In-situ growth of layered double hydroxide(LDH)has been considered a feasible method to further improve the corrosion protection of PEO coated Mg alloys,but the process is basically carried out in an autoclave.In this...In-situ growth of layered double hydroxide(LDH)has been considered a feasible method to further improve the corrosion protection of PEO coated Mg alloys,but the process is basically carried out in an autoclave.In this study,LDH was in-situ synthesized on PEO treated AM50 Mg by hydrothermal treatment at ambient pressure in the presence of chelating agents.Results indicated that the synergistic effect of sulfosalicylic acid(SSA)and ethylenediaminetetraacetic acid tetrasodium salt(EDTA)chelating agents is appropriate for Mg-Al LDH formation due to the sufficient quantity of highly stable Mg and Al complexes in the treatment bath.An appropriate hydrothermal treatment time was also revealed in this work,which can efficiently seal the pores and defects of PEO coating with a uniform LDH film.As a result,the corrosion protection of the coating was improved dramatically.The prolonged hydrothermal treatment is detrimental to the integrity of PEO layers.The influence of chelating agents on the LDH formation processes is supported by thermodynamic calculation of the equilibrium composition,and the formation mechanism of LDH film is discussed in depth.展开更多
[Objective] To explore a high efficient phytoremediation technology for soil pollution. [Method] Foliage application and root irrigation were carried out to study the influence on amaranth repair efficiency by using c...[Objective] To explore a high efficient phytoremediation technology for soil pollution. [Method] Foliage application and root irrigation were carried out to study the influence on amaranth repair efficiency by using combined treatments of phytohor- mones （IAA, GA3 SA） and chelating agents （EDTA）. [Result] The combined treatment increased the biomass of amaranth under 133Cs, 88Sr, Cr stress The 133Cs, 88Sr, Cr enrich- ment in amaranth by root irrigation were obviously higher than that by foliage appli- cation. The phytoextraction efficiency of phytohormones and chelating agents from best to poor was as following： 100 mg/L SA＋1.5 mg/kg EDTA, 500 mg/L GA3＋1.5 mg/kg EDTA, 100 mg/L IAA＋1.5 mg/kg EDTA. [Conclusion] The most appropriate treatment was the combined treatment of 100 mg/L SA＋l.5mg/kg EDTA by soil irri- gation, which could make the total absorption doses of 133Cs, 88Sr, Cr per plant achieve the maximum.展开更多
Although Cd is a pollutant of public health relevance,many dietary sources from which it can be absorbed into human tissues remain unknown.While it is well established that the biogeochemical cycle of Cd involves its ...Although Cd is a pollutant of public health relevance,many dietary sources from which it can be absorbed into human tissues remain unknown.While it is well established that the biogeochemical cycle of Cd involves its complexation with environment-derived ligands（e.g.,humic acids,HAs） and anthropogenic ones（e.g.,chelating agents,CAs）,the interaction of Cd with both of these ligands is less well understood.To gain insight,a HA–Cd complex was injected on a size-exclusion chromatography（SEC） column coupled on-line with a flame atomic absorption spectrometer（FAAS） using 10 mmol/L Tris buffer（pH 8.0） as the mobile phase.This approach allowed us to observe the intact HA–Cd complex and the retention behavior of Cd as a function of 2–20 μmol/L concentrations of ethylenediaminetetraacetic acid（EDTA）,diethylenetriaminepentaacetic acid（DTPA） or methylglycinediacetic acid（MGDA） that were added to the mobile phase.An increase of the retention time of Cd was indicative of a partial or complete abstraction of Cd from HA.Our results revealed that all CAs abstracted Cd from the HA–Cd complex at concentrations of 5 μmol/L,while MGDA and DTPA were effective at 2 μmol/L.The bioavailability of some of the on-column formed CA–Cd complexes explains the previously reported increased accumulation of Cd in periphyton in the ecosystem downstream of wastewater treatment plants.In addition,our results imply that the use of effluents which contain CAs and Cd for the irrigation of food crops can introduce Cd into the food supply and compromise food safety.展开更多
Eleven chelating agents were studied for their capabilities to mobilize the cadmium bound tp bovine serum albumin(BSA).The parameter F,which is defined as the ratio between the percentages of cadmium bound to BSA in t...Eleven chelating agents were studied for their capabilities to mobilize the cadmium bound tp bovine serum albumin(BSA).The parameter F,which is defined as the ratio between the percentages of cadmium bound to BSA in the presence and absence of chelating agents,can be used as the criterion to evaluate the mobilizing capability of chelating agent.The F values determined experimentally lead to a mobilizing capability order:DTPA>EDTA>EGTA>NTA>TR1EN>PEN>CYS>HIS>SAThe polyaminopolycarboxylate type chelators mobilize cadmium effectively.A linear relationship was found between 1gF and lg k'CdL (conditional stability constant of the cadmium chelate).展开更多
In this paper, the complexing abilities of EDTA, TTHA and Cit. with lead in the Pb(2.59 mg/g) contaminated soil were compared in the laboratory. Possibilities for lead and the threeagents to develop stable complexes i...In this paper, the complexing abilities of EDTA, TTHA and Cit. with lead in the Pb(2.59 mg/g) contaminated soil were compared in the laboratory. Possibilities for lead and the threeagents to develop stable complexes increased proportionally to the growth of lead complexible formwhen the PH values ranged between 4 and 6. Under acid conditions, logB_(Pb-TTHA)) valued as 28.1 wasmuch higher than logB_(Pb-EDTA), as 18.0 depending on producing Pb_2-TTHA (logK_(Pb_2-TTHA= 11 0) andPb-HTTHA (logK(Pb-HTTTHA)=8.2)). Conclusively, the complexing ability of TTHA with Pb still ex-aseded that of EDTA by about 10% even when the amount of TTHA added was only equal to onefourth of that of EDTA. Due to the lower cost and less harzn to crops, Cit. can still be taken as abetter chelating agent in acid soil although its coordinative capability with Pb was weaker thanEDTA and TTHA.展开更多
In a quest for better chelating therapy drugs for the treatment of intoxication by Fe, Al, oractinides, two new series of mixed catechol-bisphosphonate through amide linkage were synthesized.Benzyl group was used as p...In a quest for better chelating therapy drugs for the treatment of intoxication by Fe, Al, oractinides, two new series of mixed catechol-bisphosphonate through amide linkage were synthesized.Benzyl group was used as protecting group to avoid the breakage of amide by acid hydrolysis orimcomplete reaction in silylation-dealkylation using bromotrimethylsilane.展开更多
