Dual-template synthesis of microalgae-derived biochar for uranium removal from aqueous solution

Biochar as an adsorbent is paid more attention for treating uranium-containing wastewater. In this work, a novel microalgae-derived biochar(A-HTC) was synthesized by dual-template one-step carbonization for uranium adsorption. This biochar exhibited a maximum adsorption capacity of 472.3 mg·g −1 . Especially, A-HTC demonstrated excellent selectivity for uranium over 11 competing cations and remarkable reusability after 10 adsorption–desorption cycles. The adsorption behavior with time and uranium concentration followed the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively. Moreover, the adsorption process was spontaneous and endothermic. Zeta potential, XPS, and FTIR analyses revealed that A-HTC adsorbs U(VI) mainly through electrostatic attraction and complexation. The present study offers an innovative adsorbent and a novel method to produce biochar for uranium recovery from aquatic environments.