Removal of industrial cutting oil from oil emulsions by polymeric ultra- and microfiltration membranes.

The utilization of micro- and ultrafiltration with polymeric membranes for treatment of industrial cutting oil emulsion was investigated. The performance of 14 different membranes with pore sizes in the range of 1-800 nm, representing 8 different materials and varying hydrophobicity, was determined experimentally. Membrane permeances between 1.6 and 939 L m 2 h(-1) bar(-1) have been observed for the different samples as well as oil rejections between 3.42% and 99.99%. Membrane pore size and contact angle showed little influence on both values, while an interesting correlation is displayed to the individual membranes' capillary pressures. A possible explanation for this phenomenon is suggested based on the formation of oil films on the membrane surface. From the investigated membranes, the best-suited one for cutting oil treatment was selected and subjected to further experiments. The effect of process temperatures between 22 and 43 degrees C and of feed oil concentrations between 0 and 20 vol % on the removal performance was determined. The results correspond to the explanation suggested previously.