Removal and recovery of phosphate from water by activated aluminum oxide and lanthanum oxide

Phosphorus is a non-renewable resource for food production in modern agriculture and a leading cause of eutrophication in water bodies. Both the removal and recovery of phosphorus from water/wastewater are important. The phosphate adsorption performances of activated aluminum oxide (MO) and lanthanum oxide (LO) have been investigated. Langmuir adsorption capacities for AAO and LO of 20.88 mg/g and 46.95 mg/g, respectively, were attained. Efficient phosphate removal by AAO could only be achieved under acidic pH conditions (<similar to 5,0), whereas that by LO was not greatly influenced at pH < 10.5. The adsorption mechanism is interpreted as a ligand-exchange process, and a surface complex of monodentate nonprotonated species (=La-OPO3) has been identified by FTIR for LO. The adsorption of phosphate is quite selective, especially for LO. The dosages required to lower a phosphate concentration level of around 5.0 mg P/L to <0.5 mg P/L were determined as 0.08-0.1 g/L for LO and 1.2 g/L for AAO, respectively. The adsorbed phosphate could be completely desorbed by treatment with 0.1 M NaOH for AAO, while for LO both acid treatment (0.5 M HCl) and basic treatment (12.5 M NaOH) were viable. (C) 2014 Elsevier B.V. All rights reserved.