Synergistic Extraction Of Divalent Transition Metal And Solid-phase Microextraction Of Phenol

As a branch of solvent extraction,synergistic extraction can not only increase extraction efficiencies but also enhance extraction selectivities and separation coefficients among different elements. Compared with the extraction by using one kind of extractant, synergistic extraction is a more effective extraction and separation method. It has been widely applied to hydrometallurgy for the separation and purification of rare earths and divalent transition metals.In this paper, the extraction of zinc(II) and cadmium(II) by a netural organophosphorus extractant (tri-n-butylphosphate, TBP) and organic amines (N503, N235) is studied. The extraction effects of zinc(II) and cadmium(II) by TBP+N503 and TBP+N235 are investigated. It is shown that there are synergistic effects for zinc(II) when extracted by TBP+N235. However, no evident synergistic effects are found when zinc(II) is extracted by TBP+N503 and cadmium(II) extracted by TBP+N235 and TBP+N503. The synergistic extraction of zinc(II) by TBP+N235 is investigated systematically. The extracted compound is determined by using a slope method. The synergistic extraction equation is obtained together with equilibrium constant and thermodynamic functions. In addition, the separation of zinc(II) and cadmium(II) by TBP+N235 is discussed in this paper.Solid-phase microextraction (SPME) was introduced as a new sample-preparation method in early 1990s. Compared with traditional sample pretreatment methods, it is a simple and effective technology that does not need organic solvents and combines sampling and enrichment in one step. SPME can be coupled with many analytical instruments for the determination of targetcompounds, among which the combination of SPME with gas chromatography (GC) has been widely used because the SPME fiber can be inserted into the GC injection without any connection. SPME-GC has been extensively applied to many fields in analytical chemistry. In the present work, a method for the determination of phenol in aqueous samples has been established by coupling SPME with GC. An 85μm polyacrylate fiber is employed in the experiments. The effects of extraction method, extraction time, desorption time have been studied. Under the optimized experimental conditions, the standard curve is obtained. The relative standard deviation is calculated as 2.4%. The proposed method has been applied to the determination of phenol in salicylic acid.