• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 14
  • 6
  • 2
  • 1
  • 1
  • Tagged with
  • 29
  • 29
  • 8
  • 7
  • 7
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development and utilization of a Raman characterization method for Hydrothermal char

Brown, Avery B. 21 January 2020 (has links)
Hydrothermal carbonization is a process by which biomass in water is thermochemically converted to a brown activated carbon known as hydrothermal char. As a biomass upgrading process hydrothermal carbonization has several advantages, the process is conducted in liquid water meaning pretreatment in the form of drying is not required. The process is normally conducted in batch reactors at temperatures ranging from 180 to 350°C and reactions of 0.5 to 24 hours. These mild conditions are not energy intensive and allow for the technique to deployed cheaply. The process involves no dangerous solvents or chemicals, and the liquid product has potential applications as a liquid fuel. Hydrothermal carbonization is a cost-effective technology that provides a solution to the growing waste and biomass production of the United States. However, there is a growing interest in the processes potential to produce a material that can be utilized for advanced materials. Hydrothermal chars have been shown to be highly susceptible to post-treatment by acid, temperature and mechanical methods. With a wide variety of potential feedstocks, treatment and post-treatment conditions a deeper understanding of the structure of material and how this structure is impacted by these conditions is needed to allow for its optimal use. Vibrational spectroscopy is a powerful tool for elucidating the structure of materials. Specifically, Raman spectroscopy is largely untapped method for the characterization of Hydrothermal chars. Raman spectroscopy is a scattering method that like IR spectroscopy utilizes an incident laser to produce vibrational responses in the molecule being studied. Raman spectroscopy can potentially be used to observe the carbon structure of a molecule. Typically, observations of this structure are conducted using Nuclear Magnetic Resonance, which is a relatively slow an expensive technique. Previous use of Raman spectroscopy in the field of hydrothermal carbonization has either underutilized the technique making observations of the presence of carbon or has been mischaracterized incorrectly stating the structure. In this work we have used Density Functional Theory to elucidate the Raman patterns of polycyclic aromatic hydrocarbons such as the ones that are the building blocks of hydrothermal chars. As a result of this work we have established a fitting method that explains the origins of Raman bands that are consistent with the structural motifs observed by more expensive techniques. The theoretical method is next deployed to the Raman spectrum of hydrothermal char derived from the treatment of glucose, a common model biomass. It is shown that common Raman spectroscopy methods when applied to hydrothermal char severely change the surface of material. How Raman spectroscopy impacts the surface of hydrothermal chars was studied and methods of mitigating these changes were developed. With a full compliment of theoretical and practical tools at our disposal we then apply these methods in attempt to understand the changes that occur to the structure of glucose based hydrothermal chars as a function of temperature and time.
2

Development and utilization of a Raman characterization method for Hydrothermal char

Brown, Avery B 04 December 2019 (has links)
Hydrothermal carbonization is a process by which biomass in water is thermochemically converted to a brown activated carbon known as hydrothermal char. As a biomass upgrading process hydrothermal carbonization has several advantages, the process is conducted in liquid water meaning pretreatment in the form of drying is not required. The process is normally conducted in batch reactors at temperatures ranging from 180 to 350°C and reactions of 0.5 to 24 hours. These mild conditions are not energy intensive and allow for the technique to deployed cheaply. The process involves no dangerous solvents or chemicals, and the liquid product has potential applications as a liquid fuel. Hydrothermal carbonization is a cost-effective technology that provides a solution to the growing waste and biomass production of the United States. However, there is a growing interest in the processes potential to produce a material that can be utilized for advanced materials. Hydrothermal chars have been shown to be highly susceptible to post-treatment by acid, temperature and mechanical methods. With a wide variety of potential feedstocks, treatment and post-treatment conditions a deeper understanding of the structure of material and how this structure is impacted by these conditions is needed to allow for its optimal use. Vibrational spectroscopy is a powerful tool for elucidating the structure of materials. Specifically, Raman spectroscopy is largely untapped method for the characterization of Hydrothermal chars. Raman spectroscopy is a scattering method that like IR spectroscopy utilizes an incident laser to produce vibrational responses in the molecule being studied. Raman spectroscopy can potentially be used to observe the carbon structure of a molecule. Typically, observations of this structure are conducted using Nuclear Magnetic Resonance, which is a relatively slow an expensive technique. Previous use of Raman spectroscopy in the field of hydrothermal carbonization has either underutilized the technique making observations of the presence of carbon or has been mischaracterized incorrectly stating the structure. In this work we have used Density Functional Theory to elucidate the Raman patterns of polycyclic aromatic hydrocarbons such as the ones that are the building blocks of hydrothermal chars. As a result of this work we have established a fitting method that explains the origins of Raman bands that are consistent with the structural motifs observed by more expensive techniques. The theoretical method is next deployed to the Raman spectrum of hydrothermal char derived from the treatment of glucose, a common model biomass. It is shown that common Raman spectroscopy methods when applied to hydrothermal char severely change the surface of material. How Raman spectroscopy impacts the surface of hydrothermal chars was studied and methods of mitigating these changes were developed. With a full compliment of theoretical and practical tools at our disposal we then apply these methods in attempt to understand the changes that occur to the structure of glucose based hydrothermal chars as a function of temperature and time.
3

