Gamma Irradiation Synthesis of Carboxymethyl Chitosan-Nanoclay Hydrogel for the Removal of Cr(VI) and Pb(II) from Aqueous Media

Hydrogel composites comprised of N,O carboxymethyl chitosan crosslinked with different weight ratios of acrylic acid and fabricated with nanoclay particle were prepared via gamma irradiation at 25 kGy irradiation dose. The prepared composites were coded as CsAA(1)Cl, CsAA(2)Cl and CsAA(3)Cl based on the weight ratio of acrylic acid to the chitosan derivative. The claimed hydrogels were characterized by FTIR, TGA and XRD. The TGA data implied that the incorporation of clay nanoparticles enhanced the thermal stability of the composites; the decomposition temperature increased up to 500 ? for CsAA(3)Cl. Three AFM outcomes were used to compare the surface features of the samples; topography, height and surface roughness. The topography data reveals that the nanoclay particles incorporated in CsAA(3)Cl are intercalated and exfoliated. Then, the optimized sorbent (CsAA(3)Cl) was investigated as green sorbents for chromium (VI) and lead (II). The data revealed that CsAA(3)Cl displayed maximum removal performance towards both lead and chromium with removal efficiencies 125 mg/g and 205 mg/g respectively at the optimum application conditions within 90 min only. Also, it was found that the optimum pH value was 9 for chromium and 8 for lead. The data proved that the adsorption of both cations followed pseudo-first order kinetic model. The prepared composites showed acceptable metal uptake capacity at three successive cycles.

Automated summary

Different weight ratios of acrylic acid were crosslinked with N,O carboxymethyl chitosan to prepare hydrogel composites, with the addition of nanoclay particles. The optimized sorbent (CsAA(3)Cl) exhibited excellent removal performance for chromium(VI) and lead(II), with removal efficiencies of 125 mg/g and 205 mg/g, respectively, within 90 minutes.