Esta tese apresenta a obtenção de sílica xerogel a partir de carvão de cascas de arroz e a modificação da sua superfície com um ligante orgânico tipo base de Schiff. O objetivo da utilização deste resíduo agroindustrial é a obtenção de um adsorvente capaz de atuar no tratamento de águas contaminadas contendo íons cádmio II, em uma concepção de valorização de resíduos. A sílica contida na biomassa foi obtida na forma de silicato de sódio através de extração química com solução de hidróxido de sódio, seguida de hidrólise e condensação do monômero através do processo solgel. A modificação da superfície da sílica com o ligante salen foi realizada utilizando o 1,2-dicloroetano como espaçador bifuncional. A sílica xerogel modificada foi avaliada através de análises de isotermas de adsorção e dessorção de nitrogênio (BET/BJH), difração de raios-X (DRX), análise química elementar (CHN), espectroscopia de infravermelho com transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV) e termogravimetria (TG/DTG). A análise elementar indicou que 0,341 mmol/g de 1,2-dicloroetano e 0,095 mmol/g de salen foi ancorado na superfície da sílica, que apresentou estabilidade térmica até 209°C e área de superfície específica de 106,4 m²/g. Foi realizado um estudo sobre a capacidade de adsorção de íons cádmio (II) pela sílica modificada e não modificada. Os resultados indicam a superior capacidade de adsorção de cádmio pela sílica modificada, em soluções com baixa concentração do íon. / This thesis presents the obtainment of silica xerogel by rice husk charcoal and its surface modification using an organic ligand type Schiff-base. The purpose of this agro-industrial residue utilization is the production of an adsorbent capable to remove heavy metals present in contaminated waters. The silica contained in the biomass was obtained by alkaline extraction in sodium silicate with hydrolysis through sol-gel process, and modified with salen, using 1,2-dichloroethane as bi-functional spacer. The modified xerogel silica was evaluated through analysis of nitrogen adsorption/desorption isotherms (BET/BJH), X-ray diffraction (XRD), chemical elementary analysis (CHN), Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM) and thermogravimetric analysis (TG/DTG). The elementary analysis pointed that 0,341mmol/g of the 1,2-dichloroethane and 0,095mmol/g of the salen was anchored to the silica surface, that presented thermal stability until 209°C and specific surface area of 106,4 m²/g. An evaluation about the ion cadmium II adsorption capacity of the silica modified and unmodified was performed. The results pointed to the superior cadmium adsorption capacity for the modified silica if low ion concentration solutions.

Escalating energy and environmental issues are driving researchers and industries throughout the world to study gas separation. Being common toxic gases, volatile organic compounds (VOCs) must be removed from the atmosphere. When compared to the conventional adsorption process, e.g. packed bed to separate VOC, the adsorbent hollow fibre has exhibited advantages in low-pressure drop, easy operation and lower capital cost with high adsorption performance. This research investigates the optimisation and development of single and multi-channel adsorbent hollow fibres to improve the mechanical properties, flexibility, adsorbent loading and enhance adsorption capacity. These fibres are made up of an adsorbent (13X zeolite, HiSiv 1000 zeolite powder and HiSiv 3000 zeolite powder) held together with a polymer (polyethersulfone) binder through wet/wet spinning followed by a phase inversion process. Single adsorbent hollow fibres were optimised by changing the ratio of adsorbent to the polymer, the viscosity of polymer/adsorbent/solvent mixtures, the pre-treatment temperature and by adding a pore former. This optimal recipe of polymer/adsorbent/solvent mixtures was then used to fabricate tri-lobe and hexagonal multi-channel adsorbent hollow fibre. The adsorption performance and mechanical properties of these multi-channel fibres were compared to those of the single adsorbent hollow fibres. Dynamic adsorption challenges were carried out using n-butane as the VOC model gas to provide breakthrough curves using a flame ionisation detector (FID) hydrocarbon analyser. Scanning electron microscopy (SEM) was used to characterise the surface and porous structures of the different adsorbent hollow fibres formation. Adsorption isotherm experiments were also used to measure the surface area of adsorbent hollow fibres. In order to understand the transport mechanism of gases through adsorbent hollow fibres, single and multi-channel fibres were modelled using a computational fluid dynamics (CFD) using COMSOL software 5.2, thus enabling the prediction of breakthrough time and mass transfer for the new geometries of adsorbent hollow fibre.