Utilisation of barium-modified analcime in sulphate removal: Isotherms, kinetics and thermodynamics studies

Analcime and commercial zeolite were employed as a precursor for preparing sorbent material for SO42− removal over barium modification. Three sorbents were prepared: barium-modified analcime (ANA-Na-Ba), barium-modified acid-washed analcime (ANA-Ac-Na-Ba) and barium-modified zeolite (ZSM5-Na-Ba). Of the prepared materials, ANA-Ac-Na-Ba was the most efficient sorbent material for SO42− removal, with a maximum sorption uptake of 13.7 mg g−1 at room temperature. Batch sorption experiments were performed to evaluate the effect of initial pH, initial SO42− concentration, sorbent dosage, temperature and contact time of sorption. Several isotherms were applied to describe the experimental results and Bi-Langmuir was found to provide the best correlation for adsorption of SO42− on ANA-Ac-Na-Ba. Kinetic studies were applied for the most effective sorbent material, ANA-Ac-Na-Ba, and the results showed that the sorption process follows pseudo-second-order kinetics.