Enhanced Removal of Brilliant Orange by Poly(4-vinylpyridine)/Acid-Activated Bentonite Composite

The present work describes the adsorption of brilliant orange textile dye BO on treated clay TC and a new composite TC55 prepared by combining the TC and poly(4-vinylpyridine) (P4VP), a cationic polymer. The net negative structural charge of TC promotes high adsorption capacity toward cationic dyes. The preparation of composites by modification of minerals through compositing with polycations is used to enhance adsorption capacities for anionic dyes. Moreover, several factors’ effects, such as the contact time, pH of dye solution, adsorbent dosage, initial dye concentrations, and temperature, on the adsorption capacity were investigated. The results showed that TC55 fixed more dye molecules than TC. Afterward, the adsorption equilibrium time for TC and TC55 was 60 minutes. In addition, the kinetics of dye adsorption was found to follow the pseudo-second-order model, and the adsorption isotherm was very well described by the Langmuir model for all adsorbents. It is worth indicating that the adsorption capacities of TC and TC55 at 295 K and pH = 4.11 were 178 and 222 mg/g respectively. Indeed, the study of the temperature effect on the adsorption rate indicates that the reaction was endothermic. However, the values of the free energy showed that the adsorption was physisorption.