Microwave-Assisted preparation of Chitosan/ZnO nanocomposite and its application in dye removal

Chitosan/Zinc Oxide Nanocomposite (CS/ZnO Nanocomposite) could be prepared by different physical and chemical methods for various applications. The microwave heating technique was used to chemically prepare CS/ZnO nanocomposite due to the shorter time needed for reactions relative to conventional heating. Series of CS/ZnO nanocomposites were prepared on a function of time (4, 7, 10, 12, 15 min) and microwave power (90,360,600, 800 W) to determine the optimum conditions of the preparation technique. Results revealed that 800 W power and 10 min time were the optimum condition for the preparation process. FT-IR, XRD, TEM, DLS and UV-Vis were used as spectral characterization for the prepared nanocomposites. The results have confirmed that nanocomposite was prepared via the complexation reaction between surface zinc cations of zinc oxide nanoparticles and chitosan (CS) functional groups. TGA analysis showed the enhancement in the thermal properties of nanocomposite compared to neat CS. Further, the efficiency of the prepared nanocomposite for methylene blue dye removal was investigated and compared with neat CS. Dye concentration, materials concentration, pH and contact time were investigated to evaluate the optimum condition for dye removal. It was found that the optimum conditions for MB dye removal by CS/ZnO nanocomposite and CS were 20 mg/L as dye concentration and 60 mg/L of material concentration at pH 9 for 60 min. At these conditions, the modification of CS by ZnO nanoparticles enhanced the MB dye removal from 81% to 96.7%.