Immobilization of Copper from Aqueous Solution and Contaminated Sediment Using Modified Clinoptilolite

The efficiency and mechanism of modified clinoptilolites immobilizing Cu from aqueous solutions and contaminated sediments were investigated. The results showed that the clinoptilolite modified by lanthanum chloride (LaCl₃) at a particle size of 0.5–1.0 mm could remove 65% of Cu²⁺ from 100 mg L⁻¹ of Cu²⁺ solutions at the sorbent:solution mass ratio of 1:100. The equilibrium data fitted well to the Langmuir isotherm model with a maximum adsorption capacity of 21.09 mg Cu²⁺ g⁻¹ at 25 °C. The Dubinin–Radushkevich adsorption model indicated that the adsorption of Cu²⁺ by modified clinoptilolite can be identified as chemisorption. The pseudo-second-order model could well represent the kinetics of the adsorption. The results of toxicity characteristic leaching procedure (TCLP) and Community Bureau of Reference (BCR) sequential extraction procedure showed that the modified clinoptilolite could reduce the leaching of Cu in the sediment and effectively transform Cu from the acid extractable or reducible fractions to the oxidizable or residual fractions. The presented work showed that the modified clinoptilolite holds great potential to remove Cu²⁺ from water, and to stabilize Cu-contaminated sediment.