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-10T11:33:17Z No. of bitstreams: 1 2016 - Fernanda Melo Pereira Taran.pdf: 1274160 bytes, checksum: 1abefb4abb6f8800458c7eb63d22a94c (MD5) / Made available in DSpace on 2017-01-10T11:33:17Z (GMT). No. of bitstreams: 1 2016 - Fernanda Melo Pereira Taran.pdf: 1274160 bytes, checksum: 1abefb4abb6f8800458c7eb63d22a94c (MD5) Previous issue date: 2016-01-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This study aimed to evaluate the in vitro adsorption of fumonisin B1 (FB1) through the use of different strains and concentrations of Saccharomyces cerevisiae in conditions simulating the digestive tract of horses. The experimental design was completely randomized in a factorial 4x5 with four yeast strains (1, 2, 3 and 4) and five concentrations for each strain of 1x107, 5x107, 1x108, 5x108 and 1x109 CFU.mL-1 at pH 2 and 6.8 with three replicates per treatment. In vitro adsorption experiments were carried out in microcentrifuge tubes containing buffered solution mycotoxin and yeast at 39 ? C. The concentration of FB1 was 5 ?g.mL-1. The supernatant of samples containing fumonisin not adsorbed were analyzed and quantified by CLAE. The results of the in vitro adsorption were subjected to a regression analysis based on the S. cerevisiae concentration and yeast strains. It was observed at pH 2 and 6.8 a significant interaction between S. cerevisiae concentration and yeast strain (P <0.001). At pH 2, the the amount of FB1 adsorbed by different yeast strains did not differ with 1x107, 5x107, 1x108 CFU.mL-1, only showed effects for the highest concentrations of 5x108 and 1x109 CFU.mL-1 (P<0.001). At pH 6.8, the differences occurred to concentration of 1x108, 5x108 and 1x109 CFU.mL-1 (P<0.001), but had no effect on lower concentrations (5x107 and 1x107 celulas.mL-1). At the highest concentration of 1x109 CFU.mL-1, strain 4 (SC-47) demonstrated a greater capacity to adsorb FB1, 39.4% and 37.5% at pH 2.0 and 6.8, respectively. In addition, linear responses were observed in the adsorption capacity in all strains evaluated under conditions of acidic and neutral pH. The results demonstrate that the ability of S. cerevisiae to adsorb FB1 is strain-dependent and the pH value may influence the amount of FB1 removed from the solution according to the strain used / Avaliou-se a adsor??o in vitro de fumonisina B1 (FB1) atrav?s do uso de diferentes cepas e concentra??es de Saccharomyces cerevisiae em condi??es que simulam o trato digestivo de equinos. O delineamento experimental foi inteiramente casualizado em esquema fatorial 4x5, com quatro cepas de levedura (1, 2, 3 e 4) e cinco concentra??es para cada cepa de 1x107, 5x107, 1x108, 5x108 e 1x109 UFC.mL-1, sob pH 2 e 6,8 com tr?s repeti??es por tratamento. Os ensaios de adsor??o in vitro foram conduzidos em microtubos contendo solu??o tamponada de micotoxina e levedura a 39 ?C. A concentra??o de FB1 foi de 5 ?g.mL-1. As amostras do sobrenadante contendo as fumonisinas n?o adsorvidas foram analisadas e quantificadas por CLAE. Os resultados foram submetidos ? an?lise de regress?o em fun??o da concentra??o de levedura e cepas de levedura. Observou-se, tanto em pH 2 como a 6,8, intera??o significativa entre concentra??o de FB1 e cepa de levedura (P<0,001). No pH 2, as cepas de levedura n?o diferiram em rela??o a quantidade de FB1 adsorvida nas concentra??es de 1x107, 5x107, 1x108 UFC.mL-1, apenas apresentaram efeito significativo para as concentra??es mais elevadas de 5x108 e 1x109 UFC.mL-1 (P<0,001). Em pH 6,8, as diferen?as ocorreram para as concentra??es de 1x108, 5x108 e 1x109 UFC.mL-1 (P<0,001), n?o apresentando efeito significativo nas concentra??es mais baixas (1x107e 5x107 UFC.mL-1). Na concentra??o mais elevada de 1x109 UFC.mL-1, a cepa 4 (SC-47) demonstrou maior capacidade para adsorver FB1, 39,4% e 37,5% em pH 2,0 e 6,8, respectivamente. Al?m disso, foram observadas respostas lineares na capacidade de adsor??o em todas as cepas avaliadas sob condi??es de pH ?cido e neutro. Os resultados demonstram que a capacidade de adsor??o de FB1 pela S. cerevisiae ? cepa-dependente e que o valor de pH pode influenciar na quantidade de FB1 removida da solu??o de acordo a cepa utilizada.