the greatest contribution to AT adsorption on a molar basis was from the Fe oxides in the nonresidual fractions, indicating that the Fe oxides played an important role in controlling the environmental behavior of AT in an aquatic environment.
基金Supported by the National Natural Science Foundation of China(No.50879025)
文摘Artificial neural network（ANN） and full factorial design assisted atrazine（AT） multiple regression adsorption model（AT-MRAM） were developed to analyze the adsorption capability of the main components in the surficial sediments（SSs）. Artificial neural network was used to build a model（the determination coefficient square r2 is 0.9977） to describe the process of atrazine adsorption onto SSs, and then to predict responses of the full factorial design. Based on the results of the full factorial design, the interactions of the main components in SSs on AT adsorption were investigated through the analysis of variance（ANOVA）, F-test and t-test. The adsorption capability of the main components in SSs for AT was calculated via a multiple regression adsorption model（MRAM）. The results show that the greatest contribution to the adsorption of AT on a molar basis was attributed to Fe/Mn（–1.993 μmol/mol）. Organic materials（OMs） and Fe oxides in SSs are the important adsorption sites for AT, and the adsorption capabilities are 1.944 and 0.418 μmol/mol, respectively. The interaction among the non-residual components（Fe, Mn oxides and OMs） in SSs interferes in the adsorption of AT that shouldn’t be neglected, revealing the significant contribution of the interaction among non-residual components to controlling the behavior of AT in aquatic environments.
基金supported by the Chinese Agriculture Research System(No.CARS-35-06B)111 Project(No.B17030)the Sichuan Science and Technology Program(No.2021ZDZX0012).
文摘Due to its high efficiency,Fe(Ⅱ)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants.A lot of chemical Fe sludge alongwith various refractory pollutantswas concomitantly produced,whichmay cause secondary environmental problemswithout proper disposal.We here innovatively proposed an effective method of achieving zero Fe sludge,reusing Fe resources(Fe recovery=100%)and advancing organics removal(final TOC removal>70%)simultaneously,based on the in situ formation of magnetic Ca-Fe layered double hydroxide(Fe_(3)O_(4)@CaFe-LDH)nano-material.Cations(Ca^(2+)and Fe^(3+))concentration(≥30 mmol/L)and their molar ratio(Ca:Fe≥1.75)were crucial to the success of the method.Extrinsic nano Fe_(3)O_(4)was designed to be involved in the Fe(Ⅱ)-catalytic wastewater treatment process,and was modified by oxidation intermediates/products(especially those with COO-structure),which promoted the co-precipitation of Ca^(2+)(originated from Ca(OH)_(2)added after oxidation process)and byproduced Fe^(3+)cations on its surface to in situ generate core-shell Fe_(3)O_(4)@CaFe-LDH.The oxidation products were further removed during Fe_(3)O_(4)@CaFe-LDH material formation via intercalation and adsorption.Thismethodwas applicable to many kinds of organicwastewater,such as bisphenol A,methyl orange,humics,and biogas slurry.The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs.This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(Ⅱ)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials.
基金Supported by the National Natural Science Foundation of China (Nos. 41001140 and 40671087)
文摘Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect of ionic strength （0-1 000 mmol kg-1） adjusted by NaCl or CaCl2 on adsorption of Bt toxin by a lateritic red soil, a paddy soil and these soils after chemical removal of organic-bound or free Fe and Al oxides, as well as by pure minerals （goethite, hematite and gibbsite） which are widespread in these soils, were studied. The results indicated that when the supporting electrolyte was NaCl, the adsorption of Bt toxin by the lateritic red soil and paddy soil increased rapidly until the ionic strength reached 250 mmol kg-1 and then gradually slowed down with the increase of ionic strength; while in ease the supporting electrolyte was CaCl2, the adsorption of Bt toxin enhanced significantly at low ionic strength （〈 10 mmol kg-1） and then decreased as the ionic strength increased. The adsorption of Bt toxin by the tested minerals and soils after the removal of organic-bound or free Fe and Al oxides also increased with increasing ionic strength controlled by NaCl. Removing organic-bound Fe and Al oxides obviously increased the adsorption of Bt toxin in the tested soils. Differently, removing free Fe and Al oxides increased the Bt adsorption by the paddy soil, but decreased the adsorption by the lateritic red soil. The study indicated that the varieties of ionic strength and the presence of Ve and Al oxides affected the adsorption of Bt toxin by the soils, which would contribute to the further understanding of the fate of Bt toxin in the soil environment and provide references for the ecological risk assessment of transgenic Bt plants.
