Adsorption of cobalt(II) ions from aqueous solutions by palygorskite

摘要

A study on the removal of cobalt ions from aqueous solutions by palygorskite was conducted under batch conditions. The effect of time, pH of the dispersion, ionic strength, temperature and initial metal concentration on the adsorption of Co~(2+) onto palygorskite was investigated. The adsorption of Co~(2+) was a fast process that followed the pseudo-second-order kinetics. This process could be described by the Langmuir model and gave a maximum Co~(2+) adsorption capacity of 8.88 mg/g at 35 ℃. The adsorption was dependent on pH and was influenced by the ionic strength. The adsorption mechanism primarily involved inner-sphere complex-ation, with minor contributions of the exchange of structural Mg_2+ ions. Palygorskite could be completely regenerated with Na_2CO_3 and continued to exhibit excellent Co~(2+) adsorption even after three consecutive cycles.