微乳液-中空纤维膜萃取钕的工艺研究

Extraction of neodymium using a nonionic water-in-oil microemulsion within hollow-fiber membrane

提出了一种新的膜分离过程即非离子W/O型微乳液-中空纤维膜萃取,所用非离子型微乳液体系为(OP-7+OP-4)/苯甲醇/D2EHPA/煤油/盐酸.在不同微乳液流速、料液流速、微乳液内相盐酸浓度、料液浓度、以及不同中空纤维膜数等条件下进行了微乳液-中空纤维膜逆流萃取Nd3+的研究.结果表明,微乳液和料液流速越小,萃取率越高,内相富集倍数越大.微乳液内相盐酸浓度越大,萃取率越高,但富集倍数反而减小.料液初始浓度越小,萃取率和富集倍数越大.当微乳液流速为6 mL/min、料液与微乳液流速比为3∶1、微乳液内相盐酸浓度为4 mol/L、料液浓度为200 mg/L时,经过微乳液在三个中空纤维膜萃取器中的串联萃取,Nd3+的萃取率达96.3%,内相Nd3+浓度为4238 mg/L,是萃余料液浓度的572.7倍,内相富集倍数为21.2.膜萃取过程与膜溶剂萃取相比对Nd3+有更高的萃取效率.

A novel membrane extraction technique using a water- in- oil nonionic microemulsion within a hollow- fiber- contactor（MHFC） for the extraction and enrichment of neodymium is put forward in this paper. The microemulsion was composed of polyoxyethylene（7 ） nonylphenol （OP - 7 ）, polyoxyethylene （4） nonylphenol（OP- 4）, benzylacohol, D2EHPA[2- （2- ethylhexylphosphonic acid], kerosene as well as hydrochloride acid. The hollow fiber membrane was made of polysulphone. The neodymium extraction using this new technique under various conditions were carried out. Results showed that the lower the flow rate of microemulsions, the feed solutions and the initial feed concentrations, the higher the neodymium extraction percentage and the enrichment - fold. It also showed that with the increasing of HCl concentration in receiving phase, the extraction percentage increased, on contrary, the enrichment- fold of Nd^3＋ in receiving phase decreased. While the extraction for Nd^3＋ was undergone at the following conditions, i.e. the initial feed concentration was 200 mg/ L, the microemulsion flow rate was 6 mL/min, the flow rate ratio of feed solution to microemulsion was 3：1, the HCl solution concentration was 4 mol/L and 3 HFM modules were used, the extraction percentage reached as high as 96.3%, the Nd^3＋ concentration in receiving phase was 4 238 mg/L which was 572.7 and 21.2 fold respectively compare with the raffinatc concentration （i. e. 7.4 mg/L） and the initial feed concentration.