Removal of crystal violet dye from aqueous solution using yeast-treated peat as adsorbent: thermodynamics, kinetics, and equilibrium studies

Peat has been used for the removal of various dyes by adsorption. This study presents a new approach to increase the efficiency of peat for the removal of crystal violet (CV) dye from synthetic wastewater. The use of yeast-treated peat (Y peat) resulted in higher adsorption capacity than using untreated peat. Other factors that would affect the adsorption process, such as dye concentration, pH, and temperature, were also investigated. The dye uptake by peat and Y peat was supported by thermodynamics and kinetics studies. The Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips models were applied to the adsorption studies. Experimental data based on linear regression, simulated isotherms, and error analyses showed that the adsorption of CV followed the Sips model with maximum adsorption capacities of 8.16 and 17.95 mg g−1 for peat and Y peat, respectively. Thermodynamics studies revealed that the adsorption process was both spontaneous and endothermic in nature. Kinetics data fitted to the pseudo-first-order, pseudo-second-order, Elovich, intra-particle diffusion, and Boyd models revealed that adsorption of CV on peat and Y peat followed the pseudo-second-order model, which was supported by the diffusion mechanism.