Extraction of heavy metals by chelators attached to silica gel by a corkscrew mechanism

Abstract

Silica gel and a molecular sieve were used as supports for hydrocarbons with β‐diketone or salicylaldoximine chelating moieties attached. The effectiveness of removal of copper from ammoniacal solution or cadmium from buffered (pH 7–11) media were measured. The effect of chelation versus sorption were compared for the two metals and as a function of pH for the cadmium series. Copper (5 ppm) could be completely extracted by substituted β‐diketones or salicylaldoximines supported on silica, but controls indicated that about 85% was due to sorption. Supported β‐diketones on molecular sieve (Linde 3A) removed 90% of the copper, and about half was due to sorption. Cadmium (1 ppm) was most effectively removed at pH 9 or 10, and adsorption was a major effect above pH 8.

Key words:

• Supported
• remediation
• heavy metals
• chelating agents
• P‐diketones
• salicylaldoximines