The capability of traditional ligand in countering rapid passivation on nanoscale zero-valent iron(nZVI)surface is inadequate,and the precise electron transfer mechanism remains elusive.In this study,we reported that ...The capability of traditional ligand in countering rapid passivation on nanoscale zero-valent iron(nZVI)surface is inadequate,and the precise electron transfer mechanism remains elusive.In this study,we reported that myo-inositol hexakisphosphate(IHP),a redox-inactive organophosphorus in soil,could highly enhance Cr(VI)reduction and immobilization in comparison with typical ligands(TPP,EDTA,oxalate and phosphate).And the effects of IHP concentration,Cr(VI)concentration and initial pH were systematically investigated.Cr Kedge XANES and XPS analysis revealed that Cr(III)was the exclusive form in solid products regardless of IHP existence.Results of ATR-FTIR and FESEM inferred that IHP was adsorbed on nZVI surface via inner-sphere complexation,thus averting encapsulation of[Fe,Cr](OH)_(3)coprecipitate and impeding solid particles agglomeration.Additionally,IHP expedited the production of surface-bound Fe(II),primarily attributable to the interaction between nZVI and oxygen.These surface-bound Fe(II)species played a pivotal role in Cr(VI)reduction.Electrochemical analysis unveiled that IHP lowered redox potential of Fe(III)/Fe(II),thereby facilitating reaction between Fe(II)and Cr(VI),whereas inhibited direct electron transfer from nZVI core to Cr(VI).Our findings proposed a novel potential ligand for alleviating nZVI passivation in Cr(VI)removal and deepened our understanding in the process of electron transfer.展开更多
Nano zero-valent iron(nZVI)is a promising phosphate adsorbent for advanced phosphate removal.However,the rapid passivation of nZVI and the low activity of adsorption sites seriously limit its phosphate removal perform...Nano zero-valent iron(nZVI)is a promising phosphate adsorbent for advanced phosphate removal.However,the rapid passivation of nZVI and the low activity of adsorption sites seriously limit its phosphate removal performance,accounting for its inapplicability to meet the emission criteria of 0.1 mg P/L phosphate.In this study,we report that the oxalate modification can inhibit the passivation of nZVI and alter the multi-stage phosphate adsorption mechanism by changing the adsorption sites.As expected,the stronger antipassivation ability of oxalate modified nZVI(OX-nZVI)strongly favored its phosphate adsorption.Interestingly,the oxalate modification endowed the surface Fe(III)sites with the lowest chemisorption energy and the fastest phosphate adsorption ability than the other adsorption sites,by in situ forming a Fe(III)-phosphate-oxalate ternary complex,therefore enabling an advanced phosphate removal process.At an initial phosphate concentration of 1.00 mg P/L,pH of 6.0 and a dosage of 0.3 g/L of adsorbents,OX-nZVI exhibited faster phosphate removal rate(0.11 g/mg/min)and lower residual phosphate level(0.02 mg P/L)than nZVI(0.055 g/mg/min and 0.19 mg P/L).This study sheds light on the importance of site manipulation in the development of high-performance adsorbents,and offers a facile surface modification strategy to prepare superior iron-basedmaterials for advanced phosphate removal.展开更多
采用改进的两步法在原位基础上合成了以纳米零价铁(nano Zero Valent Iron,nZVI)为核芯的核壳型介孔二氧化硅(nZVI@mesoSiO_2).同时,通过简单地调控铁源用量得到具有单一nZVI核芯和不同壳层厚度的核壳型纳米复合材料.结果发现,铁源用量...采用改进的两步法在原位基础上合成了以纳米零价铁(nano Zero Valent Iron,nZVI)为核芯的核壳型介孔二氧化硅(nZVI@mesoSiO_2).同时,通过简单地调控铁源用量得到具有单一nZVI核芯和不同壳层厚度的核壳型纳米复合材料.结果发现,铁源用量的增加会导致核芯尺寸减小、壳层厚度增加及颗粒比表面积下降.当铁源用量为2.78 g时,得到的nZVI@mesoSiO_2不仅具有较高的比表面积和单一且均匀的孔径分布,而且对2,4,6-三氯苯酚(2,4,6-Trichlorophenol, 2,4,6-TCP)的去除表现出很高的性能.影响因素实验表明,材料的最佳投加量为1.0 g·L^(-1),体系适宜初始pH为5.0,污染物初始浓度升高会导致去除效果下降,并且反应体系内乙二胺四乙酸(EDTA)的存在可以提高2,4,6-TCP的去除率.材料的重复利用实验结果表明,经过多次循环反应后会导致材料nZVI核芯的失活和孔道的堵塞.本研究不仅为制备可控壳层厚度的核壳型介孔材料提供了理论指导,而且为进一步改性合成对2,4,6-TP具有高选择性的复合材料提供了依据.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42030709 and 42377303)the National Key Research and Development Program of China(No.2020YFC1806803).
