Improving photocatalytic performance of nickel oxide infused chitosan nanocomposite for adsorption of organic dyes

Abstract

One of the most significant issues worldwide is access to safe drinking water for human consumption, which has necessitated high intensification efforts from scientists to come up with a lasting solution. Nanotechnology-treated water contains no bacteria and organic dyes and is deemed superior to such methods of treatment. In this paper, an investigation into the light-induced effect on chitosan nanoparticles containing biosynthesized NiO nanoparticles was carried out. The synthesized nanocomposites have utilized characterizations using several methods, like FETEM, FTIR, XRD, XPS, and UV-visible spectroscopy. Under this work, the synthesis and characterization of the NiO@CS nanocomposite, used as an adsorbent to remove organic dyes from water. The organic dyes used were, among others, Congo red (CR) and Malachite green oxalate (MGO). The effect of temperature, pH, dosage, pH, and time on the removal efficiency (%) of adsorbent towards various colours was separately investigated. Kinetics isotherms Langmuir, Freundlich and Temkin as well as thermodynamic parameters (ΔG°, ΔH° and ΔS°) were observed. The linear correlation coefficient, R₂ of the Langmuir adsorption isotherm was almost equal to 1 for all colors which suggests that the adsorption occurred as a monolayer. Adsorption occurred with a reduction in negative enthalpy, free energy, and a drop in entropy at 30°C. The adsorbent was reusable for three cycles without a reduction in removal efficiency (%). Therefore, the NiO@CS nanocomposite may be feasibly applied toward commercial applications from organic colors from aqueous solutions.