ABSTRACT
Microporous polypropylene (PP) hollow fiber (PPHF) membranes have been widely used in microfiltration and ultrafiltration processes for water treatment, because of their good mechanical properties, good chemical resistance, good thermal stability, high surface areas and low cost [1, 2]. It is well known that fouling occurs more often and more seriously on a hydrophobic, than on a hydrophilic, surface. Surface fouling is a major obstacle for the application of PPHF membranes in bioreactors for wastewater treatment [3-6]. Owing to the hydrocarbon nature and the low polarity, PP has a very low surface free energy (20-25 mJ/m2), which results in highly hydrophobic membranes [7]. Surface modification and functionalization is a good approach to modify the surface properties of materials without affecting their bulk properties [8-10]. Methods, including chemical treatment [11, 12], plasma deposition[13-17], UV-induced surface graft polymerization [18-20], high energy irradiation [21, 22], and ozone-induced surface graft polymerization [23, 24] have been used to enhance the surface hydrophilicity of PP membranes.
