Removal of As(III) and As(V) from aqueous solutions using nanoscale zero valent iron-reduced graphite oxide modified composites

Abstract

Nanoscale zero valent iron (NZVI) has high adsorption capacity of As(III) and As(V), but it is limited in practical use due to its small particle size and aggregation effect. Reduce graphite oxide (RGO) has been used as a support because of its high surface area. In order to utilize the advantage of NZVI and RGO as well as to avoid the disadvantage of NZVI, we loaded NZVI onto RGO via chemical reactions in this study. The adsorption capacity of As(III) and As(V), as determined from the Langmuir adsorption isotherms in batch experiments, was 35.83 mg g−1 and 29.04 mg g−1, respectively. And the adsorption kinetics fitted well with pseudo-second-order model. The residual concentration was found to meet the standard of WHO after the samples were treated with 0.4 g L−1 NZVI–RGO when the initial concentration of As(III) and As(V) were below 8 ppm and 3 ppm. Especially, when the initial concentration of As(III) was below 3 ppm, the residual concentration was within 1 ppb; whereas, the residual concentration was undetected when the initial concentration of As(III) was 1 ppm.