A NOVEL H2S MONITOR USING COPPER (II) OXIDE AND RAMAN SPECTROSCOPY: A PROOF OF CONCEPT

Development of a novel aqueous hydrogen sulfide (H2S) detector is presented in this thesis. Nano copper (II) oxide (CuO) was selected as the detector material. Nano-CuO was synthesized by thermal oxidation and wet synthesis. CuS is produced from the reaction of CuO with H2S and Raman spectroscopy was used for its detection. The research presented in this thesis aimed at optimizing the parameters to produce coupons of CuO that can be used to detect H2S (aq) over the concentration range of 3.81 x10-3 ppm – 3.91 x10-9 ppm (0.1 M – 0.1 µM) by using Raman spectroscopy. Four specific objectives were devised to (1) determine the optimal synthetic technique for CuO, (2) determine which synthesis provides optimal CuO/CuS Raman spectra, (3) determine the linear range and detection limit of H2S by measuring the Raman Spectrum of CuS and, (4) to determine the rate of accumulation of CuS in human serum. The nano-CuO material with the optimal CuO/CuS Raman bands of interest was synthesized by thermal oxidation, where copper mesh (149 µm) was heated at 400 °C in air for 2 hours. The limit of detection of H2S (aq) by the optimal CuO is 1.22 x10-8 ppm (3.59 x10-7 M) with a linear range extending from 7.53 x10-3 – 1.22 x10-8 ppm (6.56 x10-1 – 3.57 x10-7 M). This study has provided new knowledge through (1) the development of a novel methodology to measure H2S (aq) concentration in serum by using CuO and Raman spectroscopy, (2) the discovery that CuO is specific to H2S and does not interact with proteins in human serum or other sulfur compounds at clinical concentrations, (3) determination that H2S (aq) detection is linear over the 7.53 x10-3 – 1.22 x10-8 ppm range with no interference of the Raman band from other biomaterials, and (4) the rate of accumulation is 0.1441 R/s