Novel adsorbent, Fe（Ⅲ）-loaded ligand exchange cotton cellulose adsorbent [Fe（Ⅲ） LECCA], was used to in vestigate the adsorption performances and mechanism of fluoride removal from aqueous solutions. The adsorben...Novel adsorbent, Fe（Ⅲ）-loaded ligand exchange cotton cellulose adsorbent [Fe（Ⅲ） LECCA], was used to in vestigate the adsorption performances and mechanism of fluoride removal from aqueous solutions. The adsorbent was found to adsorb fluoride rapidly and effectively. The fluoride removal was influenced by pH. Adsorption mode followed first-order reaction at different temperature, theapparent adsorption activated energy Ea was 6.37 kJ·mol^-1, and adsorption enthalpy △H was 5.35 kJ·mol^-1. The adsorption enfluoride on adsorbent was 3.2 mmol·g^-1 （dry weight）. The maximal integer coordination ratio of fluoride with Fe（Ⅲ） LECCA was 3：1. The ligand exchange mechanism of adsorption was elucidated through chemical methods and IR spectral analysis.展开更多
Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ...Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe^3+) dosage. The existence of a critical pH value determining the catalysis ofFe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.展开更多
通过微生物试验,比较了草酸浓度对微生物还原高岭土中Fe(Ⅲ)所起的作用;用环境扫描电镜(ESEM)和能量弥散X-射线谱图(EDS)分析了处理前后高岭土的结构变化。结果表明,在异化铁还原菌(dissimilatory iron reducing bacteria,DIRB)存在下,...通过微生物试验,比较了草酸浓度对微生物还原高岭土中Fe(Ⅲ)所起的作用;用环境扫描电镜(ESEM)和能量弥散X-射线谱图(EDS)分析了处理前后高岭土的结构变化。结果表明,在异化铁还原菌(dissimilatory iron reducing bacteria,DIRB)存在下,加入0.2g/L的草酸,对Fe(Ⅲ)的还原效果最好;草酸浓度过高或过低对Fe(Ⅲ)的还原都有抑制,当草酸浓度为1.5g/L时,微生物活性完全被抑制,此时Fe(Ⅲ)的还原量较低。化学对比试验表明,高岭土中Fe(Ⅲ)的还原随草酸浓度的增加逐渐增大,当草酸浓度达到13.0g/L时,化学处理1天后Fe(Ⅲ)的还原量与微生物处理4天相当。ESEM和EDS的测试结果表明,高岭土中微生物还原Fe(Ⅲ)的过程,并不改变高岭土的主要结构,铁元素被微生物选择性的还原。展开更多
Microbial Fe(Ⅲ)reduction is a significant driving force for the biogeochemical cycles of C,O,P,S,N,and dominates the natural bio-purification of contaminants in groundwater(e.g.,petroleum hydrocarbons,chlorinated eth...Microbial Fe(Ⅲ)reduction is a significant driving force for the biogeochemical cycles of C,O,P,S,N,and dominates the natural bio-purification of contaminants in groundwater(e.g.,petroleum hydrocarbons,chlorinated ethane,and chromium).In this review,the mechanisms and environmental significance of Fe(Ⅲ)(hydro)oxides bioreduction are summarized.Compared with crystalline Fe(Ⅲ)(hydro)oxides,amorphous Fe(m)(hydro)oxides are more bioavailable.Ligand and electron shuttle both play an important role in microbial Fe(Ⅲ)reduction.The restrictive factors of Fe(Ⅲ)(hydro)oxides bioreduction should be further investigated to reveal the characteristics and mechanisms of the process.It will improve the bioavailability of crystalline Fe(Ⅲ)(hydro)oxides and accelerate the anaerobic oxidation efficiency of the reduction state pollutants.Furthermore,the approach to extract,culture,and incubate the functional Fe(Ⅲ)reducing bacteria from actual complicated environment,and applying it to the bioremediation of organic,ammonia,and heavy metals contaminated groundwater will become a research topic in the future.There are a broad application prospects of Fe(Ⅲ)(hydro)oxides bioreduction to groundwater bioremediation,which includes the in situ injection and permeable reactive barriers and the innovative Kariz wells system.The study provides an important reference for the treatment of reduced pollutants in contaminated groundwater.展开更多
文摘Novel adsorbent, Fe（Ⅲ）-loaded ligand exchange cotton cellulose adsorbent [Fe（Ⅲ） LECCA], was used to in vestigate the adsorption performances and mechanism of fluoride removal from aqueous solutions. The adsorbent was found to adsorb fluoride rapidly and effectively. The fluoride removal was influenced by pH. Adsorption mode followed first-order reaction at different temperature, theapparent adsorption activated energy Ea was 6.37 kJ·mol^-1, and adsorption enthalpy △H was 5.35 kJ·mol^-1. The adsorption enfluoride on adsorbent was 3.2 mmol·g^-1 （dry weight）. The maximal integer coordination ratio of fluoride with Fe（Ⅲ） LECCA was 3：1. The ligand exchange mechanism of adsorption was elucidated through chemical methods and IR spectral analysis.
