Insights on the adsorption of malachite green behavior using a bio-inorganic composite of chitosan-cellulose itaconate/nickel oxide

Abstract The detrimental impacts of dye-containing wastewater discharge on aquatic ecosystems and water quality make it a major environmental concern. The newly synthesized matrix that composed of chitosan-crosslinked cellulose itaconate (CS–CLI) integrated with nickel oxide (NiO) nanoparticles was tested in the removal of malachite green (MG) dye from aqueous solutions. Both surface and core structure of all adsorbents were examined, moreover, different factors affecting the adsorption process such as pH, temperature, contact time, and initial dye concentration were assessed using batch adsorption mode. The findings showed that operating parameters had a significant impact on adsorption efficacy, with optimal removal occurring at pH 7 and 25 °C. At 5 mg/L MG, the removal percentages reached 91% for CS–CLI, 88.9% for NiO, and 81.8% for CS–CLI/NiO, under conditions of pH 7 and 25 °C. The composite's highest adsorption capacity was 11.56 mg/g. Chemisorption was a significant factor in dye uptake, according to kinetic tests that demonstrated the adsorption process followed the pseudo-second-order model. A multi-step adsorption mechanism comprising both surface adsorption and diffusion within the adsorbent structure was proposed by intraparticle diffusion studies. The Freundlich isotherm model provided a more accurate description of equilibrium data, suggesting multilayer adsorption on a heterogeneous surface. The Langmuir isotherm provided the best explanation for the equilibrium results, and adsorption kinetics strongly correlated with the pseudo-second-order model (R 2 = 0.999). It was discovered that the greatest adsorption capacities were 18 mg/g for CS–CLI/NiO, 23.4 mg/g for CS–CLI, and 36.1 mg/g for NiO. Overall, the results show that the CS–CLI/NiO composite is a viable, reasonably priced, and environmentally benign adsorbent for the treatment of dye-contaminated wastewater.