Fabrication of graphene oxide–keratin–chitosan nanocomposite as an adsorbent to remove turbidity from tannery wastewater

Excessive turbidity in water is aesthetically unappealing and severely malfunctions the photosynthesis process of aquatic ecosystems. This study aimed to evaluate the effectiveness of a nanocomposite adsorbent made of graphene oxide–keratin–chitosan for removing turbidity from tannery influent. The nanocomposite was fabricated with simple solution casting methods. Material dispersibility, bonding between composite materials (amide linkage), and the surface morphology of the nanocomposite were analyzed with the ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. At pH of 6, 2 g/L of adsorbent and a 25-min contact time resulted in about 88% of turbidity elimination. After the adsorption process, the total suspended solids, total dissolved solids, salinity, biochemical oxygen demand, and chemical oxygen demand of the tannery wastewater were reduced by 55%, 29%, 12%, 58%, and 75%, respectively. The optimum dosage of the nanocomposite with the maximum turbidity removal capacity was 12.62 mg/g. According the adsorption kinetic and isotherm models, the graphene oxide–keratin–chitosan nanocomposite played a key role in the turbidity removal process with chemisorption and electrostatic multilayer adsorption. This study provided methodological and mechanistic insights into the procedures of investigating the removal of turbidity from tannery wastewater with a novel composite material.