Application Of Floatation Complexation Extraction On Separation And Concentration Of Organics With Amphoteric Functional Groups, And The Study On The Separation Mechanism

According to the advantage of solvent sublation and complexation extraction, the Flotation Complexation Extraction (FCE) was proposed. Since it has many advantages, such as excellent concentration efficiency, excellent selectivity, lower wastage of organic solvent, simply operation of back-extraction and the solvent reclamation, it has demonstrates a good prospect in the polar organic solutes of its separation and concentration, recover and application.In this paper, FCE was successfully applied to separate and concentrate L-tryptophane and Para-Aminobenzoic Acid (PABA), which belong to organics with amphoteric functional groups, and satisfactory results were obtained. Moreover, their separation mechanisms were studied. Specific studies are described below.In the first part, FCE was applied to separate and concentrate the model compound L-tryptophane from aqueous phase. The effect of pH, extraction solvent, electrolyte (NaCl), concentration of Di(2-ethylhexyl) phosphoric Acid (P204) in organic phase, air flow rate and flotation time were investigated in detail, and the optimal conditions for FCE were obtained. Under the optimal conditions, the L-tryptophane was separated and concentrated from aqueous phase. After the back-extraction, the product was characterized by SEM and FTIR. The purity of the product was determined by HPLC, and the L-tryptophane content was 99.26%. The kinetics of the separation process in L-tryptophane by FCE was also investigated. The experimental results showed that the FCE process of L-tryptophane obeys 2.5 order kinetic equations. Moreover, the comparison of FCE and complexation extraction was discussed in this part.In the second part, FCE was successfully applied to separate and concentrate the model compound Para-Aminobenzoic Acid (PABA) from actual water, and satisfactory results were obtained. The effect of pH, extraction solvent, electrolyte (NaCl), concentration of P204 in organic phase, air flow rate and flotation time were investigated in detail, and the optimal conditions for FCE were gained. Under the optimal conditions, the PABA was separated and concentrated from aqueous phase. After the back-extraction, the product was characterized by FTIR, and it was shown to be PABA. The purity of the product was determined by HPLC. The comparison of FCE and complexation extraction was also discussed.In the third part, the separation mechanism of the separation and concentration of organics with amphoteric functional groups by FCE was studied. There are two processes in the FCE, bubble masstransfer and complexation transfer. And the complexation reaction between the organics with amphoteric functional groups and P204 is the most important step, which controls the kinetic process of FCE. Actually, the bubble masstransfer process strengthened the complexation extraction. The experimental results demonstrate that FCE is shown to be a more effective way of separating and concentrating model compounds than complexation extraction. The essential difference of the FCE and the traditional complexation extraction was investigated.