3D-printed multilayer membranes for photocatalytic degradation of ciprofloxacin

Aquatic contamination arising from anthropogenic activities has already become a global problem that has measurable impacts on the health of ecosystems. Nowadays, some pharmaceutic compounds and pesticides are defined as persistent chemicals because they can resist even biological or physicochemical treatments. Here, the presence of persistent chemicals as antibiotics poses a double threat since, in addition to their impact on the ecosystems, their presence in the water matrixes helps develop bacterial resistance. The efficient removal or degradation of antibiotics, usually found at nanogram-litre concentrations, demands new technologies and materials. This work offers an avant-garde solution based on the advanced manufacturing of a 3D-printed multilayer photocatalytic membrane able to degrade ciprofloxacin, one of the most employed antibiotics. The processing of the PVDF-HFP-based multilayer membrane used in this work requires the intersection of classical solvent casting and salt leaching processing with direct ink writing (DIW) as a printing technology. All in all, combining these processing protocols enables assembling multilayers with different functions in the same membrane. In detail, double-layer membranes with a thickness of approximately 1 mm (0.5 mm per layer) based on PVDF and TiO2 nanoparticles were produced. The membranes display robust chemical and mechanical stability and interconnected pore structure with an average pore size of around 30 µm. The photocatalytic tests proved that the multilayer membrane degraded approximately 45 % ciprofloxacin under UV radiation for 250 min. This work sheds light on a new 3D-printed hybrid and multilayered platform that combines different functionalities by introducing different polymeric scaffolds, active materials (e.g., nanoparticles) or processing conditions in each level of our multi/layered system.