Development of Non-Fouling Piezoelectric Ultrafiltration Membranes

摘要

The goal of this project is to prepare piezoelectric ultrafiltration membranes from KYNAR poly(vinylidene fluoride) and to evaluate the resistance of such membranes to fouling by colloidal materials normally found in saline and brackish water. The techniques commonly used for poling and for measurement of the piezoelectric activity of extruded, oriented poly(vinylidene fluoride) films were found to be either unsuitable or ineffective for membranes. Other methods for measurement of piezoactivity were investigated, and it appears that determination of the pyroelectric coefficient offers the best chance for detection of piezoactivity in membranes. Modified methods of poling were also investigated, but thus far piezoactivity has not been detected with certainty in any of the 'poled' membranes. A procedure to determine, independently, the flux declines due to compaction and to fouling was developed. Under the test conditions, colloidal ferric hydroxide fouled these membranes rapidly, but colloidal silica did not foul them. No significant difference in rate or extent of fouling has been found between unpoled and 'poled' membranes. A cell was designed and constructed for investigation of the effects of ultrasonic pressure pulses on fouling and cleaning of membranes.