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Pré-oxidação e adsorção em carvão ativado granular para remoção dos herbicidas Diuron e Hexazinona de água subterrânea; Preoxidation and adsorption in granular activated carbon for the removal of Diuron and Hexazinone from groundwater

DANTAS, Angela Di Bernardo; PASCHOALATO, Cristina Filomena Pereira Rosa; BALLEJO, Renata Rueda; DI BERNARDO, Luiz
Fonte: ABES Publicador: ABES
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
1023.4172%
O cultivo da cana-de-açúcar exige a utilização de herbicidas, destacando-se o Diuron e a Hexazinona. Alguns dos poços de abastecimento de Ribeirão Preto (SP) construídos no Aquífero Guarani estão situados em pontos de recarga, e a presença de solo de textura arenosa nessas áreas aumenta a vulnerabilidade da água subterrânea à contaminação por herbicidas. Neste trabalho foram monitorados alguns poços localizados na área de recarga e estudou-se a remoção de Diuron e Hexazinona por meio da adsorção em carvão ativado granular (CAG) e da pré-oxidação com cloro e dióxido de cloro em uma instalação piloto de escoamento contínuo. Verificou-se que o tempo de saturação do CAG no ensaio com a pré-oxidação foi inferior ao obtido no ensaio sem a pré-oxidação com ambos os oxidantes, possivelmente pela formação de subprodutos que competiram com a adsorção dos herbicidas.; The cultivation of sugarcane demands the use of herbicides such as Diuron and Hexazinone. Some supply wells from Ribeirão Preto, SP, Brazil, built in the Guarani Aquifer are located in recharge points, and the presence of sandy Quartzarenic Neosol in these areas increases the vulnerability of the groundwater to contamination from herbicides This paper reports the water quality monitored in some wells located in the recharge area and the removal of Diuron and Hexazinone by means of adsorption in granular activated carbon (GAC)...

Tratamento anaeróbio de pentaclorofenol em reator de leito fluidificado alimentado com água residuária sintética contendo glicose como fonte única de carbono; Anaerobic treatment of pentachlorophenol in a fluidized bed reactor fed with synthetic wastewater containing glucose as a single carbon source

FREIRE, Flavio Bentes; PIRES, Eduardo Cleto; FREIRE, José Teixeira
Fonte: ABES Publicador: ABES
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
817.7351%
Neste trabalho foi utilizado um reator anaeróbio de leito fluidificado (RALF), tratando água residuária sintética contendo pentaclorofenol (PCP), submetido a condições operacionais menos idealizadas. Utilizou-se um reator com volume de 16 litros, com partículas de carvão ativado granular como meio suporte. O desempenho do reator foi verificado pelas análises usuais de monitoramento (pH, alcalinidade, DQO, ácidos voláteis) e também por análises de microscopia e concentração de PCP. A presença de PCP no sistema, nas concentrações utilizadas, não alterou de maneira significativa a qualidade da biomassa presente, e nem os parâmetros de monitoramento. Em concentrações afluentes de PCP variando de 1 a 6 mg/L, foram observadas eficiências médias de remoção de 92% e 70%, respectivamente.; In the present work, an anaerobic fluidized bed reactor (AFBR) was used for the treatment of a synthetic wastewater containing pentachlorophenol (PCP) subjected to less idealized operating conditions. The reactor was a 16 litres tank with granular activated carbon particles as support media. Evaluation of AFBR performance was done by the analysis of usual monitoring parameters (pH, alkalinity, COD, volatile acids) together with microscopy and PCP concentration analysis. The presence of PCP under the concentrations used did not significantly alter the amount of biomass and the performance monitoring parameters. Removal average efficiencies of the order of 92% and 70% were obtained for PCP inflow concentrations in the range of 1 to 6mg/l.; Fapesp

Tratamento de água de reservatórios por dupla filtração, oxidação e adsorção em carvão ativado granular; Double filtration, oxidation and granular activated carbon adsorption for treating lake water

