Comparative study of nano-iron hydroxide impregnated granular activated carbon (Fe–GAC) for bromate or perchlorate removal

• Fe–GAC removed perchlorate through adsorption but removed bromate through adsorption then reduction.
• Less FeOOH was favorable to remove perchlorate, while more FeOOH favored the removal of bromate.
• Bromate reduction to bromide was the main mechanism for bromate removal by Fe–GAC.

A comparative study of nano-iron hydroxide impregnated granular activated carbon (Fe–GAC) for bromate or perchlorate removal from water was carried out in this study. SEM, FTIR, BET and XPS characterization of Fe–GAC revealed that nanoscale iron hydroxide (FeOOH) particles with SO42− attached were evenly distributed on the surface of GAC. Fe–GAC exhibited much greater removal capacity for bromate than perchlorate, furthermore, Fe–GAC can remove bromate through firstly adsorption then reduction to bromide and remove bromate completely after 50 h. Less FeOOH of Fe–GAC was favorable to remove perchlorate, while more FeOOH of Fe–GAC favored the removal of bromate. According to bromide products analysis, bromate reduction by Fe–GAC was the main mechanism. Fe–GAC performed well through a broad pH range (2–10) with the optimal pH 6–8 for bromate reduction, but the removal of perchlorate was more pH dependent. In all, Fe–GAC can remove bromate or perchlorate, and bromate reduction played an important role for bromate removal.

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