Evaluation of graphite and activated carbon as suitable water purification media for in-situ resource utilisation (ISRU) on Mars

Authors

Ciaran Archenoul

Document Type

Geography, Earth and Environmental Sciences Article

Abstract

Eventual human missions to the red planet will require large-scale in-situ resource utilisation to meet their objectives. Perhaps the most critical element for developing a sustainable architecture is propellant production from the products of water electrolysis and atmospheric carbon dioxide. The purpose of this study was to assess how graphitic materials may be used as porous filters to remove solvated ions from Martian water prior to electrolysis, reducing the overall complexity of ISRU systems. The two materials under study were PG25 graphite and activated carbon powder.

A comprehensive three-technique characterisation of both materials was performed, using helium pycnometry, N₂ gas adsorption, and mercury intrusion porosimetry. Helium pycnometry revealed a skeletal density of 2.201 g/cm³ and 1.925 g/cm³ for graphite and activated carbon respectively. Gas adsorption experiments and application of BET theory revealed a surface area of 0.51m²/g for graphite and 1800 m²/g for activated carbon, with the isotherm shape and C value for activated carbon being consistent with microporosity and/or adsorption onto high energy surface sites. Mercury porosimetry confirmed significant macroporosity in the graphite and extensive mesoporosity in the activated carbon, although the microporous regime was unresolved due to instrumental limitations. ICP-OES analysis showed effective sodium and calcium ion removal in the case of the pure graphite (80 – 90%), whereas particulate contamination from the activated carbon doped samples precluded an analysis of its performance. Therefore, graphite was determined to be the most suitable material for water purification in the context of ISRU. Future studies may focus on optimisation of the surface chemistry of the graphite via oxidation, as well as refining performance through variable flow rate and filter dimensions.

Publication Date

2025-12

Publication Title

The Plymouth Student Scientist

Volume

18

Issue

2

ISSN

1754-2383

Deposit Date

2025-12

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Archenoul, Ciaran (2025) "Evaluation of graphite and activated carbon as suitable water purification media for in-situ resource utilisation (ISRU) on Mars," The Plymouth Student Scientist: Vol. 18: Iss. 2, Article 2.
DOI: https://doi.org/10.70156/1754-2383.1539
Available at: https://pearl.plymouth.ac.uk/tpss/vol18/iss2/2