Silva, Giulliano Guimaraes; Naval, Liliana Pena; Di Bernardo, Luiz; Dantas, Angela Di Bernardo
Fonte: ASSOC BRASILEIRA ENGENHARIA SANITARIA AMBIENTAL; RIO DE JANEIRO Publicador: ASSOC BRASILEIRA ENGENHARIA SANITARIA AMBIENTAL; RIO DE JANEIRO
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
1029.911%
Este trabalho teve como objetivo avaliar o tratamento de água bruta proveniente de um reservatório de água, utilizando instalação piloto de dupla filtração (DF), composta por filtro ascendente de pedregulho (FAP) e filtro rápido descendente de areia (FRD), seguida de uma unidade de pós-tratamento com carvão ativado granular (CAG). Adicionalmente, foi verificado o efeito da pré e interoxidação (entre o FAP e o FRD) na eficiência global do tratamento e na formação de subprodutos orgânicos halogenados (SOH). Em função dos resultados obtidos, foi observado que a pré-oxidação melhorou a qualidade do efluente do FAP e a interoxidação favoreceu que resultassem valores menores de turbidez e cor no efluente do FRD. O processo de tratamento por adsorção em carvão ativado granular, utilizado como pós-tratamento, mostrou-se eficiente para assegurar a qualidade dos efluentes finais nos ensaios realizados, especialmente, em relação à remoção de matéria orgânica, cianobactérias e cor. As concentrações máximas de SOH encontrados nos efluentes do FRD e do FCAG não ultrapassaram os valores limites da Portaria nº 2.914/2011 do Ministério da Saúde.; This study evaluated the treatment of raw lake water using a double filtration (DF) pilot plant consisting of an up-flow gravel filter (UGF) in series with a down-flow sand filter (DSF) and followed by a post-treatment granular activated carbon (GAC) unit. Additionally...

Avaliação do desenvolvimento da microbiota e da remoção de COT em filtros biologicamente ativos.; Evaluation of microbial growth and total organic carbon removal in biologically active filters.

Teixeira, Fernanda Tambelli
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/04/2008 PT
Relevância na Pesquisa
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Este trabalho visa avaliar o desenvolvimento microbiano e a capacidade de degradação de carbono orgânico total (COT) em quatro colunas adsorvedoras pósfiltração, em escala de bancada, em três ensaios em batelada: o primeiro de longa duração (84 dias) com afluente de água filtrada clorada com baixa concentração de COT (1,4 mg/L); o segundo de longa duração (84 dias) com afluente de solução de glicose e água filtrada clorada com concentração de COT de 6,0 mg/L e o terceiro de curta duração (21 dias) e com o mesmo afluente utilizado no segundo teste. Foi utilizado carvão ativado granular (CAG) de mesmas características nas colunas adsorvedoras, exceto as faixas de diâmetros dos grânulos, que variaram de 0,5 a 0,71 mm (coluna 1A), de 0,84 a 1,0 mm (coluna 1B) e de 1,0 a 1,19 mm (coluna 1C) nas três colunas que tinham o diâmetro interno de 1,2 cm. A coluna 2, com diâmetro interno de 2,1 cm, recebeu CAG com grânulos na mesma faixa de diâmetros da coluna 1B (0,84 a 1,0 mm). As eficiências de remoção de COT no primeiro ensaio foram bem menores (46 a 74%) do que aquelas dos ensaios 2 (94 a 97%) e 3 (96 a 97%). Estes últimos apresentaram grande desenvolvimento da microbiota e elevadas eficiências de remoção de COT...

Remoção de compostos orgânicos causadores de gosto e odor em águas de abastecimento em sistemas pós-filtros adsorvedores de carvão ativado granular.; Removal of taste and odor producing organic substances in water supply in post-filter granular activated carbon adsorber systems.

Ferreira, Carolina Alves de Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 13/11/2009 PT
Relevância na Pesquisa
927.8901%
O objetivo desta pesquisa foi o de estudar o desempenho de pós-filtros adsorvedores de carvão ativado granular de origem mineral e de origem vegetal, com relação a, principalmente, remoção de 2-metilisoborneol e trans-1,10-dimetiltrans- 9-decalol. Os ensaios experimentais foram conduzidos na estação de tratamento de água Alto da Boa Vista, empregando-se quatro filtros piloto em acrílico com diâmetro interno de 14,2 cm e 1,5 m de profundidade de meio filtrante cada, sendo dois deles preenchidos com o carvão ativado granular Filtrasorb 300 da CALGON (filtros 1 e 3) e os outros dois, com o carvão ativado granular 119 12x25 da CARBOMAFRA (filtros 2 e 4). Os filtros operaram em paralelo, 24 h por dia, 7 dias por semana, sendo o 3 e 4 abastecidos com água filtrada da estação; e o 1 e 2, com água filtrada ozonizada. A taxa média de aplicação nos filtros durante os ensaios foi de 143 m3m2.d, o que gerou um tempo de contato no leito vazio médio de 15 min. O tempo médio total de detenção nas colunas de ozonização ficou em 21 min e a dosagem média total de ozônio aplicada na água filtrada da estação em 1,11 mgL. Os valores de 2-metilisoborneol na água filtrada da estação de tratamento foram superiores aos da água ozonizada...

