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

Silica gel and a molecular sieve were used as supports for hydrocarbons with beta-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 beta-diketones or salicylaldoximines supported on silica, but controls indicated that about 85% was due to sorption Supported beta-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.