Kinetic, equilibrium and thermodynamic investigations for the bio-sorption of dyes onto crosslinked Pleurotus ostreatus-based bio-composite

Abstract

ABSTRACT Water pollution due to dyes has a significant impact on the environment and causes unfavourable risks for human health. This study aimed to synthesise a crosslinked Pleurotus ostreatus-based bio-composite as an efficient low cost biosorbent and investigate its bio-sorption performance for dyes via kinetic, isotherm and thermodynamic parameters. The characterisation of the bio-composite was determined by Fourier transform infrared spectrophotometer, field-emission scanning electron microscopy, differential scanning calorimetry and X-ray diffraction. Two reflections peaks, 2θ = 13° and 21°, were revealed in the X-ray diffraction pattern of the bio-composite. The effects of contact time, pH and initial dye concentration were investigated as the physical-chemical parameters. The neutral pH was found as an optimum pH for dyes. The reuse test revealed that the bio-sorbent was capable of using 5 times for dyes. The pseudo-first order and pseudo-second order kinetic models were applied to determine the mechanism of the adsorption process. The isotherm investigation was conducted using the Langmuir and Freundlich isotherm models. The experimental data was determined to be in the good agreement with the pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacity was measured to be 77.11 and 40.11 mg/g for the bio-sorption of malachite green and methylene blue, respectively. The thermodynamic studies of the bio-sorption showed that the adsorption process was a spontaneous endothermic process and that disorder increased during the process. This study indicated that the synthesised bio-sorbent could be used as an eco-friendly, cost-effective and recyclable bio-composite for the bio-sorption of dyes from aqueous solution.