The current work is focused on the study of the bio-sorption of hexavalent chromium from aqueous solution using sisal natural fiber(Agave sisalana) treated by various chelating agents(ligands) such as urea(UR),thiocar...The current work is focused on the study of the bio-sorption of hexavalent chromium from aqueous solution using sisal natural fiber(Agave sisalana) treated by various chelating agents(ligands) such as urea(UR),thiocarbamide(TC), ethylenediaminetetraacetic acid(EDTA), and diphenyl carbazide(DCZ). The fiber treatments were investigated using Fourier Transform Infrared Spectroscopy(FTIR) and Scanning electron microscope(SEM). The kinetics of chromium bio-sorption was studied in batch presses under the effect of some physicochemical factors such as the nature of chelating agent(F@UR, F@TC, F@DCZ, and F@EDTA),adsorbent dose(2–10 g·L^(-1)), chromium initial concentration(100–500 mg·L^(-1)), solution pH(1–6), and batch temperature(20 ℃–50 ℃). This study resulted in an optimum adsorption at a chromium initial concentration of 100 mg·L^(-1), at pH 2, and at 20 ℃. The obtained results showed clearly that the treatment with chelating agent boosts the adsorptive capacity of A. sisalana fibers Cr(VI) 10.9 mg·g^(-1) to 58.6 mg·g^(-1). The modeling study showed that the adsorption kinetics obey the pseudo-second-order model, with an R2 in the range of 0.991 and 0.999. The bio-sorption isotherms followed the Langmuir model; the maximum uptake capacity of(F@N, F@UR,F@TC, F@DCZ, and F@EDTA) was found to be respectively, 12.3 mg·g^(-1), 25.33 mg·g^(-1), 28.73 mg·g^(-1),42.54 mg·g^(-1), and 61.45 mg·g^(-1). The determined adsorption thermodynamics parameters such as enthalpy,free energy, and entropy showed that the adsorption process is exothermic, spontaneous, and has a stable configuration.展开更多
To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydroth...To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydrothermal method.Different chelating agents including polyaspartic acid（PASP） and ethylenediaminetetraacetic acid（EDTA） were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys.The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres,while the coating prepared with EDTA consisted of many flower-like particles.Moreover,the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP.Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating.Immersion test of the coated samples in simulated body fluid（SBF） demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.展开更多
A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment. The amount of adsorbed ch...A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment. The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the remodel of Cr(Ⅲ) by sediment from solutions and the inhibiting effect was in the order:citric acid > tartaric acid > EDTA, salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.展开更多
Bleaching of the kaolin ore from Shaziling Kaolin Mine in Jiangxi Province of China was studied with the aim of enhancing the quality and value of the ore to meet the requirements from the ceramics manufacturers. Fact...Bleaching of the kaolin ore from Shaziling Kaolin Mine in Jiangxi Province of China was studied with the aim of enhancing the quality and value of the ore to meet the requirements from the ceramics manufacturers. Factors affecting the reductive bleaching of kaolin ore with sodium dithionite as the bleaching agent were studied and optimized to increase the whiteness of the kaolin ore from 38. 5% to about 65%. However, it was found that in the conventional bleaching process, a washing step to remove the ferrous ions from the bleached kaolin suspension was indispensable, which made the process complicated and restricted the capacity of the production. In addition, the whiteness of the bleached kaolin products was unstable. To solve the above problems, a new technique with the application of chelating agents in the bleaching process was developed to remove ferrous ions and get rid of the washing step. The bleaching process of kaolin was simplified. The whiteness of the bleached kaolin products was stabilized as well as increased to about 70%. The mechanism of the bleaching process and the action of the chelating agents were discussed.展开更多
Surfactants play a critical role in enhanced oil recovery(EOR) applications;however,their performance is often compromised in harsh reservoir conditions,such as high temperature and high salinity,due to precipitation ...Surfactants play a critical role in enhanced oil recovery(EOR) applications;however,their performance is often compromised in harsh reservoir conditions,such as high temperature and high salinity,due to precipitation caused by interactions with multivalent metal ions.Chelating agents were introduced into oilfields for various purposes due to their ability to sequester metal ions.In this work,we conducted a comprehensive investigation about chelating agent-surfactant(CS) flooding for carbonate reservoirs,as an alternative to the well-established alkaline surfactant(AS) flooding used in sandstone.The tested surfactants include sodium dodecyl sulfate(anionic)(SDS),dodecyltrimethylammonium bromide(cationic)(DTAB),Triton X100(nonionic),and a locally synthesized zwitterionic surfactant.The tested chelating agents include diethylenetriaminepentaacetic acid(DTPA),ethylenediaminetetraacetic acid,and glutamic acid N,N-diacetic acid.pH and temperature,as dominant factors in chelating agent solubility and brine stability,were modified to test chelating agent solutions of different concentrations and their mixtures with surfactants.Interfacial tension reduction by chelating agents alone,surfactants alone,and their mixtures were measured.Wettability alteration brought by chelating agents and surfactants on carbonate rock surfaces was evaluated using the static contact angle method.Based on the obtained results,chelating agents can be applied as low-cost additives for surfactant stabilization in high salinity conditions.The addition of chelating agents significantly improved the stability of SDS and DTAB in salt solutions and seawater.At a relatively low concentration(0.25 wt%),DTPA was able to stabilize DTAB of 1.00 wt% in seawater at high temperature(90℃).DTPA,among the tested three chelating agents,exhibited a stronger stabilization effect on surfactants of different ion types.When chelating agents are to be applied in brine,an optimal applicable pH range of 5-9 is recommended so not to induce solubility issue of chelating agents or stability issues of metal ions.In this range,IFT reduction is more significant at high pH,while wettability alteration is more significant at low pH.The combination of a cationic surfactant with a chelating agent forms a low adsorption wettability modifier which can change strongly oil-wet rock to water-wet conditions,thus significantly increasing the residual oil recovery from oil-wet carbonate formations.Zwitterionic and nonionic surfactants are also applicable to combine with a chelating agent for EOR purposes.Anionic surfactant SDS,however,showed a growing inhibition on the wettability alteration effect induced by EDTA as the concentration of SDS increased.展开更多
