9 Apr 2026

Photocatalytic Degradation of Microcystins from a Field-Collected Cyanobacterial Assemblage by 3D Printed TiO2 Structures Using Artificial Versus Solar Irradiation

Abstract: Microcystins from freshwater cyanobacteria cause adverse effects to humans and ecological receptors through multiple exposure routes requiring adaptable and diverse treatment technologies. Photocatalysis of MCs using TiO2 is a promising technology; however, TiO2 photocatalysts as unbound nanoparticles in suspension are impractical to deploy. 3D Printing provides a means to immobilize TiO2, producing deployable photo-catalyst structures with extensive geometric freedom. The objective of this proof-of-concept experiment was to incrementally increase the environmental complexity while comparing photocatalysis rates of MCs by 3DP TiO2 structures using polylactic acid as the binder. Degradation half-lives of MCs were shorter in TiO2 embedded in 3DP PLA relative to PLA-only controls with differences in half-lives ranging from 3.6 to 10h. The one exception was the outdoor solar and an algal assemblage, where significant differences could not be discerned due to the already rapid photolysis rates. Ultimately, photocatalysis rates were comparable to those previously published for TiO2 3DP structures in a laboratory environment and TiO2 fixed- films demonstrating feasibility of 3DP to immobilize TiO2 photocatalysts under a range of conditions. This is the first time that MC concentrations from a field-collected HAB were photocatalytically degraded in both solar simulated light and sunlight using a custom-made advanced photocatalytic nano- composite with enhanced performance through high surface area design enabled by 3D printing. These data inform future development of scalable, retrievable, and operationally flexible structures with immobilized TiO2.

12 Feb 2026

Investigation of Graphene Nanoplatelets for Adsorptive Removal of Aqueous Munitions Compounds 2,4,6-Trinitrotoluene (TNT) and Hexahydro-1,3,5-Trinitro-S-Triazine (RDX)

Abstract: Graphene nanoplatelets (GnPs) were evaluated against munitions compounds 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-s-triazine (RDX) in aqueous solutions for adsorptive removal performance. Fourier transform infrared and Raman spectroscopy were employed to characterize samples and inform adsorption mechanisms. Adsorption kinetics and isotherm studies were conducted in deionized water and compared with granular activated carbon (GAC). Evaluations were conducted with varying pH levels, ionic strengths, and temperatures and with surface water solutions to assess the impact of environmental factors on performance and further inform adsorption mechanisms. This study demonstrated that GnPs exhibited more rapid adsorption than GAC. Furthermore, TNT was adsorbed with greater capacity by GnPs compared to GAC, while GnPs removed RDX in greater capacity only when results were normalized for surface area. The more planar structure of GnPs may have contributed to performance enhancements relative to GAC. Adsorption was not impacted by variations in pH or ionic strength, indicating stable performance in different environments. Thermodynamic analysis indicated that removal was more favorable at higher temperatures. Furthermore, π-π interactions likely facilitated TNT removal by GnPs, while RDX was removed through physisorption by van der Waals forces. This study advanced understanding of environmental management of munitions compounds, as the adsorptive performance of GnPs for munitions compounds in solutions within a natural environmental matrix were evaluated, and key mechanisms supporting adsorptive removal of these compounds were informed. Overall, this study demonstrated the effectiveness of GnPs in treating water contaminated with TNT or RDX, particularly when rapid adsorption is preferred.