Adsorption of heavy metals on amine-functionalized SBA-15 prepared by co-condensation: Applications to real water samples

Abstract

SBA-15 functionalized with 3-aminopropyltrimethoxy-silane was studied as potential absorbent for Cd 2+, Co 2+, Cu 2+, Zn 2+, Pb 2+, Ni 2+, Al 3+ and Cr 3+. The adsorption capacity and selectivity of the materials were investigated in single and multi-metal solutions. Using single-metal solutions, the adsorbent was found to have an affinity (molar basis) for metal ions in decreasing order of Al 3+ > Cu 2+ > Ni 2+ > Zn 2+ > Co 2+ > Cd 2+ > Pb 2+ > Cr 3+. Using very dilute solutions, i.e., 10 ppm, more than 95% of cations were removed, except Co 2+ and Cr 3+, indicating the high sensitivity of the current adsorbent. The affinity for coexisting metal cations decreased in the order of Al 3+ > Ni 2+ > Cr 3+ > Pb 2+ > Zn 2+ > Cd 2+ > Co 2+ > Cu 2+. The adsorption capacities in multi-metal solutions were lower than in single-metal ones because of competition between metallic elements for the amine groups, with a preference for Al 3+. The amine-modified SBA-15 adsorbent exhibited an excellent selectivity against sodium, potassium, and calcium, indicating that the ionic strength does not affect the adsorption properties. Application of this material to remove copper in tap water, river water, and electroplating wastewater was shown to be successful.