Effective removal and recovery of phosphorus using ZnAl-COOH-modified biochar via hydrogen bonds

Abstract

The global community is facing the dual problem of water eutrophication and a shortage of phosphate rock resources. In this study, carboxylated ZnAl-hydroxide-modified biochar (LDH/PMA/BC) was synthesised to remove and recover phosphorus (P) from water through highly selective adsorption and desorption of P. The results of adsorption experiments indicated that LDH/PMA/BC has an high removal rate for low concentrations of P, and the maximum capacity for adsorption of P was 109 mg g−1. Furthermore, when a low concentration of P coexisted with a high concentration of competitive ions, LDH/PMA/BC could selectively adsorb P through hydrogen bonding, and its removal rate for P reached 99 %–100 % of its removal rate without competitive ions. In addition, LDH/PMA/BC maintained 85 %–93 % of its initial adsorption capacity in 10 adsorption–desorption cycles, and the P recovery rate reached 95 %. These results indicate the potential of LDH/PMA/BC as an adsorbent for removing and recovering P from wastewater.