基金supported by the National Natural Science Foundation of China(Nos.51290282,51578537,51420105012)the National Water Pollution Control and Treatment Science and Technology Major Project(No.2014ZX07405003)
文摘Antimony（Sb）, which can be toxic at relatively low concentrations, may co-exist with Mn（Ⅱ）and/or Fe（Ⅱ） in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption pathways of Sb（Ⅲ and V） species in the presence of Mn（Ⅱ） and Mn-oxidizing bacteria, with or without Fe（Ⅱ）. Batch experiments were conducted to determine the oxidation and adsorption characteristics of Sb species in the presence of biogenic Mn oxides（BMOs）, which were formed in-situ via the oxidation of Mn（Ⅱ） by a Mn-oxidizing bacterium（Pseudomonas sp. QJX-1）. Results indicated that Sb（Ⅲ） ions could be oxidized to Sb（V） ions by BMO, but only Sb（V） originating from Sb（Ⅲ） oxidation was adsorbed effectively by BMO. Introduced Fe（Ⅱ） was chemically oxidized to Fe OOH, the precipitates of which mixed with BMO to form a new compound, biogenic Fe–Mn oxides（BFMO）. The BMO part of the BFMO mainly oxidized and the Fe OOH of the BFMO mainly adsorbed the Sb species. In aquatic solutions containing both As（Ⅲ） and Sb（Ⅲ）, the BFMO that formed in-situ preferentially oxidized Sb over As but adsorbed As more efficiently. Chemical analysis and reverse transcription real-time polymerase chain reaction revealed that the presence of Fe（Ⅱ）, As（Ⅲ） and Sb（Ⅲ） accelerated the oxidation of Mn（Ⅱ） but inhibited the activity of Mn-oxidizing bacteria. These results provide significant insights into the biogeochemical pathways of Sb, Mn（Ⅱ） in aquatic ecosystems, with or without Fe（Ⅱ）.
基金financially supported by the National Natural Science Foundation of China (Nos. 51004060, 51104074, and 51174105)the Natural Science Foundation of Yunnan Province (No. 2010ZC018)
文摘A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron microscope（TEM）, and H2-temperature-programmed reduction（H2-TPR） techniques. The gas–solid reactions between these oxides and methane for syngas generation as well as the catalytic performance for selective oxidation of carbon deposition in O2-enriched atmosphere were investigated in detail. The results show that the samples with the presence of Fe2O3show much higher activity for methane oxidation compared with the Ce0.7Zr0.3O2solid solution,while the CeO2-contained samples represent higher CO selectively in methane oxidation than the Fe2O3/Al2O3sample. This suggests that the iron species should be the active sites for methane activation, and the cerium oxides provide the oxygen source for the selective oxidation of the activated methane to syngas during the reaction between methane and Fe2O3/Ce0.7Zr0.3O2. For the oxidation process of the carbon deposition, the CeO2-containing samples show much higher CO selectivity than the Fe2O3/Al2O3sample, which indicates that the cerium species should play a very important role in catalyzing the carbon selective oxidation to CO. The presence of the Ce–Zr–O solid solution could induce the growth direction of the carbonfilament, resulting in a loose contact between the carbon filament and the catalyst. This results in abundant exposed active sites for catalyzing carbon oxidation, strongly improving the oxidation rate of the carbon deposition over this sample. In addition, the Fe2O3/Ce0.7Zr0.3O2also represents much higher selectivity（ca. 97 %） for the conversion of carbon to CO than the Fe2O3/CeO2sample, which can be attributed to the higher concentration of reduced cerium sites on this sample. The increase of the Zr content in the Fe2O3/Ce1-xZrxO2samples could improve the reactivity of the materials for methane oxidation, but it also reduces the selectivity for CO formation.
