Preparation Of Nio And NiO/Al₂O₃Using Natural Plants As Templates And Their Adsorption Properties

Nickel oxide (NiO) is a very important functional material, due to its uniqueelectrical, magnetic and catalytic properties; It has been widely used in various fields,including battery anode material, electrochemical capacitor, optical materials,gas-sensing materials and catalysis. Because the performances of these materials largelydepend on the structure of as-synthesized products, how to prepare the special structureof NiO materials has attracted significant attention.In recent years, biological template method is a new technology developed forpreparing materials. It is that the structures of biological materials are used as thetemplates and the as-synthesized materials can be formed through impregnation inprecursor and calcination methods. In this paper, biomorphous NiO were synthesizedusing impregnation and calcination methods with pine and cotton template, andbiomorphous NiO/Al2O3were synthesized by hydrothermal method with waste cottonT–shirt template. Different characterization techniques such as thermogravimetry-differential thermal analysis (TG-DTA), fourier transform infrared spectra (FTIR),scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used toinvestigate the structures of as-synthesized products. The adsorption properties of Pb2+,Methyl Blue and Congo Red on as-synthesized products were studied in batch adsorptionstudies, where the amount of adsorbent, the pH of solution, initial concentration,adsorption time and temperature were evaluated. The results showed that as-synthesizedadsorbent could be used effectively for removal Pb2+and anionic dyes in aqueous solution;The adsorption capacity of adsorbent was greatly affected by the pH value of initialsolution, and the adsorption capacity was enhanced with an increase in initialconcentration. The adsorption process was very fast and the adsorption equilibrium couldbe achieved in a short time.The characteristics of kinetic model and the adsorption isotherm model were alsoanalyzed. The adsorption data were analyzed using pseudo-first-order model,pseudo-second-order model and intra-particle diffusion kinetic model. It was found that all the adsorption process followed the pseudo-second order model. The equilibriumadsorption data were analyzed using Langmuir, Freudlich and Dubinin–Radushkevichisotherms. The results indicated that the adsorption isotherms of Pb2+on biomorphousNiO were well fitted with Langmuir model, the adsorption isotherms of Methyl Blue onbiomorphous NiO were well described by Dubunin-Radushkevich model, and theadsorption isotherms of Congo Red on biomorphous NiO/Al2O3were successfully fittedwith Freundlich model.