Development of Efficient Biochar Produced from Orange Peel for Effective La(III) and Y(III) Adsorption

In this work, orange peel (OP) was used as raw material to produce biochar. The effect of oxygen-limited carbonization temperature (200, 400, and 600°C) on the physicochemical properties and adsorption behavior of orange peel biochar (OPB) toward La(III) and Y(III) in aqueous media was studied. The prepared OPB samples were characterized by SEM, FTIR, and XRD. The experimental results exhibited effective removal of La(III) and Y(III) from aqueous solution by OPB. The carbonization promoted the pore development, and the adsorption process occurred rapidly. The main chemisorption of La(III) and Y(III) on OPB was analyzed by the Langmuir and pseudo-second-order kinetic model, and the participations of electrostatic attraction, exchange, and hydroxyl and carboxyl complexation in OPB were confirmed. The Langmuir maximum capacity of 55.57 mg/g and 31.49 mg/g was obtained at the optimum pH range of 4~6 and the OPB dosage of 1 g/L and 2 g/L for La(III) and Y(III). The efficient orange peel biochar with high adsorption performance can be obtained by considering suitable carbonization temperature.