University of Twente Student Theses


CO2 sequestration using bacterial surface layers

Stel, Bart (2013) CO2 sequestration using bacterial surface layers.

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Abstract:Natures unparalleled way of creating functional nanostructures through selfassembly has inspired the use of biomimetic methods to develop novel processes and materials. An interesting model system is formed by the self-assembly of the SbpA protein (Lysinibacillus sphaericus - ATCC 4525, MW 132 kDa) into surface layers (S-layers). Crystalline S-layers are known to mineralize CaCO3 on their surfaces, a process also responsible for so called ‘whiting events’ in lakes. Dffusion of CO2 to solution is the main source of carbon, which therefore identifies this process as a natural way for atmospheric carbon sequestration. In order to explore the mechanisms of CO2 sequestration, the formation of CaCO3 on immobilized crystalline S-layer arrays is analyzed using complementary surface science techniques. Structural information is obtained using Atomic Force Microscopy (AFM) while chemical information is obtained by X-ray Absorption Spectroscopy (XAS). The use of UHV-compatible liquid cells during XAS measurements makes it possible to directly compare the results obtained by in-situ AFM and XAS. This work shows that the CaCO3 precipitation pathway on S-layers includes the formation and subsequent stabilization of Amorphous Calcium Carbonate (ACC) versus the thermodynamically most stable polymorph of CaCO3 – calcite. Furthermore ACC has been found to form and remain stable on S-layers at concentrations far below its known solubility limit. It is therefore concluded that S-layers both catalyze and stabilize the formation of ACC. Moreover, the experimental approach combining in situ XAS and AFM proves to be a powerful method to track biomolecular mechanisms with high spatial and temporal resolution.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Nanotechnology MSc (60028)
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