The Extraction Of Moiybdenum In Thirteen Alcohol Poiyoxyethylene Ether(1308)-Sulfate Aqueous Two-Phase Systems

The extraction and separation performance of molybdenum(VI) in aqueous solution were systematically studied by aqueous two-phase systems(ATPS) composed of isotridecanol ethoxylates(1308)- sulfate(Li2SO4/(NH4)2SO4/MgSO4)- H2 O.Firstly, the thermodynamic properties of 1308-(Li2SO4/(NH4)2SO4/MgSO4)-H2 O aqueous two-phase systems were researched. The experimental results show that the cloud point in 1308 aqueous solution first decreases and then gradually increases and reaches the minimum when 1308 concentration is 40 g/L with increasing 1308 concentration, and markedly decreases after adding three sulfates for salting out effect,and is in direct proportion to three sulfate concentration. The ability to lower the cloud point temperature is Li2SO4>MgSO4>(NH4)2SO4. The two-phase area of aqueous two-phase systems composed of three sulfates all increases with increasing temperature,and slightly changes with changing aqueous pH, and the ability to form two phase is consistent with their salting capability for the used three sulfates.Secondly, the extraction performance of molybdenum(VI) in aqueous solution were studied by 1308-(Li2SO4/(NH4)2SO4/MgSO4)-H2 O aqueous two-phase system. The experimental results show that the extraction rate and distribution coefficient of molybdenum increases with increasing three sulfate concentration, and the extraction ability is successively Li2SO4>(NH4)2SO4>MgSO4. The solubilization capacity of molybdenum increases with increasing 1308 concentration, but the emulsification of ATPS appears easily if 1308 concentration is too high. The extraction of molybdenum first increases and then reduces with increasing aqueous pH within the scope of pH=1.00-7.00 and is higher at pH=2.00-3.00. The extraction rate and distribution coefficient of molybdenum decreases with the increase of temperature within 30-70 ℃,and the appropriate temperature is 30-40 ℃. The time of stirring and equilibrium are all short. FT-IR analysis shows that there is not evident change of absorption peak position of C-O-C groups in 1308 molecule with or without molybdenum(VI) in 1308-rich micellar phase, indicating that there is weak interaction between 1308 molecule and molybdenum anion. DLS analysis shows that the size of 1308 micellar phase slightly enlarges and apparent zeta potential has a little change from positive to negative.Therefore, we can conclude that extraction mechanism of molybdenum anion is due to relatively high hydrophobic nature of polymolybdate anion and salting-out effect of phase-forming sulfate, and enters into 1308 micellar core by solubilization mode.Thirdly, the stripping and separation performance of molybdenum(VI) were studied.The experimental results show that the extraction rate of molybdenum decreases with increase of the amount of added metal cations, and increases with adding charge modifier octadecyl amine ethoxylate ether(1815), in the meanwhile, the extraction of metal cations are basically invariant after adding 1815, as a result, the separation between molybdenum and Cu(II)、Co(II)、Ni(II)、Mn(II)、Zn(II)、Fe(III)、Al(III) can be achieved.The stripping of molybdenum increases with raising temperature and aqueous pH, and slightly increases with increasing ammonium sulfate concentration from 50 to 200 g/L,but the paste forms for too high ammonium sulfate concentration.