Composition and Dynamic Adsorption of Crude Oil Components Dissolved in Synthetic Produced Water at Different pH Values

The effect of pH on the extent and type of dissolved components in synthetic produced water samples prepared from seven crude oils was investigated. More nitrogen containing compounds, probably due to improved water solubility of pyridinic nitrogen functionalities, were seen at the low pH. The affinity of the water-soluble compounds for air water interfaces was in most cases higher at higher pH. This was due to increased oxygen content in the water-soluble species, probably associated with carboxylic acid functionalities. Differences in the affinity of water-soluble crude oil components to gas bubbles are anticipated to influence the oil removal efficiency by gas flotation. The dynamic interfacial adsorption was followed by a maximum bubble pressure tensiometer, while the dissolved species were characterized by total organic carbon measurements, total nitrogen measurements, FT-IR spectroscopy, and UV/vis spectroscopy.