Heavy metal stabilization and alkali neutralization are crucial for the management of municipal solid waste incineration fly ash(MSWI FA).In this study,the effects of oxalic acid(OA)and citric acid(CA)washing on heavy...Heavy metal stabilization and alkali neutralization are crucial for the management of municipal solid waste incineration fly ash(MSWI FA).In this study,the effects of oxalic acid(OA)and citric acid(CA)washing on heavy metal migration and alkali changes were investigated.Besides,three agents were selected to stabilize acid-washed fly ash(FA),and the effects of heavy metal stabilization under different disposal environments and the changes in their form distributions were comparatively analyzed.The experimental results demonstrated that with increasing organic acid concentration,the amount of Cd and Pb extracted from MSWI FA increased,whereas the amount of alkalis tended to decrease.Moreover,the leaching concentration of heavy metals and the percentage of unstable forms increased after acid washing.The alkalis content in the products decreased to 7.91-8.75 after stabilization,which met the standards of hazardous waste landfills.Compared with other agents,sodium diethyldithiocarbamate(DDTC)exhibited excellent heavy metal stabilization performance.After the addition of 1%DDTC,the leaching concentrations of Cd and Pb decreased to values lower than the national standard limit.Additionally,the curing rates of Cd and Pb were greater than 98%under the two leaching conditions.With the addition of DDTC,the percentage of stable forms increased,and the percentages of stable Cd and Pb forms increased to 87.68%and 99.03%,respectively,after treatment with 2%DDTC.The above results corroborated that CA coupled with DDTC stabilization can significantly reduce Cd and Pb toxicity and neutralize alkalinity in FA.展开更多
Four different chelating agents,ethylenediamine tetraacetic acid,citric acid,glucose,and sucrose,were selected to synthesize MnCr_(2)O_(4)catalysts(spinel structure)with sol-gel method.Among the prepared catalysts,MnC...Four different chelating agents,ethylenediamine tetraacetic acid,citric acid,glucose,and sucrose,were selected to synthesize MnCr_(2)O_(4)catalysts(spinel structure)with sol-gel method.Among the prepared catalysts,MnCr_(2)O_(4)-S-700,which had the largest specific surface area,showed the best catalytic performance,with a T80 temperature window of 200-260℃ and a denitrification rate of up to 91.6%at 220℃.Hydrogen temperature programmed reduction,ammonia temperature programmed desorption,and X-ray photoelectron spectroscopy results showed that MnCr_(2)O_(4)-S-700 possessed more chemisorbed oxygen Oαas well as active sites(Mn^(3+)+Mn^(4+))and(Cr^(3+)+Cr^(5+)),which improved acidity and redox capacity.There was abundant electron transfer between Mn and Cr elements(Cr^(5+)+Mn^(3+)→Cr^(3+)+Mn^(4+)),enhancing the redox capacity of catalysts.According to the in situ diffuse reflectance infrared transform spectroscopy spectra,it could be concluded that the MnCr_(2)O_(4)-S-700 catalyst followed not only the Langmuir-Hinshelwood mechanism but also the Eley-Rideal mechanism.This work displays the effect of the complexation mechanism of chelating agents on the SCR reaction with NH_(3)over spinel catalysts.展开更多
The effects of annealing temperatures and chelating agents on the structural and optical properties of ZnO nanoparticles were investigated.The average particle size of ZnO nanoparticles increased with increase of anne...The effects of annealing temperatures and chelating agents on the structural and optical properties of ZnO nanoparticles were investigated.The average particle size of ZnO nanoparticles increased with increase of annealing temperatures.The decrease of the full width at half maximum(FWHM)with increasing annealing temperatures inferred increase of particle/grain growth.The grain sizes were also observed to be increased with increase of annealing temperatures.From the absorption spectra of the samples,the absorption was red-shifted and the energy band gap was blue-shifted with increase of annealing temperatures.A sharp UV emission peak was observed and the intensity of this peak increased with annealing temperatures corresponding to the high crystallinity in the samples.At high annealing temperature of 700℃,ZnO exhibited a less intense deep level emission.This negligible deep level emission was attributed to the oxygen vacancies created at higher annealing temperatures.展开更多
YMn2O5nanorods were synthesized through a modified polyacrylamide gel route.The synthesis strategy in this work is based on a sol-gel process using a polyacrylamide gel method in which oxalic acid,citric acid or tarta...YMn2O5nanorods were synthesized through a modified polyacrylamide gel route.The synthesis strategy in this work is based on a sol-gel process using a polyacrylamide gel method in which oxalic acid,citric acid or tartaric acid is employed as the chelating agent.In the gel routes,oxalic acid was used as a carboxyl chelating agent,while citric acid or tartaric acid was a carboxyl and hydroxyl chelating agent.The as-prepared samples were characterized by means of techniques such as X-ray powder diffraction(XRD)measurement,thermogravimetric analysis(TG),differential scanning calorimetry analysis(DSC),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),thermal expansion measurement and field-emission scanning electron microscopy(SEM)investigations.It was found that oxalic acid is the best chelating agent with Y(NO3)3·6H2O and Mn(CH3COO)2·4H2O as precursors to prepare a single orthorhombic YMn2O5nanorods at 1000°C.Scanning electron microscope observation shows that the morphology of YMn2O5powders is significantly dependent on the chelating agent.The peaks(single orthorhombic YMn2O5nanorods)at 642,600,573,546,521,493,486,468,448 and 400cm?1were observed from FTIR spectra.The phase,surface morphology and chelation mechanisms of YMn2O5samples have been discussed on the basis of the experimental results.展开更多
