The salt content of crude oil that enters a petroleum refinery should be kept to a minimum to limit corrosion and fouling issues associated with salts. Desalting is usually performed as the first step in refining. Desalting of strong emulsion-forming crude oils, such as oil sand-derived bitumen, is more challenging. This work investigated the desalting behavior of oil sands bitumen to determine whether salts were present mainly in emulsified connate water, or whether salts were also present outside of emulsified water. A four step desalting procedure was performed and the removal of ionic species in the aqueous phase was monitored, with emphasis placed on anion quantification. With consecutive washing steps, the anion and cation concentrations did not always decrease monotonically and these observations were supported by conductivity measurements. The ratio of anions, notably carbonate/sulfate and chloride/sulfate, did not remain constant either. With repeated water washing, the pH of the aqueous phase became more acidic. The pH from the first washing step was 7.3 and with subsequent washing steps, the pH decreased, reaching as low as 4.7 in one of the experiments. The desalting behavior was therefore not consistent with a description of bitumen that retained salts only in emulsified connate water. At least some salts had to be present as solids in the bitumen to explain variability in anion ratios. It was also speculated that some salts could be present in ionic or coordination interactions with bitumen.

中文翻译：

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沥青的脱盐行为

进入炼油厂的原油的盐含量应保持在最低水平，以限制与盐相关的腐蚀和结垢问题。脱盐通常作为精炼的第一步进行。强乳化原油的脱盐，例如油砂衍生的沥青，更具挑战性。这项工作研究了油砂沥青的脱盐行为，以确定盐类是否主要存在于乳化原生水中，或者盐类是否也存在于乳化水中。执行四步脱盐程序并监测水相中离子物质的去除，重点放在阴离子定量上。随着连续洗涤步骤，阴离子和阳离子浓度并不总是单调下降，这些观察结果得到电导率测量的支持。阴离子的比率，特别是碳酸盐/硫酸盐和氯化物/硫酸盐，也没有保持恒定。通过反复水洗，水相的 pH 值变得更加酸性。第一个洗涤步骤的 pH 值为 7.3，在随后的洗涤步骤中，pH 值下降，在其中一个实验中降至 4.7。因此，脱盐行为与仅在乳化原生水中保留盐分的沥青的描述不一致。至少一些盐必须以固体形式存在于沥青中以解释阴离子比率的可变性。还推测一些盐可能存在于与沥青的离子或配位相互作用中。第一个洗涤步骤的 pH 值为 7.3，在随后的洗涤步骤中，pH 值下降，在其中一个实验中降至 4.7。因此，脱盐行为与仅在乳化原生水中保留盐分的沥青的描述不一致。至少一些盐必须以固体形式存在于沥青中以解释阴离子比率的可变性。还推测一些盐可能存在于与沥青的离子或配位相互作用中。第一个洗涤步骤的 pH 值为 7.3，在随后的洗涤步骤中，pH 值下降，在其中一个实验中降至 4.7。因此，脱盐行为与仅在乳化原生水中保留盐分的沥青的描述不一致。至少一些盐必须以固体形式存在于沥青中以解释阴离子比率的可变性。还推测一些盐可能存在于与沥青的离子或配位相互作用中。至少一些盐必须以固体形式存在于沥青中以解释阴离子比率的可变性。还推测一些盐可能存在于与沥青的离子或配位相互作用中。至少一些盐必须以固体形式存在于沥青中以解释阴离子比率的可变性。还推测一些盐可能存在于与沥青的离子或配位相互作用中。