Influence of ultrasonic on the flow behavior and disperse phase of cellulose nano-particles at fluid–fluid interface

Abstract

Nano-particles can localize at oil–water (O/W) interface, reduce residual oil saturation, increase the viscosity of brine and decrease the viscosity of crude oil emulsion. However, cost and environmental concerns have limited field application of inorganic, metal and metal oxides nano-particles. In this study, ascorbic acid was used for the first time to synthesize cellulose nano-particles (CNP) extracted from okra mucilage. The physical properties of the CNP including their size distribution and crystalline structures were investigated by transmission electron microscope, dynamic light scattering, Fourier transform infrared spectroscopy and X-ray diffraction. The rheological properties of the cellulose nano-fluid (CNF) were compared with the bulk okra mucilage and commercial polymer xanthan. The interfacial properties of the CNF at the interface of the O/W system were investigated at different concentrations and temperatures. The effect of the interaction between electrolyte and ultrasonic was determined. The combined method of ultrasonic, weak acid hydrolysis and nano-precipitation was effective in producing rod-like and polygonal nano-particles with a mean diameter of 100 nm, increased yield of 51% and preserved crystallinity, respectively. The zeta potential result showed that the CNF is stable, and the surface charge signifies long-term stability of the fluid when injected into oil field reservoirs. From the experimental results, concentration, particle morphology and the surface charge of the solutions were the contributing factors that influenced the rheology of the system. The CNF, okra and xanthan exhibited shear-thinning and pseudo-plastic behavior. The R2 value for the model is very close to unity, indicating that the power-law model describes nearly perfectly the rheological behavior. The consistency index increased as the flow behavior indices decreased with the increase in the concentration. The interfacial tension (IFT) decreased with the increase in concentration of CNF, electrolyte and temperature. Temperature, concentration of CNF and electrolyte were the main factors that influenced the IFT reduction. The results show that investing in ultrasonic-assisted weak acid hydrolysis is easier, cost-effective and can reduce energy consumption making the method economically advantageous compared to conventional methods. The characteristic properties of the CNF suggest that it has potentials to be used to recover trapped oil from pores of reservoirs.