Kinetic and Isotherm Study on the Adsorption of Crystal Violet in Water Using Low-Cost Adsorbent of Coal Fly Ash

The kinetic and isotherm study on the adsorption of crystal violet (CV) on coal fly ash (CFA) has been studied. Before being used as an adsorbent, CFA was characterized with AAS, XRF, FT-IR, and XRD to determine the mineral components in CFA. The adsorption study of crystal violet in water with CFA includes the effects of solution pH, mass adsorbent, crystal violet concentration, and contact time on the adsorption process. The pseudo-second-order kinetic model best expressed the crystal violet adsorption behavior on CFA with the rate constant (k) of 1.24×10-1 g mg-1 min-1. The Langmuir isotherm model was found to be the best model to describe the adsorption, with a maximum adsorption capacity of 10.14 mg g-1 at room temperature. Based on the value of adsorption energy as well as the best isotherm model, the adsorption of CV on CFA forms a monolayer and can be classified as chemisorption.