Adsorption of copper(II) onto perlite

Perlite samples activated by H2SO4 solutions were utilized as adsorbents for the removal of Cu(II) ions from solutions at different pHs, ionic strengths, and temperatures. It has been found that the amount of Cu(II) adsorbed increased with increased pH, whereas it decreased as the ionic strength, temperature, and acid activation increased. Adsorption isotherms correlated reasonably well with the Langmuir adsorption isotherm and Langmuir parameters of adsorption isotherm (Q(m) and K) were found with the aid of the linearized Langmuir isotherm. The entalphy change for Cu2+ adsorption has been estimated as -5.14 +/-1 and 4.38 +/-1 kJ/mol for unexpanded and expanded perlite samples, respectively. Proton stoichiometry (x) was calculated from Kurbatov plot using the amount of Cu(II) adsorbed at different pH. The dimensionless separation factor (R) has shown that perlite can be used for removal of Cu(II) ion from aqueous solutions, but unexpanded perlite is more effective. (C) 2001 Academic Press.