Pré-oxidação e adsorção em carvão ativado granular para remoção dos herbicidas Diuron e Hexazinona de água subterrânea

Dantas, Angela di Bernardo; Paschoalato, Cristina Filomena Pereira Rosa; Ballejo, Renata Rueda; di Bernardo, Luiz
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 373-380
POR
Relevância na Pesquisa
806.9703%
The cultivation of sugarcane demands the use of herbicides such as Diuron and Hexazinone. Some supply wells from Ribeirão Preto, SP, Brazil, built in the Guarani Aquifer are located in recharge points, and the presence of sandy Quartzarenic Neosol in these areas increases the vulnerability of the groundwater to contamination from herbicides This paper reports the water quality monitored in some wells located in the recharge area and the removal of Diuron and Hexazinone by means of adsorption in granular activated carbon (GAC), preceded or not by preoxidation with chlorine and chlorine dioxide in a pilot plant. The results indicated that Diuron was more strongly adsorbed than Hexazinone and that the saturation time of the GAC in the test with preoxidation was shorter than in the test without preoxidation, which may have occurred mainly due to the formation of by-products that competed with the adsorption of the herbicides.

Removal of chromium (VI) and cadmium (II) from aqueous solution by a bacterial biofilm supported on granular activated carbon

Quintelas, C.; Tavares, M. T.
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Publicado em //2001 ENG
Relevância na Pesquisa
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A biofilm of Arthrobacter viscosus, supported on granular activated carbon, removed between 100% and 50% of Cr(VI) and between 100% and 20% of Cd(II) from solutions with initial concentrations between 4–11 mgmetal Lˉ¹ and a flow residence time of 1.2 min. For experiments of lower initial concentrations, a steady-state removal of 50% was reached after 71 bed volumes of Cr solution passed through the biosorbent bed and a steady-state removal of 30% was reached after 47 bed volumes of Cd solution passed through a similar bed. Final uptakes of 8.5 mgCr gˉ¹ carbon and 4.2 mgCd gˉ¹ carbon were determined for initial concentrations of 10 mgCr Lˉ¹ and 11 mgCd Lˉ¹, respectively. The influence on the overall process of two different surface treatments of the support was evaluated and compared with the behavior of a support not treated.; Fundação para a Ciência e Tecnologia (FCT) - PRAXIS/P/EQU/12017/1998.

Lead(II) and Iron(II) removal from aqueous solution : biosorption by a bacterial biofilm supported on granular activated carbon

Quintelas, C.; Tavares, M. T.
Fonte: A B Academic Publishers Publicador: A B Academic Publishers
Tipo: Artigo de Revista Científica
Publicado em //2002 ENG
Relevância na Pesquisa
920.3605%
A biofilm of Arthrobacter viscosus supported on granular activated carbon (GAC) removed between 100% and 50% of Pb (II) and between 100% and 30% of Fe (II) from solution with initial concentration between 8-85 mgPb 1ˉ¹ and 2.5-42 mgFe 1ˉ¹ and a flow residence time of 1.2 min. The maximum uptake capacities of the system biofilm/GAC ranged from 4.8 mgPb/gGAC to 24.2 mgPb/gGAC and 1.8 mgFe/gGAC to 18.4 mgFe/gGAC. The behaviour of granular activated carbon with two different surface treatments (treated with HNO3 or H2O2) was studied and best results were achieved with the support treated with HNO3. The polysaccharide and polymeric net was also studied, and it was concluded that the production of polysaccharides and polymers was much higher in the GAC-HNO3.; Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS/P/EQU/12017/1998.

Competitive biosorption of ortho-cresol, phenol, chlorophenol and chromium(VI) from aqueous solution by a bacterial biofilm supported on granular activated carbon

Quintelas, C.; Sousa, E.; Silva, F.; Neto, S.; Tavares, M. T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /09/2006 ENG
Relevância na Pesquisa
909.1412%
A biofilm of Arthrobacter viscosus supported on granular activated carbon was used to remove chromium and organic compounds (chlorophenol, phenol and o-cresol) from aqueous solutions. The compounds were studied as single solutes and in different combinations between them and Cr(VI). Optimum Cr(VI) adsorption was observed at a phenol concentration of 100 mg/l and at an initial concentration of the metal of 60 mg/l. The maximum values of biosorption of organic compounds were 9.94 mg/g for phenol, 9.70 mg/g for chlorophenol and 13.99 mg/g for o-cresol. In terms of removal percentage, after 15 h of experiment, the affinity order was as follows: phenol > chlorophenol > o-cresol > chromium(VI).; Fundação para a Ciência e Tecnologia (FCT)

