Experimental Investigation of a novel CO

This dissertation was written as a part of the MSc in Environmental Management and Sustainability at the International Hellenic University and investigates the precipitation of calcium carbonate nanoparticles using a hollow fibre gas liquid membrane contactor/precipitator concept. The current climate challenges and subsequent need for this technology are reviewed, with emphasis on the cement industry. A summary of CCUS, mineralization, and membrane technologies is presented, as well as a review of current applications in the literature. Experiments were conducted using a custom precipitator operating in bubbling mode with titania (TiO2), zirconia (ZrO2), and alumina (Al2O3) single tube ceramic membranes. Membranes were treated with hexyltrimethoxysilane to increase hydrophobicity, using either immersion (TiO2, ZrO2) or chemical vapour deposition (Al2O3). Polypropylene polymeric membranes were also used in two different 3MTM Liqui-CelTM hollow fibre membrane modules, operating in contactor and bubbling modes. The liquid phase was a solution of calcium chloride (CaCl2), ammonium hydroxide (NH4OH3) and double distilled water and the gas phase was pure CO2. Samples were taken in five-minute intervals to measure pH and temperature, and experiments were terminated when a plateau of pH variation was observed. All liquid was vacuum filtered, and the precipitate was dried overnight at 110⁰C then weighed. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) were used to characterize the crystal size and morphology.