Next Article in Journal
The Role of Siliceous High-Magnesium Basalts during the Formation of a Neoproterozoic Mafic-Ultramafic Intrusion in the Tarim Craton (China)
Previous Article in Journal
Distribution of “Invisible” Noble Metals between Pyrite and Arsenopyrite Exemplified by Minerals Coexisting in Orogenic Au Deposits of North-Eastern Russia
Previous Article in Special Issue
Evidence for a Carbonatite-Influenced Source Assemblage for Intraplate Basalts from the Buckland Volcanic Province, Queensland, Australia
Open AccessArticle

Influence of pH on Molecular Hydrogen (H2) Generation and Reaction Rates during Serpentinization of Peridotite and Olivine

1
SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China
2
Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
3
Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
4
CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China
5
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
*
Authors to whom correspondence should be addressed.
Minerals 2019, 9(11), 661; https://doi.org/10.3390/min9110661
Received: 3 September 2019 / Revised: 24 October 2019 / Accepted: 25 October 2019 / Published: 28 October 2019
Serpentinization produces molecular hydrogen (H2) that is capable of supporting communities of microorganisms in hydrothermal fields, which suggests that serpentinization may be closely related to the origin of life at the early history of the Earth and possibly other planets. In this study, serpentinization experiments were performed at 300 °C and 3.0 kbar with natural olivine and peridotite as starting reactants to quantify the influence of acidic and alkaline solutions on the processes of serpentinization. The results reveal that acidic and alkaline solutions greatly influence molecular hydrogen (H2) generation and the rates of serpentinization. Acidic (pH = 2.50) and alkaline solutions (pH = 13.5) increased H2 production and the rates of peridotite serpentinization. Highly acidic solutions (2 M HCl), however, decreased the production of H2 after peridotite serpentinization by around two orders of magnitude. The decrease in H2 production was associated with a sharp decline in the rates of reaction; e.g., when peridotite was reacted with neutral solutions (0.5 M NaCl), 88% of reaction progress was achieved after an experimental duration of 27 days, and the reaction extent decreased by ~50% for experiments with highly acidic solutions (2 M HCl) over the same period. In contrast, for experiments with solely olivine, highly acidic solutions (2 M HCl) promoted the rates of olivine serpentinization and H2 production. The contrasting effect of highly acidic solutions (2 M HCl) on the processes of olivine and peridotite serpentinization may reflect the influence of pyroxene minerals, which could release SiO2 during peridotite serpentinization and, consequently, hydrogen generation and reaction rates may decrease. The experimental results of this study suggest that H2 production and the rates of serpentinization can be greatly influenced by acidic and alkaline solutions and co-existing minerals (e.g., pyroxene). View Full-Text
Keywords: olivine; serpentinization; pyroxene minerals; aluminum; molecular hydrogen olivine; serpentinization; pyroxene minerals; aluminum; molecular hydrogen
Show Figures

Figure 1

MDPI and ACS Style

Huang, R.; Sun, W.; Song, M.; Ding, X. Influence of pH on Molecular Hydrogen (H2) Generation and Reaction Rates during Serpentinization of Peridotite and Olivine. Minerals 2019, 9, 661.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop