Synthesis, characterization and applications of xanthan gum based synthetic polymers in organic and inorganic contaminations removal from aqueous solution

Abstract

Abstract : This thesis involves the hybridization of xanthan gum (XG) with vinyl monomers for their application in the adsorption of synthetic dyes and metal ions from aqueous solution. Nanostructured materials were incorporated within the XG-based hydrogel networks to achieve hydrogel nanocomposites with tailored functionality. Carbon based nanomaterials (multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO)) and ceramics (silicon dioxide (SiO2)) were incorporated within the hydrogel networks. The applicability of the prepared hydrogel nanocomposites as adsorbents were investigated for adsorption of methylene blue (MB), methyl violet (MV) and cadmium(II) in batch absorption experiments. XG-based absorbent was prepared via microwave-assisted free radical graft co-polymerization of poly acrylic acid (PAA) onto XG (mwXG-g-PAA). The structure, morphology and thermal stability of XG and mwXG-g-PAA were carried out by means of modern analytical methods such as 1H NMR, FTIR, SEM, XRD and TGA. The synthesized graft co-polymer was appliedfor cationic MB dye removal from aqueous solution. This adsorbent exhibited excellent adsorption ability towards MB under basic condition of pH 10. The results demonstrate xanthan gum grafted poly acrylic acid can be used as absorbent for removal of toxic dyes from wastewater. Xanthan gum-cl-poly acrylic acid (XG-cl-pAA) hydrogel and xanthan gum-cl-poly acrylic acid /oxidized-MWCNTs (XG-cl-pAA/o-MWCNTs) hydrogel nanocomposite were synthesized by microwave-assisted copolymerization, in which N,N′-methylenebisacrylamide (MBA) was used as a cross-linking agent. FTIR, SEM, XRD and TGA techniques were used to verify the structure, morphology and thermal stability of the prepared materials. These adsorbents were then examined for the adsorption of MB from aqueous solution. The effects of pH, contact time and equilibrium concentration on the MB dye adsorption were investigated in batches. The results revealed that XG-cl-pAA/o-MWCNTs hydrogel nanocomposite could be employed as a potential candidate in the remediation of MB contaminated wastewaters. In addition, the adsorption-desorption cycle of XG-cl-pAA/o-MWCNTs hydrogel nanocomposite was repeated several times without significant loss of adsorption capacity...Ph.D. (Chemistry