The affordability of desktop 3D printers unlocks additive manufacturing (AM) as a technology enabler to discover novel solutions to tomorrow’s environmental challenges. Our research team is exploring fused filament fabrication of polymer composites containing micron-scale zeolite and nano-scale photocatalytic TiO<sub>2</sub> particles for contaminant adsorption and destruction, respectively. Additive manufacturing enables on-demand customization of high surface area geometries and rapid prototyping of deployable and retrievable devices that are unattainable for unbound powders. This presentation focuses on compounding zeolite (37 – 180 μm) into the biocompatible polymer polylactic acid (PLA) by twin screw extrusion to fabricate PLA-zeolite composite filaments. The filaments were 3D printed into customizable geometries to investigate the PLA-zeolite composite for removal of a model contaminant (ammonia) from water. Experiments involved multiple zeolite loadings in the composite (0, 8, 16, 23, 33% w/w), with measured zeolite mass concentrations determined by thermogravimetric analysis. Structure and dispersion were imaged by scanning electron microscopy. Several different prototype PLA-zeolite geometries removed 40 – 70% of ammonia from a synthetic freshwater within 48 hours, indicating functionality of the embedded zeolite persisted post-printing. Subsequent static adsorption experiments with sampling points (0, 4, 24, 48, 96 hours) indicated higher zeolite loadings allowed faster adsorption kinetics, but slower kinetics relative to unbound zeolite powder. While ammonia adsorption to unbound zeolite reached steady state after 4 hours, equilibrium was not attained for the PLA-zeolite composites after 96 hours. This suggests the embedded zeolite had additional capacity which may be exploited with design optimization or greater equilibration time. Contaminated-water contact kinetics may be facilitated by void spaces that are potentially tunable by print parameters. Future experiments include adsorption isotherms in dynamic systems. This first principles research supports the exciting potential to apply AM as technology enabling tool for fabricating customizable devices for environmental remediation and monitoring. Future applications of PLA-zeolite and PLA-TiO<sub>2</sub> composites include adsorption of emerging contaminants and destruction of hydrocarbons and toxins.

Taking it outside: additive manufacturing filled polymer composites for environmental monitoring and remediation

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.