Preparation of nanocomposite of zinc oxide with nanocrystalline cellulose from Luffa sponge for removal of metronidazole from aqueous solutions

This paper reports the utilization of Luffa aegyptiaca sponge to isolate cellulose and prepare nanocrystalline cellulose (NCC). Nanoparticles of Zinc oxide (ZnO NPs) were also prepared by sol–gel procedure. The NCC and ZnO NPs were utilized to form NCC/ZnO nanocomposites. A comparative study was carried out for metronidazole elimination from aqueous solutions by NCC and the nanocomposite. The formed NCC and NCC/ZnO nanocomposite were characterized using a Fourier Transform Infrared spectroscope (FTIR), Brunauer-Emmett-Teller (BET) analyzer, thermogravimetric Analyzer (TGA), and X-ray diffractometer (XRD). The BET result displayed that the nanocomposite has high surface area (260 m²/g). The XRD result showed that an excellent ZnO NP was synthesized with a good crystallinity index while both profiles of NCC and NCC/ZnO showed a typical cellulose I crystalline structure. The influence of pH, dosage, initial concentration, contact time, and temperature on the metronidazole adsorption was investigated. Kinetics, isotherms, and thermodynamic models were used to evaluate the adsorption. The optimum conditions for the removal of metronidazole from the aqueous solution were found to be pH 7, 0.08 g adsorbent mass, 50 mg/L, 45 mins for NCC/ZnO, and pH 7, 0.08 g adsorbent mass, 50 mg/L, 60 mins for NCC. According to the obtained data, models of pseudo-second-order and Langmuir isotherm best fit both adsorption processes, having higher correlation values. The adsorption was also found to be endothermic, favorable, and spontaneous.