Removal of erythrosine B dye from wastewater using chitosan boric acid composite material: Experimental and density functional theory findings

In this study, the chitosan boric acid (Ch-B) composite has been prepared and characterized with sophisticated analytical techniques such as FT-IR, SEM, and EDX. The prepared Ch-B adsorbent was applied for the adsorption of erythrosine B (EB) dye from water samples under the optimized parameters of pH, adsorbent dosage, time, and temperature. Results shows that the Ch-B adsorbent removes 96.5% of EB dye at pH 5, using 0.05 g of adsorbent. The adsorption equilibrium data have been subject to the Langmuir, Freundlich, and D-R adsorption equilibrium models, which demonstrates that the Freundlich model was the best fit with good correlation coefficient value (R2 = 0.991), while energy E (9.18 KJ mol 1) calculated from D-R model suggested that the physical adsorption nature of the adsorption. Beside this, the thermodynamic and kinetic experiments were performed to check the feasibility and adsorption mechanism of EB-dye onto Ch-B adsorbent, which shows that the adsorption is endothermic (ΔH = 0.124) and spontaneous in nature due to the negative values of Gibbs free energy (i.e., ΔG KJ mol 1 = 13.01, 17.06, and 17.60). The kinetic models show that the adsorption equilibrium is best fitted with pseudo second order kinetic model due to good correlation coefficient (R2 = 0.99). Moreover, the interaction phenomenon between adsorbent and adsorbate was analyzed through DFT calculations.