Removal and recovery of phosphorus from solution by bifunctional biochar

The bifunctional biochar(N/CaO/BC) was prepared by a simple high temperature calcination using melamine and biomass material of sugarcane bagasse and agricultural wastes eggshell. Its structure and properties were analyzed by SEM, XRD, BET, and XPS. The adsorption capacity was evaluated in the phosphorus solutions. The effect of initial pH, concentration and temperature on adsorption were investigated. Nano-CaO were disperse evenly on the surface of Biochar, resulting a special specific surface area and porous structures. It has a rich nitrogen and CaO and the adsorption capacity could obtain 251.16 mg P/g at 300 K over a broad range of pH. The electrostatic force caused by C = NH+ and precipitation reaction caused by CaO are the main driving forces of phosphorus removal and it exhibited a good P adsorption selectivity. P-rich N/CaO/BC contain P, N, C, Ca elements, which could provide nutrients to the soil and promotes the growth of crops. The dual-functionalization strategy of biochar provides a new way for the reuse of waste biomass and a new method for P utilization as resource in agricultural production.