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 hydrocarbon s with beta-diketone or salicylaldoximine chelating moieties attached. The effectiveness of removal of copper from ammoniacal solution or ca dmium from buffered (pH 7-11) media were measured. The effect of chela tion versus sorption were compared for the two metals and as a functio n of pH for the cadmium series. Copper (5 ppm) could be completely ext racted by substituted beta-diketones or salicylaldoximines supported o n silica, but controls indicated that about 85% was due to sorption Su pported beta-diketones on molecular sieve (Linde 3A) removed 90% of th e 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.