基金supported by the Beijing Municipal Science and Technology Project (No. Z181100005518007)the National Key Research and Development Program of China (No. 2017YFC0505303)+1 种基金the National Natural Science Foundation of China (Nos. 51978054 and 51678053)Beijing Municipal Education Commission through the Innovative Transdisciplinary Program ‘Ecological Restoration Engineering’ (No. GJJXK210102)。
文摘Bimetallic oxides composites have received an increasing attention as promising adsorbents for aqueous phosphate (P) removal in recent years. In this study, a novel magnetic composite MZLCO was prepared by hybridizing amorphous Zr-La (carbonate) oxides (ZLCO) with nano-FeOthrough a one-pot solvothermal method for efficient phosphate adsorption. Our optimum sample of MZLCO-45 exhibited a high Langmuir maximum adsorption capacity of 96.16 mg P/g and performed well even at low phosphate concentration. The phosphate adsorption kinetics by MZLCO-45 fitted well with the pseudo-second-order model, and the adsorption capacity could reach 79% of the ultimate value within the first 60 min. The phosphate adsorption process was highly p H-dependent, and MZLCO-45 performed well over a wide p H range of 2.0-8.0. Moreover, MZLCO-45 showed a strong selectivity to phosphate in the presence of competing ions (Cl^(-), NO_(3)^(-), SO_(4)^(2-), HCO_(3)^(-), Ca^(2+), and Mg^(2+)) and a good reusability using the eluent of Na OH/Na Cl mixture, then 64% adsorption capacity remained after ten recycles. The initial 2.0 mg P/L in municipal wastewater and surface water could be efficiently reduced to below 0.1mg P/L by 0.07 g/L MZLCO-45, and the phosphate removal efficiencies were 95.7% and 96.21%, respectively. Phosphate adsorption mechanisms by MZLCO-45 could be attributed to electrostatic attraction and the inner-sphere complexation via ligand exchange forming Zr/La-O-P, -OH and CO_(3)^(2-)groups on MZLCO-45 surface played important roles in the ligand exchange process. The existence of oxygen vacancies could accelerate the phosphate absorption rate of the MZLCO-45 composites.
基金financially supported by the European Union’s Horizon 2020 Research&Innovation Programme under the Marie Sklodowska Curie Grant Agreement(No.813438)。
文摘Iron(Fe)minerals are commonly used to remove phosphorus(P)from waste streams,producing P-loaded Fe(Ⅲ)oxides or Fe(Ⅱ)phosphate minerals(e.g.,vivianite).These minerals may be used as fertilizers to enhance P circularity if solubilized in soil.Here,we tested the P fertilizer value of recycled Fe phosphates(FePs)in a pot trial and in an incubation experiment,hypothesizing that P release from FePs is possible under Fe(Ⅲ)-reducing conditions.First,a pot trial was set up with rice(Oryza sativa)in all combinations of soil flooding or not,three P-deficient soils(acid,neutral,and calcareous),and six FePs(three Fe(Ⅲ)Ps and three Fe(Ⅱ)Ps)referenced to triple superphosphate(TSP)or zero amendments.Shoot P uptake responded to TSP application in all treatments but only marginally to FePs.The redox potential did not decrease to-200 mV by flooding for a brief period(13 d)during the pot trial.A longer incubation experiment(60 d)was performed,including a treatment of glutamate addition to stimulate reductive conditions,and P availability was assessed with CaCl_(2)extraction of soils.Glutamate addition and/or longer incubation lowered soil redox potential to<-100 mV.On the longer term,Fe(Ⅲ)minerals released P,and adequate P was reached in the calcareous soil and in the neutral soil amended with Fe(Ⅲ)P-sludge.It can be concluded that prolonged soil flooding and organic matter addition can enhance the P fertilizer efficiency of FePs.Additionally,application of FeP in powder form may enhance P availability.
基金supported by the National Natural Science Foundation of China (Nos. 41071165 and 30890130)
文摘The adsorption of phosphate onto ferrihydrite(FH) and two FH-humic acid(HA) complexes, obtained by co-precipitating FH with low(FH-HA1) and relatively high amounts of humic acid(FH-HA2), was studied through kinetics and isotherm experiments to determine the differences in phosphate adsorption between FH-HA complexes and FH and to reveal the mechanisms of phosphate adsorption onto two soil compositions. The isoelectric point(IEP) and the specific surface area(SSA) of the mineral decreased as the particle porosity of the mineral increased, which corresponded to an increase in the amount of organic carbon. The adsorption capacity of phosphate was higher on FH than on FH-HA1 and FH-HA2 at the scale of micromoles per kilogram. The initial adsorption rate and adsorption affinity of phosphate decreased with an increase in the amount of HA in the mineral. The sensitivity of phosphate adsorption to the change in the pH was greater for FH than for FH-HA complexes. Ionic strength did not affect the adsorption of phosphate onto FH and FH-HA1 at a lower p H, and the increase in the ionic strength promoted phosphate adsorption at a higher p H.However, for the FH-HA2 complex, the increase in the ionic strength inhibited the adsorption of phosphate onto FH-HA2 at a lower p H and increased the adsorption at a higher pH.
