Study On Recovery Of Trace Vanadium(Ⅴ) From Aqueous Solution Using Continuous Packed Foam Separation Column

The recovery process, separation performance of Vanadium(V) and axial diffusion characteristic in liquid phase of packing layer were studied with simulated aqueous solution containing trace Vanadium(V) as raw materials in packed foam fractionation column under the conditions of continuous steady-state operations by lauramidopropylamine oxide as foaming agent and collector of Vanadium(V).Firstly, the interfacial property and foaming characteristic were studied about the four nonionics surfactants: iso-tridecanol polyoxyehtylene ether(10), dodecyl polyglucoside, lauramidopropylamine oxide and N-polyoxyethylated-N-octadecylamine(15). The experimental results show that dodecyl polyglucoside is the best and iso-tridecanol polyoxyehtylene ether(10) is the lowest in the ability of decreasing interfacial tension and is on the contrary in the efficiency of decreasing interfacial tension among four surfactants. The ranking of foaming ability is the same as the one of decreasing interfacial tension. The ranking of foam stability is lauramidopropylamine oxide > dodecyl polyglucoside > iso-tridecanol polyoxyehtylene ether(10) > N-polyoxyethylated-N-octadecylamine(15). The screening experiments of surfactants indicate that lauramidopropylamine oxide is suitable for recovering vanadium(V) by foam fractionation method as foaming agent and collector of vanadium(V).Secondly, the recovery performance of vanadium(V) were studied in packed foam column under continuous steady-state operating conditions with lauramidopropylamine oxide as foaming agent and V(V) trapping agent. The experimental results indicate that the recovery rate and enrichment of vanadium(V) firstly increase and then decrease and get to maximum value in p H=4.0 among p H=2.0-6.0, the recovery rate of vanadium(V) increases gradually and then maintains constant and but the enrichment of vanadium(V) decreases gradually with enhancing air flow, the changing rule of recovery rate and enrichment of vanadium(V) is the same as the one of air flow when increasing lauramidopropylamine, the recovery rate and enrichment of vanadium(V) are all decrease with increasing feed flow and vanadium(V) concentration, the enrichment of vanadium(V) increases gradually and the recovery rate of vanadium(V) decreases gradually with increasing foam layer height, the recovery rate and enrichment of vanadium(V) increase slowly with increasing packing layer height.Third, the separation performance between vanadium(V) and metal ions was studied. The results indicate that the recovery rates increase and separation factors decrease gradually for Pb(II), Cu(II), Fe(III) and the separation factors of other metal ions are basically unchanged and maintain higher values with increasing aqueous solution p H. the separation efficiency is better and the separation factor is all greater among vanadium(V) and Co(II), Ni(II), Cu(II), Zn(II), Cr(III) except Fe(III) and Pb(II) at p H=4.0, metal ions are enriched in aqueous phase and vanadium(V) is enriched in foam phase, the recovery rate and enrichment of vanadium(V) are not influenced hardly and it can be achieved for the separation among vanadium(V) and metal ions.Finally, the axing backmixing was studied in aqueous phase of packing layer. The results show that the backmixing increases with increasing superficial gas velocity and decreases with increasing superficial liquid velocity. The gas holdup is higher obviously in bubble area with packing layer than the one with no packed liquid bath, so there is greater mass transfer area and higher mass transfer rate.