Sorption of carbon tetrachloride (CT) by zero-valent iron (ZVI) is the rate-limiting step in the degradation of CT, so the sorption capacity of ZVI is of great importance. This experiment was aimed at enhancing the so...Sorption of carbon tetrachloride (CT) by zero-valent iron (ZVI) is the rate-limiting step in the degradation of CT, so the sorption capacity of ZVI is of great importance. This experiment was aimed at enhancing the sorption of CT by ZVI and the degradation rate of CT by modification of surfactants. This study showed that ZVI modified by cationic surfactants has favorable synergistic effect on the degradation of CT. The CT degradation rate of ZVI modified by cetyl pyridinium bromide (CPB) was higher than that of the unmodified ZVI by 130%, and the CT degradation rate of ZVI modified by cetyl trimethyl ammonium bromide (CTAB) was higher than that of the unmodified ZVI by 81%. This study also showed that the best degradation effect is obtained at the near critical micelle concentrations (CMC) and that high loaded cationic surfactant does not have good synergistic effect on the degradation due to its hydrophilicity and the block in surface reduction sites. Furthermore degradation of CT by ZVI modified by nonionic surfactant has not positive effect on the degradation as the ionic surfactant and the ZVI modified by anionic surfactant has hardly any obvious effects on the degradation.展开更多
ZVI/nZVI凭借其优异的污染物去除性能以及在环境修复中的其他优点,引起了国内外研究人员的极大关注。基于中国知网和Web of Science核心合集数据库中英文文献数据,对国内外微生物协同零价铁(ZVI)/纳米零价铁(nZVI)的相关文献进行年代分...ZVI/nZVI凭借其优异的污染物去除性能以及在环境修复中的其他优点,引起了国内外研究人员的极大关注。基于中国知网和Web of Science核心合集数据库中英文文献数据,对国内外微生物协同零价铁(ZVI)/纳米零价铁(nZVI)的相关文献进行年代分布、期刊分布、关键词共现、时间演进及突现等方面的文献计量分析。结果显示,年度论文总数的增长趋势可分为3个阶段。中国是这一领域最活跃的国家,Journal of Hazardous Materials是出版物数量最多的期刊。有关ZVI与微生物的研究重点是甲烷生产、厌氧消化、脱氯作用;微生物协同nZVI的研究集中于微生物群落、修复、生物毒性、生物炭。关键词的时间演进图谱将其分为9种聚类,关键词的突现分析表明细胞分子水平的机理研究和零价铁生物毒性的创新可能是未来的研究方向。展开更多
Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（...Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,Fourier-transform infrared（FTIR） spectroscopy and Brunauer–Emmett–Teller（BET） analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr（Ⅵ） removal performance. The results showed that the Cr（Ⅵ） removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG（10.00%） and ZⅥ（29.80%）. Furthermore, the removal rate of Cr（Ⅵ） by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr（Ⅵ） removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr（Ⅵ） via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy（XPS） was used to analyze the mechanisms of Cr（Ⅵ） removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr（Ⅵ） was immobilized via the formation of Cr（III） hydroxide and Cr（III）–Fe（III）hydroxide/oxyhydroxide on the surface of EG-ZⅥ.展开更多
Process control parameters influencing microbial perchlorate reduction via a flow-through zero-valent iron （ZVI） column reactor were investigated in order to optimize perchlorate removal from water. Mixed perchlorat...Process control parameters influencing microbial perchlorate reduction via a flow-through zero-valent iron （ZVI） column reactor were investigated in order to optimize perchlorate removal from water. Mixed perchlorate reducers were obtained from a wastewater treatment plant and inoculated into the reactor without further acclimation. Examined parameters included hydraulic residence time （HRT）, pH, nutrients requirement, and perchlorate reduction kinetics. The minimum HRT for the system was concluded to be 8 hr. The removal efficiency of 10 mg. L-1 influent perchlorate concentration was reduced by 20%-80% without control to the neutral pH （HRT = 8 hr）. Therefore pH was determined to be an important parameter for microbial perchlorate reduction. Furthermore, a viable alternative to pH buffer was discussed. The microbial perchlorate reduction followed the first order kinetics, with a rate constant （K） of 0.761 hr-1. The results from this study will contribute to the implementation of a safe, cost effective, and efficient system for perchlorate reduction to below regulated levels.展开更多