Etude du traitement de la biomasse par voie hydrothermale pour la récupération de molécules et de minéraux à haute valeur ajoutée / Study of the hydrothermal pretreatment of biomass for the recovery of high added value minerals and molecules

Guillot, Marie 18 December 2014 (has links)
La croissance démographique mondiale, associée à une augmentation générale du niveau de vie, se traduit par l'explosion des besoins en matières premières et énergie. Afin de relever ce défi, une attention accrue est accordée aux énergies et ressources naturelles renouvelables. Parmi elles, la biomasse est particulièrement prometteuse. Elle présente des avantages certains (abondance, répartition homogène) mais aussi plusieurs inconvénients (faible densité énergétique, humidité élevée,…). Pour surmonter ces difficultés, la torréfaction est la méthode la plus connue, mais elle induit une augmentation des taux de cendres et une perte de matière. La carbonisation hydrothermale (HTC) est une alternative possible. L'objet de cette thèse est l'étude de la HTC comme moyen de bonifier la biomasse lignocellulosique. Trois axes principaux ont été considérés: augmentation de la densité énergétique, récupération de molécules, et minéraux d'intérêt. L'étude porte d'abord sur la HTC de systèmes moléculaires représentatifs de ceux présents dans le bois. Le hêtre a été étudié comme biomasse modèle, permettant de déterminer des conditions expérimentales optimales, appliquées ensuite à diverses biomasses. Enfin d'autres méthodes d'activation ont été testées telles que les micro-ondes et les fluides supercritiques. Les hydrochars obtenus après HTC présentent une diminution concomitante des ratios atomiques H/C et O/C. La phase liquide contient différentes molécules d'intérêt (furfural,…). Enfin, les teneurs en cendres diminuent après HTC du fait d'une lixiviation partielle de certains éléments (alcalins et alcalino-terreux). En conclusion, la HTC semble être une alternative intéressante à la torréfaction ; elle permet la production d'hydrochars avec des teneurs élémentaires adaptées à une utilisation en gazéification et la récupération de molécules et minéraux. L'intérêt et la faisabilité technique ont été démontrés en particulier sur des biomasses humides (plantes agricoles) ou polluées (broyats de déchetterie). / Population growth, coupled with a general increase in standard of living, result in a booming demand for raw material and energy. To face this challenge, an increased attention is paid to the use of renewable energies and natural resources. Among them, biomass is especially promising. Its advantages (abundance, distribution all over the Earth) are balanced by several drawbacks (low energy density, high moisture content,…). To overcome these problems, torrefaction is the most traditional way, but it has some inconveniences (increased ash content, loss of material). Hydrothermal carbonisation (HTC) is a possible alternative. The purpose of this thesis is the study of HTC a means to beneficiate the lignocellulosic biomass. Three main aims were identified: increase of the energy density, recover molecules and minerals of interest. The study initially focused on HTC of molecular model systems present in wood. Beech wood was also studied, as a model biomass. This study allowed determining optimal experimental conditions for treatment of further biomasses. Finally, other activation methods have been tested, such as microwaves, and supercritical fluids. Hydrochars obtained after HTC feature a concomitant decrease of the atomic H/C and O/C ratios. Liquid phase contains different molecules of interest (furfural,…). Finally, ash content decreases after HTC owing to a partial leaching of some elements (alkali and alkaline earth metals). In conclusion, HTC seems to be an interesting alternative to torrefaction as it allows for the production of hydrochars suitable for gasification, and the recovery of molecules and minerals of interest. The interest and technical feasibility have been demonstrated in particular for biomasses with high moisture (agricultural crops) or with high pollutant contents (grounds of waste disposal).
4

