COD adsorption and optimization from produced water using chitosan–ZnO nanocomposite

In this study, chitosan/ZnO nanocomposite was synthesized and employed for the first time as a selective adsorbent in produced water (PW) for the chemical oxygen demand (COD). Physical characteristics were studied using XRD, SEM, FTIR, BET, TGA, and XPS. Results showed that ZnO nanoparticles mobilized onto chitosan. The COD adsorption followed Langmuir isotherm with maximum monolayer adsorption. With a high coefficient of determination (0.98), COD adsorption followed the pseudo-second-order kinetics model. Furthermore, central composite design (CCD) in response surface methodology (RSM) was employed to assess different parameters’ impact on COD adsorption. The parameters analyzed contain; solution pH, nanocomposite dose, and contact time. The COD removal efficiency was reported to be as high as 94.56%. The experimental results were in good accord with the model’s predictions, demonstrating the value of the RSM technique in terms of optimization. Based on the present findings, it is possible to conclude that chitosan/ZnO nanocomposite, as a biocompatible, environmentally benign, and cost-effective material, can be a viable option for adsorption of organic pollutants and a way forward to a sustainable environment.