Adsorption of Pb(II), Cd(II), and Cu(II) ions onto SiO2/kaolinite/Fe2O3 composites: modeling and thermodynamics properties

Abstract

A new route for the preparation of SiO2/kaolinite/Fe2O3 composites from Sweileh sand deposits, west Amman, Jordan. Chemical and XRF analysis results indicated that sand deposits composed mainly from SiO2, kaolin clay, iron salts, and titanium, calcium, magnesium and sodium salts. SiO2/kaolinite/Fe2O3 nanocomposites were prepared by treating Sweileh sand samples with concentrated hydrochloric acid and sodium hydroxide. pH solution, adsorbent dose, initial metal ion concentration, contact time, and temperature effects on adsorption process were examined. Langmuir isotherm has the best fitting to the experimental data (R2 = 0.9999), with adsorption capacity, qmax of 166.67 mg/g, 163.93 mg/g and 153.85 mg/g for Pb(II), Cd(II) and Cu(II) ions, respectively. The negative values of ΔGo and the positive value of ΔHo indicated the adsorption process was spontaneous and endothermic.