Enhanced adsorptive removal of hazardous methyl violet 2B and methyl orange dyes by Algerian diatomite-loaded polysaccharide-based hydrogel beads

Abstract

The present paper is devoted to the synthesis of hybrid biocomposites through immobilization of Algerian treated diatomite (TD) within the semi-interpenetrating network of carboxymethyl cellulose/dextran sulfate (CMC/DS). The physicochemical properties of the cross-linked beads were investigated by SEM, XRD, FTIR and TGA. Biocomposite beads were explored as adsorbents for the removal of cationic methyl violet 2B-(MV2B) and anionic methyl orange-(MO) dyes. The swelling ability in different media were studied. The outcomes revealed that the TD was successfully immobilized in CMC/DS matrix through hydrogen bonding which improved the structural stability of biocomposites. TD depicted to improve the adsorption capacity of hydrogels. Indeed, the beads prepared at low TD levels (5 and 10 % (w/w)) showed higher adsorption capacities (925.92 and 892.86 mgg−1) compared to the matrix (877.19 mg g−1). MV2B adsorption modeling showed the process well fitted the pseudo-second order kinetics and Langmuir models. Furthermore, the role of TD was better considered during the MO adsorption study. Pristine hydrogel were not able to effectively remove it (10 %), while for biocomposites the efficiency reached 62–98 %. The suggested mechanism for MO adsorption involved ion exchange, pore-filling and π-electron specific interactions. Lastly, reusability study confirm that C/D-TD biocomposites are promising materials for anionic/cationic dyes adsorption.