Magnetic biochar composite decorated with amino-containing biopolymer for phosphorus recovery from swine wastewater

Amino hybrid biopolymer-decorated magnetic biochar composites (MTBC-2 N and MTBC-4 N) derived from green tea waste were synthesized and employed to recover phosphorus (P) from aqueous solution and swine wastewater, respectively. The amino hybrid biopolymer decoration decreased the surface area of the biochar composites but increased the nitrogen content of the MTBC-2 N and MTBC-4 N samples. The MTBC-2 N and MTBC-4 N remarkably promoted the dephosphorization of P-polluted waters than the raw biochar without amino hybrid biopolymer decoration. The kinetic adsorption of P onto MTBC-2 N and MTBC-4 N was simulated using the pseudo-second-order kinetic model and reached equilibrium within 4 h. The P adsorption isotherm was best fitted by the Langmuir model with the maximum adsorption capacities of 53.56 and 62.06 mg P/g for MTBC-2 N and MTBC-4 N, respectively. The tested MTBC-2 N and MTBC-4 N were regenerated and exhibited acceptable reusability. In addition, the adsorption of P onto MTBC-2 N and MTBC-4 N was regulated by electrostatic attraction and surface complexation processes. More than 88.2% and 96.5% of P were recovered by MTBC-2 N and MTBC-4 N from swine wastewater, respectively. Moreover, the pot experiment showed that the P-loaded biochar composites could potentially be used as alternative P fertilizers.

Automated summary

Amino hybrid biopolymer-decorated magnetic biochar composites derived from green tea waste were effective in recovering phosphorus from aqueous solution and swine wastewater. The adsorption process followed the pseudo-second-order kinetic model and Langmuir isotherm. The composites showed high phosphorus recovery rates from swine wastewater and demonstrated reusability. Additionally, the P-loaded biochar composites could potentially be used as alternative P fertilizers.