Study On Recovery Of Molybdenum From Solution Using Quaternary Ammonium Surfactant

It had been studied about recovering molybdenum(VI) from aqueous solution usingquaternary ammonium surfactants and fabricating ammonium molybdate with organicsolvents precipitation method using CTAC-molybdenum complex sediment as rawmaterial. The studied major contents were as follows:First, the complex precipitating process of molybdenum was studied from aqueoussolution using four kinds of quaternary ammonium surfactants. The experimental resultsshowed that the optimal pH was3.5about creating four molybdenum complex compounds,the precipitation ratio of molybdenum increased and then decreased with increasing of pHand molar ratio between quaternary ammonium salts and molybdenum, the precipitationratio decreased with increasing temperature. The DTA analytical results showed that thefour kinds of molybdenum complex deposits all generated MoO₃after decomposed by twotimes.Second, the fabricating process of ammonium molybdate was studied withwater-soluble organic solvent precipitation method using CTAC-molybdenum complexsediment as raw material. The experimental results showed that the crystal ratio ofammonium molybdenum first increased and then tended to certain values with increasingof the volume ratio of the precipitation agent, ammonia concentration, shock time, holdingtime, and adding amount of NH₄Cl. In addition, the crystal ratio increased and thendecreased with increasing of the concentration of CTAC-molybdenum complex. Under thesame conditions, the changing rule of crystal ratio was as follows along with the solventspecies: acetone was maximum, isopropyl alcohol was second, ethanol was minimum. Theresults of XRD showed that the three ammonium molybdate were the same substance.SEM analysis showed that the precipitation production was of uniform size, gooddispersion, and particle size of about1μm.Finally, the recovery trace molybdenum was studied from aqueous solution withfoam fractionation method using hexadecyl trimethyl ammonium chloride as blowingagent. The experimental results indicated that the recovery ratio and enrichment ratio ofmolybdenum increased and then decreased along with increasing pH. The recovery ratio increased and the enrichment ratio decreased along with increasing gas flow and surfactantconcentration. The maximum recovery ratio and enrichment ratio of molybdenum were90.26%and10.74, respectively, under the optimal conditions. The process was zero-orderkinetics, and the fitting equation was C=-0.2841T+4.266, the linear correlationcoefficient was R2=0.9969.