Isolation and modification of organosolv lignocellulosic compounds as demulsifiers for crude oil demulsification

Abstract

The most challenging aspect in petroleum industry is the formation of undesired emulsion, which causes major problems such as equipment corrosion, excess cost on transportation as well as low quality oil production. The use of chemical additives of so called demulsifier is widely used along with other conventional methods to accelerate crude oil and brine separation. The demulsifier selection recently moves towards low cost environmental friendly materials. The potential use of lignocellulose based-demulsifier for crude oil demulsification has not been explored yet due to lack of research in this regard. The present study thus, focused on the synthesis of demulsifiers based on lignocellulosic compounds from empty fruit bunch and so are cellulose derivatives as an alternative demulsifier for crude oil demulsification. The oil palm empty fruit bunch was treated by two-stage organosolv treatment and peroxide bleaching to extract lignocellulose compounds. The cellulose derivatives were prepared by modification of extracted cellulose. The synthesized demulsifiers were characterized using the Fourier transform infrared, nuclear magnetic resonance spectroscopy, gel permeation chromatography, thermogravimetric analyzer, scanning electron microscope, X-Ray diffractometer as well as relative solubility number measurement. The performance of demulsifiers was evaluated using bottle test method at 250 to 750 mg L-1 demulsifier dosage, temperature at 30 to 90 oC and pH 4 to 10 of brine. The synthetic emulsion system was prepared by emulsifying 10 ‰ salinity of brine and heptane/toluene mixture (7:3) with 20 weight ratio of resin to asphaltene. The result revealed that the cellulose in ionic liquid, 1-Butyl-3-methylimidazolium chloride showed the best performance among the tested lignocellulose compounds with 98 % of phase separation capacity, ? and 0.18 mL h-1 of phase separation rate, µ with 750 mg L-1 of demulsifier dosage at 70 oC and neutral pH of brine. The synthesized cellulose derivatives also performed at similar performance on phase separation capacity though their phase separation rate was higher than 0.5 mL h-1. The interfacial tension was reduced from 30 mN m-1 to 19 mN m-1. The selected demulsifiers (bleaching filtrate BF-1, quarternized cellulose, QC and cellulose, DC) from each type of lignocellulose based demulsifier were used in the kinetic study. Demulsifier DC and QC followed kinetic controlled adsorption while BF-1 followed diffusion controlled adsorption. For flocculation and coalescence study, water droplets aggregation showed coalescence as controlling step for all demulsifiers DC, QC and BF-1. Finally, the present synthesized demulsifiers may become an alternative chemical for crude oil demulsification due to their promising demulsification performance as biodegradable materials.