Kim JP  Kim JJ  Ryu JH

Vol. 8,  No. 3, pp. 119-128, Sep.  2002

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In the present study the membrane filtration characteristics of a commercially available synthetic water-based cutting oil through two kinds of ultrafiltraiton membranes (HFI-45-CM50 and HFI-43-CM100) with molecular weight cut-offs of 50,000 and 100,000, respectively, have been investigated in detail. Among these membreaes, the hydrophilic one (HFI-45-CM50) was found to show a satisfactory result for both the permeate flux and the permeability of oil components, whereas the permeate flux obtained with the hydrophobic membrane (HFI-43-CM100) appears to be significantly low, indicating that synthetic cutting oil was easily wetted on the hydrophobic membrane surface and induced more membrane fouling. The effect of material characteristics of the membrane on the filtration characteristics was found to be much more signficant compared with the mean pore size of the membrand. Backflushing by nitrogen gas was applied to reduce the formation of a gel layer and membrane fouling. With the hydrophilic membrane, the backflushing was found to increase the permeate flux, whereas the backflushing resulted in a decrease in flux for the hydrophobic membrane. The flux recovery was observed to be highest when the membranes fouled with waste synthetic cutting oil were immersed into a cleanning solution for more than 72 hours and then backflushed by nitrogen gas.