Preparation of Composite Hollow-Fiber Reverse Osmosis Membranes by Plasma Polymerization.

摘要

A tandem plasma polymerization apparatus for continuous coating of hollow fibers has been built. The apparatus allows two treatments of a moving substrate to be carried out in successive chambers with no cross-contamination. The apparatus employs internal electrodes and can be used at a variety of frequencies. High flow rates can be achieved at low pressures. A study of the effects of changing plasma polymerization variables on the properties of the resultant plasma polymer has been carried out using tetrafluoroethylene in this apparatus. This system is unusually sensitive to power input and the plasma polymer is exceptionally easy to characterize by ESCA. Pressures below 100 millitorr have been indicated for appreciable deposition on the substrate. The distribution of plasma power density has been found to be non-uniform within the interelectrode gap in keeping with the known physics of glow discharges. The reverse osmosis properties of plasma polymer coated hollow fibers are described. Salt rejections of 87-93% have been achieved at fluxes of 1.5-4.0 g.f.d. with fiber take up rate of 50-100cm/min. All plasma polymerizations were studied at a frequency of 10kHz using magnetic enhancement. Pyridine and acetylene +Nitrogen are the monomers employed. The reverse osmosis properties obtained were sensitive to the nature of the hollow fiber,presumably because of surface pore size.