文摘The types, contents and morphologies of crystalline Fe oxides and their relations to phosphate adsorptionon the clay fractions in soils with variable charge in southern China were investigated by means of XRD, TEM,EMA and chemical analysis methods.Results indicated that the types and contents of crystalline Fe oxidesvaried with the soils examined. The dominant crystalline Fe oxide was hematite in the latosols and goethitesin the red soils.In yellow-brown soils, the only crystalline Fe oxide was goethite.The difference between Aldand Alo came mainly from the Al substituting for Fe in the pe oxides. The crystal morphology of goethiteappeared mainly as subrounded flat or iso-dimensional rather than acicular particles. Hematites occurredin plates of various thickness. Their MCDa/MCDc ratios in the latosols and red soils were generally above1.5 and below 1.5, respectively. The MCD values of goethites and hematites were 15-25nm and 20-35nm,and their specific surface areas were 80-120m￣2/g and 35-75m￣2/g, respectively.The goethite crystals weregenerally smaller. Variations of the total amounts of crystalline Fe oxi es in clay fractions were not related tophosphate adsorption. The types, contents and morphologies of crystalline Fe oxides in the soils remarkablyaffected phosphate adsorption characteristics of the soils. The phosphate adsorption of goethite was muchgreater than that of hematite. The higher the MCD /MCDc rotio of hematite, the lower the phosphateadsorption.
基金supported by the National Natural Science Foundation of China(Nos.41830753,42277201,42377242,and 41977286)the Scientific Research Foundation of Guangzhou University(No.YJ2023027)the College Student Innovation and Entrepreneurship Training Program(No.S202311078057).
文摘Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We hypothesized that Fe(oxyhydr)oxide(FeOOH)minerals precipitated in situ from indigenous Fe in groundwater may immobilize As,providing a solution for safely using As-contaminated groundwater in irrigation.To confirm this hypothesis and identify the controlling mechanisms,we comprehensively evaluated the transport,speciation changes,and immobilization of As and Fe in agricultural canals irrigated using As-contaminated groundwater.The efficiently removed As and Fe in the canals accumulated in shallow sediment rather than subsurface sediment.Linear combination fitting(LCF)analysis of X-ray absorption near edge spectroscopy(XANES)indicated that As(Ⅴ)was the dominant As species,followed by As(Ⅲ),and therewas no FeAsO_(4) precipitate.Sequential extraction revealed higher contents of amorphous FeOOH and associated As in shallower sediment than in the subsurface layer.Stoichiometric molar ratio calculations,SEM-EDS,FTIR,and fluorescence spectroscopy collectively demonstrated that the microbial reductive dissolution of amorphous FeOOH proceeded via reactive dissolved organic matter(DOM)consumption in subsurface anoxic porewater environment facilitating high labile As,whereas in surface sediment,the in situ-generated amorphous FeOOH was stable and strongly inhibited As release via adsorption.In summary,groundwater Fe^(2+)can efficiently precipitate in benthic surface sediment as abundant amorphous FeOOH,which immobilizes most of the dissolved As,protecting agricultural soil from contamination.This field research supports the critical roles of the phase and reactivity of in situ-generated FeOOH in As immobilization and provides new insight into the sustainable use of contaminated water.