An investigation into human biowaste management using microwave hydrothermal carbonization for sustainable sanitation

Afolabi, Oluwasola O. D. January 2015 (has links)
The prolonged challenges and dire consequences of poor sanitation, especially in developing economies, call for the exploration of new sustainable technologies. These need to be: capable of effectively treating human faecal wastes without any health or environmental impacts; scalable to address rapid increases in population and urbanization; capable of meeting environmental regulations and standards for faecal management; and competitive with existing strategies. Further and importantly, despite its noxiousness and pathogenic load, the chemical composition of human biowaste (HBW) indicates that it may be considered to be a potentially valuable, nutrient-rich renewable resource, rather than a problematic waste product. This doctoral study therefore investigated microwave hydrothermal carbonization (M-HTC) as a sanitation technology for processing HBW - to convert it into a safe, pathogen-free material, while also recovering inherent value and providing an economic base to sustain the technology. To this end, the products of M-HTC treatment of sewage sludge, human faecal sludge, synthetic faecal simulant and human faeces were characterized with a suite of techniques and tests to demonstrate pathogenic deactivation, and the intrinsic value of the resultant solid char and liquor.
5

Hydrothermal carbonization of anaerobically digested effluent of sewage sludge to synthesize hydrochar for remediation of methylene blue dye from water

Sivaprasad, Shyam January 2021 (has links)
No description available.
6

Hydrothermally carbonized wood as a component in biobased material for 3D-printing / Hydrotermiskt karboniserat trä som komponent i biobaserat material för 3D-printing

Hendeberg, Matilda January 2020 (has links)
Consumers put higher demands on low environmental impact from the products they use, and the materials they consist of. As a result, more research is being made on finding environmentally friendly production techniques and materials. Hydrothermal carbonization (HTC) is a relatively environmentally friendly method that has been used in this study. Cellulose and pine, the latter, one sample with and one without bark, were carbonized at 220 °C and 240 °C for two hours. This generated solid carbon products that could be used in composites with the biopolymer Polylactide (PLA). The composites were thereafter extruded as filaments and used for 3D printing. X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that HTC of all precursors generated an amorphous carbon material, with carbon microspheres and increased aromaticity. Three different composites were produced from PLA and 0.1 wt% of the solid carbon products from all three precursors carbonized at 240 °C. Composites were also made from PLA and 1 wt% non-carbonized pine with bark, and 1 wt% of pine with bark carbonized at 240 °C. Filaments were extruded from neat PLA, as well as the composites of 0.1 wt% carbonized cellulose and 0.1 wt% carbonized pine with bark mentioned above. The filaments were used to 3D print six dog bones per filament according to the ISO standard ISO 527-2 1BA. There was one instance of clogging for each filament from the composite materials, but it was easily solved. No mechanical tests could be performed, although the 3D printed models’ physical properties were visually observed, and no deficiencies were found. Both extrusion and 3D printing were successful. / Konsumenter ställer högre krav på att material och produkter de använder har liten påverkan på miljön. Till följd av detta lägger forskningen mer resurser på att hitta miljövänliga tillverkningsmetoder och material. Hydrotermisk karbonisering (HTC) är en relativt miljövänlig process som har använts i denna studie. Tall (ett prov med och ett utan bark) samt cellulosa karboniserades vid 220 °C och 240 °C i två timmar, för att på detta vis producera en fast kolprodukt som kunde användas i en komposit med biopolymeren Polylaktid (PLA). Kompositen extruderades sedan till filament som användes vid 3D printing. Röntgenpulverdiffraktion (XRD), Svepelektronmikroskopi (SEM) och Fourier-transform infraröd spektroskopi (FTIR) visade på att HTC hade genererat amorfa kolmaterial, med mikrosfärer och ökad aromaticitet från både cellulosa och båda tallproverna. Samtliga produkter från karbonisering vid 240 °C användes för att göra tre olika kompositer med vardera 0,1 vikt% kolmaterial. Kompositer tillverkades även från PLA och 1 vikt% tall med bark, samt 1 vikt% tall med bark karboniserad vid 240 °C. Filament extruderades av ren PLA samt ovan nämnda kompositer med 0.1 vikt% karboniserad cellulosa och 0.1 vikt% karboniserad tall med bark. Dessa användes vid 3D printing för att skriva ut sex hundben per filament, enligt ISO standarden ISO 527-2 1BA. Vid ett tillfälle för vardera av de två kompositerna täpptes mynningen till 3D skrivaren igen av partiklar i filamenten. Detta löstes dock enkelt. Mekaniska tester kunde tyvärr inte utföras på hundbenen, men inga fysiska brister beskådades på dem. Både extrudering och 3D printing var lyckade.
7

