Studying the effect of acidic and basic species on the physiochemical properties of polymer and biopolymer at different operational conditions

This paper describes an investigation and analysis of the physiochemical properties of polymer and biopolymer, namely interfacial tension (IFT) and viscosity, at elevated temperature and salinity. The methodology applied entails the testing and evaluation of the two surface-active components stearic acid and quinoline, which represent acidic and basic components respectively, in n-decane as a model oil in contact with polymeric solutions. The polymeric solutions contain Polyacrylamide (PAM) or Xanthan Gum (XG) in water at different saline levels. The results indicate that the effectiveness of polymer and biopolymer were significantly affected by the acidic or basic medium. Acidic systems have been found to be more active than basic systems in the reduction of IFT at room temperature. It is also noted that changing the water base from distilled water to seawater had no significant impact on IFT. Furthermore, an analysis at temperatures of 80 +/- 5 degrees C was conducted which indicated that there is an increase in IFT for all systems compared to a low temperature for both polymer and biopolymer systems. In respect to the effect of ageing time at high temperature, IFT increased slightly in the presence of polymer systems. However, in the case of biopolymer, IFT decreased with time at high temperature. A study of rheological properties of these systems shows that the viscosity of polymer or biopolymer solutions decreased, with a subsequent increase in shear rates. Average values of viscosity of 45-100 cP at a low shear rate of 3 rpm and 5-9 cP at the high shear rate of 600 rpm were observed for both polymer and biopolymer systems. Acidic and basic components do not affect the viscosity of the solutions at ambient temperature, whereas the addition of seawater results in a slight decrease in viscosity. On the other hand, the application of higher temperature leads to a significant decrease in viscosity. As such, the highest reduction in viscosity was observed over time when surface-active components and seawater were used. (C) 2020 Elsevier B.V. All rights reserved.