수용액내에 계면활성제 미셀(micelle)을 형성시킴으로써 TBP와 같은 저분자량 유기용질을 효과적으로 제거할 수 있는 한외여과의 실험적 연구를 수행하였다. 회분식 한외여과장치를 사용하여 양이온 계면활성제(cetyltrimethylammonium bromide : CTAB) 용액에 첨가제로 sodium salicylate(NaSal)을 넣어 보유액(retentate)의 농도와 분리막의 기공 크기, 첨가제의 양에 따른 TBP의 제거율을 살펴보았다. 계면활성제의 임계 미셀 농도 이상에서 미셀을 형성하여 유기용질들을 미셀 안으로 가용화시킨 후, 한외여과막을 이용하여 여과하였을 때 미 셀은 분리막에 의해 차단되고 투과된 용액에는 미셀 형성에 참여하지 못한 극히 미량의 계면활성제와 유기용질만 존재하였다. 여과가 진행되면서 보유액(retentate)의 계면활성제 농도가 고농도에 이르면 분리막 근처에 젤층을 형성할 뿐만 아니라 첨가제에 의해 점도가 상승하기 때문에 플럭스는 현저하게 감소하였다. 첨가제인 NaSal의 농도가 높아질수록 점도가 급격하게 증가하여 플럭스가 매우 빠르게 감소하였다. 일정한 계면활성제의 농도에 대하여 투과액(permeate)에서의 TBP의 농도가 증가하고 플럭스가 매우 급격하게 감소하게 되는 첨가제 NaSal의 임계농도가 존재함을 확인하였다. 그러나, 임계농도이하의 첨가제가 들어간 경우에는 TBP의 제거율을 98%이상으로 유지할 수 있었는데, 이는 구형의 계면활성제 미셀이 망상구조(networked structure)형태로 미셀이 구조전이를 하였기 때문이다.

Micellar-enhanced ultrafiltration was performed to remove an organic compound of low molecular weight such as tert-butyl phenol(TBP) from aqueous solution. The surfactant used here was cetyltrimethylammonium bromide(CTAB) and sodium salicylate(NaSal) was added to enhance the rejection efficiency. By using batch type ultrafiltration cell, the effects of the additive NaSal concentration in the retentate were investigated on the rejection efficiencies of TBP in terms of the molecular weight cut-offs or the membrane and molar ratios or NaSal, CTAB and TBP. When CTAB was added to the solution at concentrations well above its critical micelle concentration, the surfactant formed micelles and TBP molecules were dissolved into the micelle. And then, the micellar solution was forced to pass through an ultrafiltration membrane of which pore size was smaller than the micelle size. In ultrafiltration process, the micelle which contained TBP was rejected by the membrane. Thus, very little amounts of CTAB and TBP were contained in the permeate. As the filtration of the micellar solution proceeded, not only the solution viscosity was rapidly increased but the gel layer of highly concentrated CTAB was formed on the membrane surface. Consequently, the flux was reduced considerably. The results showed that, for a given molar ratio of NaSal to CTAB, there existed a critical concentration of NaSal, above which the flux was declined rapidly and the solution exhibited a remarkable viscoelasticity. However, below the critical concentration of Nasal, the rejection efficiencies of TBP were maintained above 98% due to the transition of micellar structure from spherical to worm-like networked micelle.

Micellar Enhanced Ultrafiltration(MEUF) Rejection Efficiency Micelle Surfactant Solution Cetyltrimethylammonium Bromide Sodium Salicylate

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