Engineering MOF-Enhanced 3D-Printed Monoliths for Scalable and Sustainable Water Filtration Solutions: Tackling Contaminant Leaching and Adsorption

Abstract Clean water, a basic requirement for the existence of life, is inaccessible to millions of people all around the world due to serious challenges like water pollution. Conventional methods of water purification often fall short of eliminating micro-sized and soluble contaminants, hence innovative approaches involving nanomaterials can be investigated for more successful solutions. Metal-organic frameworks (MOFs) offer a promising alternative for water filtration that can absorb pollutants due to their abandoned and well-structured nano-porosity built within their structure. However, secondary contamination from leached MOF materials remains a concern. In this work, we propose the designing and manufacturing of MOF laden monolith 3D structure (MLMS). Extrusion-based additive manufacturing is used to construct the host structure of the MLMS with macro-scale porosity using the Moiré pattern. Copper-based MOFs (Cu-MOFs) are grown and conditioned on the host for proper adhesion force that can minimize leaching while absorbing pollutants, thus demonstrating the functionality of MLMS. Cu-MOFs growth, distribution, and leaching rate have been studied using commonly available 3D printing material PLA, which shows about 12.8%-75.8% surface area coverage by MOFs attained at various numbers of MOFs synthesis cycles. Additionally, 16.1% leaching from the host has been observed at a high flux (4.14×103 L m−2 h−1) water flux, which demonstrates better adhesion characteristics between the host and MOFs. The adsorption efficiency of malachite green (MG) dye by the MLMS has been studied, where 17.19% and 50.25% MG removal efficiency from stagnant and flowing (1.18×103 L m−2 h−1) conditions, respectively, have been achieved. The results show the potential of a wide range of applicability of MOF-loaded 3D-printed constructions for scalable and efficient water filtration systems, competent in working under both stationary and dynamic flow conditions. This research paves the way for further investigation of MOF-based filtering devices aiming at a larger spectrum of water pollutants.