Titanium dioxide (TiO₂) nanoparticles have been applied in membrane antifouling performance modification for years. However, the influence of TiO₂ nanoparticle dispersion status during the blending process on membrane properties and the inner mechanism has seldom been focused on. Herein, we investigated the influence of the various dispersing statuses of TiO₂ nanoparticles on membrane properties and antifouling performance by exploring various blending processes without changing the original recipe. Polyethylene glycol (PEG) was employed as a pore-forming agent during the membrane preparation process, and also as a pre-dispersing agent for the TiO₂ nanoparticles via the steric hindrance effect. Compared to the original preparation process of the PVDF/TiO₂ composite membrane, the pre-dispersing of TiO₂ via PEG ensured a modified membrane with uniform surface pores and structures on cross-sectional morphologies, larger porosity and water permeability, and more negative zeta potential. The contact angle was decreased by 6.0%, implying better hydrophilicity. The improved antifouling performance was corroborated by the increasing free energy of cohesion and adhesion, the interaction energy barrier (0.43 KT) between the membrane surfaces and approaching foulants assessed by classic XDLVO theory and the low flux decline in the filtration experiment. A kinetics mechanism analysis of the casting solutions, which found a low TSI value (<1.0), substantiated that the pre-dispersion of TiO₂ with PEG contributed to the high stability and ultimately favorable antifouling behaviors. This study provides an optimized approach to the preparation of excellent nano-TiO₂/polymeric composite membranes applied in the municipal sewage treatment field.

Herein, the influence of various contents of polyethylene glycol (PEG) on the dispersion of TiO₂ nanoparticles and the comprehensive properties of PVDF/TiO₂ composite membranes via the steric hindrance interaction was systematically explored. Hydrophilic PEG was employed as a dispersing surfactant of TiO₂ nanoparticles in the pre-dispersion process and as a pore-forming additive in the following membrane preparation process. The slight overlap shown in the TEM image and low TSI value (<1) of the composite casting solution indicated the effective dispersion and stabilization under the steric interaction with a PEG content of 6 wt.%. Properties such as the surface pore size, the development of finger-like structures, permeability, hydrophilicity and Zeta potential were obviously enhanced. The improved antifouling performance between the membrane surface and foulants was corroborated by less negative free energy of adhesion (about −42.87 mJ/m²), a higher interaction energy barrier (0.65 KT) and low flux declination during the filtration process. The high critical flux and low fouling rate both in winter and summer as well as the long-term running operation in A/O-MBR firmly supported the elevated antifouling performance, which implies a promising application in the municipal sewage treatment field.