Enhancing U(VI) adsorption by loading biochar with phosphate-solubilizing bacteria: Adsorption behavior and mechanism

A novel biochar composite material (P/PMBC72), which combines the advantages of biochar and microorganisms, was prepared to remove U(VI) from aqueous solution in this study. The use of P/PMBC72 resulted in a removal efficiency of 93.4 %, representing an increase of 23.5 % over that obtained using PMBC. The adsorption behavior of P/PMBC72 was in excellent agreement with both the Langmuir isotherm and the pseudo-second-order kinetic model. Thermodynamic analysis revealed that the adsorption of U(VI) by P/PMBC72 is spontaneous and endothermic. Moreover, P/PMBC72 exhibits excellent selectivity for the adsorption of U(VI) and can be reused multiple times. Spectral analysis revealed that the interaction mechanism between P/PMBC72 and U(VI) is mainly H 2 (UO 2 ) 2 (PO 4 ) 2 ·8 H 2 O precipitation, complexation and ion exchange with Al and Mg. This study confirms that P/PMBC72 is a promising material for the remediation of wastewater containing U(VI). • P/PMBC72 combines the advantages of biochar and microorganisms. • Maximum adsorption capacity of U(VI) by P/PMBC72 could up to 220.88 mg g −1 . • Precipitation and complexation are the major adsorption mechanisms of U(Ⅵ) by P/PMBC72. • After five cycles, the removal rate of uranium (VI) by P/PMBC72 can reach 87 %.