Fabrication of Polysulfone/Titania Fibrous Membranes with Enhanced Air Filtration Performance

Till recent years, air quality has seriously deteriorated due to the surge of industrial, agricultural and domestic activities. Particulate matter, which mainly caused by the vehicle exhaust, fuel combustion, and industry emission, are considered to be the most serious sources of the air pollution and a major cause of adverse health effects. It has both acute and chronic effects on human health, ranging from upper respiratory irritation to acute respiratory infections, chronic bronchitis, asthma or even lung cancer. Furthermore, stricter emission limits have also contributed to the urgent need for better quality of air. Therefore, designing and fabricating of air filters which could efficiently filtrate the particles in air are of great importance to the human health and development of the country.In this thesis, polysulfone (PSU) is chosen as the starting polymer for the preparation of fibrous filter medium through electro spinning technology owing to a range of desirable properties such as high temperature resistant, good chemical stability, resistant to abrasion, and excellent hydrolytic stability. We investigated the influence of the concentration of PSU solution, the ratio of N,N-dimethylformaimde (DMF) and N-methyl pyrrolidone (NMP), and the electrospinning parameters on the structure and performance of fibrous membranes. The results showed that PSU fibrous membranes achieved the optimized filtration performance when the concentration of PSU solution is25wt%and the solvent is DMF or the ratio of DMF and NMP is1. Due to the3-dimensional porous structure of electrospun fibrous membranes, the dispersing effect is enhanced during the particle transmit in fibrous membranes, eventually, the particles could adhere on the surface of fibers more efficiently. Thus, enlarging the surface area of fibrous membranes could greatly improve the filtration performance. Taking this into consideration, hierarchical structured PSU fibrous membranes with high surface area and surface roughness were controllably fabricated by the incorporation of titania nanoparticles (TiO2NPs) via multi-jet electrospinning. The as-prepared hybrid membranes exhibited improved filtration efficiency of99.97%and pressure drop of45.3Pa (under face velocity of32IVmin) compared with pristine PSU membranes. Moreover, the fibrous membranes were endowed with promising superhydrophobicity with a water contact angle up to152°by employing the TiO2NPs incorporation. Furthermore, the relevance among the surface area, roughness and filtration performance is intensively studied by Frenkel-Halsey-Hill theory.