The Measurement of Methane Dissolved in Water Using Raman Spectroscopy Assisted with CCl4 Extraction

While under laboratory conditions, the concentration of methane dissolved in water is too low to be detected because of the low solubility of methane using Raman spectroscopy. In the present paper, a novel approach based on CCl4 extraction was introduced, and used in the measurement of methane dissolved in water using Raman spectroscopy under laboratory conditions. Saturated aqueous solution of CH4, CCl4 solution after extraction of CH4 from the saturated aqueous solution and the saturated CCl4 solution of CH4 were prepared, and the Raman spectra of three samples were obtained. The obtained results show that the CH4 dissolved in saturated aqueous solution(the concentration of CH4 is about 1.14 mmol.L-1) can't been detected using Raman spectroscopy under laboratory conditions, but the CH4 Raman peak can be clearly seen in the spectra obtained for CCl4 solution after extraction. All the results demonstrate that the proposed approach can improve the Raman spectroscopy sensitivity of methane detection dissolved in water, and this approach has significant potential to be developed as an effective method for detection of methane dissolved in water.