Removal of Anionic Dye in Acid Solution by Self Crosslinked Insoluble Dendronized Chitosan

Abstract

Insoluble Dendronized Chitosan (DCTS) was prepared to improve the adsorption capacity of chitosan (CTS) as well as to lower its solubility at lower pH for efficient removal of acid dye, Acid Blue 9 (AB 9) from aqueous solutions. Dendronized chitosan was prepared by grafting ‘dendrimer-like’ Polyamidoamine (PAMAM) onto CTS surface using Michael addition reaction followed by amidation reaction. The obtained CTS derivative became insoluble at any pH medium due to self inter- and intra-molecular cross linking during the reaction without any external crosslinker. The adsorption capacity of the CTS derivative was studied using batch method with respect to various parameters like, initial pH of the dye solution, initial dye concentration, adsorption temperature and adsorption time. The batch study showed that the adsorption capacity of CTS derivative increased many times than that of chitosan. From the adsorption kinetic study, it was found that the adsorption of dye molecule on the adsorbent surface obeyed pseudosecond- order kinetic instead of generally reported pseudo-first-order kinetic. Dsorbent surface obeyed pseudo-second-order kinetic instead of generally reported pseudo-first-order kinetic. The adsorption equilibrium showed that the Langmuir equation represented best fit of the experimental data than that of Freundlich equation. The desorbed DCTS could be reused for the adsorption of the acid dyes. The results in this study showed that DCTS may be an attractive candidate for removing anionic dyes from the wastewater.