Study On Recovery Of Trace Molybdenum(â…¥) From Aqueous Solution Using Continuous Foam Separation Method

The purpose of this study is to investigate the separation performance ofmolybdenum (â…¥) in foam column and packed foam column under continuous steady-stateoperating conditions with quaternary ammonium salt surfactant as the foaming agents.Firstly, the interfacial property of the four cationic surfactants(DTAC, TTAC, CTAC,OTAC) was studied. We obtain the relationship of interfacial tension and concentration,and then getting the critical micelle concentration(CMC), the saturation adsorptioncapacity and the molecular cross-sectional area. The experimental results show that thesaturation adsorption capacities firstly increase and then decrease with the increase ofcarbon number of the hydrophobic group.Secondly, the separation performance of molybdenum (â…¥) was studied in foamcolumn and packed foam column under continuous steady-state operating condition withhexadecyl tri-methyl ammonium chloride as the surfactant. The experimental resultsindicate: for packed foam column, there are little effects of liquor pH, air flowrate andsurfactant concentration on recovery rate and enrichment rate of molybdenum withinexperimental conditions, but with the increase of feed flow rate, recovery rate andenrichment rate all decline clearly, while the effects of these process parameters onseparation performance of foam column is relatively obvious; However, the enrichmentrate increases and the recovery rate decreases with the increase of blister layer height infoam column, and there are of reverse rules with the increase of packing layer height inpacked foam column.Finally, the macroscopical dynamics of the separation process was studied in foamcolumn and packed foam column. the separation process could be regarded as an chemicalreaction process, the equlvalent chemical reaction constants were introduced, and wediscussed the average stay time and variancem by pulse method, obtianed the distributiondensity functions of a series of residence time. At the same time, the mathematical modelof separation process was analyzed. The results indicate that there is little liquidbackmixing and in favor of advancing separation efficiency in packed foam column; according to first order reaction characteristics to calculate recovery rate, the theoreticaland the experimental values are almost equal, the process of foam separation could beregarded as first order reaction.