Hybrid MOF+COF modified PVDF membranes for enhanced microfiltration of pharmaceutical contaminants

One of the key directions in membrane process development is the exploration of novel materials and the modification of commonly used ones. Designing membrane structures with programmable properties enhances process efficiency and broadens application potential. This study employed hybrid MOF + COF (metal-organic framework + covalent organic framework) structures to modify polyvinylidene fluoride (PVDF) microfiltration membranes. These compounds possess a highly developed structure and large specific surface area, contributing to excellent adsorption capabilities. Such modifications can improve the removal of organic contaminants, including pharmaceuticals and personal care products, during microfiltration. The aim of this study was to evaluate the impact of MOF + COF modification on the surface and performance characteristics of PVDF membranes and to assess their potential for pharmaceutical removal from water. An in-house synthesized ZIF-8+TpPa structure was used for membrane modification. Tetracycline was selected as a model pharmaceutical. Surface and structural properties were analyzed using FTIR, XRD and contact angle measurements. Filtration performance was evaluated in a conventional microfiltration setup under varying operational conditions: feed temperatures of 25 °C, 30 °C, and 40 °C, and pressures of 0.5, 1, and 1.5 bar. Structural analysis confirmed the successful synthesis and incorporation of MOF + COF structures onto the membrane surface. Cross-flow filtration showed that tetracycline removal increased from 742.9 mg/m 2 (unmodified) to 1222.4 mg/m 2 (modified membranes). Higher feed pressure improved removal efficiency. However, the temperature effect was non-monotonic, with a decline in efficiency observed at 40 °C compared to 25 °C and 30 °C.