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  • 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

Utilisation of gasification carbon residues:activation, characterisation and use as an adsorbent

Tuomikoski, S. (Sari) 04 November 2014 (has links)
Abstract Gasification is an energy conversion method for the utilisation of biomass for obtaining energy (heat and power). In the gasification process carbon residue is formed as a waste. For improving the cost-effectiveness of the gasification process the utilisation of this waste is important and the present legislation also creates requirements for the utilisation of waste material. Activated carbon is typically used for purification of water, for example, wastewaters as well as gaseous emissions. Consequently, commercial activated carbon is fairly expensive and its preparation is energy consuming. However, this inhibits sometimes its widespread use in wastewater treatment and therefore there is a need to develop cost-effective adsorbents from alternative biomass-based low-cost raw materials to remove harmful substances from aqueous solutions. The first aim of this thesis was to determine physical and chemical properties of carbon residues from wood gasification, and fly ashes from burning processes were used as reference samples. The properties are essential to known when evaluating the potential utilisation applications for unknown carbon residue samples. Properties of carbon residue indicate that it would be suitable adsorbent due to the high carbon content but its activation or modification is needed. The second aim was to modify this industrial carbonaceous by-product by physical and chemical activation and chemical modification methods to maximise the adsorption capacity of material. Based on our results, adsorption properties can be enhanced by using zinc chloride as a chemical activating agent, carbon dioxide as a physical activating agent and ferric chloride in the chemical modification and adsorbents with specific surface areas 285, 590 and 52 m2 g-1 were produced, respectively. The third aim was to test produced adsorbents to anions removal. Chemically activated carbon residue removes phosphate well and physically activated carbon residue removes phosphates and nitrates. Chemically modified carbon residue was observed to be suitable sorbent for sulphate removal. Optimal initial pH and concentration were determined and effect of time was studied and kinetic calculations and isotherm analysis was done for studied adsorbents. / Tiivistelmä Kaasutus on tehokas tapa hyödyntää biomassaa sähkön- ja lämmöntuotannossa. Kaasutuksessa muodostuu jätteenä hiilijäännöstä, jonka hyödyntäminen on tärkeää kaasutusprosessin kustannustehokkuuden parantamiseksi. Myös nykyinen lainsäädäntö asettaa vaatimuksia jätemateriaalien hyödyntämiselle. Aktiivihiiltä on tyypillisesti käytetty mm. jäteveden sekä kaasujen puhdistukseen. Aktiivihiili on kuitenkin kallista ja sen valmistaminen on energiaa kuluttava prosessi, mikä rajoittaa sen käyttöä. Tämän vuoksi tarvitaan uutta tietoa myös kustannustehokkaampien adsorbenttien valmistamiseen soveltuvista vaihtoehtoisista biomassapohjaisista raaka-aineista. Tutkimuksen tavoitteena oli aluksi määrittää puun kaasutuksessa muodostuneen hiilijäännöksen fysikaalisia ja kemiallisia ominaisuuksia, joiden tunteminen on tärkeää arvioitaessa soveltuvia hyödyntämiskohteita kyseiselle tuntemattomalle jätemateriaalille. Referenssinäytteinä käytettiin polttolaitoksilla muodostunutta lentotuhkaa. Hiilijäännöksen ominaisuuksien perusteella se voisi olla soveltuva adsorbentti, mutta aktivointi tai modifiointi on välttämätöntä hiilijäännöksen adsorptiokapasiteetin parantamiseksi. Työn toinen tavoite oli parantaa hiilijäännöksen adsorptio-ominaisuuksia fysikaalisesti ja kemiallisesti aktivoimalla tai kemiallisesti modifioimalla. Tulosten perusteella adsorptio-ominaisuuksia voidaan parantaa parhaiten käyttämällä sinkkikloridia kemiallisessa aktivoinnissa, hiilidioksidia fysikaalisessa aktivoinnissa ja rautakloridia kemiallisessa modifioinnissa, jolloin valmistettujen adsorbenttien ominaispinta-alat olivat 285, 590 ja 52 m2 g-1. Työn kolmas tavoite oli tutkia valmistettujen adsorbenttien adsorptiokykyä anionien poistossa laboratoriomittakaavassa. Kemiallisesti aktivoitu hiilijäännös poistaa tehokkaasti fosfaattia, fysikaalisesti aktivoitu fosfaattia ja nitraattia ja kemiallisesti modifioitu hiilijäännös on hyvä sorbentti sulfaatinpoistossa. Adsorptiokokeissa määritettiin optimaalinen alku pH ja alkukonsentraatio ja lisäksi tutkittiin ajan vaikutusta adsorptioon. Tulosten perusteella tehtiin kinetiikkamallinnusta sekä isotermianalyysi.
2

