皂角苷对芘的增溶作用及影响因素

Enhanced solubilization of pyrene by saponin,a plant-derived biosurfactant

研究了一种从植物中提取的生物表面活性剂——皂角苷(saponin)对芘的增溶作用,以及pH、离子强度、重金属离子等对增溶作用的影响.结果表明,皂角苷对芘有明显的增溶作用,其质量溶解率(WSR)约为0.0467,大于常用的TritonX、Brij、Tween等类型的非离子表面活性剂,说明皂角苷能更有效地增强芘的溶解.皂角苷分子中存在可电离的酸性基团,溶液的pH、离子强度等对皂角苷的临界胶束浓度(CMC)及其增溶作用有明显的影响.随着溶液pH值的增大(4.0～8.0),芘在皂角苷溶液中的表观溶解度及WSR值逐渐降低,说明高pH减弱了皂角苷对芘的增溶作用;但随溶液离子强度的增大(NaCl浓度0.01～1.00mol·L-1),芘在皂角苷溶液中的表观溶解度及WSR值逐渐增大,说明高离子强度增强了皂角苷对芘的增溶作用.因此,在低pH和高离子强度下,皂角苷对芘的增溶作用更强.皂角苷与重金属存在络合作用,Zn2+和Cd2+等重金属离子的加入降低了皂角苷溶液的pH及其CMC值,进而增强了皂角苷对芘的的增溶作用.

Biosurfactants have great advantages in the remediation of organic contaminated soils because of their environmentally friendly nature. The solubilization of pyrene by saponin,a plant-derived biosurfactant,was studied and the results indicated that saponin can greatly enhance the solubilization of pyrene in solution and the weight solubilization ratio （MSR） of saponin to pyrene was greater than those of some representative nonionic surfactants. The enhanced solubilization of pyrene by saponin showed strong dependence on the solution pH and ionic strength. It decreased as the solution pH increased from 4.0 to 8.0,but increased as the NaCl concentration increased from 0.01 mol·L^-1 to 1.0 mol·L^-1,which can be attributed to the increased or decreased critical micelle concentration （CMC） of saponin solution with the changing pH or ionic strength,respectively. Saponin was more effective in enhancing pyrene solubilization at low pH and high ionic strength. In addition,heavy metal ions （Zn^2＋ and Cd^2＋） can also enhance the solubilization of pyrene by saponin.