Ανάπτυξη και εφαρμογή κατάλληλων προσροφητικών μέσων για την απομάκρυνση βρωμικών ιόντων από ψυκτικά νερά

Μεγαλόπουλος, Σαράντος - Φοίβος; Megalopoulos, Sarantos - Foivos

dc.contributor.author	Μεγαλόπουλος, Σαράντος - Φοίβος	el
dc.contributor.author	Megalopoulos, Sarantos - Foivos	en
dc.date.accessioned	2022-09-08T07:38:53Z
dc.date.available	2022-09-08T07:38:53Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/55623
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.23321
dc.rights	Default License
dc.subject	Βρωμικό ιόν	el
dc.subject	Ενεργός Άνθρακας	el
dc.subject	Ερυθρά ιλύς	el
dc.subject	Υπολειμματικό βιοκτόνο	el
dc.subject	Επεξεργασία του νερού	el
dc.subject	Bromate ion	en
dc.subject	Activated Carbon	en
dc.subject	Red Mud	en
dc.subject	Residual biocide	en
dc.subject	Water treatment	en
dc.title	Ανάπτυξη και εφαρμογή κατάλληλων προσροφητικών μέσων για την απομάκρυνση βρωμικών ιόντων από ψυκτικά νερά	el
dc.contributor.department	Εργαστήριο Ανόργανης και Αναλυτικής Χημείας	el
heal.type	doctoralThesis
heal.classification	Αναλυτική Χημεία	el
heal.classification	Περιβαλλοντική Μηχανική	el
heal.classification	Χημική Μηχανική	el
heal.classification	Περιβαλλοντική Χημεία	el
heal.language	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2022-02-11
heal.abstract	Cooling is the most important auxiliary function in industry. Water is the prominent cooling media, abducting heat from heated equipment which is subsequently released in the environment. Due to scarcity and cost of this very important resource, water must be in position to carry out cooling for as long as possible, remaining in the cooling circuit. In open recirculating cooling circuits, which are the most common cooling equipment, keeping water within the circuit gives birth to three fundamental phenomena: creation of scale, corrosion and microbial growth. A variety of biocides are used to deal with microbial growth, of different nature (organic, inorganic), mode of action (active against cell membrane or cytoplasm) and speed (acute or slower). Chlorine is the most commonly used biocide for the disinfection of both drinking and cooling water. In cases, however, where cooling water is intentionally maintained at higher values, to render it less corrosive to the equipment, bromine in the form of HOBr/OBr- is also a common strategy. Bromine in the form of HOBr/OBr-, which can be found in the cooling water after being directly fed or after chlorination of Br- rich water bodies, decays (oxidizes) to (the carcinogenic to animals and possibly carcinogenic to humans) bromate ion - BrO3-. BrO3- becomes dangerous for the broad environment after water has fulfilled its cooling duty and is released to its downstream final recipient (lakes, rivers, the sea etc.). Both the American Environmental Protection Agency (EPA) and the European Union Commission have set the maximum contaminant level for bromate in drinking water at 10μg/L. The oxidation of HOBr/OBr- to BrO3- is a natural process which is being accelerated (catalyzed) under the conditions prevailing in a cooling circuit where copper and nickel oxides are found along with abundant sunlight and residual Cl2. The analytical method developed and used for trace level determination of bromate in cooling water, was ion chromatography. The chromatographic system comprised of anion determining quaternary ammonium columns (guard and measurement) able to bond bromate in combination with conductivity detector. Under cooling water conditions, where many competitive anions are present due to various chemical additions as well as due to concentration at the cooling tower, chloride (Cl-) as well as chlorite (ClO2-) ion can be co-eluted and thus impeding bromate determination. In a number of actual cooling water samples where this phenomenon caused noise, it was properly dealt with. The development of a statistical model based on multiple linear regression to predict the concentration of residual bromine (which is the precursor of bromate in disinfected cooling water) is the initial research step of this thesis. The concentration of residual bromine is taken as the dependent variable whereas the electric conductivity of cooling water, the contact time between bromine and cooling water, its organic load, its temperature and the applied Br2 dose are taken as the