Adsorption of fatty acids on mineral surfaces, the experimental implication of sorption-protection theory for fatty acids diagenesis and the use of flash pyrolysis to comprehend the fatty acid-mineral interactions

Abstract

A theoretical concept of adsorption as a substantial step during diagenesis has been experimentally verified for long chain fatty acids on calcite and clay minerals. The primary focus of this research is to establish an empirical method via experimental work to test the major hypothesis developed for the preservation of organic matter via minerals related to the formation of geomacromolecules or kerogen. Addressing diagenesis, this research project is focused on the two major components of the sedimentary system i.e. fatty acids and minerals. The fatty acid is one of the most reactive organic compounds in the sedimentary system and is considered as an important precursor for petroleum hydrocarbons. Considering the importance of fatty acids in petroleum system, its adsorption on different minerals is challenging as well as equally important. Clay and calcite minerals have unique properties of adsorption, and catalysis and hence their affinity toward organic compounds has many implications in the petroleum industry and sedimentary system. A novel experimental method is developed to quantify the adsorption of fatty acids on mineral surfaces. Adsorption work coupled with flash pyrolysis is used to gain insight into fatty acids bonding with the mineral surfaces. Besides that flash pyrolysis work is used to apprehend the adsorption levels by benchmarking the difference in fatty acids adsorption on mineral surfaces. Like adsorption, a novel method is developed on Pyrolysis-GC-MS to recognise the breakdown products of three phases of fatty acids; pure fatty acids, fatty acids adsorbed on minerals and fatty acid salts. This is the first study of its kind when a comprehensive experimental work is executed at laboratory scale to mimic the adsorption of fatty acids during diagenesis. Findings from each experimental result are conclusive and interpreted in a close relation to natural settings. Project conclusions are used to understand the sorption and protection of fatty acids in the context of diagenesis and thus have major implications for the generation of hydrocarbons in marine sediments. Also, flash pyrolysis being a major part of the project is used for first time to address the diagenetic change linked with the industrial problem and then the solution is reported.