Coating Strategies for 3D Printed Beads Decorated with Metal Organic Frameworks and Graphene Oxide for Degradation and Adsorption of Water Contaminants

Abstract

Modular nanoenabled water treatment systems offer significant potential for developing compact, high-performance solutions, making them highly attractive for point-of-use (POU) and point-of-entry (POE) applications. This study focuses on the fabrication of a sequential catalytic and adsorption system featuring iron-based metal–organic frameworks (MOF) and graphene oxide (GO) coated on 3D printed beads. Results indicate that the combination of nitrogen doping and bimetallic core incorporation synergistically enhances the catalytic activity of MOF, improving the contaminant degradation rate by 81% and overall efficiency by 64%. The degradation mechanism analysis revealed that this synergy arises from the formation of multiple reactive oxygen species generation pathways. To address the challenges of nanomaterials reusability and environmental concerns associated with nanomaterials release, silica-based 3D-printed beads with high surface areas were fabricated using 3D printing and coated with MOF and GO using dip coating, biocoating, and cross-linking. In terms of coating stability, cross-linking demonstrated the highest durability in oxidizing environments, while biocoating emerged as the most effective method for the neutral adsorption stage. By integrating these optimized coatings into a sequential batch system, the nanoenabled beads achieved 99.5% contaminant removal within 2 h. Furthermore, the bead-based system demonstrated successful geometric scale-up and exceptional reusability, maintaining 68% removal efficiency over 15 cycles, a greater than 7-fold enhancement compared to conventional dispersion systems. Ultimately, this work provides a highly stable, modular framework that overcomes the fundamental mobility and recovery limitations of particulate nanomaterials, demonstrating significant practical viability and paving the way for advanced, scalable point-of-use and point-of-entry water purification systems.