Liquid liquid extraction of EU III and SM III using phosphonium Ionic liquids and organophosphorus extractants

Abstract

Title of the thesis LIQUID-LIQUID EXTRACTION OF Eu (III) AND Sm (III) newlineUSING PHOSPHONIUM IONIC LIQUIDS AND ORGANOPHOSPHORUS newlineEXTRACTANTS newlineThe present work deals with the investigation of solvent extraction of Sm(III) newlineand Eu(III) from chloride medium using two phosphonium ionic liquids Cyphos IL 104 newline(trihexyl(tetradecyl) phosphonium bis-2,4,4-(trimethylpentyl) phosphinate), newline[P66614][D2EHP] (Trihexyl tetradecyl phosphonium bis(2-ethylhexyl)phosphate) and an newlineorganophosphorus extractant di-(2-ethylhexyl)phosphoric acid (D2EHPA). Effect of newlinedifferent extraction parameters such as equilibrium pH, extractant, metal ion newlineconcentration, salt, diluent and temperature has been investigated. In addition to that, the newlineextraction and separation behaviour of samarium and europium are studied in presence newlineof some transition and rare earth metals. The concentrations of Sm (III) and Eu (III) in newlineaqueous solution both before and after extraction are measured by double beam UV newlinevisible spectrophotometer. The concentration of transition metals is analyzed using an newlineAtomic Absorption Spectrophotometer (AAS). Concentration of Sm (III) and Eu (III) in newlinepresence of other rare earth elements is analyzed by an ICP-OES. The complex newlineformation ability and extraction mechanism of samarium and europium with different newlineextractants are explained by FTIR spectra and slope analysis method. Stripping and newlinereusability of extractants is essential for economic and environmental protection. So, newlinevarious stripping agents such as H2SO4, HNO3 and oxalic acid are employed for newlinestripping process. newlineRecovery of Sm (III) and Eu (III) from the secondary sources such as SmCo newlinemagnetic waste and tube light waste are investigated. Samarium, cobalt separation from newlineleach liquor of magnetic waste and yttrium, europium separation from leach liquor of newlinetube light waste are obtained through McCabe-Thiele plot and counter-current newlineextraction. Precipitation stripping is carried out using oxalic acid. McCabe-Thiele plot newlineindicated three counter-current stages required for complete extraction of cobalt from the newlineleach liquor of magnetic waste at A:O ratio of 1:1.5 using Cyphos IL 104. The raffinate newlinecontained 2.02 g/L samarium and 0.02 mg/L cobalt. 0.1 mol/L oxalic acid is used for newlinecomplete precipitation of cobalt. Similarly, complete removal of yttrium from the leach newlineliquor of tube light waste using D2EHPA is achieved in two stages at O:A ratio of 1:1.5. newlineThe result indicated that the raffinate contained 5.0 mg/L Y, 0.10 g/L Eu and 0.164 g/L newlineCa. 0.4 mol/L oxalic acid is used for complete precipitation of yttrium. The proposed newlineflow sheets are designed for recovery of samarium and cobalt from SmCo magnetic newlinewaste and recovery of yttrium and europium from tube light waste powder newline