文摘Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe^3+) dosage. The existence of a critical pH value determining the catalysis ofFe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.
文摘通过微生物试验,比较了草酸浓度对微生物还原高岭土中Fe(Ⅲ)所起的作用;用环境扫描电镜(ESEM)和能量弥散X-射线谱图(EDS)分析了处理前后高岭土的结构变化。结果表明,在异化铁还原菌(dissimilatory iron reducing bacteria,DIRB)存在下,加入0.2g/L的草酸,对Fe(Ⅲ)的还原效果最好;草酸浓度过高或过低对Fe(Ⅲ)的还原都有抑制,当草酸浓度为1.5g/L时,微生物活性完全被抑制,此时Fe(Ⅲ)的还原量较低。化学对比试验表明,高岭土中Fe(Ⅲ)的还原随草酸浓度的增加逐渐增大,当草酸浓度达到13.0g/L时,化学处理1天后Fe(Ⅲ)的还原量与微生物处理4天相当。ESEM和EDS的测试结果表明,高岭土中微生物还原Fe(Ⅲ)的过程,并不改变高岭土的主要结构,铁元素被微生物选择性的还原。
基金This work was supported by the National Natural Science Foundation of China(Grant No.21606214)the Water Pollution Control and Control of Major National Science and Technology Projects in China(No.2018ZX07109-003)。
文摘Microbial Fe(Ⅲ)reduction is a significant driving force for the biogeochemical cycles of C,O,P,S,N,and dominates the natural bio-purification of contaminants in groundwater(e.g.,petroleum hydrocarbons,chlorinated ethane,and chromium).In this review,the mechanisms and environmental significance of Fe(Ⅲ)(hydro)oxides bioreduction are summarized.Compared with crystalline Fe(Ⅲ)(hydro)oxides,amorphous Fe(m)(hydro)oxides are more bioavailable.Ligand and electron shuttle both play an important role in microbial Fe(Ⅲ)reduction.The restrictive factors of Fe(Ⅲ)(hydro)oxides bioreduction should be further investigated to reveal the characteristics and mechanisms of the process.It will improve the bioavailability of crystalline Fe(Ⅲ)(hydro)oxides and accelerate the anaerobic oxidation efficiency of the reduction state pollutants.Furthermore,the approach to extract,culture,and incubate the functional Fe(Ⅲ)reducing bacteria from actual complicated environment,and applying it to the bioremediation of organic,ammonia,and heavy metals contaminated groundwater will become a research topic in the future.There are a broad application prospects of Fe(Ⅲ)(hydro)oxides bioreduction to groundwater bioremediation,which includes the in situ injection and permeable reactive barriers and the innovative Kariz wells system.The study provides an important reference for the treatment of reduced pollutants in contaminated groundwater.