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2018-08-22T11:24:50Z No. of bitstreams: 1 2010 - Vin?cius Machado dos Santos.pdf: 995846 bytes, checksum: 696b6b0e2360cb9f5762b0890f9801b2 (MD5) / Made available in DSpace on 2018-08-22T11:24:50Z (GMT). No. of bitstreams: 1 2010 - Vin?cius Machado dos Santos.pdf: 995846 bytes, checksum: 696b6b0e2360cb9f5762b0890f9801b2 (MD5) Previous issue date: 2010-09-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / A study was carried out to evaluate the use of Saccharomyces cerevisiae cell wall (SCCW) as an anti-mycotoxin additive in broiler chicks? diets slaughtered at 22 day age on performance, carcass characteristics and organ weights. It was used a randomized complete block design with four treatments in a factorial 2 (with aflatoxin, without aflatoxin) x 2 (with adsorbent, without adsorbent). For the performance parameters evaluated, there was a significant difference only on feed intake, when the SCCW was added to the rations. There was no interaction between aflatoxin and SCCW factors in the diet on the performance variables studied. The addition of SCCW to the chicks? diets stimulated the feed intake during 1-21 days of age. However, that did not reflect a significant increase in weight gain, or a change in feed conversion. There was a significant interaction between factors aflatoxin and SCCW on the weight post-fasting, cold carcass weight and thigh+upper weight. For the absolute hot carcass weights, breast, back and wings and carcass yields and relative weights of the cuts it was not observed a significant interaction between factors. The growth performance of broilers in the period 1-21 days old was not influenced by the levels of aflatoxin and SCCW factors used in experimental diets. Nevertheless for body weight after fasting, the cold carcass weight and absolute weight of the thigh + drumstick, the SCCW acted as an anti-mycotoxin additive by minimizing the aflatoxin toxicity. / Objetivou-se com este experimento avaliar a utiliza??o da parede celular de Saccharomyces cerevisiae (PCSC) como aditivo antimicotoxina em ra??es destinadas a frangos de corte abatidos aos 22 dias de idade sobre o desempenho, caracter?sticas de carca?a e pesos de ?rg?os. Foi adotado um delineamento experimental em blocos casualizados, com 4 tratamentos dispostos em um esquema fatorial 2 (sem aflatoxina; com aflatoxina) x 2 (sem adsorvente; com adsorvente). Para os par?metros de desempenho avaliados, observou-se diferen?a significativa apenas sobre o consumo alimentar, quando a PCSC foi adicionada ?s ra??es. N?o houve intera??o entre os fatores aflatoxina e PCSC nas ra??es sobre as vari?veis de desempenho estudadas. A adi??o de PCSC ? ra??o dos frangos estimulou o consumo de ra??o no per?odo de 1 a 21 dias de idade, entretanto, isso n?o se refletiu em aumento significativo no ganho de peso dos frangos ou altera??o na convers?o alimentar. Houve intera??o significativa entre os fatores aflatoxina e PCSC sobre o peso vivo p?s-jejum, carca?a resfriada e o peso da coxa+sobrecoxa. Para os pesos absolutos de carca?a quente, peito, dorso e asas, rendimento das carca?as e pesos relativos dos cortes n?o se observou intera??o significativa entre os fatores estudados. O desempenho zoot?cnico de frangos de corte no per?odo de 1 a 21 dias de idade n?o foi influenciado pelos n?veis dos fatores aflatoxina e PCSC utilizados nas ra??es experimentais. J? para peso vivo p?s-jejum, peso da carca?a resfriada e peso absoluto da coxa+sobrecoxa, houve uma poss?vel atua??o da PCSC como aditivo antimicotoxina, ao minimizar a a??o t?xica da aflatoxina.

