Development of low pressure filter testing vessel and analysis of electrospun nanofiber membranes for water treatment

Abstract

Polymeric electrospun nanofibrous membranes were investigated for use in water filtration applications. A customized pressure vessel was designed according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) to be used to test the membrane for its filtration properties. Low pressure filtration was focused on due to previous research that suggested that high pressure water testing of electrospun polymeric nanofibrous filters could decrease the filtration capability by expanding the pore size within the membrane. During testing it was found that this technology does reduce pathogens but will only remove a portion of them per pass, and thus is not adequate for use as a one pass pathogenic filter. The filter was found to be well suited for the reduction in the amount of suspended and dissolved solids, increasing clarity, and reduction of odor. A scanning electron microscope (SEM) was used to study the electrospun fibrous pads to narrow down on an ideal parameter set that gave the desirable characteristics for the application of filtration. The composition of the polymer, and electrospinning parameters, were also manipulated to give a hydrophilic, or absorbent, membrane to facilitate a low pressure differential for filtration. It was demonstrated that this type of filtration membrane can be manufactured inexpensively while not requiring electricity or other external power source to generate large pressure differentials and flow. This is desirable because it allows this technology to be used in areas where both basic utilities and clean water are limited, for example in remote Africa and India. It was also shown that this filter has benefits over best selling commercial water filters currently on the market. This technology may be best suited for enhancement of tap water where healthier and cleaner water is desired. Pre-filtration of reverses osmosis (RO) or other ultrafine filter system, to increase the life of the primary filter while decreasing fouling and maintenance may be another application.