Synthetic calcite (CaCO3) particles are found in a broad range of applications. The geometry of particles produced from limestone or precipitation are versatile but limited to basic shapes. The microalga Emiliania huxleyi produces micro‐structured calcite platelets, called coccoliths. This article presents the results of an application‐orientated study, which includes characteristic values also used in the calcite industry for particle evaluation. It is demonstrated that coccoliths are significantly different from all industrial particles produced so far. Coccoliths are porous particles, mainly consisted of calcium carbonate, with further elements such as Mg, Si, Sr, and Fe often embedded in their structure. Their structure is extremely sophisticated, while the overall particle morphology and particle size distribution are homogeneous. This study gives a first inside into the potential of these exceptional objects and may set further impulses for their utilization in specific calcite particle applications.
Thermogravimetric analysis of a coccolith-containing biogenic broth showed a three-step degradation process. According to this system behavior, the biogenic broth was heated to specific temperatures and characterized in terms of its morphology, surface chemistry, and crystallinity. The elemental and organic composition of the treated samples was also evaluated and compared to the reference material. The presented results were acquired in an effort to exploit pretreatment scenarios for such a biogenic system that would improve and support a separation process.
In response to the escalating world water demand and aiming to promote equal opportunities, reverse osmosis desalination has been widely implemented. Desalination is however constantly subjected to fouling and scaling which increase the cost of desalination by increasing the differential pressure of the membrane and reducing the permeate flux. A bench-scale desalination equipment has been used in this research to investigate the mitigation of fouling and scaling. This study involved the performance of membrane autopsy for fouling characterisation with special attention to flux decline due to sulphate precipitation and biofouling. Visual inspection, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and microbiology tests (API) were performed. Results obtained showed the presence of diatoms, pseudomonas and polysaccharides as the main foulants causing biofouling. Analysis revealed sulphate deposits as well as aluminium, calcium and silica as the main elements contributing to inorganic scaling. Findings pointed out that the pre-treatment system of the small-scale reverse osmosis water treatment was inefficient and that selection of pre-treatment chemicals should be based on its compatibility with the membrane structure. The importance of characterisation for the verification of fouling mechanisms is emphasised.
Coccolithen sind mikrostrukturierte Calcitpartikeln, die von Mikroalgen in der Natur produziert werden. Ihre komplex strukturierte Morphologie und enge Partikelgrößenverteilung unterscheidet sie von synthetischen Partikeln und macht sie interessant für verschiedenste Anwendungsgebiete. Coccolithen können nicht künstlich hergestellt werden und müssen deshalb durch Kultivierung gewonnen werden. In dieser Arbeit wird gezeigt, dass die Eigenschaften von Coccolithen nicht starr sind. Die Variation der Prozessparameter, Medienkomposition und Aufreinigungsstrategie ermöglicht bestimmte Eigenschaften von Coccolithen zu verändern. Dazu gehören die chemische Zusammensetzung, der Anteil von organischem Material und der Oberflächencharakter. Dadurch können Coccolithen zukünftig ihrem potenziellen Einsatzgebiet angepasst werden.
Biogene Calcitpartikeln (Coccolithen) aus Mikroalgen verfügen über hochkomplexe, dreidimensionale Strukturen, die so bei technischen Partikeln noch nicht bekannt sind. Es ist daher lohnenswert, Coccolithen in Bezug auf eine potenzielle industrielle Anwendung zu untersuchen. Diese Arbeit stellt einen effizienten phototrophen Bioprozess zur Gewinnung von Coccolithen vor und gibt einen Einblick in das Anwendungspotenzial dieser außergewöhnlichen Partikeln.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.