Nano zero-valent iron (nZVI) is widely used in the arsenic (As) remediation of groundwater. During the remediation, nZVI reacts with As and then forms As-loaded nZVI. Unfortunately, some concerns occur regarding the release of As-loaded nZVI particles and their subsequent transport in aquatic environments, as well as the As release from As-loaded nZVI. This study investigated the fate and transport of the three types of As-loaded nZVI (As-loaded pristine, chitosan-modified and polyaniline-modified nZVI) at two levels of As loadings (low and high), under conditions related to practical groundwater remediation.

In batch studies, the alkaline condition and the presence of humic acid were found to enhance the As release from all types of As-loaded nZVI. Ca²⁺ did not affect the As re...[ Read more ]

Nano zero-valent iron (nZVI) is widely used in the arsenic (As) remediation of groundwater. During the remediation, nZVI reacts with As and then forms As-loaded nZVI. Unfortunately, some concerns occur regarding the release of As-loaded nZVI particles and their subsequent transport in aquatic environments, as well as the As release from As-loaded nZVI. This study investigated the fate and transport of the three types of As-loaded nZVI (As-loaded pristine, chitosan-modified and polyaniline-modified nZVI) at two levels of As loadings (low and high), under conditions related to practical groundwater remediation.

In batch studies, the alkaline condition and the presence of humic acid were found to enhance the As release from all types of As-loaded nZVI. Ca²⁺ did not affect the As release from As-loaded pristine nZVI at both low and high As loadings, but affected the As release from both types of As-loaded nZVI (As-loaded chitosan-modified and polyaniline-modified nZVI) at high As loading. Surface modification and high As loading reduced the As release from the three types of As-loaded nZVI.

In column studies, surface modification and high As loading enhanced the mobility of the three types of As-loaded nZVI. The As in the effluent was from the As release when nZVI was not detected. It was evident that the mobility of the three types of As-loaded nZVI particles were limited, at both As loadings. Thus, the As release, instead of As-loaded nZVI particles, can cause wide As contamination in groundwater.

This study is the first time to systematically investigate the fate and transport of As-loaded nZVI in groundwater system. The findings could assess the potential risk caused by the As released from the As-loaded nZVI under different geochemical conditions and also provide guidelines for the selections of surface modification as well as the nZVI dosage regarding the As release in groundwater.