The Li3V2（PO4）3/C composite cathode material was synthesized via sol-gel method using three different chelating agents （citric acid, salicylic acid and polyacrylic acid） at pH value of 3 or 7. The crystal structur...The Li3V2（PO4）3/C composite cathode material was synthesized via sol-gel method using three different chelating agents （citric acid, salicylic acid and polyacrylic acid） at pH value of 3 or 7. The crystal structure, morphology, specific surface area and electrochemical performance of the prepared samples were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and galvanostatic charge/discharge test. The results show that the effects of pH value on the performance of the prepared materials are greatly related to the chelating agents. With salicylic acid or polyacrylic acid as the chelating reagent, the structure, morphology and electrochemical performance of the samples are greatly influenced by the pH values. However, the structure of the materials with citric acid as the chelating agent does not change as pH value changes, and the materials own uniform particle size distribution and good electrochemical performance. It delivers an initial discharge capacity of 113.58 mA·h/g at 10C, remaining as high as 108.48 mA·h/g after 900 cycles, with a capacity retention of 95.51%.展开更多
Fine soil generated from the soil washing process can be the second problem, as contaminants are concentrated in the fine soil, and also took the difficult forms to treat because soluble and exchangeable fractions are...Fine soil generated from the soil washing process can be the second problem, as contaminants are concentrated in the fine soil, and also took the difficult forms to treat because soluble and exchangeable fractions are already removed by soil washing process; therefore, the fine soil is indicated to hazardous waste, and discarded in hazardous waste landfill. Thus, this research would be performed that arsenic and heavy metals formed difficult to remove in the fine soil were converted to more treatable fractions with chelating agents. Moreover, feasibility study to apply the second remediation targeted to the fine soil inquired. As a result, the chelating agent was decided 50 mM Na2EDTA, and it could develop the complex. In addition, the result of sequential extraction showed that Mn/Fe-oxide fraction, comprised about 28% of amount at first, was decreased about 16%, and organic fraction, consisted approximately 20%, was also decreased about 11%, while exchangeable fraction and carbonate fraction were increased. This result means that the difficult fractions removed could change fractions） by chelating agent. This research can provide the possibility hazardous waste because of difficulty to remediate. the more treatable fractions （exchangeable and carbonate to treat the fine soil, although the fine soil was regarded to展开更多
In this paper,ordered mesoporous alumina(OMA)support with the high surface area(328 m^(2)g^(-1))and the large pore volume 0.74(cm^(3)·g^(-1))was synthesized by homogeneous precipitation method.And the influence o...In this paper,ordered mesoporous alumina(OMA)support with the high surface area(328 m^(2)g^(-1))and the large pore volume 0.74(cm^(3)·g^(-1))was synthesized by homogeneous precipitation method.And the influence of EDTA on the physical and chemical properties of the modified catalysts was also studied.The characteristic results showed that the addition of EDTA could adjust the metal-support interaction and improved the acidity of the corresponding catalyst.Combined with the catalytic performance results,the EDTA-modified Ni Mo E(1.0)/OMA catalyst displays the highest DBT hydrodesulfurization conversion(97.7%).展开更多
In the interest of accelerating aniline degradation, Fe2+ and chelated Fe2+ activated persulfate oxidations were investigated in neutral pH condition. Three kinds of chelating agents were selected including citric aci...In the interest of accelerating aniline degradation, Fe2+ and chelated Fe2+ activated persulfate oxidations were investigated in neutral pH condition. Three kinds of chelating agents were selected including citric acid, oxalic acid and ethylenediamine tetraaceatate(EDTA) to maintain available Fe2+. The results indicate that the concentration of chelating agent and ferrous ion didn't follow a linear relationship with the degradation rate of aniline. A 1/1 ratio of chelating agent/Fe2+ results in a higher degradation rate compared to the results by other ratios. The oxidation enhancement factor using oxalic acid was found to be relatively low. In contrast, citric acid is more suitable chelating agent in the ferrous iron activated persulfate system and aniline exhibits a highest degradation with a persulfate/Fe2+/citric acid/aniline molar ratio of 50/25/25/1 compared to other molar ratios.展开更多
For realizing the effective flotation of refractory copper ox-idized ores and developing the activation-flotation theory , the influences of nine different organic chelating agents on xanthate collection pcnver and it...For realizing the effective flotation of refractory copper ox-idized ores and developing the activation-flotation theory , the influences of nine different organic chelating agents on xanthate collection pcnver and its adsorption characteristics ivere studied in the flotation of malachite and chrysocolla representatively selected by means of XPS,IR, absorbed quanti-ty measurements and flotation tests.For easily-dissolved malachite flotation , a small amount of chelating agent can obviously enhance xanthate collecting power and make malachite floated easily , and so reduces the consumption of xanthate. For hard-dis-晄olved chrysocolla, chelating agent is able to increase its recovery to 90% , but the chelating agent consumption is high. Chelating agent and xanthate can produce synergistic adsorptions, which follmv Freundlich's adsorption equation on malachite and Chrysocolla surfaces. The high chemical activity of chelating agent and its synergistic activation on xanthate are the key to improving xanthate collection poiver. The synergistic activation of chelat-ing agent on xanthate on melachite surfaces is clearly stronger than on chrysocolla surfaces. According to experimental results, it can be thought that the synergistic activation results from the synergistic complexation of chelating agent and xanthate with copper ions to form biligand-tribasic co-ordination complex.展开更多
基金the financial support from National Natural Science Foundation of China(No.52071067)Mobility Programme of the Sino-German Center(M-0056)+3 种基金Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program(RC231178)Natural Science Foundation Project of Liaoning Province(2022-YGJC-16)the Fundamental Research Funds for the Central Universities(N2302019)Qianqian Chen would like to acknowledge China Scholarship Council for the award of fellowship(NO.202206080011).
