Probing the Interaction between Fluoride and the Polysaccharides in Al(III)- and Zr (IV)-Modified Tea Waste by Using Diverse Analytical Characterization Techniques

The objective of this study was to assess the efficacy of interaction between fluoride and a household tea waste (HTW) material modified using aluminium sulfate and zirconyl oxy chloride. Tea waste is an inexpensive source of biomass comprising lignin, cellulose and hemicelluloses, condensed tannins and proteins. The incorporation of Al (III) and Zr (IV) was accomplished by dilute nitric acid hydrolysis of the tea waste material. The polymeric aluminium and zirconium cations interact with tea waste through the surface hydroxyl, carbonyl, carboxylic functional groups and glycosidic linkages. Since, Al (III) and Zr (IV) ion are hard acids, they interact with the hard base fluoride effectively. The mechanism was supported through Thermogravimetric analysis (TGA), Fourier Transform Infra-Red (FT-IR) spectrometry, Fourier Transform Raman (FT-Raman) spectrometry, Energy Dispersive X ray spectrometry (EDS), X-ray Diffraction (XRD) and X-ray Photo Electron Spectroscopy (XPS) techniques. Preliminary batch adsorption studies resulted in linear and nonlinear Langmuir adsorption capacities as 17.51 and 17.54 mg g(-1) respectively at pH 7.0. The sustainable adsorbent shows prospective application for de-fluoridation of water.