Comparative Study of the Reactivity and Selectivity Characteristics of Three SIlica Gel Phases-Immobilized-8-Hydroxyquinoline for Separation and Pre-concentration of Chromium (III) from Water Samples

摘要

8-Hydroxyquinoline (8HQ) was used to modify the silica gel surface via the physical adsorption method (phase I), as well as a chemical immobilization approach (phase II and III). The loading process of 8-hydroxyquinoline on the surface of silica gel is simple, direct, and based on only a one step reaction procedure. The three synthesized silica gel phases (I-III) were analytically compared according to their metal-uptake, extraction, and selective properties toward a series of di- and trivalent metal ions. The study of the selectivity characters incorporated into these modified silica gel phases revealed that silica gel phase revealed that silica gel phase (I) is the highest selective one for Cr (III), with a minimum interference of the other metal ions, and silica gel phase (III) is the highest selective one for Cu (II) but with a high pronounced interference from other metal ions as Cr (III), Ni (II), and Co (II) ions. Silica gel phase (II) was found to be the lowest in metal capacity values, as well as selectivity study and kinetics of the chemical binding processes. The applications of silica phase (I) as a potential selective solid phase extractor for separation and pre-concentration of Cr (III) from natural tap water spiked with 1.0 and 4.0 ppb Cr (III) were successfully accomplished via a pre-concentration micro-column with percentage extraction and pre-concentration of 100% ± 1.5～2.0%. THe possible use of phase (I) for the direct determination of real Cr (III) concentration in sea water samples was also performed via a pre-concentration micro-column, and the results showed an actual concentration range of 0.320-1.67 ng mL~(-1) of Cr (III) in the studied samples.