Removal of coomassie brilliant blue G-250 from aqueous solutions by anion-exchange resin

In this study, the removal of the toxic dye Coomassie Brilliant Blue G-250 (CBB) from aqueous solutions was investigated using Purolite A420S, a strong base anion-exchange resin. Batch experiments were conducted to evaluate the effects of resin dosage, solution pH, contact time, initial dye concentration, and temperature on the ion-exchange performance. The optimum resin dosage was determined as 0.05 g per 25 mL solution, yielding a maximum removal efficiency of approximately 91%. The removal efficiency was found to be relatively insensitive to pH in the range of 5–9. Kinetic studies indicated rapid initial uptake followed by equilibrium after 240 min, and the experimental data were best described by the pseudo-second-order kinetic model. Equilibrium isotherm analysis showed that CBB sorption followed the Langmuir isotherm model, with a maximum sorption capacity of 5.17 mg/g. Thermodynamic parameters revealed that the sorption process is exothermic and accompanied by a decrease in entropy, indicating increased order at the solid–solution interface during ion exchange.