Control Technology for Polycyclic Aromatic Compounds- Enhancement of Solubilization by Sur face Active Compounds

本研究主要目的在探討添加界面活性 劑對氣相多環芳香烴化合物吸溶作用的影 響。研究結果顯示，界面活性劑溶液之 CMC 值隨溫度之上升而上升，在25℃時之 CMC 值最低。而添加NaOH 因為電解質之 效應，導致CMC 值隨pH 之增加而降低。 不管是靜止或是攪拌吸收，添加的陰離子 性界面活性劑(SDS)濃度在臨界微胞濃度 (CMC)之前，氣相PAHs 之吸收速率與純水 相接近。但在濃度大於CMC 後，吸收速率 明顯的隨界面活性劑濃度增加而上昇，且 氣體在溶液中的溶解度隨活性劑濃度之增 加成線性比例增加。在CMC 之前後，吸收 速率受到pH 值的影響很小，但隨攪拌轉速 之增加而明顯增加。不管是靜止或是在攪 拌轉速270rpm 時，總質傳係數皆隨界面活 性劑濃度之上升而下降，這是由於存在界 面阻力、液相黏度增加以及形成微胞後之 擴散係數降低之故。但氣體吸收速率反而 隨界面活性劑濃度之增加而增加，這是由 於形成微胞造成之PAHs 溶解效應大於質 傳效應所致。Surfactants have been known to be able to enhance the solubility of non-polar compounds and been applied to soil washing, NAPLs treatments, and so on. This is the first time for surfactants to be applied to air pollution control by using surfactant in this study. The CMC values at differenttemperatures and the solubilization of vapor phase naphthalene were measured. The results indicate that the surfactant molecules disfavor to form micelles at higher temperature in the range of 25℃~ 50℃. Rasing pH will lead to a lower CMC by adding NaOH, especially at pH=11. No matter quiescent or agitated solution, the PAHs absorption rate increase obviously only above CMC. The absorption equilibrium concentrations increase linearly in proportion to surfactant concentrations above CMC. The pH effects on absorption rate and equilibrium concentration is small. Agitation can increase the gas absorption rate and lumped mass transfer coefficient. All the lumped mass transfer coefficient decrease with surfactant concentration due to the increase of interfacial resistance, viscosity and the decrease of spherical micelle diffusion coefficient. Because the solubilization effect of micelles is greater than mass transfer coefficient reduction effect above CMC, the total net absorption rate increases. Both high pH and high speed of agitation can facilitate the mass transfer of naphthalene from gas phase into liquid. The solubility of vapor phase naphthalene can be expressed by a enhancement factor (En). The naphthalene enhancement factor of surfactant solution at 0.1 M and stir at 270 rpm relative to pure water quiescence absorption can reach 18.60. This study confirm that the ionic surfactant can increase removal efficiency of hydrophobic organic compounds from gas phase