Potentialen hos hydrokol från avloppsslam som jordförbättringsmedel / The potential of hydrochar from sewage sludge as a soil improver

Akhlaghi, Lina January 2022 (has links)
Margretelunds reningsverk i Åkersberga står såsom andra svenska avloppsreningsverk inför nya utmaningar i samband med anpassningen till ett mer hållbart och cirkulärt samhälle. För att bidra till en bra lokal miljö med få transporter och minimerad lukt, uppnå en hög grad av fosforåtervinning, samt reducera organiska och icke-organiska föreningar i slammet ska Roslagsvattenb i samarbete med IVL Svenska Miljöinstitutet utvärdera C-Greens OxyPower HTC-teknik. HTC-tekniken är hydrotermisk karbonisering (HTC) kombinerat med våtoxidation av HTC- vatten. Det våta slammet tas om hand på reningsverket och omvandlas till en fast kolanrikad produkt så kallad HTC-biokol eller hydrokol. HTC-processen innebär uppvärmning av det våta slammet (180–260°C) under högt tryck och syrefria förhållande med vatten närvarande. Hydrokolet som bildas kan uppgraderas till bränsle, jordförbättringsmedel eller aktiverat kol.  I detta arbete studerades potentialen att använda hydrokol som jordförbättringsmedel genom att undersöka biokolets fysikaliska- och kemiska egenskaper. Hydrokol jämfördes med biokol från pyrolys som också är en förkolningsprocess av biomassa vid höga temperaturer (300–650 °C) under syrefria förhållande dock utan närvaro av vatten.  Baserat på resultatet från publicerade studier, har hydrokol potentialen att ersätta eller komplettera mineralgödsel. Hydrokol förbättrar markens bördighet och produktivitet genom att t.ex. öka den totala växttillväxten, förbättrar mineraliseringen av näringsämnen och tillgängligheten av fosfor, samt ger en långsam frisättning av näringsämnen. / Margretelund's treatment plant in Åkersberga, like other Swedish sewage treatment plants, faces new challenges in connection with the adaptation to a more sustainable and circular society. In order to contribute to a good local environment with few transports and minimized odors, achieve a high degree of phosphorus recovery, and reduce organic and inorganic pollutants in the sludge, Roslagsvatten, in collaboration with the IVL Swedish Environmental Institute, will evaluate C-Green's OxyPower HTC-technology.  The HTC-technology is hydrothermal carbonization (HTC) combined with wet oxidation of HTC-water. The wet sludge is taken care of at the treatment plant and converted into a fast carbon-enriched product called HTC-biochar or hydrochar. The HTC-process involves heating the wet sludge (180–260°C) under high pressure and oxygen-free conditions with water present. The hydrochar that is formed can be upgraded to fuel, soil improver or activated carbon.  In this work, the potential of using hydrochar as a soil improver is studied by examining the biochar's physical and chemical properties. Hydrochar was compared with biochar from pyrolysis, which is also a charring process of biomass at high temperatures (300–650 °C) under oxygen-free conditions but without the presence of water.  Based on the results of published studies, hydrochar has the potential to replace or supplement mineral fertilizers. Hydrochar improves soil fertility and productivity by e.g. increase overall plant growth, improve nutrient mineralization and phosphorus availability, and provide a slow release of nutrients.
8