Elevada incidência de contaminação de micotoxinas em grãos de cereais e alimentos processados tem sido relatada em todo o mundo, principalmente em produtos destinados à alimentação animal. O objetivo desse trabalho foi explorar as tecnologias para redução das concentrações de micotoxinas, que estão disponíveis ou em desenvolvimento. A tecnologia de adsorção, assim como das metodologias disponíveis para avaliação in vitro da capacidade de adsorção foram abordadas com mais ênfase. Na etapa experimental deste projeto, avaliaram-se cinco carvões ativados quanto a suas propriedades e capacidade de adsorção de micotoxinas presentes individualmente e combinadas (multi-micotoxinas) (Aflatoxina B1, Desoxinivalenol, Fumonisina B1 e Zearalenona). O carvão que apresentou maior capacidade de adsorção multi-micotoxinas foi selecionado para um estudo das interações entre adsorvente/adsorvato e possíveis fatores interferentes. Foram avaliados parâmetros físico-químicos do carvão, o efeito do tempo de contato, efeito dose, isotermas e efeito da composição do meio e da mudança do pH. A adsorção de Aflatoxina B1 e Zearalenona não sofreu efeito dos fatores estudados, diferente da adsorção de Fumonisina B1 e Desoxinivalenol. Os resultados auxiliam na análise da interação das moléculas de micotoxinas e do carvão ativado, bem como de quais fatores podem afetar o processo de adsorção de cada uma delas. Porém mais estudos são necessários para esclarecer melhor o papel de cada um dos fatores na adsorção das micotoxinas aqui estudadas. / The high incidence of mycotoxins contamination in cereal grains and processed foods have been reported worldwide, especially in products intended for animal feed. The objective of this work was to explore the available and upcoming technologies applied for the reduction of mycotoxins present in foods with a focus on adsorption, as well as in the in vitro methodology. Following, five activated carbon were evaluated about their properties and its individual and multi-mycotoxin adsorption capacity (Aflatoxin B1, Deoxynivalenol, Fuminisin B1 and Zearalenone). The activated carbon that presented the highest capacity of multi-mycotoxin adsorption was selected to continue the study in order to explore the interactions between adsorbent / adsorbate and possible interferents. Physicochemical parameters were evaluated, the effect of the contact time, concentration, isotherms and effect of the composition of the medium and the pH change. The adsorption of Aflatoxin B1 and Zearalenone had no effect of the factors studied, different from the adsorption of Fumonisin B1 and Deoxynivalenol. The results help in the analysis of the interaction of mycotoxins and activated carbon molecules, as well as which factors may affect the adsorption process of each of them. However, more studies are needed to clarify the role of each of the factors in the adsorption of these mycotoxins studied.

Abstract Hydrogen sulfide (H2S) is an environmentally hazardous, corrosive, and toxic gas, mostly generated in gas and oil industry. For small-scale natural gas processing sites (less than 10 tonne S/day), the use of regenerable iron oxide adsorbent to adsorb H2S from natural gas is still an economical and effective method. The objective of this research project was to understand the performance of an iron oxide adsorbent, recently emerging in the Canadian market, in removing H2S from gas streams. To accomplish this, the breakthrough behaviors of H2S adsorption in a fixed-bed reactor under elevated pressures were studied. The effects of variations in superficial velocity from 0.09 m/s to 0.26 m/s, operating pressure from 4 to 50 atm absolute, and the height of the fixed-bed from 11.7 cm to 24.5 cm on breakthrough curves and sulfur loading were investigated. In all the experiments, the H2S concentration profiles of the exiting gas from the reactor were measured until the bed was saturated. It was found that the shape of the breakthrough curves depend on the superficial velocity and the inlet H2S concentration in gas streams. Under both higher superficial velocity and higher inlet H2S concentration, the shape of the breakthrough curve becomes steeper. The sulfur loading of the adsorbent depends on the superficial velocity, the inlet H2S concentration in gas streams, and the bed height. The sulfur loading decreases as the superficial velocity and the inlet H2S concentration increase, but increases as the bed height increases. The change of operating pressure does not have a significant effect on the shape of the breakthrough curve or sulfur loading of the adsorbent. The investigation was also extended using the regenerated adsorbents. A mathematical formula was developed to describe the breakthrough curves.

