Electrochemical remediation of sulfide in sour brine

天然气的开采总是伴随着加压水的生产，加压水被盐污染，主要是氯化钠（盐水）。通常，这种盐水也被硫化物污染;在这种情况下，它们被称为“酸盐水”，因为它们有硫化氢的气味。除了有气味外，酸盐水还具有腐蚀性和剧毒性，特别是当压力释放时，硫化氢释放到大气中（类似于打开一罐汽水时释放二氧化碳）。处理酸性盐水的一种方法是在合适的地点回注到地面，但这是昂贵的，因为需要将酸性盐水从生产井输送到回注井而不释放压力。所提出的研究是基于硫离子的电化学氧化为元素硫，这是环境友好的。在我们实验室中使用硫化钠和氯化钠在水中的合成溶液的先前工作已经证明，氧化以优异的化学效率和优异的电流效率发生（这意味着电能被有效地使用，而不是浪费在寄生反应中，例如水的电解）。然而，在油田中产生的酸性盐水更复杂，主要是由于具有高浓度的环烷酸，环烷酸是烃基羧酸。我们的目的是利用环烷酸的表面活性剂性质，以提高电化学氧化，避免结垢的电极由元素硫，这是在环境温度下的固体。

The extraction of natural gas is always accompanied by production of pressurized water, which is contaminated by salts, principally sodium chloride (brine). Frequently, such brines are also contaminated with sulfide; in that case they are known as "sour brines" because of their odour of hydrogen sulfide. Besides being odorous, sour brines are both corrosive and highly toxic, especially when the pressure is released, liberating hydrogen sulfide to the atmosphere (similar to releasing carbon dioxide when a can of pop is opened). One method of disposing of sour brines is reinjection to the ground at a suitable site, but this is expensive because of the need to transport the sour brine from the producer well to the reinjection well without releasing the pressure. The proposed research is based on the electrochemical oxidation of sulfide ion to elemental sulfur, which is environmentally benign. Previous work in our laboratory using synthetic solutions of sodium sulfide and sodium chloride in water has demonstrated that oxidation occurs with excellent chemical efficiency and excellent current efficiency (meaning that the electrical energy is used productively, rather than wasted in parastic reactions such as the electrolysis of water). However, sour brines produced in the field are more complex, principally due to having high concentrations of naphthenic acids, which are ydrocarbon-based carboxylic acids. Our intention is to exploit the surfactant properties of naphthenic acids to enhance electrochemical oxidation by avoiding fouling of the electrode by the elemental sulfur, which is a solid at ambient temperatures.