Sustainable carbon materials from hydrothermal processes

Titirici, Maria-Magdalena January 2013 (has links)
The world’s appetite for energy is producing growing quantities of CO2, a pollutant that contributes to the warming of the planet and which currently cannot be removed or stored in any significant way. Other natural reserves are also being devoured at alarming rates and current assessments suggest that we will need to identify alternative sources in the near future. With the aid of materials chemistry it should be possible to create a world in which energy use needs not be limited and where usable energy can be produced and stored wherever it is needed, where we can minimize and remediate emissions as new consumer products are created, whilst healing the planet and preventing further disruptive and harmful depletion of valuable mineral assets. In achieving these aims, the creation of new and very importantly greener industries and new sustainable pathways are crucial. In all of the aforementioned applications, new materials based on carbon, ideally produced via inexpensive, low energy consumption methods, using renewable resources as precursors, with flexible morphologies, pore structures and functionalities, are increasingly viewed as ideal candidates to fulfill these goals. The resulting materials should be a feasible solution for the efficient storage of energy and gases. At the end of life, such materials ideally must act to improve soil quality and to act as potential CO2 storage sinks. This is exactly the subject of this habilitation thesis: an alternative technology to produce carbon materials from biomass in water using low carbonisation temperatures and self-generated pressures. This technology is called hydrothermal carbonisation. It has been developed during the past five years by a group of young and talented researchers working under the supervision of Dr. Titirici at the Max-Planck Institute of Colloids and Interfaces and it is now a well-recognised methodology to produce carbon materials with important application in our daily lives. These applications include electrodes for portable electronic devices, filters for water purification, catalysts for the production of important chemicals as well as drug delivery systems and sensors. / Der stets wachsende globale Energiebedarf führt zu immer weiter zunehmenden Emissionen von Kohlenstoffdioxid, einem umweltschädlichen Gas, das als eines der Hauptprobleme im weltweiten Klimawandel darstellt. Bislang ist es jedoch nicht möglich, dieses Kohlenstoffdioxid in sinnvoller Weise zu verwerten oder einzulagern. Zudem existieren weitere Probleme in der globalen Energieversorgung, da viele natürlich vorkommende Rohstoffe sehr schnell ausgebeutet werden, so dass in naher Zukunft dringend alternative Energiequellen gefunden werden müssen, um den aktuellen Problemen zu begegnen. Der Wissenschaftszweig der Materialchemie zielt in diesem Zusammenhang darauf ab, dazu beizutragen, die bestehende Energieinfrastruktur nachhaltig zu verändern. Dabei stehen verschiedene Aspekte im Vordergrund: Energie sollte in allen gewünschten Mengen jederzeit verfügbar und auch speicherbar sein. Zudem sollte ihre Erzeugung ohne umweltschädliche Abfallprodukte ablaufen. Tiefgreifende Eingriffe in die Umwelt, v.a. durch den übermäßigen Abbau von Rohstoffen, sollte nicht mehr erforderlich sein. Auf diese Weise können die Folgen des bisherigen Klimawandels eingedämmt werden und neue Schäden an der Umwelt vermieden werden. Neue, grüne Industrie- und Energieprozesse schützen hier also nachhaltig den Planeten. Bei der Forschung an nachhaltigen Formen der Energieversorgung beschäftigen sich Materialchemiker in mannigfaltiger Weise mit Kohlenstoffmaterialien. Diese sollten idealerweise kostengünstig und ohne hohen Energiebedarf produziert werden können. Am vielversprechendsten sind Materialien, die eine flexibel gestaltbare Morphologie besitzen, d.h. die besondere strukturelle Eigenschaften besitzen, wie z.B. Porosität oder chemisch veränderte und damit funktionale Oberflächen. Idealerweise sollten solche neu entwickelten Materialien nicht nur als Speicher von Energie oder Energieträgern dienen, sondern auch nach ihrer Lebensdauer als funktionales Material zur Verbesserung der Bodenqualität eingesetzt werden können und dort noch weiter als potentielle Senke für Kohlenstoffdioxid dienen können. Die zuvor beschriebenen Themen und Probleme stellen den Gegenstand der vorliegenden Habilitationsschrift dar: die Entwicklung einer alternativen Methode zur Herstellung von Kohlenstoffmaterialien aus Biomasse in Wasser bei geringen Temperaturen. Dabei handelt es sich um die sogenannte hydrothermale Karbonisierung, die in den letzten fünf Jahren von einer Gruppe junger, talentierter Wissenschaftler unter der Anleitung von Frau Dr. Titirici am Max-Planck-Institut für Kolloid- und Grenzflächenforschung erarbeitet und weiterentwickelt wurde zu einer heutzutage anerkannten und verbreiteten Methode. Zudem wurden die über diesen Weg gewonnenen Materialien erfolgreich in zahlreichen, für den Alltag wichtigen Anwendungen eingesetzt, so z.B. als Elektroden in tragbaren elektronischen Geräten, als Filtermaterialien für die Aufreinigung kontaminierten Wassers, als Katalysatoren für wichtige chemische Reaktionen, als Trägermaterial für Arzneimittel und als Sensoren.
9

