Demulsification kinetics of water-in-oil crude oil emulsions using peracetic-oxidized rice husk lignin
Year: 2026
Type: article
Abstract: Crude oil water-in-oil (W/O) emulsions present persistent operational challenges during petroleum production and processing because of their resistance to droplet coalescence and phase separation. Although lignin-derived materials have emerged as promising sustainable demulsifiers, quantitative understanding of their demulsification kinetics remains limited. In this study, the time-dependent demulsification behavior of peracetic-oxidized rice husk lignin (O-RH) was investigated using laboratory-prepared Agbami crude oil emulsions, while the commercial demulsifier Separol® was evaluated under identical conditions as a performance benchmark. The effects of demulsifier dosage (200 and 300 ppm) and operating temperature (40, 50 and 60 °C) on water separation efficiency (WSE) were first evaluated, after which the optimum dosage (300 ppm) was subjected to detailed kinetic analysis. Experimental WSE data were fitted using apparent first-order, Avrami, Weibull and double-exponential kinetic models. Although all four models adequately described the experimental data, the apparent first-order model provided the most appropriate balance between goodness-of-fit, model simplicity and engineering applicability. Increasing temperature accelerated the demulsification process, with the apparent first-order rate constant increasing from 0.0544 min−1 at 40 °C to 0.0651 min−1 at 50 °C and 0.0804 min−1 at 60 °C, while the corresponding apparent activation energy was 16.92 kJ mol−1. Under the optimum operating conditions (300 ppm and 60 °C), O-RH achieved 92% water separation efficiency after 60 min, compared with 96% for Separol®, demonstrating competitive demulsification performance. FTIR, SEM and EDX analyses showed that peracetic oxidation introduced additional oxygen-containing functional groups and modified the lignin surface morphology, providing structural features consistent with the enhanced demulsification behavior. The incorporation of the additional dosage and intermediate temperature datasets strengthens the kinetic evaluation and provides a more reliable quantitative framework for assessing lignin-based demulsifiers. Overall, peracetic-oxidized rice husk lignin shows considerable promise as a sustainable alternative to conventional commercial demulsifiers for crude oil emulsion treatment.
Institutions: Nnamdi Azikiwe University, Hamburg University of Technology
Language: English
Subfield: Analytical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7214441941