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 (BrO3 - ) 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 BrO3 - adsorption capacity. AC with many oxygenated groups and a high mesopore volume exhibited a particularly favorable tendency for BrO3 - adsorption. Its adsorption of BrO3 - is best fitted using Langmuir isotherm, and forms a monolayer. A kinetic investigation revealed that the adsorption of BrO3 - 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 BrO3 - . Residual dissolved ozone reacted with AC, reducing its capacity to absorb BrO3 - . Proper dosing and staging of the ozonation processes can balance the ozone treatment efficiency, BrO3 - formation, and the subsequent removal of BrO3 - .