Preparation and Morphology Studies of Nano Zinc Oxide Obtained Using Native and Modified Chitosans

Nano zinc oxide (ZnO) with moderate surface area and high pore volume were prepared using a facile preparation method. Chitosan was utilized as both chelating and structure directing agent. The application of chitosans in this study suggested that even biowastes can be served in a productive manner economically. The surface modification of chitosan was carried out in order to increase the interaction between chitosan and zinc ions. The effect of sodium chloroacetate and isopropyl alcohol on the surface modification process was also explored. FT-IR (Fourier transform-infrared spectrometer) and TGA (Thermogravimetric analyses) analyses revealed that modified chitosans are more stable than those of unmodified chitosan. Among surface modified chitosans, CMC1 (1.5 M sodium chloroacetate and 75% isopropyl alcohol) showed enhanced surface properties. Freundlich adsorption isotherms as preliminary studies confirmed that modified chitosan showed enhanced interaction with zinc ions. The interaction of zinc salt with chitosans produced a zinc-chitosan polymer. This finally cleaved upon calcination to produce nano ZnO. The effects of different calcination temperatures indicated that 450 °C is the optimum calcination temperature to produce the nano ZnO with favored surface area (15.45 m2/g) and pore size (221.40 nm). SEM (Scanning electron microscope) and TEM (Transmission electron microscope) of ZnO indicated that uniform particle and shape distributions were obtained at low calcination temperature (450 °C)

A comprehensive study on the mechanism for controlled synthesis of ZnO-based nanomaterials via various polysaccharides as chelates

We presented the possible mechanisms regarding to formation of nano ZnO and ZnO/Zn nanocomposite by various polysaccharides as chelates. The same polysaccharide namely corn starch with different modification process led to the difference in the formation of final products. The results indicated surface interaction and the formation of intermediates mainly control the structure of final products. This study has revealed that the selected modification process for polysaccharides is an appropriate method to synthesize the formation of ZnO nanomaterials of particular interest with controlled composition. Our findings shed light on the optimization of preparation conditions for obtaining the desired final products of interest. Keywords: Polysaccharides, Mechanism, Nano ZnO, ZnO/Zn nanocomposit