Adsorption characteristics of trace levels of bromate in drinking water by modified bamboo-based activated carbons.

This study was undertaken to investigate the adsorption kinetics and isotherms of bromate (BrO) on bamboo charcoals that are activated with nitrogen and water vapor. Bamboo-based activated carbon (AC) was dipped in acid and oxidized in a mixture of potassium permanganate and sulfuric acid. Oxidation treatment considerably improved the physicochemical properties of AC, including purity, pore structure and surface nature, significantly enhancing BrO adsorption capacity. AC with many oxygenated groups and a high mesopore volume exhibited a particularly favorable tendency for BrO adsorption. Its adsorption of BrO is best fitted using Langmuir isotherm, and forms a monolayer. A kinetic investigation revealed that the adsorption of BrO by the ACs involved chemical sorption and was controlled by intra-particle diffusion. The competitive effects of natural organic matter (NOM) on AC were evaluated, and found to reduce the capacity of carbon to adsorb BrO. Residual dissolved ozone reacted with AC, reducing its capacity to absorb BrO. Proper dosing and staging of the ozonation processes can balance the ozone treatment efficiency, BrO formation, and the subsequent removal of BrO.