Folic acid modified cross-linked cationic polymer: Synthesis, characterization and application of the removal of Congo red dye from aqueous medium

This article highlights the development of a novel cross-linked cationic polyamine folic acid composites (PFCs) derived from folic acid, epichlorohydrin, ethylenediamine and its application for the adsorption of anionic Congo red (CR) dye from aqueous solution. The composite material was prepared through a simple polycondensation polymerization technique by the opening of epoxide ring of epichlorohydrin. The developed composites were characterized by various characterization techniques like ATR-FTIR, UV-vis, SEM, TGA, XRD and zeta potential. ATR-FTIR results suggested the surface modification of PFCs after adsorption of CR. FE-SEM studies showed the compact agglomerated structure with rough surface morphology of PFCs whereas the surface morphology becomes smoother after the adsorption of CR. The adsorption efficiency of PFCs was investigated under various parameters: adsorbent dose, pH of solution, temperature and ionic strength. The results demonstrated that the adsorption of CR dye strongly depends on pH and could effectively adsorb CR at near neutral condition. The adsorption results were compatible for pseudo-second-order kinetics model and Langmuir isotherm model in compared to all other models tested. Langmuir adsorption isotherm studies showed that the removal of dye reaches its highest capacity of 158.7, 204.1 and 256.4 mg/g at 25 degrees C, 35 degrees C and 45 degrees C, respectively. Moreover, desorption experiments demonstrated that the PFCs could be reused effectively due to its recyclability which makes the adsorption process towards removal of organic hazardous dye from wastewater more economically viable. (C) 2016 Elsevier B.V. All rights reserved.