A Comparative Study of the Adsorption of Industrial Dyes onto Grape Cores-Based Adsorbents from Aqueous Media

Abstract

This study aims to evaluate the effectiveness of grapes cores treated by different chemical agents in order to compare their removal efficiency of the anthraquinonic diazo azo (Supranol yellow 4GL) the Azo anionic acid (Nylosan red N-2RBL) dyes from aqueous media. Modeling of isotherms was used to select the best adsorbent; the best adsorption energies, capacities and intensities. Fitted models and data were evaluated by using the most common isotherms models namely Langmuir and Freundlich at their linear and non-linear forms. Parameters and best fit coefficient R2 were identified. Results were statically analyzed by calculating the following errors functions: ?2 statistic; RMSE and API. By using 4 g/L of adsorbent and 100 mg/L as initial NR-dye concentration; the uptakes by GC-2 and GC-3 are 90.5 and 98 % respectively, and 88.31 % onto GC-1 for adsorbent dose of 8 g/L. The adsorption process of NR-dye by GC-3 is very well represented by Freundlich isotherm in its linear and non-linear forms, the adsorption energies of 28.15 and 42.57 mg/g respectively, are the most important, in the other hand, adsorption energy found from the non-linear Langmuir isotherm is very low (0.0203 L/mg). The removal efficiencies of SY-dye by GC-2, GC-3 and GC-1 attained 99.63 %, 99.78 % and 91.9 % respectively at an initial concentration of 100 mg/L and adsorbent dose of 4 g/L. Values of maximum adsorption capacities and energies from different linear and non-linear Langmuir isotherms models for the adsorption of SY-dye by GC-3 were found to be the most important, and the non-linear models were found more suitable. In the other hand, non-linear Freundlich isotherms models are more significant than linear, and the process of the adsorption of SY-dye by GC-3 is more favorable because the adsorption energies and intensities were found very important.