Dissolved Oxygen Content Measurement in Aqueous and Hydrocarbon Liquids

Dissolved oxygen in aqueous and organic liquids affects a variety of process operations. Even at trace levels, it can lead to fouling in processing units such as separators, heat exchangers, pumps, compressors, and reactors, causing unplanned shutdowns. It can also promote corrosion in processing units and storage tanks. This study was initiated to develop a proper liquid sampling procedure which minimizes air contamination during sampling and to measure the dissolved oxygen content of different liquids employing both Oxygen Orbisphere Analyzer and GC-MSD methods. After developing an appropriate experimental setup using the aforementioned methods, the dissolved oxygen content of various liquids such as toluene, normal heptane, 1-hexene, heavy reformate, and caustic aqueous solutions were measured. The results are in reasonable agreement with reported literature under similar conditions. Selected samples were purged with air to establish oxygen saturation levels, or purged with nitrogen to evaluate the use of this gas to reduce dissolved oxygen concentrations.