Photocatalysis has become an attractive process to remove contaminants from aquatic environments, with TiO2 being the most widely used photocatalyst. In spite of the advantages of the process, two main problems still have to be overcome: reutilization/recycling of TiO2 nanoparticles, which is a time-consuming and expensive process, and the fast recombination rate of the electron???hole pairs. This work reports on the photocatalytic activity of rare earth metal doped (erbium, Er) and codoped (erbium and praseodymium, Er/Pr) TiO2 nanoparticles immobilized in a poly(vinylidene difluoride)???trifluoroethylene (PVDF???TrFE) copolymer membrane as a suitable strategy to overcome the aforementioned limitations. It is shown that doped and codoped nanoparticles were successfully immobilized into the PVDF???TrFE membranes, with a controllable degree of porosity. A high surface area (273 m2/g) was attained for these nanoparticles. The low band gap (2.63 eV) of these TiO2-modified nanoparticles, coupled with a highly porous structure (???75%) of the membrane microstructure, synergistically envisages the best photocatalytic performance by degrading 98% of a solution of methylene blue after 100 min of exposure to UV.