Effect of Alkyl Chain Length of Ionic Surfactants on Selective Removal of Asphaltene from Oil Sand Bitumen

In an attempt to find a more effective way to separate asphaltene from bitumen froth or bitumen emulsion by utilizing solvents, we added four different types of cationic (pyridinium series) and anionic (sulfate series) surfactants having different alkyl chain lengths and then compared the results. The data of the experiments showed that at given conditions (n-heptane at 50 degrees C, solvent-to-bitumen ratio of 3, and 20% water) and based on feedstock treated with 0.4 mmol of surfactant, asphaltene resin particles (colloid) with an initial negative charge showed different characteristics of adsorption of surfactants and aggregation of asphaltenes depending on the charge of the surfactants (cationic or anionic) and the alkyl chain length. Ultimately, the results showed that when methyl-pyridinium chloride (which is cationic and has the shortest alkyl chain) is added that the colloidal instability of asphaltene became the highest so that asphaltene removal increased by up to about 10% compared to treatments without surfactants. From this study, it was found that using those surfactants during froth treatment can improve the quality of the derived bitumen.