Production of chitosan from local strain of Pleurotus ostreatus (Jacq: Fries) Kummer and its application in Congo Red adsorption

This study focused on developing a fungal biomaterial to treat water contaminated with anionic Congo Red dye through adsorption. A local strain of Pleurotus ostreatus, an edible basidiomycete mushroom, was isolated from Algeria, and used as the primary source for chitosan extraction. By-products from oyster mushroom cultivation were collected for this study. The extraction process resulted in a chitosan yield of 0.512 ± 0.18 g per 100 g of biomass. The chitosan powder (with 81.97 ± 9.70% degree of deacetylation) converted to membrane was tested to remove dye. The thermogravimetric analysis (TGA) of the chitosan membrane shows that it is characterized by important thermal stability. The kinetics experiments were conducted under moderate agitation, and the following parameters were studied: initial pH (4–12); initial dye concentrations (10–80 mg/L); adsorbent dose (0.02–0.15 g/25 mL) and temperature (25–55 °C). After one day of contact between the Congo Red dye (40 mg/L) and chitosan membrane (0.06 g/25 mL) at pH 4 and at 25 °C, the percentage removal reached 95.6 ± 2.47%, corresponding to an adsorption capacity of 14.55 ± 4.35 mg/g. Adsorption kinetic of Congo Red was studied and modeled using the pseudo first-order, pseudo-second-order and intraparticle diffusion models. The adsorption process was found to follow a pseudo-second-order kinetic model. The Langmuir isotherm is applicable to this adsorption, indicating that adsorption is driven by chemisorption. The study demonstrates that the chitosan derived of chitin extracted from local Pleurotus ostreatus by-products is effective in removing dye from aqueous solutions. Production of chitosan from local strain of Pleurotus ostreatus (Jacq.: Fries) Kummer and its application in Congo Red adsorption Chitosan converted into a membrane can indeed be an effective and promising solution in the treatment of wastewater contaminated with pollutants, particularly dyes. The advantage of this cationic polysaccharide, compared to conventional adsorbents, lies in its conversion into a membranous form, allowing for a combination of adsorption and sedimentation. The use of chitosan membranes thus simplifies the treatment process and reduces the costs and efforts associated with the management of solid residues.