Development of a Bio based Thiomers for Arsenic Removal from Aqueous Environment

Abstract

newline ABSTRACT newline newlineRecently, biopolymeric materials are of utmost interest in research due to its easy availability and utility for various applications. The most important section in biopolymer class is polysaccharide, an inexhaustible polymeric raw material with fascinating structure and properties. Polysaccharide has many active sites, which can be easily explored via polymeranalogous reactions for the green chemical generation. In view of this, this thesis processes the development of innovative green materials from starch. newline newlineSulfur-based-starch derivatives were successfully prepared, via an iso-thiouronium salt intermediate, from the reaction of thiourea with chloroacetylated starch in different molar ratio. The later was synthesized by a chloroacetylation reaction. Thiolation via an iso-thiouronium ion intermediate is an innovative green approach to integrate thiol group to starch with an innocuous low-cost thiourea reagent. The thiol products are amenable for further derivatization and were modified to a sulfide and a sulfonium structure. The sulfonium structure was accomplished by exhaustive alkylation with odoethane as an alkylating agent, which resulted in permanent charge generation on the starch backbone. The above mentioned reactions were also performed via microwave heating method to achieve maximum yet uniform modification of starch. The quantification of derivatization was confirmed by iodine titration and precipitation titration. Furthermore, the characterization by FTIR spectroscopy, 1HNMR, 13C-NMR, SEM-EDX, XRD, zeta potential measurements and elemental analysis (CHNS) of the synthesized samples were performed to assign the precise structure at every synthetic stage. Evidence for the degree of substitution (DS 2.76) in thiol groups was obtained from titrimetry, SEM-EDX and elemental (CHNS) characterization results. Additionally, the generation of the permanent charge on the sulfonium structure was confirmed using zeta potential measurements. The batch experiments were performed as a functi