Avalia??o do petr?leo por termogravimetria para simula??o de curva PEV, fator de caracteriza??o e res?duo de carbono

Ribeiro, Marcilio Pelicano 27 February 2014 (has links)
Made available in DSpace on 2014-12-17T14:09:17Z (GMT). No. of bitstreams: 1 MarcilioPR_TESE.pdf: 2753388 bytes, checksum: 58b3cf541e2ed39d0ec5675d37151b31 (MD5) Previous issue date: 2014-02-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Petroleum evaluation is analyze it using different methodologies, following international standards to know their chemical and physicochemical properties, contaminant levels, composition and especially their ability to generate derivatives. Many of these analyzes consuming a lot of time, large amount of samples , supplies and need an organized transportation logistics, schedule and professionals involved. Looking for alternatives that optimize the evaluation and enable the use of new technologies, seven samples of different centrifuged Brazilian oils previously characterized by Petrobras were analyzed by thermogravimetry in 25-900? C range using heating rates of 05, 10 and 20?C per minute. With experimental data obtained, characterizations correlations were performed and provided: generation of true boiling point curves (TBP) simulated; comparing fractions generated with appropriate cut standard in temperature ranges; an approach to obtain Watson characterization factor; and compare micro carbon residue formed. The results showed a good chance of reproducing simulated TBP curve from thermogravimetry taking into account the composition, density and other oil properties. Proposed correlations for experimental characterization factor and carbon residue followed Petrobras characterizations, showing that thermogravimetry can be used as a tool on oil evaluation, because your quick analysis, accuracy, and requires a minimum number of samples and consumables / A avalia??o de petr?leo consiste em analis?-lo por diferentes metodologias, seguindo normas internacionais para conhecer suas propriedades qu?micas, f?sico-qu?micas, teor de contaminantes, composi??o e principalmente sua capacidade em gerar derivados. Muitas dessas an?lises s?o demoradas, consomem uma grande quantidade de amostras, insumos e precisam de uma organizada log?stica de transporte, cronograma de realiza??o e profissionais envolvidos. Para buscar alternativas que otimizem essa avalia??o e permitam a utiliza??o de novas tecnologias, sete amostras de diferentes petr?leos brasileiros centrifugados e caracterizados previamente pela Petrobr?s foram analisadas por termogravim?trica numa faixa de temperatura de 25 a 900?C utilizando raz?es de aquecimento de 05, 10 e 20?C por minuto. Com os dados obtidos experimentalmente, foram realizadas correla??es com as caracteriza??es disponibilizadas que permitiram: a gera??o de curvas de pontos de ebuli??o verdadeiros (Curva PEV) simulada; a compara??o entre as fra??es geradas com as devidas faixas de temperaturas de corte padr?o; uma aproxima??o para obter o fator de caracteriza??o de Watson; e comparar os res?duos de carbono micro. Os resultados mostraram uma boa possibilidade de reproduzir uma curva PEV simulada a partir da termogravimetria levando em considera??o a composi??o, densidade e outras propriedades do petr?leo; as correla??es propostas experimentalmente para o fator de caracteriza??o e res?duo de carbono acompanharam as caracteriza??es informadas pela Petrobr?s, mostrando que a termogravimetria pode ser utilizada como ferramenta na avalia??o de petr?leos, apresentando rapidez na an?lise, precis?o, al?m de necessitar de uma quantidade m?nima de amostras e insumos
3

Utilisation of industrial by-products in water treatment:carbon-and silicate-based materials as adsorbents for metals and sulphate removal

