چكيده لاتين
In this study, electrospun recycled polyethylene terephthalate (PET) nanofibers were surface modified with the aim of producing efficient microfiltration membranes for water and oil separation. For this purpose, two chemical modification approaches were used, including a sol-gel method based on tetraethylorthosilicate (TEOS) to create superhydrophilic properties and the use of methyltrichlorosilane to create superhydrophobic properties. FTIR analysis confirmed the distinct changes in surface functional groups, the formation of silica layers and the presence of Si–CH₃ groups in the superhydrophobic samples and the increase in Si–O–Si and Si–OH peaks in the superhydrophilic samples. FESEM images and EDAX-Mapping analysis showed that in the superhydrophilic sample, silica nanoparticles uniformly covered the fiber surface, and in the superhydrophobic sample, agglomerated layers increased the two-scale surface roughness. The contact angle test indicated that the raw PET sample was relatively hydrophobic with an angle of about 87 degrees, while after surface modification, the superhydrophilic membrane showed a contact angle of zero and the superhydrophobic membrane showed a contact angle of about 162 degrees. Also, the oil contact angle from underwater for the superhydrophilic membrane showed that it is a strong oil repellent in aqueous environment. The performance tests indicated that the superhydrophilic membrane had the highest water flux at 31.978 ± 19.36 l/m2/h due to the presence of Si-OH groups and a high tendency to absorb water on the surface, while the superhydrophobic membrane had a lower water flux at 33.155 ± 7.14 l/m2/h and showed a higher tendency to absorb oil in dry environment. The mechanical results also showed that the surface modification improved the mechanical strength; in particular, the superhydrophobic membrane had higher mechanical strength due to the formation of harder layers. Finally, this study demonstrated that by targeted surface modification of PET nanofibers, the wettability, filtration performance, and water/oil separation properties can be significantly improved, and recycled membranes with high added value for environmental and industrial applications can be produced. The water and oil retention and separation rates of both superhydrophilic and superhydrophobic membranes were also shown to be 97% ± 1%.
