酯萃取镁的机理
(上海大学 材料科学与工程学院, 上海 200072)
摘 要: 研究了用2-乙基己基膦酸单（2-乙基己基）酯—仲辛醇—磺化煤油组成的有机相从硫酸介质中萃取镁的行为， 考察了水相pH值、 萃取剂和SO2-4浓度等因素对萃取的影响，并采用斜率法和红外光谱法确定了萃合物的组成及萃取平衡的机理。 结果表明： 镁的萃取随平衡pH值的增大而显著提高， 亦随萃取剂浓度增大而增加， 且与SO2-4浓度无关， 萃取过程的机理为阳离子交换机理， 萃合物为MgA2·3HA， 表观萃取平衡常数KMg=10-6.73。
关键字: 萃取； 镁； 2-乙基己基膦酸单（2-乙基己基）酯； 机理
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
