Optimization of Interfacial Material Isolation from Water–Oil Emulsions by Centrifugation and Fourier Transform Infrared Spectroscopy Characterization

High Resolution Image Download MS PowerPoint Slide Water-in-oil emulsions persist due to interfacial material (IM) that forms rigid interfacial films. We evaluated six Brazilian crudes (A–F) and optimized a centrifugation protocol for IM isolation. Emulsions were screened by gravitational separation, thermostated bath and then centrifugation (9,500 rpm) as a function of residence time (15–240 min) at 60 °C, followed by a temperature sweep (20–60 °C) at fixed time (120 min). Mass balance/IM recovery and FTIR analysis selectivity were used to evaluate the method’s performance. Oils B and C yielded highly stable emulsions, whereas A, D, E and F were unstable, giving the stability order: B≈C > F≈D≈A≈E. Based on recovery and FTIR, the optimal operating window was T ≥ 50 °C and t ≥ 120 min. FTIR and elemental analysis of the interfacial material from residue (IMR) indicated higher aromaticity, increased carbonyl (∼1700 cm –1 ) and sulfoxide (∼1030 cm –1 ) bands, and larger CH 3 /CH 2 ratios relative to the parent crude. PCA of FTIR spectra separated whole/emulsified oils from fractions generated by centrifugation─IMR, emulsion phase residue (EPR), and emulsion phase supernatant (EPS)─with major IMR loadings at 3500, 2954, 2922, 2853, 1458, 1377, 1707, and 741 cm –1 . Oil B showed distinct coefficients consistent with greater aliphatic character, lower branching, and reduced polarity. Finally, water migration from EPS to EPR followed pseudo-first-order kinetics, enabling prediction of dispersed-water content over time.