Enhanced removal and stepwise recovery of inorganic and organic micropollutants from water using novel graphene oxide doped multifunctional β−cyclodextrin chitosan polymer

Abstract

Herein, graphene oxide (GO) was successfully functionalized on the multifunctional β−cyclodextrin chitosan polymer through EDTA crosslinking (GO@CS−EDTA−β−CD) for the adsorption of toxic inorganic and organic micropollutants from water. This unique adsorbent possesses important adsorptive features from each component: chitosan works as a backbone of the polymer chain, β−CD cavities adsorb the organic micropollutants via the host-guest inclusion complexation, EDTA acts as a crosslinker and provides complexation sites for heavy metal ions and GO can interact with both organic and inorganic micropollutants. After complete characterization, the polymer were explored on the adsorption of inorganic micropollutants (i.e., Hg(II), Pb(II), Cu(II) and Ni(II)) and organic one (i.e., methylene blue, MB) under different experimental conditions. In monocomponent systems, the adsorption followed the pseudo-second order (PSO) kinetics for both heavy metals and MB dye. The adsorption isotherms of heavy metals and MB followed the Langmuir and Sips models, respectively. The maximum adsorption capacities were found to be 364.90 ± 15.20, 287.40 ± 10.0, 130.40 ± 6.50, 98.90 ± 3.10, 158.40 ± 5.10 mg g−1 for Hg(II), Pb(II), Cu(II), Ni(II) and MB, respectively. In binary component systems, dye adsorption was not affected by metal ions, while the adsorption efficiency for metal ions was increased by the MB presence: possibly due to synergism. Additionally, the prepared adsorbent showed good efficiency without any significant loss in adsorption capacity even after six continuous regeneration cycles, confirming its superior reusability and stability. In short, excellent removal efficiencies for the metal ions and MB at environmental levels in model textile effluent, synthetic acid mine water make the adsorbent promising in treating water contaminated by heavy metals and/or dyes.