【摘要】 采用非分散的萃取方式,将乳状液膜体系Span80/皂化D2EHPA/煤油/液体石蜡/盐酸通过中空纤维膜对钕进行了逆流萃取,研究了乳化剂浓度、乳状液与水相流量比、内相盐酸浓度、萃取时间等因素对萃取率的影响。结果表明,乳状液和水相流量越小、乳状液内相盐酸浓度越大,萃取率越高,内相富集倍数越大。将乳液循环萃取70次后,内相富集倍数达50.2,表明乳状液在中空纤维膜萃取器中对稀土有很好的萃取和富集效果。与乳状液膜的分散萃取方式相比,非分散萃取方式的萃取速率更快,而且萃余水相澄清,液膜稳定性好,泄漏少,膜溶胀小。同时还计算了非分散萃取过程基于水相的总传质系数实验值和理论值,当调节参数Kf(络合反应传质系数)的取值为3.5×10-9m.s-1,水相流量大于10×10-6m3.s-1时,实验值与理论预测值相吻合。更多还原

【Abstract】 A non-dispersive extraction technique,using an emulsion liquid membrane within a hollow-fiber-contactor for the extraction and enrichment of Nd³⁺ from the dilute feed aqueous,was applied.The emulsion system is consisted of span80 [sorbitian monooleate],paraffin oil,D₂EHPA[2-（2-ethylhexyl-phosphonic acid）],kerosene as well as HCl solution.The extraction under various conditions such as the span80 concentrations,the flow rate of aqueous,the extraction time and HCl concentrations in receiving phase were studied.Results show that the lower the flow rates of aqueous are,the higher the extraction percentage and enrichment-fold are,and the extraction percentage increases with the increasing of HCl concentrations.When the initial Nd³⁺ concentration in feed is maintained at 1000 mg·L^-1 and the emulsion is recycled with 70 times by a counter-flow,the Nd³⁺ concentration in receiving phase is 50.2 fold compared with its initial concentration.It also proves that this non-dispersive extraction technique can overcome the serious problems appearing in dispersive extraction of liquid membrane,such as the leakage of solute concentrated in internal phase and the swelling of membrane.The overall mass-transfer coefficients of Nd³⁺ were also calculated and the data indicate that when the aqueous flow rate Q_w≥1×10^-6 m³·s^-1 and the forward reaction rate constant is adjusted to be 3.5×10^-9 m·s^-1,the calculation values of overall mass transfer coefficients gives the best fit to experimental data.更多还原