Browsing by Subject "Calcium carbonate"
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Item Open Access Bioinspired organic-inorganic composite materials(2016-05) Eren, Egemen DenizNature has been an inspiration and information source for scientists over centuries, for developing new materials. A great e ort has been spent in order to understand biological materials. The biomineralization process is observed in the nature and it creates perfectly hierarchical structures, which give the living organisms extraordinary properties. It is also a fact that along with the nature; living creatures such as nacre and bacteria employ biomineralization in order to produce minerals for protection and navigation purposes. In addition, bone is a composite material which protects the internal organs and provides mechanical support and is a result of biomineralization process. In this thesis, the biomineralization processes of living organisms and bone is mimicked by employing peptide amphiphile nano bers as templates for inorganic materials production. Glutamic acid residue is used in order the mimic the negatively charged domains for proteins, which play crucial roles in biomineralization process in some organisms and bone. In order to mimic the structure of sea shell, which is composed of calcium carbonate, and bone, which consists of calcium phosphate, relevant mineral solutions were used. In conclusion, when organic and inorganic components are used together, they demonstrate superior mechanical properties, when compared to organic molecules alone.Item Open Access Surface spectroscopic studies of Cs+, and Ba2+ sorption on chlorite-illite mixed clay(De Gruyter Oldenbourg, 2000) Shahwan, T.; Sayan, S.; Erten, H. N.; Black, L.; Hallam, K. R.; Allen, G. C.The sorption behavior of Cs+, and Ba2+ on natural clay was investigated using ToF-SIMS, XPS, and XRD. The natural clay was composed mainly of chlorite and illite in addition to quartz and calcite. Depth profiling up to 70 Å was performed at 10 Å steps utilizing ToF-SIMS to study the amount of sorbed Cs+ and Ba2+ as a function of depth in the clay matrix. The results suggest that Cs+ and Ba2+ ions were sorbed primarily by ion exchange coupled with hydrolytic sorption. According to ToF-SIMS and XPS results, the total sorbed amount of Ba2+ was larger than that of Cs+. Quantitative determination of the primary cations within the analyzed clay before and after sorption indicated that for Ba2+ sorption, Ca2+, Mg2+ and for Cs+ sorption Ca2+, K+ were the major exchanging ions. The XRD spectra of Ba-sorbed clay contained new peaks that were identified as BaCO3.Item Open Access Uptake of Ba2+ ions by natural bentonite and CaCO3: a radiotracer, EDXRF and PXRD study(Akademiai Kiado Rt., 2002) Shahwan, T.; Atesin, A. C.; Erten, H. N.; Zararsiz, A.Ba2+ uptake by natural bentonite, CaCO3 in addition to a number of bentonite-CaCO3 mixtures with variable compositions as a function of pH and Ba2+ concentration was studied. Radiotracer method, EDXRF, and PXRD were used. The results of radiotracer experiments showed that the uptake of Ba2+ by CaCO3 was larger than its uptake by natural bentonite samples, particularly at low initial concentrations of Ba2+ and higher pH values. This finding was supported by the EDXRF results, According to the sorption data, the apparent ΔG° values of sorption were in the range -9±1 to -13±3 kJ/mol. The PXRD studies revealed the formation of BaCO3 upon sorption of Ba2+ on pure CaCO3 and on some of the bentonite-CaCO3 mixtures.