Adsorption–desorption behavior of halloysite clay for Cu2+ ions and recovery of copper by electrodeposition method
Lê Thị Duyên, Bui Hoang Bac
Abstract
Halloysite sample, obtained from Phu Tho province, Vietnam, was utilized to investigate the adsorption behavior of Cu2+ ions. Several factors influencing Cu2+ adsorption efficiency and capacity were explored, including pH value, contact time, adsorbent dose, and initial Cu2+ concentration. Under optimal conditions (0.8 g of halloysite per 50 mL of solution, an initial Cu2+ concentration of 40 mg/L, pH 6.2, a contact time of 80 minutes, and a temperature of 25°C), the study yielded an adsorption efficiency of 85.19% and a capacity of 2.14 mg/g for Cu2+ ions. Adsorption isotherm analysis was conducted using the Langmuir and Freundlich models, while the kinetics of the adsorption process were investigated through the first-order pseudo and second-order pseudo models. Furthermore, the desorption of Cu2+ ions and the recovery of Cu metal were explored, with a recovery efficiency of Cu reaching 94.65% under suitable conditions (0.3 g mass of halloysite, a current of 7.5 mA, and an electrolytic time of 5 hours at 60°C). These findings suggest the potential application of halloysite clay for removing Cu2+ ions from polluted water, recovering Cu metal, and reusing the adsorbent.