文摘In-situ growth of layered double hydroxide(LDH)has been considered a feasible method to further improve the corrosion protection of PEO coated Mg alloys,but the process is basically carried out in an autoclave.In this study,LDH was in-situ synthesized on PEO treated AM50 Mg by hydrothermal treatment at ambient pressure in the presence of chelating agents.Results indicated that the synergistic effect of sulfosalicylic acid(SSA)and ethylenediaminetetraacetic acid tetrasodium salt(EDTA)chelating agents is appropriate for Mg-Al LDH formation due to the sufficient quantity of highly stable Mg and Al complexes in the treatment bath.An appropriate hydrothermal treatment time was also revealed in this work,which can efficiently seal the pores and defects of PEO coating with a uniform LDH film.As a result,the corrosion protection of the coating was improved dramatically.The prolonged hydrothermal treatment is detrimental to the integrity of PEO layers.The influence of chelating agents on the LDH formation processes is supported by thermodynamic calculation of the equilibrium composition,and the formation mechanism of LDH film is discussed in depth.
基金Supported by the Plan for the National Defense Basic Scientific Research of the State Administration of ScienceTechnology and Industry for National Defense of China(b312011)~~
文摘[Objective] To explore a high efficient phytoremediation technology for soil pollution. [Method] Foliage application and root irrigation were carried out to study the influence on amaranth repair efficiency by using combined treatments of phytohor- mones （IAA, GA3 SA） and chelating agents （EDTA）. [Result] The combined treatment increased the biomass of amaranth under 133Cs, 88Sr, Cr stress The 133Cs, 88Sr, Cr enrich- ment in amaranth by root irrigation were obviously higher than that by foliage appli- cation. The phytoextraction efficiency of phytohormones and chelating agents from best to poor was as following： 100 mg/L SA＋1.5 mg/kg EDTA, 500 mg/L GA3＋1.5 mg/kg EDTA, 100 mg/L IAA＋1.5 mg/kg EDTA. [Conclusion] The most appropriate treatment was the combined treatment of 100 mg/L SA＋l.5mg/kg EDTA by soil irri- gation, which could make the total absorption doses of 133Cs, 88Sr, Cr per plant achieve the maximum.
基金funded by the Natural Sciences and Engineering Research Council(NSERC)of Canada
文摘Although Cd is a pollutant of public health relevance,many dietary sources from which it can be absorbed into human tissues remain unknown.While it is well established that the biogeochemical cycle of Cd involves its complexation with environment-derived ligands（e.g.,humic acids,HAs） and anthropogenic ones（e.g.,chelating agents,CAs）,the interaction of Cd with both of these ligands is less well understood.To gain insight,a HA–Cd complex was injected on a size-exclusion chromatography（SEC） column coupled on-line with a flame atomic absorption spectrometer（FAAS） using 10 mmol/L Tris buffer（pH 8.0） as the mobile phase.This approach allowed us to observe the intact HA–Cd complex and the retention behavior of Cd as a function of 2–20 μmol/L concentrations of ethylenediaminetetraacetic acid（EDTA）,diethylenetriaminepentaacetic acid（DTPA） or methylglycinediacetic acid（MGDA） that were added to the mobile phase.An increase of the retention time of Cd was indicative of a partial or complete abstraction of Cd from HA.Our results revealed that all CAs abstracted Cd from the HA–Cd complex at concentrations of 5 μmol/L,while MGDA and DTPA were effective at 2 μmol/L.The bioavailability of some of the on-column formed CA–Cd complexes explains the previously reported increased accumulation of Cd in periphyton in the ecosystem downstream of wastewater treatment plants.In addition,our results imply that the use of effluents which contain CAs and Cd for the irrigation of food crops can introduce Cd into the food supply and compromise food safety.
文摘Eleven chelating agents were studied for their capabilities to mobilize the cadmium bound tp bovine serum albumin(BSA).The parameter F,which is defined as the ratio between the percentages of cadmium bound to BSA in the presence and absence of chelating agents,can be used as the criterion to evaluate the mobilizing capability of chelating agent.The F values determined experimentally lead to a mobilizing capability order:DTPA>EDTA>EGTA>NTA>TR1EN>PEN>CYS>HIS>SAThe polyaminopolycarboxylate type chelators mobilize cadmium effectively.A linear relationship was found between 1gF and lg k'CdL (conditional stability constant of the cadmium chelate).
