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| Identifier |
uch.chemistry.msc//2005neofotistou |
| Title |
Σχηματισμός SiO2 σε υδατικά συστήματα και παρεμπόδιση του με χρήση δενδριμερών και πολυμερών |
| Alternative Title |
Formation of Silica (SiO2) in Water Systems and Its Inhibition by Use of Dendrimers and Polymers |
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Author
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Νεοφώτιστου, Ελευθερία
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Thesis advisor
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Δημάδης, Κωνσταντίνος
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| Abstract |
Deposition of sparingly soluble inorganic salts such as CaCO3, BaSO4, Mg(OH)2, SiO2, MgSiO3 etc, on critical metal surfaces (pipelines, heat exchangers) presents a severe problem for proper operation of cooling systems. The problems are related to inefficient heat transfer, reduced fluid flow, and metallic corrosion. In supersaturated waters with respect to silicate ions, condensation polymerization occurs leading to formation colloidal silica SiO2 deposits. These are tenacious scale deposits and they require either manual cleaning or removal by hazardous chemicals. Formation and deposition of SiO2 can prevented or minimized by use of chemical additives, called scale inhibitors. This study is focused on silica formation and its inhibition by molecules that possess either dendrimeric or polymeric structure. Polyaminoamide (PAMAM) dendrimers as prospective silica inhibitors due to their attractive structural characteristics, such as surface terminal groups (-NH2 or COOH), interior cavities, variety of generations (0.5-1.5-2.5 with COOH termini and 1.0 -2.0 with NH2 termini) are investigated in detail. The experimental results show that their inhibition performance depends on generation number, chemical nature of end groups and dosage levels. The results demonstrate the high inhibition efficiency of NH2 dendrimers in contrast to the low inhibition activity of the carboxylate PAMAMs. Linear poly(2-ethyl-2-oxazoline) polymers of a variety of molecular weights, which have amide groups, are also studied as SiO2 inhibitors. These are also effective inhibitors of silicate polymerization.
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| Language |
Greek |
| Subject |
πολυμερισμός, απόθεση SiO2, παρεμπόδιση, δενδριμερή ΡΑΜΑΜ, STARBURST, πολυμερή πολυ-αιθυλ-οξαζολίνης,polymerization, deposition of SiO2, inhibition, dedrimers PAMAM, STARBURST, poly(2-ethyl-2-oxazoline) polymers |
| Issue date |
2005-04-01 |
| Date available |
2005-03-17 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
184 |
Σχηματισμός SiO2 σε υδατικά συστήματα και παρεμπόδιση του με χρήση δενδριμερών και πολυμερών