Integration of hydrothermal processes on a forest-based biorefinery site

Häreskog, Linnea January 2018 (has links)
The pulp and paper industry (PPI) is a business that produce large amounts of residues annually. Besides bark, large quantities of sludge are produced from the various parts of the industrial process. The sludge that comes from the biological wastewater purification process is denoted biosludge and is known as a particularly problematic waste product. It is of interest to reduce the amount of sludge from the PPI or to find new ways of handling the produced sludge. The common way to treat the PPI sludge is by incineration in the site’s bark boiler. The material is however difficult to dewater and often does more harm than good in the boilers. Different technologies to try and dewater the sludge further have been investigated previously, one that has recently been noted is hydrothermal treatment. The technology described in this thesis work is called hydrothermal carbonization (HTC) which uses water as a reaction media to turn the sludge into a coal-like material called hydrochar. The hydrochar has a higher heating value than the initial sludge and is more hydrophobic which makes it easier to dewater. This Master’s thesis describes the process technologies of the HTC process and presents some of the recent work done within the area. The properties of different residues from the PPI are presented before the integration of an HTC process on the biorefinery site in Domsjö, Sweden is discussed using previously published articles. A survey concerning sludge from industries within a 500 km range of the Domsjö biorefinery site is made to investigate whether residual streams similar to the ones at the Domsjö site are available in the vicinity. The results show that an HTC process demands energy in the form of steam and/or electricity. A previously made pinch and total site analysis show that the most accessible steam at the Domsjö biorefinery site, that most appliances and process steps uses, is at 7 bars. There are also steam levels of 20 and 32 bar in the area, which is within the range an HTC plant requires. The HTC process water demands further treatment which puts an extra stress on the already existing water purification process. The Domsjö biorefinery site produces 6000 tonnes of biosludge per year. Several HTC companies produce units that normally treat 20000-50000 tonnes of sludge per year, which indicates that additional sludge could be added to reach full capacity. The survey shows that there are similar materials available in the surroundings. It is concluded that further investigations concerning the sludge materials must be made before real implementation consequences can be calculated.
10

Degradação de antibióticos de uso veterinário em reator de carbonização hidrotermal / Degradation of veterinary antibiotics in hydrothermal carbonization reactor