文摘In this paper, the complexing abilities of EDTA, TTHA and Cit. with lead in the Pb(2.59 mg/g) contaminated soil were compared in the laboratory. Possibilities for lead and the threeagents to develop stable complexes increased proportionally to the growth of lead complexible formwhen the PH values ranged between 4 and 6. Under acid conditions, logB_(Pb-TTHA)) valued as 28.1 wasmuch higher than logB_(Pb-EDTA), as 18.0 depending on producing Pb_2-TTHA (logK_(Pb_2-TTHA= 11 0) andPb-HTTHA (logK(Pb-HTTTHA)=8.2)). Conclusively, the complexing ability of TTHA with Pb still ex-aseded that of EDTA by about 10% even when the amount of TTHA added was only equal to onefourth of that of EDTA. Due to the lower cost and less harzn to crops, Cit. can still be taken as abetter chelating agent in acid soil although its coordinative capability with Pb was weaker thanEDTA and TTHA.
文摘In a quest for better chelating therapy drugs for the treatment of intoxication by Fe, Al, oractinides, two new series of mixed catechol-bisphosphonate through amide linkage were synthesized.Benzyl group was used as protecting group to avoid the breakage of amide by acid hydrolysis orimcomplete reaction in silylation-dealkylation using bromotrimethylsilane.
文摘The current work is focused on the study of the bio-sorption of hexavalent chromium from aqueous solution using sisal natural fiber(Agave sisalana) treated by various chelating agents(ligands) such as urea(UR),thiocarbamide(TC), ethylenediaminetetraacetic acid(EDTA), and diphenyl carbazide(DCZ). The fiber treatments were investigated using Fourier Transform Infrared Spectroscopy(FTIR) and Scanning electron microscope(SEM). The kinetics of chromium bio-sorption was studied in batch presses under the effect of some physicochemical factors such as the nature of chelating agent(F@UR, F@TC, F@DCZ, and F@EDTA),adsorbent dose(2–10 g·L^(-1)), chromium initial concentration(100–500 mg·L^(-1)), solution pH(1–6), and batch temperature(20 ℃–50 ℃). This study resulted in an optimum adsorption at a chromium initial concentration of 100 mg·L^(-1), at pH 2, and at 20 ℃. The obtained results showed clearly that the treatment with chelating agent boosts the adsorptive capacity of A. sisalana fibers Cr(VI) 10.9 mg·g^(-1) to 58.6 mg·g^(-1). The modeling study showed that the adsorption kinetics obey the pseudo-second-order model, with an R2 in the range of 0.991 and 0.999. The bio-sorption isotherms followed the Langmuir model; the maximum uptake capacity of(F@N, F@UR,F@TC, F@DCZ, and F@EDTA) was found to be respectively, 12.3 mg·g^(-1), 25.33 mg·g^(-1), 28.73 mg·g^(-1),42.54 mg·g^(-1), and 61.45 mg·g^(-1). The determined adsorption thermodynamics parameters such as enthalpy,free energy, and entropy showed that the adsorption process is exothermic, spontaneous, and has a stable configuration.
基金Funded by Shandong Provincial Natural Science Foundation,China(No.ZR2014EMM019)
文摘To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydrothermal method.Different chelating agents including polyaspartic acid（PASP） and ethylenediaminetetraacetic acid（EDTA） were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys.The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres,while the coating prepared with EDTA consisted of many flower-like particles.Moreover,the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP.Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating.Immersion test of the coated samples in simulated body fluid（SBF） demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.
文摘A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment. The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the remodel of Cr(Ⅲ) by sediment from solutions and the inhibiting effect was in the order:citric acid > tartaric acid > EDTA, salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.
文摘Bleaching of the kaolin ore from Shaziling Kaolin Mine in Jiangxi Province of China was studied with the aim of enhancing the quality and value of the ore to meet the requirements from the ceramics manufacturers. Factors affecting the reductive bleaching of kaolin ore with sodium dithionite as the bleaching agent were studied and optimized to increase the whiteness of the kaolin ore from 38. 5% to about 65%. However, it was found that in the conventional bleaching process, a washing step to remove the ferrous ions from the bleached kaolin suspension was indispensable, which made the process complicated and restricted the capacity of the production. In addition, the whiteness of the bleached kaolin products was unstable. To solve the above problems, a new technique with the application of chelating agents in the bleaching process was developed to remove ferrous ions and get rid of the washing step. The bleaching process of kaolin was simplified. The whiteness of the bleached kaolin products was stabilized as well as increased to about 70%. The mechanism of the bleaching process and the action of the chelating agents were discussed.
基金supported by the College of Petroleum Engineering&Geoscience (CPG) at King Fahd University of Petroleum and Minerals (KFUPM)。
文摘Surfactants play a critical role in enhanced oil recovery(EOR) applications;however,their performance is often compromised in harsh reservoir conditions,such as high temperature and high salinity,due to precipitation caused by interactions with multivalent metal ions.Chelating agents were introduced into oilfields for various purposes due to their ability to sequester metal ions.In this work,we conducted a comprehensive investigation about chelating agent-surfactant(CS) flooding for carbonate reservoirs,as an alternative to the well-established alkaline surfactant(AS) flooding used in sandstone.The tested surfactants include sodium dodecyl sulfate(anionic)(SDS),dodecyltrimethylammonium bromide(cationic)(DTAB),Triton X100(nonionic),and a locally synthesized zwitterionic surfactant.The tested chelating agents include diethylenetriaminepentaacetic acid(DTPA),ethylenediaminetetraacetic acid,and glutamic acid N,N-diacetic acid.pH and temperature,as dominant factors in chelating agent solubility and brine stability,were modified to test chelating agent solutions of different concentrations and their mixtures with surfactants.Interfacial tension reduction by chelating agents alone,surfactants alone,and their mixtures were measured.Wettability alteration brought by chelating agents and surfactants on carbonate rock surfaces was evaluated using the static contact angle method.Based on the obtained results,chelating agents can be applied as low-cost additives for surfactant stabilization in high salinity conditions.The addition of chelating agents significantly improved the stability of SDS and DTAB in salt solutions and seawater.At a relatively low concentration(0.25 wt%),DTPA was able to stabilize DTAB of 1.00 wt% in seawater at high temperature(90℃).DTPA,among the tested three chelating agents,exhibited a stronger stabilization effect on surfactants of different ion types.When chelating agents are to be applied in brine,an optimal applicable pH range of 5-9 is recommended so not to induce solubility issue of chelating agents or stability issues of metal ions.In this range,IFT reduction is more significant at high pH,while wettability alteration is more significant at low pH.The combination of a cationic surfactant with a chelating agent forms a low adsorption wettability modifier which can change strongly oil-wet rock to water-wet conditions,thus significantly increasing the residual oil recovery from oil-wet carbonate formations.Zwitterionic and nonionic surfactants are also applicable to combine with a chelating agent for EOR purposes.Anionic surfactant SDS,however,showed a growing inhibition on the wettability alteration effect induced by EDTA as the concentration of SDS increased.
