Contrasting impact of phosphorus dissolution on the sorption of bisphenol A and carbamazepine by phosphorus-rich chars

Phosphorus (P)-rich chars produced by phosphoric-acid-assisted pyrolysis are promising carbonaceous remediation agents for soil pollution. Nevertheless, the potential of P species dissolution from P-rich chars has been ignored, and the impact of P dissolution on the sorption of hydrophobic compounds remains greatly unaddressed to date. Herein, the P species dissolution from wood-, cellulose-, and lignin-derived P-rich chars at 200–650 °C were investigated. P release capacity ranged from 0.2 to 0.3 mg·g −1 through cyclic dissolution and the maximum release capacity was 1.6 mg·g −1 through continuous dissolution. Enhanced P dissolution in soil experiment implies that P-rich char can be a potential P source. After P species dissolution, bisphenol A (BPA) sorption increased and carbamazepine (CBZ) sorption decreased onto P-rich chars. The enhanced π-π interaction facilitated BPA sorption, while the declined double charge-assisted H-bond ((±)CAHB) weakened CBZ sorption. Combined with DFT calculations, the binding energy (ΔE) supported the contrasting interfacial sorption processes. Apart from micropore-filling, the contribution of sorption mechanisms followed the sequence of (±)CAHB > π-π interaction > H-bonding. This work not only reveals that P-rich char can serve as a promising phosphatic fertilizer for soil improvement but also casts new light on the sorption mechanisms for hydrophobic compounds.