Cross-Linked Chitosan/Gelatin Beads Loaded with Chlorella vulgaris Microalgae/Zinc Oxide Nanoparticles for Adsorbing Carcinogenic Bisphenol-A Pollutant from Water

Water polluted by phenolic compounds is a global threat to health and the environment; accordingly, we prepared a green novel sorbent biological system from a chitosan (CS), gelatin (GT), and Chlorella vulgaris freshwater microalgae (m-Alg) composite impregnated with zinc oxide nanoparticles (ZnO-NPs) for the remediation of bisphenol-A (BPA) from water. C. vulgaris was selected to be one of the constituents of the prepared composite because of its high capability in phytoremediation. The morphology and the structure of CS/GT*m-Alg/ZnO beads were characterized by SEM, FTIR, XRD, and TGA. Different monitoring experimental conditions, such as contact time, pH, BPA concentration, and sorbent dosage, were optimized. The optimum conditions for the adsorption process showed outstanding removal efficiency toward BPA at pH 4.0, contact time 40.0 min, and 40.0 mg L–1 BPA initial concentration. Langmuir, Freundlich, and Temkin isotherm models have been studied for adsorption equilibrium, and the best fit is described by the Langmuir adsorption isotherm. The adsorption kinetics has been studied using pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and intraparticle diffusion (IPD) models. The pseudo-second-order kinetic model shows the optimum experimental fit. The monolayer adsorption capacity of the prepared CS/GT*m-Alg/ZnO for BPA was determined to be 38.24 mg g–1. The prepared CS/GT*m-Alg/ZnO beads show advantageous properties, such as their high surface area, high adsorption capacity, reusability, and cost-effectiveness.