Enhancement of selective Cu(II) sorption through preparation of surface-imprinted mesoporous silica SBA-15 under high molar concentration ratios of chloride and copper ions

Abstract

We synthesized and characterized surface-imprinted poly (ethyleneimine) (PEI)-grafted mesoporous silica SBA-15 (Cu-imprinted PEI-SBA-15) for selective Cu(II) sorption from aqueous solutions. To enhance the Cu(II) selectivity of Cu-imprinted PEI-SBA-15, Cu(II) loading on PEI-SBA-15 was increased via Cu(II) sorption under high-molar-concentration ratios of chloride (Cl) and Cu(II) ions. Then, selective Cu(II) sorption sites were increased through imprinting processes (crosslinking and elution) on Cu-loaded PEI-SBA-15. Selective experiments were performed using Cu-imprinted PEI-SBA-15 prepared at various [Cl−]/[Cu(II)] ratios, ranging from 2 to 1000. In multinary solutions containing divalent ions, such as Cu(II), Pb(II), Zn(II), Ni(II), and Co(II), Cu(II) selectivity was highest (79.62) at a [Cl−]/[Cu(II)] ratio of 500; the relative Cu(II) selectivity for Cu-imprinted PEI-SBA-15 over PEI-SBA-15 was 29.24. In multinary solutions containing Cu(II) along with trivalent and tetravalent ions, such as Al(III), Cr(III), and Zr(IV), the Cu(II) selectivity was also highest (3.40) at a ratio of 500; the relative Cu(II) selectivity was 3.96. In this study, we demonstrated that the Cu(II) selectivity of surface-imprinted SBA-15 could be enhanced through its preparation under high [Cl−]/[Cu(II)] ratios.