| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4482356 | Water Research | 2012 | 10 Pages |
Nano zero-valent iron (NZVI) offers a promising approach for arsenic remediation, but the spent NZVI with elevated arsenic content could arouse safety concerns. This study investigated the fate of As(V)-treated NZVI (As-NZVI), by examining the desorption potential of As under varying conditions. The desorption kinetics of As from As-NZVI as induced by phosphate was well described by a biphasic rate model. The effects of As(V)/NZVI mass ratio, pH, and aging time on arsenic desorption from As-NZVI by phosphate were investigated. Less arsenic desorption was observed at lower pH or higher As(V)/NZVI mass ratio, where stronger complexes (bidentate) formed between As(V) and NZVI corrosion products as indicated by FTIR analysis. Compared with the fresh As-NZVI, the amount of phosphate-extractable As significantly decreased in As-NZVI aged for 30 or 60 days. The results of the sequential extraction experiments demonstrated that a larger fraction of As was sorbed in the crystalline phases after aging, making it less susceptible to phosphate displacement. However, at pH 9, a slightly higher proportion of phosphate-extractable As was observed in the 60-day sample than in the 30-day sample. XPS results revealed the transformation of As(V) to more easily desorbed As(III) during aging and a higher As(III)/As(V) ratio in the 60-day sample at pH 9, which might have resulted in the higher desorption.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (134 K)Download as PowerPoint slideHighlights► The desorption kinetics of As from As-NZVIs was well described by a biphasic model. ► The effects of As(V)/NZVI mass ratio, pH, and aging time were investigated. ► Less arsenic desorption was observed at lower pH or higher As(V)/NZVI mass ratio. ► A larger fraction of As was sorbed in the crystalline phases after aging. ► At pH 9, the transformation of As(V) to As(III) occurred during aging.
