Inkjet printing of ZIF-67 based-polymer composite membranes

Inkjet printing (IJP) has been adopted to fabricate zeolitic imidazolate frameworks (ZIFs) on commercial membranes. ZIFs, the subclass of metal–organic frameworks (MOFs), are achieving significant progress in applications such as adsorption, gas sensors, gas separation, drug delivery, and more due to their tunable porosity and high surface area. Employing IJP allows the fabrication of ZIF/MOF layers of desired geometry and thickness on porous substrates to address the limitations of traditional manufacturing techniques related to processability and mechanical strength. In this study, we report on in-situ inkjet printing of ZIF-67 on a commercial nylon membrane. The formation of ZIF-67 layers was confirmed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The performance of the inkjet-printed ZIF-67/nylon membranes was evaluated using organic dye (methylene blue) separation from water. The optimal number of printed layers for effective dye removal was investigated, and their consistency and repeatability were confirmed. The dye concentration, pH, and ZIF-67 dosage were studied to determine the optimal parameters for efficient dye removal. The printed membranes showed improved dye removal compared to the unmodified nylon, achieving 100 % removal at optimal conditions (200 printed layers, 5 ppm dye concentration, 0.32 mg/ml ZIF-67, pH 10.3). Crystals detachment was observed starting from 5th regeneration cycle that should be addressed using various printing pattern or substrate type. The work demonstrates IJP technology, an additive manufacturing approach that can be employed in the fabrication of ZIF/MOFs on commercial substrates for various applications.