Abstract Hydrogen sulfide (H2S) is an environmentally hazardous, corrosive, and toxic gas, mostly generated in gas and oil industry. For small-scale natural gas processing sites (less than 10 tonne S/day), the use of regenerable iron oxide adsorbent to adsorb H2S from natural gas is still an economical and effective method. The objective of this research project was to understand the performance of an iron oxide adsorbent, recently emerging in the Canadian market, in removing H2S from gas streams. To accomplish this, the breakthrough behaviors of H2S adsorption in a fixed-bed reactor under elevated pressures were studied. The effects of variations in superficial velocity from 0.09 m/s to 0.26 m/s, operating pressure from 4 to 50 atm absolute, and the height of the fixed-bed from 11.7 cm to 24.5 cm on breakthrough curves and sulfur loading were investigated. In all the experiments, the H2S concentration profiles of the exiting gas from the reactor were measured until the bed was saturated. It was found that the shape of the breakthrough curves depend on the superficial velocity and the inlet H2S concentration in gas streams. Under both higher superficial velocity and higher inlet H2S concentration, the shape of the breakthrough curve becomes steeper. The sulfur loading of the adsorbent depends on the superficial velocity, the inlet H2S concentration in gas streams, and the bed height. The sulfur loading decreases as the superficial velocity and the inlet H2S concentration increase, but increases as the bed height increases. The change of operating pressure does not have a significant effect on the shape of the breakthrough curve or sulfur loading of the adsorbent. The investigation was also extended using the regenerated adsorbents. A mathematical formula was developed to describe the breakthrough curves.

Statistic data indicates that about 100,000 tones of waste tire were generated each year. Current recycling market of waste tire is very small. Therefore, many waste tires remain untreated and cause severe health and safety problems in storage. PP fiber cut end is the waste material after cutting off the fiber. Traditional reuse way was to be the toy¡¦s fillers. If we can reuse the materials properly to develop a market of additional value, it will be a big contribution to the society. In this research, recycled waste tire powder and PP fiber cut end are used as oil adsorbents for the purpose of oil recovery during the process of oil spill emergency response. PP fiber cut end and waste tire powder are capable of adsorbing oil due to their hydrophobic surface property and the capillary forces developed during the contact with oil, therefore, makes them a perfect material for oil recovery. The major advantage of recycled PP fiber cut end is its high oil adsorbing capacity (approximately 48.4g/g). But, after reuse, its oil adsorbing speed was slow down, so does the oil adsorbing capacity. On the other hand, with good elasticity, the waste tire powder can be reused for more than 100 times without loosing its capability. However, the oil adsorbing capacity of waste tire powder is far less than PP fiber (approximately 2.84g/g). Finally, we combine PP fiber cut end and waste tire powder, to see if we can take the advantage of each product and make the best utilization of the composite material. Results indicate the composite material can be reused for more than 100 times without loosing its capability, and its performance is even better than the combination of each individual product. In the other test, we can see the composite material can not only adsorb engine oil and crude oil, but also adsorb emulsified oil. In the test, the composite material can recover up to 28 times of its own weight of oil. With the invented set up, the oil recover work is much easier to operate, and moreover, the composite material is less expensive. Only a squeeze roller and a collection container are required to recover oil. So, the composite material is indeed having practicability and mobility. Finally, the composite material is an excellent adsorbent compares with other products available on the market.

No description available.

abstract: Carbon nanomaterials have caught tremendous attention in the last few decades due to their unique physical and chemical properties. Tremendous effort has been made to develop new synthesis techniques for carbon nanomaterials and investigate their properties for different applications. In this work, carbon nanospheres (CNSs), carbon foams (CF), and single-walled carbon nanotubes (SWNTs) were studied for various applications, including water treatment, energy storage, actuators, and sensors. A facile spray pyrolysis synthesis technique was developed to synthesize individual CNSs with specific surface area (SSA) up to 1106 m2/g. The hollow CNSs showed adsorption of up to 300 mg rhodamine B dye per gram carbon, which is more than 15 times higher than that observed for conventional carbon black. They were also evaluated as adsorbents for removal of arsenate and selenate from water and displayed good binding to both species, outperforming commercial activated carbons for arsenate removal in pH > 8. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed. When used as Li-ion battery anode materials, the CNSs achieved a discharge capacity of 270 mAh/g at a current density of 372 mA/g (1C), which is 4-fold higher than that of commercial graphite anode. Carbon foams were synthesized using direct pyrolysis and had SSA up to 2340 m2/g. When used as supercapacitor electrode materials, a specific capacitance up to 280 F/g was achieved at current density of 0.1 A/g and remained as high as 207 F/g, even at a high current density of 10 A/g. A printed walking robot was made from common plastic films and coatings of SWNTs. The solid-state thermal bimorph actuators were multifunctional energy transducers powered by heat, light, or electricity. The actuators were also investigated for photo/thermal detection. Electrochemical actuators based on MnO2 were also studied for potential underwater applications. SWNTs were also used to fabricate printable electrodes for trace Cr(VI) detection, which displayed sensitivity up to 500 nA/ppb for Cr(VI). The limit of detection was shown to be as low as 5 ppb. A flow detection system based on CNT/printed electrodes was also demonstrated. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2015