independent ones. A cooling water sample was taken from an electric energy producing plant in the Greek territory. A low and a high value were given to each independent variable in order to simulate actual functional conditions as well as the chemical profiles cooling water tends to take. Each synthetic aliquot was fed with various bromine concentrations and after the specified contact time, residual bromine was measured using the N,N-diethyl-p-phenylenediamine (DPD) method. It was proven that the residual bromine concentration can be fairly adequately predicted, provided that the R2 of the derived model was calculated greater than 0,8. After incorporation of independent variable interactions, the adjusted R2 was found to be greater than 0,9. The validation of the model was carried out by using it inversely as bromine demand (i.e. the bromine dose required to oxidize all reducing substances in the cooling water and achieve specific bromine residual) prediction tool. Results were again satisfactory even though the derived model tends to slightly under-estimate the level of bromine demand in the majority of cases. Activated carbon’s (AC) behavior as bromate adsorber from cooling water, was investigated in the second part. Activated carbon is an obvious choice for the removal of bromate from cooling water since is widely used in industrial practice for the removal of disinfection by-products. The most effective AC among a group of Granular (GAC) and Powder (PAC) types, was initially selected. A sample of actual cooling water from the metal processing industry was used for this series of experiments, as well. Synthetic aliquots were prepared varying the pH value, Cu2+ concentration, Br2 dose as well as the dose of polyacrylate/phosphonate additives which are commonly used for the protection of the cooling circuit against scale and corrosion. The organic load concentration was adjusted and maintained constant. The tool used for the evaluation of AC’s bromate adsorbing ability was the isotherm curve. The experimental data were found to fit the Freundlich model best. pH was found to be the strongest influence on AC bromate removal ability, followed by Cu2+ concentration, polyacrylate/phosphonate additive concentration and bromine presence which is the weakest impact factor among the ones studied. The third part reports the findings of the study involving Red Mud (RM) as bromate adsorber from ultra-pure as well as cooling water, after HCl activation and CetylTrimethylAmmonium Chloride (CTAC) enrichment. CTAC was chosen as bromate adsorption enhancer after its proven effectiveness when combined with AC, as reported in literature. Initially the quantity of CTAC that can be loaded on HCl activated RM was experimentally determined. Infra Red (IR) spectra of the composed material were taken in order to verify the success of the enrichment process. Adsorption ability comparison (between HCl activated and CTAC enriched RM) was then carried out using kinetic study, isotherm curves and pH value alterations. The final step was the evaluation of bromate removal ability of each material from cooling water. In all cases CTAC enriched RM was proved more effective than HCl activated RM in adsorbing bromate. The conclusion is that residual bromine concentration in cooling water is possible and can be done relatively accurately, providing cooling circuit operators with a bromate precursor prediction tool. Bromate removal using AC is also possible even though this strategy at cooling water pH values presents challenges. Finally it was proven that RM can re-enter the economic cycle as bromate adsorber even under cooling circuit conditions such as increased concentration at the cooling tower, high pH values and strong scale forming environment. Industrial schemes through which RM in either form can be used in practice, are presented.	en
heal.advisorName	Όξενκιουν-Πετροπούλου, Μαρία
heal.committeeMemberName	Διαμαντόπουλος, Ευάγγελος
heal.committeeMemberName	Γρηγοροπούλου, Ελένη
heal.committeeMemberName	Χαραλάμπους, Αικατερίνη
heal.committeeMemberName	Παππά, Αθηνά
heal.committeeMemberName	Μαλαμής, Συμεών
heal.committeeMemberName	Τσόπελας, Φώτιος
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών	el
heal.academicPublisherID	ntua
heal.numberOfPages	219
heal.fullTextAvailability	false