3D Printing of Specialty Devices for Geochemical Investigations: Real-Time Studies of Goethite and Schwertmannite Formation

New types of laboratory reactors that are highly customizable, low-cost and easy to produce are needed to investigate low-temperature geochemical processes. We recently showed that desktop 3D printing stereolithography (SLA) can be used to efficiently fabricate a mixed flow reactor (MFR) with high dimensional accuracy comparable to traditional machining methods (Michel et al., 2018). We also showed that the SLA method allowed for the addition of complex features that are often beyond the capabilities of traditional methods. However, the stability of 3D printed parts at low-temperature geochemical conditions has not been fully evaluated. The objectives of this work were twofold: 1) to provide a framework for assessing the stability and compatibility of SLA printed materials at geochemically relevant conditions, and 2) to show how 3D printed specialty devices can enable new laboratory geochemical experiments. Part 1 of this Master's thesis presents findings for enhancing mechanical and solvent resistance properties of a commercial 3D printing material (Formlabs Clear) by UV post-curing procedures and also provide data showing its stability in aqueous solutions at pH 0, 5.7, and 12 for periods of up to 18 days. Thermal degradation patterns, mechanical analysis, and leachable fraction data are provided. Part 2 shows experiments coupling 3D printed reactors and flow devices for in situ small-angle x-ray scattering (SAXS). Schwertmannite (pH 2.7) and goethite (6.2) are precipitated from solution using various setups and observed differences in growth rates are discussed. The data show the potential of 3D printing for enabling novel laboratory geochemical experiments.