Matrix effect of sodium compounds on the determination of metal ions in aqueous solutions by underwater laser-induced breakdown spectroscopy

Journal Article · Tue Jun 30 00:00:00 EDT 2015 · Applied Optics

DOI:https://doi.org/10.1364/AO.54.006071· OSTI ID:1248909

Goueguel, Christian ^[1]; McIntyre, Dustin L. ^[2]; Jain, Jinesh ^[1]; Karamalidis, Athanasios K. ^[3]; Carson, Cantwell ^[1]

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1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
2. National Energy Technology Lab. (NETL), Morgantown, WV (United States)
3. Carnegie Mellon Univ., Pittsburgh, PA (United States)

A significant portion of the carbon sequestration research being performed in the United States involves the risk assessment of injecting large quantities of carbon dioxide into deep saline aquifers. Leakage of CO₂ has the potential to affect the quality of groundwater supplies in case contaminants migrate through underlying conduits. New remote sensing and near-surface monitoring technologies are needed to ensure that injection, abandoned, and monitoring wells are structurally sound, and that CO₂ remains within the geologic storage reservoir. In this paper, we propose underwater laser-induced breakdown spectroscopy (underwater LIBS) as an analytical method for monitoring naturally occurring elements that can act as tracers to detect a CO₂ leak from storage sites. Laboratory-scale experiments were conducted to measure Sr²⁺, Ca²⁺, K⁺, and Li⁺ in bulk solutions to ascertain the analytical performance of underwater LIBS. We compared the effect of NaCl, Na₂CO₃, and Na₂SO₄ on the analytes calibration curves to determine underwater LIBS’ ability to analyze samples of sodium compounds. In all cases, the calibration curves showed a good linearity within 2 orders of magnitude. The limit of detections (LODs) obtained for K⁺ (30±1 ppb) and Li⁺ (60±2 ppb) were in ppb range, while higher LODs were observed for Ca²⁺ (0.94±0.14 ppm) and Sr²⁺ (2.89±0.11 ppm). Evaluation of the calibration curves for the analytes in mixed solutions showed dependence of the lines’ intensity with the sodium compounds. The intensities increased respectively in the presence of dissolved NaCl and Na₂SO₄, whereas the intensities slightly decreased in the presence of Na₂CO₃. Lastly, the capabilities of underwater LIBS to detect certain elements in the ppb or in the low ppm range make it particularly appealing for in situ monitoring of a CO₂ leak.

• Research Organization: National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• OSTI ID: 1248909
• Report Number(s): NETL-PUB-1195; APOPAI
• Journal Information: Applied Optics, Vol. 54, Issue 19; ISSN 0003-6935
• Publisher: Optical Society of America (OSA)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
spectroscopy
laser induced breakdown
remote sensing and sensors