The adsorption behavior of individual Cu(II), Zn(II), and Cd(II) ions over a CuO-modified ceramic membrane synthesized from fly ash

Abstract

The ceramic membrane synthesized from fly ash as the base material with the addition of CuO was used as an adsorbent for Cu(II), Zn(II), and Cd(II) ions in an aqueous solution. The effect of CuO on the characteristics and adsorption activity of fly ash-based ceramic membrane has been studied over Cu(II), Zn(II) and Cd(II) ions with different pH of 2–8, contact time of 30–150 min, and initial concentration of metal ions of 0.1–0.7 mmol/L. The adsorption using the batch method was carried out on Cu(II), Zn(II), and Cd(II) ions individually. This study showed that the surface area and the total pore volume of the fly ash-based ceramic membrane with addition of CuO increased to about nearly eight folds and more than three folds, respectively, compared to the original fly ash-based ceramic membrane. However, the pore size of the fly ash-based ceramic membrane with addition of CuO decreased to more than a-half of the original pore size. The optimum adsorption activity of each Cu(II), Zn(II), and Cd(II) ion was achieved at a pH of 4, 6, and 5, respectively. The adsorption kinetics of Cu(II), Zn(II), and Cd(II) ions on the fly ash-based ceramic membrane with addition of CuO followed the second-order pseudo kinetics model. Moreover, the isotherm study on the adsorption of Cu(II), Zn(II), and Cd(II) ions on the fly ash-based ceramic membrane with addition of CuO followed the Langmuir isotherm model. The adsorption capacity of the fly ash-based ceramic membrane with addition of CuO for Cu(II), Zn(II) and Cd(II) ions was 205 mmol/g, 188 mmol/g, and 111 mmol/g, respectively. This study showed clearly that the fly ash-based ceramic membrane with addition of CuO was an effective adsorbent for the adsorption of Cu(II), Zn(II) and Cd(II) ions.