Removal of heavy metal ions from aqueous solutions using dithiooxamides supported on silica gel

Abstract

Silica gel was used as a support for N, N'‐ didodecyldithiooxamide, a bidentate chelating agent with sulfur and nitrogen donor atoms. Aqueous solutions of five heavy metals (0.03 M copper, lead, nickel, silver, and zinc solutions) were treated with silica gel (control) and loaded silica gel. Resulting solutions were analyzed using atomic absorption spectroscopy. Using silica gel alone (control), the percent metal extracted was 3.2+0.9 (Cu), 16.3 ±1.6 (Ni), 3.9±1.2 (Pb), 13.6 ± 4.8 (Ag), and 4.8± 1.8 (Zn). Using silica‐supported chelating agent, the percent removal was 99.1±0.3 (Cu), 70.7±1.7 (Ni), 29.1±1.7 (Pb), 83.5±0.7 (Ag), and 6.5±1.9 (Zn). The results did not correlate with the “softness”; parameter for type a or type b metals.

Key words:

• Copper
• nickel
• lead
• atomic absorption spectroscopy
• remediation
• chelation