Removal of high-concentration sulfate ions from industrial wastewater using low-cost modified Jordanian kaolin

This research investigates kaolin's adsorption potential from the Mahis area in Jordan as an adsorbent to treat wastewaters contaminated with a high concentration of sulfate ions in aqueous solutions. Artificial wastewater was studied of 500 mg/L sulfate ions concentration and at pH = 5.5. The kaolin used was modified by sorption of BaCl2 on its surface. A fixed-bed column (particle size 4 mm; bed height 7 cm; bed mass 35 g) was used to measure breakthrough curves to evaluate sulfate ions' adsorption behavior onto the modified kaolin at different flow rates. For the studied flow rates of 6.6, 12, and 24 mL/min, the measured breakthrough times are 50, 24, and 13 min respectively, while the exhaust times are 75, 50, and 40 min respectively. The measured breakthrough curves are analyzed by the mathematical models: Bohart-Adams model, Thomas model and Yoon- Nelson model. The calculated maximum adsorption capacity from the Bohart-Adams model is 46,838.34 mg/L at a flow rate of 24 mL/min. Thomas rate constant values are nearly constant at 0.0001 L/min mg at all flow rates. The estimated values from the Yoon-Nelson model of the time needed to reach 50% of the breakthrough are 43.96, 20.88, and 13.46 min the flow rates 6.6, 12, and 24 mL/min, respectively. Yoon-Nelson model fits the measured breakthrough curve to a higher degree than the Bohart-Adams model.