Poly (arylene ether ketone) with carboxyl groups ultrafiltration membrane for enhanced permeability and anti-fouling performance

In this study, a novel poly (arylene ether ketone) with carboxyl groups (C-PAEK) was synthesized by adjusting the ratio of 4-carboxylphenyl hydroquinone (4C-PH) with bisphenol A (BPA). Fourier transform infrared spectroscopy (FTIR) and 1H Proton Nuclear Magnetic Resonance (1H NMR) spectra demonstrated that C-PAEK polymer was successfully synthesized by the nucleophilic polycondensation reaction. A series of C-PAEK ultrafiltration membranes were prepared by nonsolvent-induced phase separation (NIPS) method. The effect of carboxyl content on the structure and properties of C-PAEK ultrafiltration membranes was studied by scanning electron microscope (SEM), thermogravimetric analysis, porosity, water contact angle (WCA), molecular weight cut-off (MWCO), ultrafiltration and antifouling experiments. C-PAEK membranes showed the typical asymmetric structure and finger-like channels. With the increase of carboxyl content in PAEK, the WCA of membranes decreased from 76.9 ± 1.8° (M0) to 57.3 ± 1.6° (M4). In addition, the weight loss temperature of 5% and the maximum weight loss rate temperature of C-PAEK are about 432 ℃ and 502 ℃, respectively. Among the prepared membranes, the porosity (ε) of M2 with 10 wt% carboxyl groups content increased from 82.3 ± 3.6% to 91.2 ± 1.2%, but the average pore sizes (rm) of the membranes were similar. M2 showed the highest pure water flux (511.5 L/(m2h)), which was 1.7 times of M0. Rejection and flux recovery rate (FRR) of were 96.4 ± 2.5% and 63.4%, respectively. Meanwhile, in the cyclic filtration experiment of C-PAEK membrane, with the increase of carboxyl groups, the FRR of both cycles was higher than that of the PAEK membrane. All results indicated that the membrane had high permeability, anti-fouling stability and durability. In short, the novel C-PAEK ultrafiltration membrane functionalized with 4C-PH demonstrated great potential for pollutant removal in the fields of pharmaceutical industry, food industry and bioengineering.