Fouling alleviation and enhanced salt rejection in NF membranes via incorporation of 5-amino-1-phenyl-3-(thiophen-2-yl)-1H-pyrazole-4-carbonitrile functionalized pectin in PES matrix

In the current study, the facile method of 5-amino-1-phenyl-3-(thiophen-2-yl)-1H-pyrazole-4-carbonitrile (pyrazole compound) functionalization was introduced to synthesize the new kind of pectin-based material with high functionality and hydrophilicity. The obtained pyrazole compound/pectin (PCPT) hybrid was characterized by SEM, XRD, FTIR, and EDX. Consequently, it was incorporated into the polyethersulfone (PES) nanofiltration (NF) membrane at different loadings. The pectin (PT) composite membranes (PT-0.3 and PT-0.5) were also prepared to further prove the influence of the used PT functionalization method on membrane performance. The surface properties and filtration performance of the composite membranes were studied. All composite membranes showed higher pure water flux compared to the bare membrane (PT-0) and in the best case, the pure water flux value of 43.22 L/m(2)h was obtained for the 0.3 wt% PCPT composite membrane (PCPT-0.3). PCPT-0.3 showed the highest mean pore size, porosity, surface hydrophilicity, smoothness, and negative charge among all prepared composite membranes. After incorporation of PCPT hybrid, the salt rejection was considerably enhanced with the sequence of Na2SO4 > NaCl, verifying the typical NF behavior of the membranes. For PCPT-0.3, the rejection of direct red 16 (DR16) and crystal violet (CV) was 99.82 and 98.24%, and the corresponding permeate flux was 40.2 and 40.1 L/m(2)h, respectively. Pb2+, Cu2+, and Cd2+ rejections were measured 31.00, 32.00, and 32.50% for PT-0, whereas they were 98.09, 98.32, and 98.63% PCPT-0.3, respectively. Moreover, PCPT-0.3 exhibited excellent antifouling properties, nominating the PCPT hybrid as a privileged membrane modifier for the treatment of water/wastewater.

Automated summary

In this study, a facile method was used to synthesize a new type of pectin-based material with high functionality and hydrophilicity. The obtained material was incorporated into a nanofiltration membrane, resulting in composite membranes with improved filtration performance and antifouling properties.