Proposal

Methods

Olivine grains, approximately 100 microns in diameter, were first cleaned using a sonicator to remove surface contaminants. After cleaning, the grains were dried in an oven at 60°C for several hours to ensure complete moisture removal. Following the drying process, four samples of 0.75 grams of olivine were put in four vessels with each vessel containing 20 mL of fluid. For the pH 11 condition, a stock solution of pH 11 was prepared, while for the pH 7 condition, deionized (DI) water was used. The experiments were performed in duplicates, with each set of conditions (pH 7 and pH 11) being replicated to ensure the reliability of the results. The reactions were conducted at 200°C for 16 hours under atmospheric pressure. After the reaction period, the solid residue was separated from the aqueous phase by filtration, and samples of the filtrates from both pH 7 and pH 11 conditions were collected and preserved for subsequent analysis.

The elemental composition of the dissolution products was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The filtered solutions were appropriately diluted and spiked with an internal standard (Sc and Ge) to correct for matrix effects. The concentrations of sodium (Na), magnesium (Mg), iron (Fe), calcium (Ca), nickel (Ni), and chromium (Cr) were determined by monitoring their respective isotopes. ICP-MS was performed in collision mode with no gas mode and helium (He) as the collision gas to minimize polyatomic interferences from Ar-based ions. Calibration was carried out with matrix-matched standards to account for matrix effects arising from varying concentrations of dissolved elements in the pH 7 and pH 11 solutions.

Analytes:

In the context of orange hydrogen production, key analytes should be examined using ICP-MS to ensure process efficiency, product purity, and compliance with environmental regulations. The specific analytes depend on the materials used (water, catalysts) and the potential contaminants introduced during the production process.

Key Analytes to Monitor:
Transition Metals: Iron (Fe) and Zinc (Zn) may enter the system through feedstocks, corrosion of equipment, or catalyst wear. Iron is essential in hydrogen production. Zinc needs to be monitored to ensure they do not contaminate the hydrogen or affect efficiency. Nickel (Ni) and Chromium (Cr) are common in catalysts used in electrolysis and other hydrogen production methods. Monitoring their presence ensures the catalyst’s performance and helps track degradation over time. They may also be contained in olivine as trace elements.
Alkali and Alkaline Earth Metals: Sodium (Na) and Potassium (K): Present in water sources or electrolytes, these metals may impact the efficiency of electrolysis if they accumulate. Magnesium (Mg): Often found in water, these elements can lead to scaling or fouling in electrolytic cells, reducing efficiency and requiring frequent maintenance. It is also a major element in olivines, so its concentration can reflect dissolution rate.