Kinetic study and Box–Behnken design approach to optimize the sorption process of toxic azo dye onto organo-modified bentonite

Abstract

Kinetic study was applied for sodium bentonite (Na-B) and hexadecylpyridinium bentonite (HDP-B) under different amounts, namely 50% (50HDP-B), 100% (100HDP-B), and 200% (200HDP-B) with respect to cation exchange capacity (CEC). Pseudo first-order and pseudo second-order kinetic models were performed to optimize the sorption of Congo red (CR) dye from aqueous solution. The experimental data fit the pseudo second order kinetic model well. The sorption capacity (qe) of CR dye by the organo-bentonites at equilibrium was 36.0 mg g−1 (72.1%) for 50HDP-B, 48.05 mg g−1 (96.1%) for 100HDP-B, and 49.2 mg g−1 (98.4%) for 200HDP-B. These results were considerably higher than that found by Na-B. Response surface methodology with three-variable, three-level Box–Behnken design was applied for 100HDP-B to describe the removal of CR dye. The effects of three variables, namely temperature, adsorbent dosage, and initial dye concentration, were studied. Predicted values of adsorption efficiency were found to be in good agreement with the obtained experimental values (R2 = 0.97). A second-order polynomial model successfully described the effects of independent variables on the CR dye removal. At the optimized condition, the toxic azo dye could be quantitatively removed from aqueous solution. The results of the present study suggest that the organo-bentonite can be used as an efficient sorbent for dye removal from aqueous solution.

Utilizing Agricultural Waste for Sustainable Remediation of Textile Dyeing Effluents

“…This requires meeting environmental requirements, as the industry consumes vast amounts of water and generates wastewater with high levels of pollutants, including unfixed dyes (Periyasamy, 2024). Worldwide, the manufacturing and coloring of fabrics release around 140,000 tonnes of toxic substances annually, most of which evade conventional wastewater treatments (Guezzen et al, 2020).…”

Preparation of Magnetic Composite Polyaniline/Fe3O4−Hydrotalcite and Performance in Removal of Methyl Orange

“…Among them, adsorption is the popular method because of its efficiency and economy. The adsorbents which were widely used to remove azo dyes are either inorganic such as activated carbon [3][4][5][6], hydrotalcite [7][8][9][10], diatomite [11][12][13][14][15] and bentonite [16][17][18][19], or organic such as chitosan, alginate, polysaccharide, and polymer materials [20][21][22][23][24][25][26][27][28][29][30][31] and also hybrid and composite material [32][33][34][35][36][37][38][39]. However, the most challenge for the above adsorbents is the low adsorption capacity and efficiency.…”