文獻名： The double influence mechanism of pH on arsenic removal by nano zero valent iron: electrostatic interactions and the corrosion of Fe0

 

作者： Can Wu,^a  Jingwei Tu,^a  Weizhen Liu,^a  Jing Zhang,^b  Shengqi Chu,^b  Guining Lu,^a  Zhang Lin ^a  and  Zhi Dang ^a   

^a School of Environment and Energy, The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters (Ministry of Education), Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, Guangzhou Higher Education Mega Center, South China University of Technology, Guangzhou, China

^b Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China

 

摘要：The pH has a significant impact on arsenic (As) removal by nano zero valent iron (nZVI). However, most studies consider the influence mechanism just from the aspect of electrostatic interactions. In this study, based on the different As(V) adsorption capacity of nZVI and zero valent iron (ZVI) after normalization by specific surface area, we deeply analyze the comprehensive mechanism of arsenic adsorption by nZVI at varying pH values. Batch experiment shows that pH variation has a weaker influence on the As(V) adsorption by nZVI compared to ZVI. X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES) analysis indicated that with the coexistence of low concentration As(V) species, the increasing pH value condition does not significantly change the phase of ZVI; however, it decreases the lepidocrocite (γ-FeOOH) and increases the magnetite/maghemite (Fe3O4/γ-Fe2O3) content in the corrosion products of nZVI, while the latter has stronger adsorption affinity to As(V). An increase in the solution pH causes a change in the nature of the corrosion products, enhancing the adsorption affinity of nZVI towards As(V), which complements the negative impact from electrostatic repulsive-force. This study clearly demonstrated that the corrosion of nZVI plays a more important role in As(V) adsorption compared to electrostatic interactions. This indicates that nZVI is a promising nanomaterial with unique properties that aid in the removal of As(V) in a broad pH range and complicated environment.