Human exploration of outer space, specifically Mars, remains a primary focus of NASA. One of the biggest challenges with any human mission is providing potable drinking water in a sustainable manner. Typical water treatment systems during space missions utilize filtration membranes and adsorbents to treat wastewater for reuse as potable water. However, these systems rely on consumables, which have to be brought from Earth, and have a limited lifetime potentially created additional waste. In addition, membrane processes produce a concentrated waste stream that also needs to be disposed of or treated. Martian soil is composed of a mixture of minerals, most notably TiO₂, Fe₂O₃, Fe₃O₄, and MnO, which have been used in a variety of applications as adsorbents and catalysts. This study investigates the degradation of PPCPs using a Martian soil simulant as a photocatalyst as well as a thermocatalyst. Five common PPCPs were selected for this study: caffeine, ibuprofen, naproxen, carbamazepine, and sulfamethoxazole. Photocatalytic experiments will be performed over a range of soil loadings and times to determine degradation kinetics of PPCPs. Experiments will be performed both with individual PPCPs and as a mixture. Samples will be analyzed by HPLC to determine degradation of PPCPs. Thermocatalytic experiments will be performed over a range of temperatures and times with effluent gases collected in solvent traps and again analyzed by HPLC. In addition to determining PPCP degradation, the Martian soil simulant will be analyzed by XRD and FTIR to examine bulk changes in the soil mineralogy and give further insight into degradation mechanisms. While this study is motivated by human exploration of Mars, it will give important insights into the use of common materials for the treatment of wastewater.

Dr. Cameron Oden

Postdoctoral Researcher, CU Boulder

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