Get started
Work

Rates of elemental sulphur oxidation and associated oxygen and sulphur isotope fractionation

Year: 2009
Type: dissertation
Abstract: Elemental sulphur (S⁰) is removed from sour gas deposits (high H₂S) during refinement. The resulting S⁰ is often stored onsite when the costs of shipping S⁰ to market exceeds the costs of storing it in large above ground blocks. With the aid of acidiphilic bacteria, atmospheric air and water oxidize S⁰ to sulphate (SO₄²⁻). Long term storage is under consideration; however, oxidation rates and the role of each oxygen source (O₂(g) and H₂O) is not clear. S⁰ oxidation experiments were conducted over a range of temperatures (6-32°C) to investigate reaction rates and isotopic fractionation of O and S isotopes during oxidation. The experiments also investigated the effect of integrating S⁰ oxidizing microorganisms and available nutrients on both the reaction rates and isotope fractionation. Results indicated > 95% of total SO₄²⁻ generated can be attributed to autotrophic microbial activity. Experiments conducted in a nutrient rich mineral solution showed rates increase with temperature from 0.16 (6°C) to 0.98 (32°C) μg S⁰ cm⁻² d⁻¹ (Q₁₀ ≈ 1.7 - 1.9). Experiments conducted in a nutrient poor solution (deionized water) showed oxidation rates did not increase with temperature (0.06 to 0.08 μg S⁰ cm⁻² d⁻¹) between 12 and 32°C. Oxygen isotope analysis of the generated SO₄²⁻ indicated essentially all oxygen incorporated into the SO₄²⁻ originated from H₂O. In addition, effluent samples obtained from S⁰ block effluent at SCL indicated δ¹⁸O(SO₄) generally reflected the δ¹⁸O(H₂O) in the system at the time of oxidation. While covering the S⁰ blocks with an impermeable cover would undoubtedly minimize total SO₄²⁻ accumulation in block effluent, the results of this study suggest δ¹⁸O(SO₄) can also be used to track water movement through the block.
Language: English
Open Access status: green
OpenAlex ID: W2125909557
Cites: 80
Cited by: 1
Related to: 10