Biosorption of Cr(VI) by a Bacillus coagulans biofilm supported on granular activated carbon (GAC)

Quintelas, C.; Fernandes, Bruno Daniel; Castro, J.; Figueiredo, Hugo; Tavares, M. T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /03/2008 ENG
Relevância na Pesquisa
909.1412%
The ability of a biofilm of Bacillus coagulans supported on granular activated carbon (GAC) to biosorb Cr(VI) was investigated in batch and column studies so it may be applied to low metal concentration wastewater treatment. The quantification of polysaccharides and polymeric net revealed a value of 9.19 mg/gbiosorbent for the polysaccharides and 75 mg/gbiosorbent, for the polymeric net. The results obtained with open systems showed uptake values of 1.50, 1.98 and 5.34 mg/gbiosorbent, respectively, for initial concentrations of 10, 50 and 100 mg/L of Cr(VI). Column studies performed with an industrial effluent showed values of Cr uptake of 0.090 mg/gbiosorbent, for an initial concentration of 4.2 mg/L. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion, was confirmed by FTIR. The equilibrium studies in batch systems were described by Freundlich, Langmuir, Reddlich–Peterson, Dubinin–Radushkevich, Sips and Toth model isotherms. Best fit was obtained with Toth model isotherm. Data from column studies were described by Adams–Bohart and Wolborska models. These models were found suitable for describing the dynamic behaviour of the columns with respect to the inlet chromium concentration. The whole study showed that the biofilm tested is very promising for the removal of Cr(VI) in industrial wastewater.; Fundação para a Ciência e a Tecnologia (FCT) - POCTI/QUI/44840/2002.; FEDER.

Biosorption of Cr(VI) by three different bacterial species supported on granular activated carbon : a comparative study

Quintelas, C.; Fernandes, Bruno Daniel; Castro, J.; Figueiredo, Hugo; Tavares, M. T.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica
Publicado em /05/2008 ENG
Relevância na Pesquisa
909.1412%
The ability of three different bacterial species supported on granular activated carbon (GAC) to remove hexavalent chromium from low concentration liquid solutions was investigated, in batch and column studies. The microorganisms tested were Cr(VI) reducing types: Streptococcus equisimilis (CECT 926), Bacillus coagulans (CECT 12) and Escherichia coli (CECT 515). The results showed metal uptake values of 5.82, 5.35 and 4.12 mg/gbios., respectively, for S. equisimilis, B. coagulans and E. coli, for an initial metal concentration of 100 mg/l. In the same order and for the initial concentration of 50 mg/l, metal uptake values were 2.33, 1.98 and 3.60 mg/gbios.. Finally, for the initial metal concentration of 10 mg/l, those values were, respectively, 0.66, 1.51 and 1.12 mg/gbios.. Studies made with an industrial effluent, with the aim of testing these biofilms in a real situation, showed values of Cr uptake of 0.083, 0.090 and 0.110 mg/gbios., respectively, for S. equisimilis, B. coagulans and E. coli, for an initial concentration of 4.2 mg/l of total Cr. The quantification of polysaccharides, playing a key role in the whole process, was made and it was concluded that the production of polysaccharides is higher for B. coagulans followed by S. equisimilis and E. coli (9.19...

Biosorption of Cr (VI) using a bacterial biofilm supported on granular activated carbon and on zeolite

Lameiras, Sandra Raquel de Vasconcelos; Quintelas, C.; Tavares, M. T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /03/2008 ENG
Relevância na Pesquisa
909.1412%
Two mini-columns partially filled with granular activated carbon (GAC) and/or a natural zeolite, covered by a bacterial biofilm of Arthrobacter viscosus, were used in a continuous flow system to remove Cr (VI) from solutions with initial concentration of 70 mg/l and a working pH ranging between 4.5 and 5.5. Three different set-up’s were used: two columns in series filled GAC covered with a biofilm, two columns in series filled with zeolite covered with a biofilm and a column filled with GAC followed by another column filled with zeolite, both supports covered with biofilm. Comparatively, the biosorption system supported on GAC reaches similar removal values, 19%, as the one supported on the zeolite, 18%, but when these two beds are used in combination better performances are reached, i.e. 42% removal. The maximum uptake values ranged from 0.57 mgCr/gSupport to 3.58 mgCr/gSupport. The interactions between metal ions and functional groups on the cell wall surface of the biomass were confirmed by FTIR. GAC was regenerated with steam draughting and reused twice. The first regeneration caused a decrease in the removal capacity of 38% and the second regeneration caused a total decrease in the removal capacity of 76%.; Fundação para a Ciência e a Tecnologia (FCT); Ministério da Ciência e Tecnologia; FEDER; La Habana University

