Adsorptive removal of arsenate and orthophosphate anions by mesoporous alumina

A mesoporous alumina was synthesized using aluminum alkoxide in the presence of a cationic surfactant under hydrothermal conditions. The material contains a wormhole-like mesopore structure, and exhibits high surface area (483 m2/g) and pore volume (0.82 cm3/g). The adsorption capacities of the mesoporous alumina for arsenate (61.3 mg/g) and orthophosphate (37.4 mg/g) anions in an aqueous solution were 5.1 and 2.2 times higher, respectively, with initial adsorption rates being 3.8 (1.5 mg/g min) and 1.9 (1.3 mg/g min) times faster than those obtained with an activated alumina. The textural features of larger surface area and pore volume of the mesoporous alumina compared to the activated alumina are believed to be responsible for this enhancement in adsorption behavior.