Selective Adsorption of Scandium by(2-Ethylhexylamino)Methyl Phosphonic Acid Mono-2-Ethylhexyl Ester Impregnated Resin and Its Application
The(2-ethylhexylamino)methyl phosphonic acid mono-2-ethylhexyl ester(HEHAMP)impregnated resin was prepared by loading α-amino acid phosphine extractant,known as HEHAMP,onto macroporous resin Pre-XAD-16.The study investigates the adsorption properties of scandium in a sulfuric acid medium,examining the impacts of reaction time,acidity,concentration of hydrogen sulfate ions,resin dosage and temperature.It was found that the adsorption capacity of scandium increased gradually with the increase of reaction time.Under high acidity conditions,the adsorption rate of Sc3+by SIRs-HEHAMP impregnated resin slightly decreased with increasing acidity,while within the pH range there was almost no effect on the adsorption rate of Sc3+.During the adsorption process,HSO4-did not participate in coordination.Temperature had almost no effect on the adsorption of Sc3+.The adsorption process of Sc3+by SIRs-HEHAMP followed a pseudo-second-order kinetic model.The saturated adsorption capacity of the resin for scandium(expressed as Sc2 O3)was 36.29 mg/g.Infrared spectroscopy and TG-DSC characterization were conducted on SIRs-HEHAMP impregnated resin,HEHAMP extractant,and the macroporous resin Pre-XAD-16.The results indicated that HEHAMP was successfully impregnated onto the supporting matrix Pre-XAD-16.The application of HEHAMP impregnated resin to the adsorption and recovery of Sc(Ⅲ)from a simulated sulfuric acid leaching solution of red mud was also explored.The adsorption rate of Sc(Ⅲ)was determined to be 51.71%,while that of Ti(Ⅳ)was 42.50%and Al(Ⅲ)showed negligible adsorption,the adsorption rates for Fe(Ⅲ)and rare earth ions were below 20%,and the separation factor between Sc(Ⅲ)and Ti(Ⅳ)(SF(Se/Ti))was 1.45.By introducing 6%(mass percent)hydrogen peroxide,the adsorption rate of Sc(Ⅲ)improved to 63.17%,the adsorption rates of Ti(Ⅳ)and Fe(Ⅲ)weredecreased,while other metal ions showed negligible adsorption.The separation factors between Sc(Ⅲ)and Ti(Ⅳ)(SF(Se/Ti))reached 6.94,indicating an enhancement in selectivity for scandium over titanium in the adsorption process.