基金financially supported by the National Key Research and Development Program of China(No.2017YFD0800305)。
文摘As the fundamental unit of soil,aggregates exhibit significant variations in their abilities to adsorb and desorb trace elements,depending on their size.Batch experiments were conducted to investigate the characteristics of adsorption and desorption of cadmium(Cd),copper(Cu),and lead(Pb)on and from soil aggregate fractions from three layers of a calcareous soil profile in Changxing County,Zhejiang Prvince,China.The results showed that both Langmuir and Freundlich models successfully described the isothermal adsorption processes of single Cd,Cu,and Pb on different soil aggregates.Additionally,aggregates from the bottom soil layer showed the highest maximum adsorption capacity and required the lowest energy for Cd,Cu,and Pb adsorption compared to aggregates from upper soil layers.The physicochemical properties of soil aggregates were found to govern the adsorption and desorption processes of heavy metals rather than the aggregate size,wherein the contents of iron/aluminum oxides and organic matter were the most crucial influencing factors.Cadmium displayed higher mobility than Cu and Pb in different soil aggregates,and the maximum adsorption capacities of the metal ions followed the order of Pb>Cu>Cd,while their desorption rates followed the order of Cd>Cu>Pb.Additionally,the<0.053 mm microaggregates presented the lowest desorption rates for Cd,Cu,and Pb compared to other soil aggregate fractions in each soil layer.Furthermore,the orthogonal experiment results demonstrated that the competitive adsorption between metals occurred on soil aggregates in the ternary heavy metal system,but only the desorption of Pb was significantly affected by the coexistence of Cd and Cu.
基金the Higher Education Development Fund (FRV) of the Ministry of Education, Youth and Sportsof the Czech Republic (No.217/2005)the Czech Science Foundation (No.GAR 205/04/1292)the Ministry ofEducation, Youth and Sports of the Czech Republic (Nos.MSM 6046070901 and MSM 0021620855).
文摘The binding of metallic contaminants （Pb, Cd, and Zn） and As on soil constituents was studied on four highly contaxninated alluvial soil profiles from the mining/smelting district of Pribram （Czech Republic） using a combination of mineralogical and chemical methods. Sequential extraction analysis （SEA） was supplemented by mineralogical investigation of both bulk samples and heavy mineral fractions using X-ray diffraction analysis （XRD） and scanning electron microscopy with an energy dispersive X-ray spectrometer （SEM/EDS）. The mineralogy of Fe and Mn oxides was studied by voltammetry of microparticles （VMP） and diffuse reflectance spectrometry （DRS）. Zinc and Pb were predominantly bound in the reducible fraction attributed to Fe oxides and Mn oxides （mainly birnessite, Na4Mn14O27.9H2O）, which were detected in soils by XRD and SEM/EDS. In contrast, Cd was the most mobile contaminant and was predominantly present in the exchangeable fraction. Arsenic was bound to the residual and reducible fractions （corresponding to Fe oxides or to unidentified Fe-Pb arsenates）. SEM/EDS observations indicate the predominant affinity of Pb for Mn oxides, and to a lesser extent, for Fe oxides. Thus, a more suitable SEA procedure should be used for these mining-affected soils to distinguish between the contaminant fraction bound to Mn oxides and Fe oxides.
基金funded by the National Natural Science Foundation of China (No. 51278489)Key Lab for Solid Waste Management and Environmental Safety Open fund (No. 2011-8)
文摘A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge disintegration can destroy the sludge structure and cell wall, so as change the sludge floc structure and moisture distribution, thus affecting the dewatering performance of sludge. In this article, the disintegration methods were ultrasound treatment, K2 Fe O4oxidation and KMn O4 oxidation. The degree of disintegration（DDCOD）, sludge moisture distribution and the final water content of sludge cake after centrifuging were measured. Results showed that three disintegration methods were all effective, and K2 Fe O4oxidation was more efficient than KMn O4 oxidation. The content of free water increased obviously with K2 Fe O4and KMn O4 oxidations, while it decreased with ultrasound treatment. The changes of free water and interstitial water were in the opposite trend. The content of bounding water decreased with K2 Fe O4oxidation, and increased slightly with KMn O4 oxidation, while it increased obviously with ultrasound treatment. The water content of sludge cake after centrifuging decreased with K2 Fe O4oxidation, and did not changed with KMn O4 oxidation, but increased obviously with ultrasound treatment. In summary, ultrasound treatment deteriorated the sludge dewaterability, while K2 Fe O4and KMn O4 oxidation improved the sludge dewaterability.
