Glycerol–silica gel: A new solid sorbent for preconcentration and determination of traces of cobalt(II) ion

This paper reports on the synthesis and application of glycerol-bonded silica gel as a new, very stable, inexpensive and easily prepared solid sorbent for effective preconcentration of traces of Co(II) in aqueous solutions. The synthetic route for immobilizing glycerol on silica gel is a simple two-step process. Factors influencing the sorption and desorption of cobalt ion have been investigated. Aqueous sodium citrate solution has been used as eluent for desorbing cobalt ions. The amount of cobalt, which is then eluted is measured using flame atomic absorption spectroscopy. The effect of coexisting ions on percent recovery of cobalt showed no interference from most of the ions tested. The proposed method permitted large enrichment factors of about 500 and higher. The maximum capacity of the sorbent was found to be 250 μg of cobalt per gram of sorbent. The precision of the method was 1.58% (n = 10). The method was applied to the determination of traces of Co(II) in NaCl salt (Merck) and in water samples.