Thesis (Ph.D.) in Chemical Engineering--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 192-196).

Thesis (Master)--İzmir Institute of Technology, İzmir, 2006 / Keywords: Calcite, morphology, aragonite, polymorph, composite, organic additive. Includes bibliographical references (leaves. 82-86).

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Angela M. Belcher. Vita. Includes bibliographical references.

Thesis--Columbia University. / "A critical review on water vapor pressure and solubility of major atmospheric gases in NaCl solution and sea salt solution in comparison with that in pure water": leaves 146-176. Includes bibliographies.

No description available.

D.Phil. (Chemistry) / The formation ofcalcium carbonate scale is a major problem in industry as well as in households. The scale that forms acts as an insulator, decreasing the effectiveness ofheat exchangers, be it a water cooling systems or a water heating system This raises the energy costs ofthat company and the costs of cleaning are expensive. Physical water treatment has been used for at least 50 years in the treatment ofwater with scale forming potential to reduce the formation ofthis scale. In thisthesis, tests were made on a magnetic and constantelectric field antiscaling device on the effect they have, ifany, on CaC03 scale formation. An attempt will be made to give a mechanism for any effect found. It is hoped that a contribution is made by this research in clearing up the misconceptions that abound in this controversial field ofphysical water treatment. Water with a high calcium bicarbonate content was exposed to the antiscaling devices and then calcium carbonate was forced to precipitate out ofsolution. This precipitation was followed by meauring the pH and the crystal structure ofthe precipitated calcium carbonate was studied. The most important results were that by exposing the calcium bicarbonate solution to an antiscalingdevice, the start ofprecipitation ofthe calcium carbonate was significantly delayed and the crystal structure of the calcium carbonate that formed was predominantly aragonite as opposed to calcite that usually formed.

White lime is used in many industries in South Africa but is not produced locally and must be imported. Many technologies have been suggested for the large-scale manufacture of calcium carbonate but these are not necessarily suitable for application in South Africa. This study investigated a chemical preparation of calcium carbonate combined with biological purification Calcium containing materials from the Pretoria Portland Cement, Lime Division factory at Lime Acres in the Northern Cape were studied as the starting materials for the manufacture. Investigation showed that they contained various impurities, including iron and manganese compounds which were largely responsible for the brown-grey colour of the lime products. Complete dissolution of calcium hydroxide, the purest of the potential starting materials, and subsequent hydroxide precipitation was not successful in removing all iron and manganese. Precipitation with sulfide ions was successfill, decreasing levels of metals to below the detection limit of atomic absorption spectrophotometry. Studies of all potential starting materials revealed that the levels of impurities in the starting material did not have a large effect on levels of impurities in the calcium carbonate produced. It was therefore possible to convert the residual calcium oxide or hydroxide in waste lime dusts to white calcium carbonate, a marketable prciduct Recycling of the water and starting material used in the process served to increase, rather than decrease, the purity of the calcium carbonate product. This allows for water conservation as water is not consumed in the process but merely utilised. When waste lime dust was used as the starting material, sulfate was found in the product. While still a white lime, the calcium carbonate was not chemically pure. Sulfate removal was therefore investigated and the use of sulfate-reducing bacteria was studied as a novel application. A mixed sulfate-reducing bacterial population was isolated and found to be hIghly active at sulfate concentrations between 0.2 and 2 ~~~. They were capable of autotrophic growth and could reduce sulfate in solutions with elevated pH and in calcium carbonate suspensions, although they did not grow readily in these media. A process was designed for the production of bulk quantities of calcium carbonate making use of the facilities and materials available at Lime Acres. This was tested using a small scale bench-top reactor series, with favourable results. The process would allow automatic, continuous production of large quantities of white lime using waste lime dust. Provision was also made for manufacture of smaller quantities of pure calcium carbonate using sulfate-reducing bacteria to remove the sulfate impurity.

No description available.

3 pp. / Iron deficiency is a frequent problem in ornamental plants in the desert areas of southern Arizona.

Revised; Originally Published: 2006 / 3 pp.