基金Project (No. 20030352) supported the Science and TechnologyProgram of Zhejiang Province, China
文摘Sorption of carbon tetrachloride (CT) by zero-valent iron (ZVI) is the rate-limiting step in the degradation of CT, so the sorption capacity of ZVI is of great importance. This experiment was aimed at enhancing the sorption of CT by ZVI and the degradation rate of CT by modification of surfactants. This study showed that ZVI modified by cationic surfactants has favorable synergistic effect on the degradation of CT. The CT degradation rate of ZVI modified by cetyl pyridinium bromide (CPB) was higher than that of the unmodified ZVI by 130%, and the CT degradation rate of ZVI modified by cetyl trimethyl ammonium bromide (CTAB) was higher than that of the unmodified ZVI by 81%. This study also showed that the best degradation effect is obtained at the near critical micelle concentrations (CMC) and that high loaded cationic surfactant does not have good synergistic effect on the degradation due to its hydrophilicity and the block in surface reduction sites. Furthermore degradation of CT by ZVI modified by nonionic surfactant has not positive effect on the degradation as the ionic surfactant and the ZVI modified by anionic surfactant has hardly any obvious effects on the degradation.
文摘ZVI/nZVI凭借其优异的污染物去除性能以及在环境修复中的其他优点,引起了国内外研究人员的极大关注。基于中国知网和Web of Science核心合集数据库中英文文献数据,对国内外微生物协同零价铁(ZVI)/纳米零价铁(nZVI)的相关文献进行年代分布、期刊分布、关键词共现、时间演进及突现等方面的文献计量分析。结果显示,年度论文总数的增长趋势可分为3个阶段。中国是这一领域最活跃的国家,Journal of Hazardous Materials是出版物数量最多的期刊。有关ZVI与微生物的研究重点是甲烷生产、厌氧消化、脱氯作用;微生物协同nZVI的研究集中于微生物群落、修复、生物毒性、生物炭。关键词的时间演进图谱将其分为9种聚类,关键词的突现分析表明细胞分子水平的机理研究和零价铁生物毒性的创新可能是未来的研究方向。
基金supported by the National Key Research and Development Program of China(No.2017YFD0801503)the Fundamental Research Funds for the Central Universities(No.PYVZ1703)the Higher Education and High-quality and World-class Universities(PY201606)
文摘Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,Fourier-transform infrared（FTIR） spectroscopy and Brunauer–Emmett–Teller（BET） analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr（Ⅵ） removal performance. The results showed that the Cr（Ⅵ） removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG（10.00%） and ZⅥ（29.80%）. Furthermore, the removal rate of Cr（Ⅵ） by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr（Ⅵ） removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr（Ⅵ） via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy（XPS） was used to analyze the mechanisms of Cr（Ⅵ） removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr（Ⅵ） was immobilized via the formation of Cr（III） hydroxide and Cr（III）–Fe（III）hydroxide/oxyhydroxide on the surface of EG-ZⅥ.
文摘Process control parameters influencing microbial perchlorate reduction via a flow-through zero-valent iron （ZVI） column reactor were investigated in order to optimize perchlorate removal from water. Mixed perchlorate reducers were obtained from a wastewater treatment plant and inoculated into the reactor without further acclimation. Examined parameters included hydraulic residence time （HRT）, pH, nutrients requirement, and perchlorate reduction kinetics. The minimum HRT for the system was concluded to be 8 hr. The removal efficiency of 10 mg. L-1 influent perchlorate concentration was reduced by 20%-80% without control to the neutral pH （HRT = 8 hr）. Therefore pH was determined to be an important parameter for microbial perchlorate reduction. Furthermore, a viable alternative to pH buffer was discussed. The microbial perchlorate reduction followed the first order kinetics, with a rate constant （K） of 0.761 hr-1. The results from this study will contribute to the implementation of a safe, cost effective, and efficient system for perchlorate reduction to below regulated levels.
