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Partially carboxymethylated and partially cross-linked surface of chitosan versus the adsorptive removal of dyes and divalent metal ions

Doshi, Bhairavi, Ayati, Ali, Tanhaei, Bahareh, Repo, Eveliina, Sillanpää, Mika
Carbohydrate polymers 2018 v.197 pp. 586-597
adsorbents, adsorption, aqueous solutions, chemical reactions, chitosan, crosslinking, divalent metals, dyes, effluents, heavy metals, industrial wastes, leaching, metal ions, models, sodium, sorption isotherms, toxicity, wastewater
Industrial wastes and their effluents containing dyes and heavy metals are a tremendous threat to the environment, and to treat these toxic waste streams, effective and environmentally benign methods are needed. In this study, NaCS-GL was used as an effective adsorbent, for the removal of dyes and metal ions from their aqueous solution. The presence of carboxylate groups on the NaCS-GL surface has altered the protonation of amino groups. The adsorption kinetics of dyes on NaCS-GL was initially controlled by the film diffusion or chemical reaction after which the intra-particle or pore diffusion started to govern the rate. Leaching of sodium ion confirmed the crosslinking of two carboxylate groups of NaCS-GL with the metal ions. Modeling of the adsorption isotherms revealed that the different active surface sites of NaCS-GL were involved in the adsorption of dyes and metals, suggesting the simultaneous removal of these components from the wastewater.