Reduction and immobilization of chromium(vi) by nano-scale Fe0 particles supported on reproducible PAA/PVDFmembrane

Abstract

A new class of nano-scale Fe⁰ particles (NZVI) supported on a PAA/PVDF membrane (NZVI-PAA/PVDF) were synthesized and the feasibility of using NZVI-PAA/PVDF for reductive immobilization of Cr(VI) in water was investigated through laboratory batch tests. The results showed that the Cr(VI) removal capacity of NZVI-PAA/PVDF was 181 mg Cr/g Fe at an initial Cr(VI) concentration of 20 mg L⁻¹ under pH 6.5 ± 0.1. XPS results showed that Cr(VI) was converted to nontoxic Cr(III). Interfering ions exerted various degrees of impact on NZVI-PAA/PVDF's Cr(VI) removal capacity. Specifically, Ca²⁺ alone showed the mildest impact while the presence of ions (Mg²⁺ and HCO₃⁻) exerted the greatest impact. An advantage of NZVI-PAA/PVDF is that the nano-scale Fe⁰ and resultant particles were combined within a PAA/PVDF membrane, which prevents secondary pollution. Moreover, a piece of PAA/PVDF membrane (4.7 cm diameter) can still support 6.51 mg of nano-scale Fe⁰ particles after being renewed.