Biosorption and retention of orthophosphate onto Ca(OH)2-pretreated biomass of Phragmites sp.

The biosorption of phosphorus in the form of orthophosphate (P-o) from wastewater using biomass as the sorbent is of potential importance because the P-o-loaded biomass could be applied in the agricultural sector as fertilizer and soil conditioner. However, biomass generally displays a very low affinity for P-o sorption and therefore biomass surface modification is required. In the present study, the biomass (as model grinded leaves of Phragmites sp. were used) was pretreated with Ca(OH)(2) to enhance P-o biosorption capacity (qe). The results indicate that the alkaline pretreatment resulted in a modification of surface functional groups. It was concluded that the main sorption mechanisms were ligand exchange and electrostatic attraction. A series of experiments were conducted to investigate the performance of the pretreated biomass for P-o uptake under various conditions. Isotherm and thermodynamic studies were also applied and analyzed. The biosorption process was best described by the pseudo-second order kinetic model and Langmuir isotherm, which gave a q(max) of 12.27 mg P/g at 25 degrees C and pH 7. The Ca(OH)(2) treated Phragmites biomass applied in this study for P-o recovery may present some potential advantages in terms of costs and environmental impact. (C) 2016 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.