Chitosan-cellulose composite for the adsorptive removal of anionic dyes: Experimental and theoretically approach

The chitosan-cellulose composite was prepared and employed for the adsorptive removal of Reactive Red 195 (RR195) and Reactive Red 2 (RR2) dyes. The cellulose was extracted from bagasse and then, chitosan composite was prepared by solution casting method. The adsorption dependent parameters were optimized, i.e., pH, dyes initial concentration, temperature and reaction time. At room temperature, the dyes adsorption efficiencies were 71.5 % and 97.16 % for RR2 and RR195 at pH 4 and 2, respectively. Point of zero charge found to be at 6 pH for the composite. Both dyes adsorptions data followed pseudo second order kinetics model. The RR195 dye adsorption was best explained by Langmuir isotherm model and in case of RR2 dye, the Freundlich isotherm fitted well. The characterization of the prepared composite was performed by Fourier Transform Infrared Spectroscopic analysis. In Density Functional Theory (DFT) studies, the LUMO, total energy (HF) and adsorption energies (Eads) were found to be −3.73 eV, −8413.210HF and −25.46Kcal, respectively in case of RR195 dye, while these values were −3.67 eV, −5859.036 HF, −20.69Kcal for RR2, which revealed that RR195 has the higher electron-accepting ability and reactive toward chitosan-cellulose composite. The findings revealed that the chitosan-cellulose composite have promising adsorptive efficiency and could be employed for the removal of dyes from effluents.