Removal of Bezathren green dye from aqueous solution: equilibrium, kinetic and thermodynamic study

The synthesis of efficient and low-cost adsorbents based on cetyltrimethylammonium bromide (CTAB)-modified, dodecyltrimethylammonium bromide (DTAB)-modified and tetra- n -butylammonium bromide (TBAB)-modified local sodium bentonite (B) for the removal of Bezathren green textile dye from aqueous solutions is reported. Infrared spectroscopy and XRD analysis confirmed the presence of surfactants in B. The d 001 values of the organo-bentonites were as follows: d 001 = 22.4 Å, d 001 = 18.3 Å and d 001 = 15.9 Å for B-CTAB24, B-DTAB24 and B-TBAB24, respectively. The optimal conditions for the quantitative removal of the dye using a batch process were determined, considering the effects of contact time, dose of adsorbent, initial dye concentration and temperature. The results revealed that the surfactant CTAB plays a leading role in the adsorption of the dye, and the interlayer space was not a determining factor in the adsorption. The maximum uptake capacity reached 180.2 mg g −1 within 10 min for B-CTAB24. The experimental data were well fitted by pseudo-second-order kinetics. The thermodynamic parameters of the B-CTAB24 adsorbent for the dye indicated a spontaneous and exothermic process. Graphical abstract