基金supported by the National Key Technology R&D Program (No.2018YFD0800202)。
文摘A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO)sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As)and cadmium (Cd) in water.The maximum As(Ⅲ) and Cd(Ⅱ) adsorption capacities of 1%CaSFMBO were 156.25 mg/g and 107.53 mg/g respectively in single-adsorption systems.The adsorption of As and Cd by the Ca-SFMBO sorbent was pH-dependent at values from 1 to 7,with an optimal adsorption pH of 6.In the dual-adsorbate system,the presence of Cd(Ⅱ) at low concentrations enhanced As(Ⅲ) adsorption by 33.3%,while the adsorption of As(Ⅲ) was inhibited with the increase of Cd(Ⅱ) concentration.Moreover,the addition of As(Ⅲ) increased the adsorption capacity for Cd(Ⅱ) up to two-fold.Through analysis by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR),it was inferred that the mechanism for the co-adsorption of Cd(Ⅱ) and As(Ⅲ) included both competitive and synergistic effects,which resulted from the formation of ternary complexes.The results indicate that the Ca-SFMBO material developed here could be used for the simultaneous removal of As(Ⅲ) and Cd(Ⅱ) from contaminated water.
文摘Addition of clay-rich subsoil to sandy soil results in heterogeneous soil with clay peds （2-mm） or finely ground （〈 2 mm） clay soil （FG）, which may affect the nutrient availability. The aim of this study was to assess the effect of clay soil particle size （FG or peds） and properties on nutrient availability and organic C binding in sandy soil after addition of residues with low （young kikuyu grass, KG） or high （faba bean, FB） C/N ratio. Two clay soils with high and low smectite percentage, clay and exchangeable Fe and A1 were added to a sandy soil at a rate of 20% （weight/weight） either as FG or peds. Over 45 d, available N and P as well as microbial biomass N and P concentrations and cumulative respiration were greater in soils with residues of KG than FB. For soils with KG residues, clay addition increased available N and initial microbial biomass C and N concentrations, but decreased cumulative respiration and P availability compared to sandy soil without clay. Differences in measured parameters between clay type and size were inconsistent and varied with time except the increase in total organic C in the 〈 53 μm fraction during the experiment, which was greater for soils with FG than with peds. We concluded that the high exchangeable Fe and A1 concentrations in the low-smectite clay soil can compensate a lower clay concentration and proportion of smectite with respect to binding of organic matter and nutrients.
基金Projects(51334008,51304243,51604160)supported by the National Natural Science Foundation of ChinaProject(2016zzts037)supported by the Fundamental Research Funds for the Central Universities,China
文摘Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The experimental results demonstrated that Fe?Mn binary oxide(FMBO)was the most suitable adsorbent for the separation.Under a wide pH(6.9?11.3)region,more than80%W removal efficiency and less than3%Mo loss could be obtained.In addition,the Fe?Mn binary oxide adsorbent can be regenerated by treating with3mol/L NaOH,and the W adsorption efficiency was retained after five adsorption?desorption?regeneration cycles.All these indicate that the Fe?Mn binary oxides have the potential for the separation of W from molybdate solution.
基金supported by the National Natural Science Foundation of China (21373138)Shanghai Sci. & Tech. Committee (12JC1407200)Program for Changjiang Scholars and Innovative Research Team in University (IRT1269)
文摘An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the magnetism, conductivity and biocompatibility of the Fe3O4-RGO nanosheets, the nanocomposites could be facilely adhered to the electrode surface by magnetically controllable assembling and beneficial to achieve the direct redox reactions and electrocatalytic behaviors of GOx immobilized into the nanocomposites. The biosensor exhibited good electrocatalytic activity, high sensitivity and stability. The current response is linear over glucose concentration ranging from 0.05 to 1.5 m M with a low detection limit of0.15 μM. Meanwhile, validation of the applicability of the biosensor was carried out by determining glucose in serum samples. The proposed protocol is simple, inexpensive and convenient, which shows great potential in biosensing application.
基金supported by the National Natural Science Foundation of China(Grant no.51672075,21271069,51772092,51704106)Science and Technology Program of Hunan Province(Grant no.2015JC3049)
文摘A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polypropylene separator(Celgard 2400)close to the sulfur cathode.The special nanotubes are in-situ catalyzed by Fe3C nanoparticles.They could entrap lithium polysulfides(Li PSs)to restrain the shuttle effect and reduce the loss of active material.The battery with the modified separator and sulfur cathode shows an excellent cycle performance.It has a high rate performance,580.5 mAh/g at the high current rate of 4 C relative to 1075 mAh/g at 0.1 C.It also has an initial discharge capacity of 774.8 m Ah/g measured at 0.5 C and remains 721.8 mAh/g after 100 cycles with a high capacity retention of 93.2%.The outstanding performances are notable in recently reports with modified separator.
