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2020 2

2014 1

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The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Yameng Li, Ziyu Liang

《环境科学与工程前沿（英文）》 2020年 第14卷 第6期 doi: 10.1007/s11783-020-1273-6

摘要： Abstract • Simply doping sands with ZVI achieved an even activation of ZVI by oxidants. • Sand doping facilitated proportional As trapping along the ZVI/oxidants column. • ZVI/sand/oxidants are highly efficient for arsenic removal. • ZVI/sand/oxidants reduced significantly the Fe2+ leaching and effluent turbidity. • More than 54% of arsenic was reduced to As(III) in ZVI/sand/oxidants system. The coupling of zero-valent iron (ZVI) with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater. However, the uniform activation of ZVI throughout the column and the proportional removal of target contaminants are urgently required for the prevention of premature filter clogging and the extension of the effective column operational time. In this study, we successfully achieved this objective by simply doping granular sand with ZVI at appropriate weight ratios. When pure ZVI packed column was spiked with oxidants, the majority of As trapping occurred between the column inlet and the first sampling point. In a packed column with a 1:20 mixture of ZVI and sand, the average As removal efficiency was 36 (1st), 13.1 (2nd), 18.5 (3rd), 19.2 (4th) and 5.9% (5th outlet). The overall arsenic removal performance of the composite filling system of ZVI/sand was equally as efficient as that of the previous pure ZVI-packed system. Moreover, the leaching of Fe was significantly reduced with an increased sand ratio, resulting in clearer water with less turbidity. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that more than 54% of the arsenic was reduced to As(III). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the extensive corrosion of the ZVI surface, which resulted in various species of iron oxyhydroxides responsible for the highly efficient sequester of arsenic through reduction, adsorption, and coprecipitation.

关键词： Arsenic     ZVI     Sand     Oxidants     Fixed-bed Column     Removal    

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Rapid and long-effective removal of broad-spectrum pollutants from aqueous system by ZVI/oxidants

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Siwen Leng, Na Ma, Palwasha Faiz

《环境科学与工程前沿（英文）》 2020年 第14卷 第5期 doi: 10.1007/s11783-020-1268-3

摘要： Abstract • The coupling of oxidants with ZVI overcome the impedance of ZVI passive layer. • ZVI/oxidants system achieved fast and long-effective removal of contaminants. • Multiple mechanisms are involved in contaminants removal by ZVI/oxidant system. • ZVI/Oxidants did not change the reducing property of ORP in the fixed-bed system. Zero-valent iron (ZVI) technology has recently gained significant interest in the efficient sequestration of a wide variety of contaminants. However, surface passivation of ZVI because of its intrinsic passive layer would lead to the inferior reactivity of ZVI and its lower efficacy in contaminant removal. Therefore, to activate the ZVI surface cheaply, continuously, and efficiently is an important challenge that ZVI technology must overcome before its wide-scale application. To date, several physical and chemical approaches have been extensively applied to increase the reactivity of the ZVI surface toward the elimination of broad-spectrum pollutants. Nevertheless, these techniques have several limitations such as low efficacy, narrow working pH, eco-toxicity, and high installation cost. The objective of this mini-review paper is to identify the critical role of oxygen in determining the reactivity of ZVI toward contaminant removal. Subsequently, the effect of three typical oxidants (H2O2, KMnO4, and NaClO) on broad-spectrum contaminants removal by ZVI has been documented and discussed. The reaction mechanism and sequestration efficacies of the ZVI/oxidant system were evaluated and reviewed. The technical basis of the ZVI/oxidant approach is based on the half-reaction of the cathodic reduction of the oxidants. The oxidants commonly used in the water treatment industry, i.e., NaClO, O3, and H2O2, can be served as an ideal coupling electron receptor. With the combination of these oxidants, the surface corrosion of ZVI can be continuously driven. The ZVI/oxidants technology has been compared with other conventional technologies and conclusions have been drawn.

关键词： Zero-Valent Iron (ZVI)     Oxidants     Heavy Metals (HMs)     Metalloids     Nitrate     Phosphate    

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Process control factors for continuous microbial perchlorate reduction in the presence of zero-valent iron

ARTHUR Robert D.,TORLAPATI Jagadish,SHIN Kyung-Hee,CHA Daniel K.,YOON Yeomin,SON Ahjeong

《环境科学与工程前沿（英文）》 2014年 第8卷 第3期   页码 386-393 doi: 10.1007/s11783-013-0593-1

摘要： 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 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 ( ) of 0.761 hr . 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.

关键词： perchlorate     zero-valent iron (ZVI)     microbial reduction     hydrogen    

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标题 作者 时间 类型 操作

The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Yameng Li, Ziyu Liang

期刊论文

Rapid and long-effective removal of broad-spectrum pollutants from aqueous system by ZVI/oxidants

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Siwen Leng, Na Ma, Palwasha Faiz

期刊论文

Process control factors for continuous microbial perchlorate reduction in the presence of zero-valent iron

ARTHUR Robert D.,TORLAPATI Jagadish,SHIN Kyung-Hee,CHA Daniel K.,YOON Yeomin,SON Ahjeong

期刊论文