Cellular responses and phenol bioremoval by green alga Scenedesmus abundans: Equilibrium, kinetic and thermodynamic studies

This research aims to study the effect of phenol on growth, metabolism, antioxidant activity and its bioremoval by Scenedesmus abundans. High phenol concentrations reduced the chlorophyll and dry weight of S. abundans. As phenol concentration increased, the total lipid, protein and amino acid content increased. The hydroxyl radical scavenging activity, ferric reducing antioxidant power, total antioxidant capacity and catalase enzyme were generally enhanced by phenol concentrations. The biosorption ability of dried S abundans biomass for the phenol removal from the aqueous solution was also examined as a function of pH, biosorbent dosage, contact time and initial phenol concentrations. The optimum biosorption was achieved at pH 6, 0.5 g/100 ml algal dose, 90 min contact time and 100 mg/L phenol concentration. The biosorption models of Langmuir, Freundlich, Dubinin?Radushkevich and Temkin were well applied, providing the experimental data with the best fit. The maximum biosorption capacity was 57.8 mg/g at the optimum conditions. The kinetic biosorption was also well described by the pseudo-first order, with film and intra-particle controlled the biosorption mechanism. The thermodynamic parameters revealed that the process of biosorption was feasible, spontaneous and endothermic. The ?G0 values indicate that physisorption is the process of phenol biosorption on S. abundans. Additionally, by scanning electron microscopy, Fourier transform infrared and X-ray diffraction analysis, the biosorbent characterization was assessed. Therefore, S. abundans could be used as a promising biosorbent for removal of phenol and other organic contaminants. The removal capability of phenol by S. abundans can also encourage the use of the wasted biomass as a feedstock for biofuel production giving it a green environmentally sustainable operation. (c) 2021 Elsevier B.V. All rights reserved.