Runtti, H. (Hanna) 17 June 2016 (has links)
Abstract Pollutant (such as metals and sulphate) contamination exists in the wastewaters of many industries, including mining operations, metal plating facilities, and tanneries. Adsorption is one of the most commonly used processes for the removal of pollutants from waters and wastewaters due to its high efficiency and simple operation. Activated carbon is the most frequently used adsorbent material, although its high cost inhibits its widespread use in wastewater treatment. Therefore, there is a need to develop other adsorbents from alternative inexpensive raw materials such as locally available industrial and mineral waste and by-products. The aim of this thesis was to study the possibility of using industrial waste materials such as carbon residue, metakaolin, blast-furnace slag and analcime as an inexpensive sorbent for iron, copper, nickel, arsenic, antimony and sulphate removal from aqueous solutions. To enhance their adsorption capacity, different chemical treatments (i.e. activation, modification, geopolymerisation) were performed. As a result, the level of removal of iron, copper and nickel by carbon residue and zinc chloride activated carbon residue was higher than that by the commercial activated carbon. Iron chloride modified carbon residue was the most effective sorbent material for sulphate removal when compared to the other studied chemically modified/activated carbon residues. Blast-furnace slag and metakaolin geopolymers as well as their raw materials, were examined for the simultaneous removal of nickel, arsenic and antimony from the spiked mine effluent. In the case of blast-furnace slag, geopolymerisation clearly increased the efficiency of nickel, arsenic and antimony removal to a beneficial level. The barium chloride modified blast-furnace-slag geopolymer was a very efficient sorbent material for sulphate removal and it could thus be a technically feasible sulphate sorbent for wastewater treatment (e.g. in the mining industry in applications in which very low sulphate levels are desired). Barium chloride modified acid washed analcime could also be a potential sorbent for sulphate removal. / Tiivistelmä Teollisuuden jätevedet kuten kaivosvedet ja metalliteollisuuden prosessien jätevedet voivat sisältää monenlaisia haitallisia ja jopa myrkyllisiä aineita kuten metalleja ja sulfaattia. Adsorptiota käytetään yleisesti esimerkiksi metallien ja orgaanisten yhdisteiden poistossa vesiliuoksista, koska se on tehokas ja yksinkertainen menetelmä. Aktiivihiili on yleisimmin käytetty adsorbenttimateriaali vedenpuhdituksessa, mutta sen hinta joissain tapauksissa rajoittaa sen käyttöä. Tämän vuoksi on tarvetta kehittää vaihtoehtoisia adsorbenttimateriaaleja edullisista raaka-aineista. Viime vuosien aikana on raportoitu mm. teollisuus- ja mineraalijätteistä, joita voidaan hyödyntää vesien ja jätevesien puhdistuksessa. Tämän työn tavoitteena oli hyödyntää teollisuudesta muodostuvia jätemateriaaleja (hiilijäännös, metakaoliini, masuunikuona ja analsiimi) raudan, kuparin, nikkelin, arseenin, antimonin tai sulfaatin poistossa malli- ja jätevesistä. Materiaaleja käsiteltiin erilaisilla kemikaaleilla (aktivointi, modifiointi tai geopolymerointi), jotta niiden adsorptiotehokkuudet paranisivivat poistettavia aineita kohtaan. Tulokset osoittivat, että raudan, kuparin ja nikkelin poisto oli sekä käsittelemättömällä että sinkkikloridilla aktivoidulla hiilijäännöksellä korkeampi kuin kaupallisella aktiivihiilellä. Arseenin, nikkelin ja antimonin poistoa kaivosvedestä tutkittiin masuunikuona- ja metakaoliinigeopolymeereillä, joista masuunikuonageopolymeeri osoittautui tehokkaimmaksi metallien poistajaksi. Bariumkloridilla modifioitu masuunikuonageopolymeeri puolestaan poisti erittäin tehokkaasti sulfaattia kaivoksen jätevedestä. Rautakloridilla modifioitu hiilijäännös ja happopesty bariumkloridilla modifioitu analsiimi osoittatuivat myös lupaavaksi materiaaliksi sulfaatin poistossa.

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