Santos Júnior, Laurivê Antônio dos 28 September 2015 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-02-01T06:57:35Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Laurivê Antônio dos Santos Júnior - 2015.pdf: 5217600 bytes, checksum: 7f6935b2ba3d2fba5d6b3a116bca276f (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-02-01T07:08:48Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Laurivê Antônio dos Santos Júnior - 2015.pdf: 5217600 bytes, checksum: 7f6935b2ba3d2fba5d6b3a116bca276f (MD5) / Made available in DSpace on 2016-02-01T07:08:49Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Laurivê Antônio dos Santos Júnior - 2015.pdf: 5217600 bytes, checksum: 7f6935b2ba3d2fba5d6b3a116bca276f (MD5) Previous issue date: 2015-09-28 / Antibiotics are widely used in human and veterinary medicine. After consumption, much of the drug is excreted unchanged or in the form of metabolites, and through the release of sewage treatment plants, agricultural waste and leaching, reach natural ecosystems. The occurrence of antibiotics in aquatic environments has become a growing concern worldwide mainly due to the emergence of resistance genes in pathogenic bacteria. The indiscriminate use and the use of subtherapeutic doses of antibiotics cause the emergence of resistance. In Goiás, a recent survey showed the presence of bacteria resistant to multiple antibiotics in hospital wastewater and Goiania sewage treatment plant. The wastewater treatment processes based on biological degradation have low efficiency of removal of residual drugs due to recalcitrant structure and biocide effect of antibiotics. The objective of this research was to evaluate the efficiency of hydrothermal decomposition of the antibiotic ampicillin, enrofloxacin, oxytetracycline, and tylosin sulphaquinoxaline. For this purpose, the antibiotic solutions were prepared at a concentration of 50 μg.mL-1 and pH correction to the range 3-7, with phosphoric acid solution for the hydrothermal carbonization treatment. Treatment by the hydrothermal carbonization process of oxytetracycline with pH adjustment made with phosphoric acid, pH 3, 170 ° C temperature and 90 minutes reaction time showed total decomposition as a result of this antibiotic (100%). The highest decomposition rate (98.37%) for enrofloxacin was observed when they were used the reaction time of 120 minutes, pH 3, 200 ° C temperature and phosphoric acid as a catalyst. The highest decomposition rate of ampicillin (94.86%) was observed when using time of 120 minutes reaction, pH 4, 200 ° C temperature and phosphoric acid as a catalyst. The most suitable conditions for the decomposition of sulphaquinoxaline, observing the greatest reduction rate (95.71%) was observed when they were used the reaction time of 120 minutes, pH 5, temperature 180 ° C and phosphoric acid as a catalyst. All conditions, except for the pH 7, led to complete decomposition of tylosin (100%) of the samples. The best condition for the decomposition of tylosin, observing a lower energy expenditure, and reaction time spent catalyst was one which was used 90 minutes reaction time, pH 4, 180 ° C temperature and phosphoric acid as a catalyst. In the germination test with Allium cepa, the solutions treated, except ampicillin, had similar germination rates found in the control group. The solutions of antibiotics with no treatment showed higher rates of growth of buds when compared to the control group. These results show that the hydrothermal carbonization process has potential for future applications decomposition of antibiotics in contaminated water and effluent. / Antibióticos são largamente utilizados na medicina humana e veterinária. Após o consumo, grande parte dos fármacos é excretada inalterada ou sob forma de metabólitos, e por intermédio dos lançamentos de estações de tratamento de esgotos, resíduos agrícolas e lixiviação, alcançam os ecossistemas naturais. A ocorrência de antibióticos nos ambientes aquáticos tem se tornado uma preocupação crescente em todo o mundo especialmente devido ao aparecimento de genes de resistência em bactérias patogênicas. O uso indiscriminado e a utilização de doses subterapêuticas de antibióticos provocam o surgimento de resistência. Em Goiás, uma pesquisa recente demonstrou a presença de bactérias resistentes a vários antibióticos em efluentes hospitalares e na estação de tratamento de esgotos de Goiânia. Os processos de tratamento de efluentes baseados na degradação biológica apresentam baixa eficiência de remoção de fármacos residuais devido à estrutura recalcitrante e ao potencial biocida dos antibióticos. O objetivo desta pesquisa foi avaliar a eficiência da decomposição hidrotermal dos antibióticos ampicilina, enrofloxacina, oxitetraciclina, sulfaquinoxalina e tilosina. Com este intuito, soluções dos antibióticos foram preparadas com concentração de 50 μg.mL-1 e com correção de pH para a faixa 3-7, com solução de ácido fosfórico, para o tratamento com carbonização hidrotermal. O tratamento pelo processo de carbonização hidrotermal da oxitetraciclina com correção de pH feita com ácido fosfórico, pH 3, temperatura de 170ºC e tempo de reação de 90 minutos apresentou como resultado a decomposição total deste antibiótico (100%). A maior taxa de decomposição (98,37%) para a enrofloxacina foi observada quando foram utilizados tempo reacional de 120 minutos, pH 3, temperatura de 200ºC e ácido fosfórico como catalisador. A maior taxa de decomposição da ampicilina (94,86%) foi observada quando se utilizou tempo de reação de 120 minutos, pH 4, temperatura de 200ºC e ácido fosfórico como catalisador. As condições mais adequadas para a decomposição da sulfaquinoxalina, observando a maior taxa de redução (95,71%), foi observada quando foram utilizados tempo reacional de 120 minutos, pH 5, temperatura de 180ºC e ácido fosfórico como catalisador. Todas as condições, exceto o pH 7, levaram a decomposição total da tilosina (100%) das amostras. A melhor condição para a decomposição da tilosina, observando menor gasto energético, tempo reacional e gasto de catalisador, foi aquela onde se utilizou tempo de reação de 90 minutos, pH 4, temperatura de 180ºC e ácido fosfórico como catalisador. No teste de germinação com Allium cepa, as soluções tratadas, exceto a ampicilina, apresentaram taxas similares de germinação as encontradas no Grupo Controle. As soluções dos antibióticos sem tratamento apresentaram taxas superiores de crescimentos dos brotos quando comparadas ao Grupo Controle. Esses resultados mostram que o processo de carbonização hidrotermal apresenta potencial para futuras aplicações de decomposição de antibióticos em águas e efluentes contaminados.

Page generated in 0.1357 seconds