Adsorption of phosphate by the cellulose-based biomaterial and its sustained release of laden phosphate in aqueous solution and soil

A new quaternary ammonium anion exchanger derived from the cellulose-based biomaterial (sugarcane bagasse) was prepared for phosphate adsorption and then the phosphate saturated bio-sorbent was used as a slow-release phosphate fertilizer in water or soil. Results indicated that the adsorption of phosphate by the quaternary ammonium based sugarcane bagasse (QA-SB) was increased with the increase of temperature, and the adsorption was optimal at pH of 4.33-5.88. The capture of phosphate by the QA-SB in fixed-bed column was calculated to be 18.9-21.4 mg/g in the background of Cl− or NO3− (100 mg/L). In particular, the amount of laden phosphate was significantly decreased to 9.1 mg/g in the presence of coexisting SO42− (100 mg/L). As a result, a stronger competitve effect of SO42− on phosphate capture was observed as compared with those of Cl−, and NO3−. Results also indicated that the laden phosphate on the QA-SB could be desorbed efficiently and the recovery of phosphate onto the regenerated QA-SB still attained about 94.5% after 4 cycles. The slow-release of laden phosphate in aqueous solution could be continuously conducted for 12 d, with 43.6% of laden phosphate (11.6 mg/g) released. In contrast, phosphate (7.4 mg/g) released in soil reached equilibrium within 4 d, accounting for only 27.8% of laden phosphate released.