室温离子液体对氨基苯磺酸的萃取性能

Extraction of Aminobenzene Sulfonic Acids with Room-temperature Ionic Liquids

系统研究了[C4mim][PF6],[C6mim][PF6],[C6mim][BF4]和[C8mim][BF4]室温离子液体对间氨基苯磺酸、对氨基苯磺酸稀水溶液的萃取平衡.实验结果表明:萃取温度和相体积比的变化对分配比影响不大;水相pH值对萃取平衡有较大的影响,氨基苯磺酸在离子液体/水体系中的分配比在pH=4.2时达到最大值;水相中CaCl2或Na2SO4的存在能较大幅度地提高氨基苯磺酸的分配比;离子液体的阴离子的性质对分配比有显著的影响,阴离子为[BF4]-的离子液体对氨基苯磺酸的萃取能力大于阴离子为[PF6]-的离子液体;咪唑环上烷基链的长度也对萃取效果有一定的影响.在所研究的离子液体中,[C6mim][BF4]和[C8mim][BF4]对氨基苯磺酸有较好的萃取性能,且萃取相中的氨基苯磺酸可回收利用,离子液体也可循环使用.

Room-temperature ionic liquids [C4mim][PF6], [C6mim][PF6], [C6mim][BF4] and [C8mim][BF4] have been used for the extraction of m-arninobenzene sulfonic acid （m-ABSA） and p-aminobenzene sulfonic acid （p-ABSA） from aqueous solutions. The results showed that changes of temperature and phase ratio had no obvious effect on the distribution ratio, whereas pH values of aqueous phase affected significantly the extraction equilibrium and the maximum distribution ratio was observed at pH=4.20. Distribution ratio of ABSA was found to increase greatly in the presence of CaCl2 or Na2SO4 in the aqueous phase. It was noted that the nature of anion of the ionic liquids had also remarkable effect on the distribution ratio, and the ionic liquids with [BF4]^-anion had much higher extraction efficiency for ABSA than those with [PF6]^-anion. The extraction efficiency was also affected to a certain extent by the length of alkyl chain of imidazolium cation. Among the ionic liquids studied, [C6mim][BF4] and [C8mim][BF4] had better extraction efficiency for ABSA, and ABSA in the extraction phase could be retrieved, the ionic liquids reused.