酯萃取鎂的機(jī)理
(上海大學(xué) 材料科學(xué)與工程學(xué)院, 上海 200072)
摘 要: 研究了用2-乙基己基膦酸單（2-乙基己基）酯—仲辛醇—磺化煤油組成的有機(jī)相從硫酸介質(zhì)中萃取鎂的行為， 考察了水相pH值、 萃取劑和SO2-4濃度等因素對萃取的影響，并采用斜率法和紅外光譜法確定了萃合物的組成及萃取平衡的機(jī)理。 結(jié)果表明： 鎂的萃取隨平衡pH值的增大而顯著提高， 亦隨萃取劑濃度增大而增加， 且與SO2-4濃度無關(guān)， 萃取過程的機(jī)理為陽離子交換機(jī)理， 萃合物為MgA2·3HA， 表觀萃取平衡常數(shù)KMg=10-6.73。
關(guān)鍵字: 萃取； 鎂； 2-乙基己基膦酸單（2-乙基己基）酯； 機(jī)理
phosphonic acid mono-2-ethylhexyl ester from sulfate media
（School of Materials Science and Engineering,
Shanghai University, Shanghai 200072, China）
Abstract:The extraction of magnesium from sulfate medium using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester in sulfonated kerosene was studied. The effects of pH value, concentration of extractant and SO2-4 on the extraction of magnesium were investigated. The composition of extracted complex and mechanism of extraction were determined by the slope method and IR spectra. The extraction mechanism of the system was found to be cation-exchange. The results show that the extraction rates of magnesium rise with the increases of pH and extractant concentration, but are independent of SO2-4 concentration. The numerical analysis result of magnesium distribution data shows the formation of MgA2·3HA in the organic phase with formation constant KMg=10-6.73.
Key words: solvent extraction; magnesium; 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester; mechanism
