The Interplay between Organic Compounds and Mineral Surfaces:Applications from Enhanced Oil Recovery to Design of New Materials

• Main Author: Nielsen, Anne Rath
• Format: Book
• Language: English
• Published: Department of Chemistry, Faculty of Science, University of Copenhagen 2019
• Subjects: Arctic
• Online Access: https://curis.ku.dk/portal/da/publications/the-interplay-between-organic-compounds-and-mineral-surfaces(301820d5-3736-4e77-ab3d-e74c7a280ee3).html; https://soeg.kb.dk/permalink/45KBDK_KGL/1pioq0f/alma99123538268705763

The interplay between minerals and organic compounds, where organic compounds include e.g. crude oil, pesticides, proteins or polysaccharides, takes place everywhere in natural environments. Organicmineral interactions affect the state of our groundwater where pesticides affect the drinking water quality and the interactions affect the availability of reliable energy resources by governing our ability to extract oil from reservoirs. Enhanced oil recovery (EOR) techniques aim to increase production of oil by chemically changing the conditions in the reservoir. One EOR technique is to flood reservoirs with diluted seawater (<5000 ppm), which can increase oil extraction for some reservoirs. Increasing oil production just a few percent provides significant economic gains and opens for better exploitation of existing reservoirs, postponing environmental risky deep water and Arctic exploration. In biomineralisation, organisms use the organic-mineral interplay to form biocomposites i.e., hierarchically organised materials constituted by a mineral phase and organic components. The biocomposites have advanced properties compared to each constituent and the materials can be a prerequisite for survival of the organisms. The material design of biocomposites can be mimicked using synthetic biopolymers and minerals. This process can lead to controlled formation of novel composite materials with superior properties. Thus, for many aspects of society and industry, the understanding of the organic-mineral interactions is important and further insights can push new technologies forward. The goal of this thesis was to investigate organic-mineral interplay in two classes of systems. In the first class of systems, the organic-mineral interaction occurs between the mineral surfaces in oil reservoirs and organic functional groups in crude oil. In the second class of systems, the organic-mineral interaction occurs between novel synthetic biopolymers known as peptoids and calcium carbonate, in an early precursor of nacre mimetic composite material. There are several approaches for investigating organic-mineral interactions. In this work I applied a top-down approach where I deduce the response of complex natural rocks as a function of solution composition (Study I and II). I also applied a bottom-up approach where I investigated properties of specific functional groups on calcium carbonate formation and combined them to build nano-composites (Study III and IV). More specifically in Study I, I cleaned the surface of a mineral mixture aged in crude oil made to model sandstone material. I used a range of organic solvents followed by a characterisation of the organic constituents that strongly adhered to mineral surfaces, thereby investigating if we can retrieve a clean mineral surface. In Study II, I investigated how changes in solution salinity conditions affected the adhesion strength between the sandstone pore surface and functional groups present in crude oil. In Study III, I investigated the thermodynamic barrier of nucleation for calcite on surfaces functionalised with synthetic peptoids; the so-called B28 peptoid, and on SAMs expressing individual functional groups exposed in B28. I quantified the interaction strength between the functional groups and the (104) calcite surface. In Study IV, I used our findings from Study III to start making nacre-inspired nano-composites using constant solution conditions. Even though I investigated different systems and phenomena in the top-down and bottom-up approach, the underlying interest was the organic-mineral interaction. In all studies, I used nanoscale techniques such as atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) because these are strong tools for characterisation. These techniques are surface sensitive and provide insight into the interactions between organic compounds and minerals.