文摘The capability of traditional ligand in countering rapid passivation on nanoscale zero-valent iron(nZVI)surface is inadequate,and the precise electron transfer mechanism remains elusive.In this study,we reported that myo-inositol hexakisphosphate(IHP),a redox-inactive organophosphorus in soil,could highly enhance Cr(VI)reduction and immobilization in comparison with typical ligands(TPP,EDTA,oxalate and phosphate).And the effects of IHP concentration,Cr(VI)concentration and initial pH were systematically investigated.Cr Kedge XANES and XPS analysis revealed that Cr(III)was the exclusive form in solid products regardless of IHP existence.Results of ATR-FTIR and FESEM inferred that IHP was adsorbed on nZVI surface via inner-sphere complexation,thus averting encapsulation of[Fe,Cr](OH)_(3)coprecipitate and impeding solid particles agglomeration.Additionally,IHP expedited the production of surface-bound Fe(II),primarily attributable to the interaction between nZVI and oxygen.These surface-bound Fe(II)species played a pivotal role in Cr(VI)reduction.Electrochemical analysis unveiled that IHP lowered redox potential of Fe(III)/Fe(II),thereby facilitating reaction between Fe(II)and Cr(VI),whereas inhibited direct electron transfer from nZVI core to Cr(VI).Our findings proposed a novel potential ligand for alleviating nZVI passivation in Cr(VI)removal and deepened our understanding in the process of electron transfer.
基金supported by the National Key Research and Development Program of China(Nos.2022YFA1205602,and 2023YFC3707801)the National Natural Science Foundation of China(Nos.U22A20402,22376073,21936003 and 22306119)China Postdoctoral Science Foundation(No.2023T160419).
文摘Nano zero-valent iron(nZVI)is a promising phosphate adsorbent for advanced phosphate removal.However,the rapid passivation of nZVI and the low activity of adsorption sites seriously limit its phosphate removal performance,accounting for its inapplicability to meet the emission criteria of 0.1 mg P/L phosphate.In this study,we report that the oxalate modification can inhibit the passivation of nZVI and alter the multi-stage phosphate adsorption mechanism by changing the adsorption sites.As expected,the stronger antipassivation ability of oxalate modified nZVI(OX-nZVI)strongly favored its phosphate adsorption.Interestingly,the oxalate modification endowed the surface Fe(III)sites with the lowest chemisorption energy and the fastest phosphate adsorption ability than the other adsorption sites,by in situ forming a Fe(III)-phosphate-oxalate ternary complex,therefore enabling an advanced phosphate removal process.At an initial phosphate concentration of 1.00 mg P/L,pH of 6.0 and a dosage of 0.3 g/L of adsorbents,OX-nZVI exhibited faster phosphate removal rate(0.11 g/mg/min)and lower residual phosphate level(0.02 mg P/L)than nZVI(0.055 g/mg/min and 0.19 mg P/L).This study sheds light on the importance of site manipulation in the development of high-performance adsorbents,and offers a facile surface modification strategy to prepare superior iron-basedmaterials for advanced phosphate removal.
