Synergistic removal of As(V) from aqueous solution by nanozero valent iron loaded with zeolite 5A synthesized from fly ash

Abstract

Nanozero valent iron (NZVI) loaded on zeolite 5A can efficiently remove As(V) in water through the synergism of zeolite 5A and NZVI. In this study, zeolite 5A was first obtained by ion exchange using zeolite 4A synthesized from fly ash and CaCl2, and then NZVI-5A zeolite was synthesized by a reduction method to load NZVI on zeolite 5 A. NZVI-5A zeolite had a specific surface area of 238 m2/g. The As(V) removal capacity by NZVI-5A zeolite was 72.09 mg/g by the Langmuir model fitting, and the removal capacity was almost not affected by solution pH in the pH range of 4–12. As(V) was removed by the precipitation of Ca2+ in zeolite 5A with As(V), Ca2+ and NZVI with As(V), and the reduction and inner ball complex reaction of NZVI. The As(V) removal efficiency by NZVI-5A zeolite was almost unaffected by the coexistence of CO32-, SO42-, NO3- and Cl- but decreased with high concentrations of PO43- in solution. The NZVI-5A zeolite could efficiently remove metal ions coexisting with As(V) in solution. The As(V) removal efficiency by the NZVI-5A zeolite was 84.0% after 5 cycles, and the NZVI-5A zeolite could be separated from the solution with an external magnetic field.