Experimental and theoretical investigations for the removal of chromium (III) from aqueous solutions using sugarcane bagasse

Abstract

The isotherms behavior via Langmuir, Freundlich and Temkin isometric models are investigated. Langmuir shows within the studied concentrations of chromium(III)  that the adsorption  has no any effect, Freundlich shows that the adsorption process occurs on heterogeneous surfaces has an exponential distribution of the active sites and their energies indicating the heterogeneity of the relative energy distribution within the adsorption sites. Temkin isometric model, where the interaction between the adsorbent material and the active sites of the adsorbent has emphasized the nature of the adsorption between the chromium (III)and the sugarcane bagasse through b = -∆H and determined the type of chemical adsorption as Temkin's calculated results using solver. ANOVA matched the experimental results. Two-Factor affecting the results of industrial water treating the containing the ion (Cr^{3 +}) with a variation in the efficacy of the treatment when the concentration of the chromium ion changed (from 600 to 3000 ppm) or the material used in the changed treatment of (SB-N or SB-KOH) and KOH-SB outperformed N-SB at all applied conditions. The internal diffusion equation shows that the adsorption of chromium (III) on the SB-KOH surface is governed by two phases of the outer mass transfer (boundary layer diffusion) and (the internal diffusion phase) within the pores of the absorbent. The theoretical study showed that the mechanism of chromium (III) binding with alginate Cr³⁺-alginate bond cannot be electrostatically linked, because of the bond length in the formed complex which is smaller than the sum of the two diameters Cr³⁺ and O^2-. This explains the isotherm results of Freundlich and Langmuir due to the increase of the maximum adsorption capacity q_m and the proportion of chromium(III) retention time at high concentrations forming a strong bond allowing to retain chromium(III) in sugarcane bagasse and thus form complexes between chromium(III) and alginate (COO^-, O^2-).