환외여과에 있어서 Si 콜로이드 용액의 투과유속 감소 및 오염특성

Flux Decline and Fouling Mechanism of Si Colloidal Solution During the Ultra-Filtration

Si 미립자를 함유한 콜로이드용액의 중공사막에 의한 한외여과 투과유속 감소특성을 검토하였다. 중공사막의 시간변화에 따른 투과유속 감소현상은 막표면에 형성된 케익층의 증가 및 세공막힘에 기인하였다. 흐름형태를 달리했을 경우의 준 정상상태에서 dead-end flow의 투과유속은 cross flow의 약 60 % 이었다. Cross flow에서 운전압력이 증가함에 따라 $J/J_w$는 감소하였으며, $0.5kg_f/cm^2$일 때의 64.2 %에서 $2.0kg_f/cm^2$일 때 45.7%로 감소하였다. 공급유량이 3 L/min일 때 초기저항은 세공막힘이 지배적이며, 공급유량이 1 L/min에서 3 L/min로 증가함에 따라 $R_c$는 약 40 % 감소한 $1.79{\times}10^{12}{\sim}2.34{\times}10^{12}m^{-1}$ 이었으나 $R_p$는 크게 변하지 않은 $1.71{\times}10^{12}m^{-1}$이었다.

Behavior of permeate flux decline was examined through the hollow fiber membrane in ultrafiltration system for Si colloidal solution. Flux decline with time was due to the growth of Si cake deposited on the membrane surface and the pore blocking by Si particles for the hollow fiber membrane. At the pseudo steady state of operation, the permeate flux of dead-end flow was 60 % to that of the cross flow. The ratio of permeate flux to the pure water flux, $J/J_w$, decreased with increasing the trans-membrane pressure, from 64.2 % for $0.5kg_f/cm^2$ to 45.7 % for $2.0kg_f/cm^2$. When the feed flow rate was 3 L/min, the pore blocking model was dominant at the initial period of filtration and was followed by the cake filtration model. And with increasing the feed flow rate from 1 L/min to 3 L/min, $R_c$ was $1.79{\times}10^{12}{\sim}2.34{\times}10^{12}m^{-1}$ which was the about 40 % decreased value to that of the 1 L/min while $R_p$ was not changed and was $1.71{\times}10^{12}m^{-1}$ approximately.