SOLVENT AND SOLID EXTRACTION OF METAL IONS WITH 4-n-DODECYL-6-(2-THIAZOLYLAZO)- RESORCINOL

摘要

The solvent extraction characteristics of several transition metal ions with 4-n-dodecyl-6-(2-thiazolylazo)resorcinol (DTAR) in 4-methyl-2-pentanone (MIBK) have been investigated. Copper (Ⅱ) has been well extracted with DTAR and MIBK. An acid-base equilibrium of DTAR has been also checked in the solvent extraction system with MIBK. The second acid dissociation constant of DTAR has been measured to be 10~(-9.97). The extraction constant of DTAR has been simultaneously obtained to be 10~(5.3), which is a large value compared with other extraction reagents. Solid extraction of the same metal ions with DTAR-impregnated polymer beads (DTAR-XAD-7) and DTAR-embedded Langmuir-Blodgett membrane coated on a quartz plate (DTAR-LB) has been also studied. It was found that copper (Ⅱ) can be also successfully extracted with DTAR-LB as well as DTAR-XAD-7. The change in adsorption spectra of the plate to that of Cu(Ⅱ)-complex from that of the reagent itself was observed upon immersing it in a Cu(Ⅱ) solution. The extraction characteristics of several heavy metal ions with DTAR-XAD-7 have been compared with those of DTAR in MIBK. The order of the extractability with DTAR-XAD-7 is Cu(Ⅱ) > Co(II) > Ni(Ⅱ), which is similar to that with DTAR in MIBK. It was concluded that DTAR could be widely used as an extractant in a solid extraction system as well as in an ordinary solvent extraction.