Rheological properties of extracted oil from sludge

Abstract

Oily sludge is a viscous complex mix of hydrocarbons, water, metals, and suspended fine solids. This by-product’s persistent toxic composition poses serious environmental concerns, making its containment one of the biggest challenges facing petroleum industries. The main objective of this research is to study the rheological properties of extracted oil. Petroleum sludge is considered a non-Newtonian fluid. However, after the application of Electro-Kinetic phenomena, demulsification of the matrix took place, and separated phases started expressing different behaviours. The diffuse double layer of the sludge components, particularly those known as emulsifiers (e.g. asphaltenes, and resins), were affected by DC field. Since they were affected in different ways, the separation of phases was facilitated, where each component expressed different physicochemical properties (including viscosity, and shear rate). Accordingly, the measurement of rheological properties permitted to follow adequately the changes observed in the oil matrix. Then, viscosity was measured as a function of strain at the top, middle, and bottom areas of the anode, cathode and central areas. However, the elastic modulus, which is a measure of the stiffness of the sludge, was presented as a function of frequency for the same areas. It can be concluded, that the EK (Electro-Kinetic) remediation directly affects the rheological properties of the sludge, by targeting the microstructure of the sludge. Disturbing the thermodynamically stable system, and affect the energy barrier (resultant of the attractive and repulsive forces), which prevents particles from coalescence. It seems that DC field affected the zeta potential of the system, by changing the balance of ions in the diffuse double layer. It is visible particularly in the presence of high Conductive metals.