Chemical modification of Aspergillus flavus extracted chitosan for uranium remediation from aqueous solution

Abstract

ABSTRACT Fungal chitosan derived from Aspergillus flavus AFC was employed in the synthesis of a cross-linked polystyrene biopolymer, P-AFC, which was investigated as a biosorbent material for the effective removal of uranium ions U(VI) from aqueous solutions. The characterisation of both fungal biopolymers was achieved using Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. The efficacy of the P-AFC biosorbent in removing uranium from an aqueous solution reached equilibrium in 240 minutes at an initial uranium concentration of 50 ppm, a biosorbent amount of 0.4 g/L, and a pH of 4.0. The maximum biosorption capacity for U(VI) was determined to be 128.21 mg g−1 at room temperature, calculated using the Langmuir model. Furthermore, kinetic and thermodynamic analyses indicated that the biosorption process was characterised by chemisorption, was exothermic, and occurred spontaneously (ΔHo = –59.98 kJ mol−1 and ΔSo = –113.32 J K−1 mol−1). Recycling experiments demonstrated that the material could be reused up to five times without a noticeable decrease in removal efficiency.