Efficient reduction of bromate in water by nano-iron hydroxide impregnated granular activated carbon (Fe-GAC)

Abstract

Nano-iron hydroxide impregnated granular activated carbon (Fe-GAC) was prepared and tested for reduction of bromate in water. SEM, BET and FTIR characterization of Fe-GAC revealed that nanoscale iron hydroxide (FeOOH) particles with SO42− attached were evenly distributed on the surface of GAC. Fe-GAC can effectively remove bromate in water through firstly adsorption then reduction. The nano-iron hydroxides on GAC enhanced bromate removal rate and the equilibrium bromate adsorption capacity. More FeOOH of Fe-GAC favored the reduction of bromate. Bromate reduction by Fe-GAC was the main mechanism for bromate removal. Fe-GAC performed well through a broad pH range (2–10) with the optimal pH 6–8 for bromate reduction. According to XPS analysis, Fe(III) of Fe-GAC was reduced to Fe(II) during the bromate reduction to bromide. Fe(III)/Fe(II) acted as a catalyst and accelerated the bromate reduction rate by carbon of GAC. The four inorganic anions (SO42−, Cl−, CO33− or PO43−) all exhibited inhibiting effects on bromate removal by Fe-GAC with the following order: PO43−>CO33−>Cl−>SO42−. In all, Fe-GAC is a promising material for efficient reduction of bromate in water.