Separation of Tb^(3+) , Dy^(3+) , Ho^(3+) , Er^( 3+) with Solvent Impregnated Resins Containing Di-(2,4,4-trimethylpentyl) Phosphinic Acid

Solvent impregnated resins (SIR) with di (2,4,4 trimethylpentyl)phosphinic acid (Cyanex 571) were studied by adsorption of the extractant into Amberlite XAD 4; XAD 7; XAD 1180 polymeric adsorbents. The results shas that Cyanex 571/XAD 7 impregnated resins containing extractant of 0 35～0 45 g·g -1 resin have a favorable extractive activity in HCl medium. The rare earths (Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ ) are separated by using SIR as the column stationary phase. The better separation effect is obtained at lower load and slower elution rate.

Extractant(2,3-dimethylbutyl)(2,4,40-trimethylpentyl) phosphinic acid(INET-3) impregnated onto XAD-16 and its extraction and separation performance for heavy rare earths from chloride media

（2,3-Dimethylbutyl）（2,4,40-trimethylpentyl）phosphinic acid（INET-3） was impregnated onto dry macroporous resins XAD-16 and pretreated XAD-16 with ethyl alcohol and HCl（Pre-XAD-16） to prepare the solvent impregnated resins SIRs-INET-3/XAD-16 and SIRs-INET-3/Pre-XAD-16. The molecular weight distribution of the low molecular weight（LMW） polymers washed off by ethyl alcohol during XAD-16 pretreatment was determined by gel permeation chromatography（GPC）. The macroporous resins（XAD-16 ＆ Pre-XAD-16）, the corresponding solvent impregnated resins（SIRs-INET-3/XAD-16 ＆SIRs-INET-3/Pre-XAD-16） and the PVA coated SIRs-INET-3/Pre-XAD-16 with boric acid as cross-linking agent were characterized by FT-IR, SEM-EDS and TGA. The effects of XAD-16 pretreatment and PVA coating technology on RE（III） adsorption equilibrium time, INET-3 losses during extraction and adsorption capacity were investigated. The adsorption kinetics, selectivity and stripping behaviors of SIRs-INET-3/XAD-16 were further studied. The washed off LMW polymers had the Mn of 36,656, Mw of 40,310 and polydispersity coefficient of 1.10. The SIRs-INET-3/XAD-16 had shorter equilibrium time,less INET-3 loss and more Tm（III） adsorption capacity than the SIRs-INET-3/Pre-XAD-16. The PVA coated SIRs-INET-3/Pre-XAD-16 had less INET-3 loss and more Tm（III） adsorption capacity but longer equilibrium time than the uncoated SIRs-INET-3/Pre-XAD-16. The adsorption of RE（III） on the SIRsINET-3/XAD-16 followed the pseudo-second-order kinetic model. The Tm（III） accumulative adsorption amounts onto SIRs-INET-3/XAD-16 after eight extraction stages was 23.6 mg/g. The separation factors of adjacent heavy RE（III） β（Er/Ho）, β（Tm/Er）, β（Yb/Tm） and β（Lu/Yb） values were 1.76, 2.59, 2.56 and 1.19,respectively. The adsorbed Lu（III） onto the SIRs-INET-3/XAD-16 can be stripped completely by 1.0 mol/L H2SO4.