基金sponsored by Jiangsu Provincial Science and Technology Program Project(Nos.BE2022604 and BE2021701).
文摘Heavy metal stabilization and alkali neutralization are crucial for the management of municipal solid waste incineration fly ash(MSWI FA).In this study,the effects of oxalic acid(OA)and citric acid(CA)washing on heavy metal migration and alkali changes were investigated.Besides,three agents were selected to stabilize acid-washed fly ash(FA),and the effects of heavy metal stabilization under different disposal environments and the changes in their form distributions were comparatively analyzed.The experimental results demonstrated that with increasing organic acid concentration,the amount of Cd and Pb extracted from MSWI FA increased,whereas the amount of alkalis tended to decrease.Moreover,the leaching concentration of heavy metals and the percentage of unstable forms increased after acid washing.The alkalis content in the products decreased to 7.91-8.75 after stabilization,which met the standards of hazardous waste landfills.Compared with other agents,sodium diethyldithiocarbamate(DDTC)exhibited excellent heavy metal stabilization performance.After the addition of 1%DDTC,the leaching concentrations of Cd and Pb decreased to values lower than the national standard limit.Additionally,the curing rates of Cd and Pb were greater than 98%under the two leaching conditions.With the addition of DDTC,the percentage of stable forms increased,and the percentages of stable Cd and Pb forms increased to 87.68%and 99.03%,respectively,after treatment with 2%DDTC.The above results corroborated that CA coupled with DDTC stabilization can significantly reduce Cd and Pb toxicity and neutralize alkalinity in FA.
基金supported by the National Natural Science Foundation of China(Grant No.52102367)the Fundamental Research Funds for the Central Universities(WUT,effect of the synthesis method on denitrification performances of the Mn-based spinel catalysts).
文摘Four different chelating agents,ethylenediamine tetraacetic acid,citric acid,glucose,and sucrose,were selected to synthesize MnCr_(2)O_(4)catalysts(spinel structure)with sol-gel method.Among the prepared catalysts,MnCr_(2)O_(4)-S-700,which had the largest specific surface area,showed the best catalytic performance,with a T80 temperature window of 200-260℃ and a denitrification rate of up to 91.6%at 220℃.Hydrogen temperature programmed reduction,ammonia temperature programmed desorption,and X-ray photoelectron spectroscopy results showed that MnCr_(2)O_(4)-S-700 possessed more chemisorbed oxygen Oαas well as active sites(Mn^(3+)+Mn^(4+))and(Cr^(3+)+Cr^(5+)),which improved acidity and redox capacity.There was abundant electron transfer between Mn and Cr elements(Cr^(5+)+Mn^(3+)→Cr^(3+)+Mn^(4+)),enhancing the redox capacity of catalysts.According to the in situ diffuse reflectance infrared transform spectroscopy spectra,it could be concluded that the MnCr_(2)O_(4)-S-700 catalyst followed not only the Langmuir-Hinshelwood mechanism but also the Eley-Rideal mechanism.This work displays the effect of the complexation mechanism of chelating agents on the SCR reaction with NH_(3)over spinel catalysts.
文摘The effects of annealing temperatures and chelating agents on the structural and optical properties of ZnO nanoparticles were investigated.The average particle size of ZnO nanoparticles increased with increase of annealing temperatures.The decrease of the full width at half maximum(FWHM)with increasing annealing temperatures inferred increase of particle/grain growth.The grain sizes were also observed to be increased with increase of annealing temperatures.From the absorption spectra of the samples,the absorption was red-shifted and the energy band gap was blue-shifted with increase of annealing temperatures.A sharp UV emission peak was observed and the intensity of this peak increased with annealing temperatures corresponding to the high crystallinity in the samples.At high annealing temperature of 700℃,ZnO exhibited a less intense deep level emission.This negligible deep level emission was attributed to the oxygen vacancies created at higher annealing temperatures.
基金supported by the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics(11076008)the National Natural Science Foundation of China(61178018,51202024)+1 种基金the Ph.D.Funding Support Program of Education Ministry of China(20110185110007)the Fundamental Research Funds for the Central Universities(2672012ZYGX2012J048)
文摘YMn2O5nanorods were synthesized through a modified polyacrylamide gel route.The synthesis strategy in this work is based on a sol-gel process using a polyacrylamide gel method in which oxalic acid,citric acid or tartaric acid is employed as the chelating agent.In the gel routes,oxalic acid was used as a carboxyl chelating agent,while citric acid or tartaric acid was a carboxyl and hydroxyl chelating agent.The as-prepared samples were characterized by means of techniques such as X-ray powder diffraction(XRD)measurement,thermogravimetric analysis(TG),differential scanning calorimetry analysis(DSC),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),thermal expansion measurement and field-emission scanning electron microscopy(SEM)investigations.It was found that oxalic acid is the best chelating agent with Y(NO3)3·6H2O and Mn(CH3COO)2·4H2O as precursors to prepare a single orthorhombic YMn2O5nanorods at 1000°C.Scanning electron microscope observation shows that the morphology of YMn2O5powders is significantly dependent on the chelating agent.The peaks(single orthorhombic YMn2O5nanorods)at 642,600,573,546,521,493,486,468,448 and 400cm?1were observed from FTIR spectra.The phase,surface morphology and chelation mechanisms of YMn2O5samples have been discussed on the basis of the experimental results.
