Fabrication of superhydrophobic PET filter material with fluorinated SiO2 nanoparticles via simple sol–gel process

Abstract

A high moisture content in the flue gas of iron and steel sintering process causes the issue of filter material pasting, which leads to a decrease in the filtration effect and service life of the filter material. Surface modification of the filter materials is a useful strategy for their hydrophobicity enhancement. Therefore, the Sol–gel method was employed to modify the polyethylene glycol terephthalate (PET) filter with tetraethyl orthosilicate(TEOS) as precursor and perfluorodecyl triethoxysilane (PFDTES) as modifier. Field emission scanning electron microscope (FESEM), Fourier transform infrared spectrometer (FT-IR), and contact angle tester were used to characterize the PET filter materials before and after modification, and exhaustive filter efficiency was evaluated by the comprehensive performance test machine. The particle size and distribution of SiO2 nanoparticles were analyzed using a nanometer particle size analyzer, the effects of TEOS/PFDTES loading on the hydrophobic performance and filtration performance of the filter material have been discussed. Based on the results of these studies, superhydrophobic stability of the filter material was evaluated. The results show that the microscopic pore structure of PET filter materials was retained after modification. TEOS modified PET (T-PET) filter materials were completely wetted with static contact angle (WCA) of 0°. The surface energy of PFDTES modified PET (F-PET) filter materials was reduced, the WCA was 144.6 ± 1.6° and WSA was 7.6 ± 4.5°. For TEOS/PFDTES co-modified PET (TF-PET), the SiO2 nanoparticles was modified by the long fluorine chain -CH2CH2(CF2)7CF3 groups, endowing TF-PET with superhydrophobic property. With the increasing of TEOS loading, TF-PET fiber presented significant enhancement of roughness, while average particle size of SiO2 nanoparticles on the fiber surface gradually decreased. The particle size distribution first increased sharply, and then, slowly decreased when TEOS addition was enhanced. TF-PET filter material possessed WCA of 163.2 ± 2.3°, while when TEOS: PFDTES mass ratio was 2.5:2, WSA was 6.2 ± 1.9° with filtration efficiency (0.3 μm) of 68.61%.