Modification of wool fibre's structural properties as a cheap adsorbent for the elimination of Cr6+ and Rhodamine6g dye from aqueous solution.

Wool, a naturally occurring biopolymer made up of amino acids, is employed as an adsorbent for both modified and unmodified forms of the dyes rhodamine6G (R6G) and Cr6+. The two-step procedure of (i) ring opening polymerization (ROP) and (ii) condensation reaction was used to modify the structure of wool fibre. Both the ROP and the condensation provide steric free chain expanding groups as well as adsorption-improving groups. The FT-IR spectrum, which showed peaks about 1725 and 1630 cm-1 corresponding to the CO and CN stretchings, respectively, confirmed the structural modification. By detecting a slight hump at 8.5 ppm, 1H NMR was able to validate the later functional group. DSC, TGA, FE-SEM, EDX, and water contact angle (WCA) were also used to characterize it. With the aid of a UV-visible spectrophotometer, the quantitative adsorption of both Cr6+ and R6G by modified and unmodified Wool fibre was monitored. For the adsorption of Cr6+ and R6G, the pseudo first order and pseudo second order kinetics were used. The multilayer coating of adsorbate onto adsorbent was confirmed by the Langmuir adsorption isotherm. Thermodynamic parameters were calculated and compared to values found in the literature.

Synthesis, characterization and adsorption behavior of cotton fiber based Schiff base.

Structural modification of Cotton (Cot) fiber was carried out using ε-caprolactone (CL) as a monomer and oxydianiline (ODA) as a Schiff base forming agent in the presence of V2O5 catalyst in dimethylsulfoxide medium for 24h under air atmosphere (0.10MPa) at 80°C. The obtained products were analyzed for the characteristics and also for its adsorption of hexavalent chromium (Cr(VI)) and rhodamine 6G (R6G) dye molecules. The 1H NMR spectrum confirms the Schiff base formation at 8.7ppm. The adsorption study confirms the Pseudo second order kinetics with Langmuir adsorption model. The structurally modified Cot fiber based Schiff base exhibited the highest adsorption behavior through chemical interaction forces. The thermodynamic parameters were determined and confirmed the endothermic adsorption process.