基金Project(2007BAQ01055)supported by the National Key Technology R&D Program of ChinaProject(2011SCU11081)supported by the Sichuan University Funds for Young Scientists,ChinaProject(20120181120103)supported by Ph.D.Programs Foundation of the Ministry of Education of China
文摘The Li3V2（PO4）3/C composite cathode material was synthesized via sol-gel method using three different chelating agents （citric acid, salicylic acid and polyacrylic acid） at pH value of 3 or 7. The crystal structure, morphology, specific surface area and electrochemical performance of the prepared samples were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and galvanostatic charge/discharge test. The results show that the effects of pH value on the performance of the prepared materials are greatly related to the chelating agents. With salicylic acid or polyacrylic acid as the chelating reagent, the structure, morphology and electrochemical performance of the samples are greatly influenced by the pH values. However, the structure of the materials with citric acid as the chelating agent does not change as pH value changes, and the materials own uniform particle size distribution and good electrochemical performance. It delivers an initial discharge capacity of 113.58 mA·h/g at 10C, remaining as high as 108.48 mA·h/g after 900 cycles, with a capacity retention of 95.51%.
文摘Fine soil generated from the soil washing process can be the second problem, as contaminants are concentrated in the fine soil, and also took the difficult forms to treat because soluble and exchangeable fractions are already removed by soil washing process; therefore, the fine soil is indicated to hazardous waste, and discarded in hazardous waste landfill. Thus, this research would be performed that arsenic and heavy metals formed difficult to remove in the fine soil were converted to more treatable fractions with chelating agents. Moreover, feasibility study to apply the second remediation targeted to the fine soil inquired. As a result, the chelating agent was decided 50 mM Na2EDTA, and it could develop the complex. In addition, the result of sequential extraction showed that Mn/Fe-oxide fraction, comprised about 28% of amount at first, was decreased about 16%, and organic fraction, consisted approximately 20%, was also decreased about 11%, while exchangeable fraction and carbonate fraction were increased. This result means that the difficult fractions removed could change fractions） by chelating agent. This research can provide the possibility hazardous waste because of difficulty to remediate. the more treatable fractions （exchangeable and carbonate to treat the fine soil, although the fine soil was regarded to
基金financially supported by the National Natural Science Foundation of China(No.21878330,21676298)the National Key R&D Program of China(2019YFC1907602)the CNPC Key Research Project(2016E-0707)。
文摘In this paper,ordered mesoporous alumina(OMA)support with the high surface area(328 m^(2)g^(-1))and the large pore volume 0.74(cm^(3)·g^(-1))was synthesized by homogeneous precipitation method.And the influence of EDTA on the physical and chemical properties of the modified catalysts was also studied.The characteristic results showed that the addition of EDTA could adjust the metal-support interaction and improved the acidity of the corresponding catalyst.Combined with the catalytic performance results,the EDTA-modified Ni Mo E(1.0)/OMA catalyst displays the highest DBT hydrodesulfurization conversion(97.7%).
基金Project(2010B050200007)supported by the Foundation of Science and Technology Planning Project of Guangdong Province,ChinaProject(2011ZM0054)supported by the Fundamental Research Funds for the Central Universities,China+1 种基金Project(2011K0013)supported by the Research Fund Program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology,ChinaProject(2012)supported by the Research Funds of Guangdong Provincial Key Laboratory of Atmospheric environment and Pollution Control,China
文摘In the interest of accelerating aniline degradation, Fe2+ and chelated Fe2+ activated persulfate oxidations were investigated in neutral pH condition. Three kinds of chelating agents were selected including citric acid, oxalic acid and ethylenediamine tetraaceatate(EDTA) to maintain available Fe2+. The results indicate that the concentration of chelating agent and ferrous ion didn't follow a linear relationship with the degradation rate of aniline. A 1/1 ratio of chelating agent/Fe2+ results in a higher degradation rate compared to the results by other ratios. The oxidation enhancement factor using oxalic acid was found to be relatively low. In contrast, citric acid is more suitable chelating agent in the ferrous iron activated persulfate system and aniline exhibits a highest degradation with a persulfate/Fe2+/citric acid/aniline molar ratio of 50/25/25/1 compared to other molar ratios.
文摘For realizing the effective flotation of refractory copper ox-idized ores and developing the activation-flotation theory , the influences of nine different organic chelating agents on xanthate collection pcnver and its adsorption characteristics ivere studied in the flotation of malachite and chrysocolla representatively selected by means of XPS,IR, absorbed quanti-ty measurements and flotation tests.For easily-dissolved malachite flotation , a small amount of chelating agent can obviously enhance xanthate collecting power and make malachite floated easily , and so reduces the consumption of xanthate. For hard-dis-晄olved chrysocolla, chelating agent is able to increase its recovery to 90% , but the chelating agent consumption is high. Chelating agent and xanthate can produce synergistic adsorptions, which follmv Freundlich's adsorption equation on malachite and Chrysocolla surfaces. The high chemical activity of chelating agent and its synergistic activation on xanthate are the key to improving xanthate collection poiver. The synergistic activation of chelat-ing agent on xanthate on melachite surfaces is clearly stronger than on chrysocolla surfaces. According to experimental results, it can be thought that the synergistic activation results from the synergistic complexation of chelating agent and xanthate with copper ions to form biligand-tribasic co-ordination complex.
