The use of antibacterial filter media is one of the means of liquid disinfection and elimination of pathogenic microorganisms during filtration of liquids. The advent of nanotechnology has facilitated the application of nano fiber based membranes in filtration operations. The melt electro spun fibers due to their low thickness are used in the production of this type of filter medium. The unique properties of nano fibers such as their high specific areas, internal pore continuity and chemical affinity at nano scale has transformed nano fiber based membranes into one of the main part of the absorption based separation filtration technology. In this work, antibacterial polypropylene filter medium were made using melt electro-spun nm. In order to produce nano fibers, an innovated melt electro-spun in laboratory scale apparatus different to other conventional equipment was built. The apparatus allows production of samples with advantages such as high durability and the high rate of filtration. Optimized performance and efficiency of the apparatus were obtained using trial and error method during production of vast number of samples. Antibacterial performance of polypropylene nano filters were compared with those made using ordinary polypropylene fibers. Filtration efficiency was determined by measuring factors such as fiber diameter, filter porosity and distribution of nano particle additives using image processing technique. High quality images were prepared using scanning electron microscope (SEM). The former were processed using Matlab software. Image processing technique was used to estimate percentage average of dominant diameter and porosity. Dominant diameter is described as diameter of the majority fibers. Measured fiber diameter and porosity were found to provide the highest filtration efficiency. Also, diameter distribution was calculated using image processing techniques. It was found that diameter had wide distribution due to fiber production conditions. In order to evaluate the suitability of the samples as means of dusty air filtration medium, additional experiments were conducted. The results showed that filters made using nano fibers were more highly effective than filters made using ordinary fibers in this kind of application. Also, it was found that filters made using nano polypropylene fibers due to lower fiber diameter and lower porosity, were capable of trapping smaller particles in comparison with those made of polypropylene fibers with ordinary dimension. Antibacterial ability of the experimental samples was also evaluated. Results firmly point to the higher ability of filter medium made using nano fibers than those containing ordinary fibers. In this respect it was concluded that nano fibers filter containing clay particles exhibit better antibacterial properties in comparison with nano fibers filters containing nano titanium dioxide particles. According to FTIR results, it was stated that no chemical changes occurred in polypropylene polymer structure due to addition of clay or titanium dioxide particles to the polypropylene melt. Finally it was concluded that the experimental nano samples due to their unique properties can be used as effective means for elimination of athogenic microorganism or trapping of nano particles in various fields of liquid filtration. Keywords: Nano fibers, liquid filtration, antibacterial, melt electro spinning, nano particles, separation and membrane, image processing, polypropylene
