Equilibrium and thermodynamic studies on the removal of basic black dye using calcium alginate beads

The potential use of calcium alginate beads for removal of dyes from colored effluents in dynamic batch mode has been studied. Basic black dye, which is one of the most commonly used dyes in leather industry, has been chosen for the study. The parameters that affect the dye adsorption such as contact time, initial concentration of dye, solution pH and temperature have been investigated and optimized conditions have been determined. Maximum adsorption capacity of 57.70 mg g−1 has been achieved at an initial concentration of 300 mg L−1, with 4 g L−1 of alginate dosage, at pH 4.0 and at room temperature (30 ± 1 °C). Adsorption isotherm studies clearly indicate that the Langmuir isotherm shows a better fit for adsorption of the dye by alginate beads, implying a homogeneous and monolayer binding surface. Kinetic data of adsorption of dye on to calcium alginate beads fits well to pseudo-second order kinetic model. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° have been determined, which indicates a spontaneous endothermic adsorption process.