Effects of coconut granular activated carbon pretreatment on membrane filtration in a gravitational driven process to improve drinking water quality

Silva, Flávia Vieira da; Yamaguchi, Natália Ueda; Lovato, Gilselaine Afonso; Silva, Fernando Alves da; Reis, Miria Hespanhol Miranda; Amorim, M. T. Pessoa de; Tavares, Célia Regina Granhen; Bergamasco, Rosangêla
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
Relevância na Pesquisa
909.1412%
This study evaluates the performance of a polymeric microfiltration membrane, as well as its combination with a coconut granular activated carbon (GAC) pretreatment, in a gravitational filtration module, to improve the quality of water destined to human consumption. The proposed membrane and adsorbent were thoroughly characterized using instrumental techniques, such as contact angle, Brunauer–Emmett–Teller) and Fourier transform infrared spectroscopy analyses. The applied processes (membrane and GAC + membrane) were evaluated regarding permeate flux, fouling percentage, pH and removal of Escherichia coli, colour, turbidity and free chlorine. The obtained results for filtrations with and without GAC pretreatment were similar in terms of water quality. GAC pretreatment ensured higher chlorine removals, as well as higher initial permeate fluxes. This system, applying GAC as a pretreatment and a gravitational driven membrane filtration, could be considered as an alternative point-of-use treatment for water destined for human consumption.; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)

Adsorption of fluorobenzene onto granular activated carbon: Isotherm and bioavailability studies

Carvalho, M.F.; Duque, A.F.; Gonçalves, I.C.; Castro, P.M.L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2007 ENG
Relevância na Pesquisa
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The adsorption of a recalcitran fluoroaromatic compound, fluorobenzene (FB), onto granular activated carbon (GAC) was evaluated. The respective isotherm was obtained and the Langmuir, Freundlich and Redlich–Peterson models were fitted to the experimental data, with the Redlich–Peterson model giving the best fitting. Freundlich model also provided a good fit but the Langmuir model could not adequately fit the experimental data, especially at high FB concentrations. Maximal adsorption capacity of FB onto GAC was foundto be 388 mg of FB per gram of GAC. The reversibility of the adsorption of FB onto GAC was investigated, both in the absence and presence of microorganisms. Abiotic desorption of FB occurred to a small extent (between 3% and 22%, for amounts of FB initially adsorbed to the GAC between 37 and 388 mg g 1), and bioregeneration of GAC was shown to occur when the matrix was exposed to a FB degrading culture, with 58–80% of the adsorbed FB being biodegraded. A residual amount of FB showed not to be bioavailable, suggesting that part of the adsorbed FB may be irreversibly bound. The fraction of the non-bioavailable FB increased at higher amounts of adsorbed FB, from 19% to 33%. The results indicate that the GAC employed in this study has a good capacity to adsorb FB and that bioregeneration of this matrix is a feasible process.

Production and characterization of granular activated carbon from activated sludge

Al-Qodah,Z.; Shawabkah,R.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2009 EN
Relevância na Pesquisa
815.042%
In this study, activated sludge was used as a precursor to prepare activated carbon using sulfuric acid as a chemical activation agent. The effect of preparation conditions on the produced activated carbon characteristics as an adsorbent was investigated. The results indicate that the produced activated carbon has a highly porous structure and a specific surface area of 580 m²/g. The FT-IR analysis depicts the presence of a variety of functional groups which explain its improved adsorption behavior against pesticides. The XRD analysis reveals that the produced activated carbon has low content of inorganic constituents compared with the precursor. The adsorption isotherm data were fitted to three adsorption isotherm models and found to closely fit the BET model with R² equal 0.948 at pH 3, indicating a multilayer of pesticide adsorption. The maximum loading capacity of the produced activated carbon was 110 mg pesticides/g adsorbent and was obtained at this pH value. This maximum loading was found experimentally to steeply decrease as the solution pH increases. The obtained results show that activated sludge is a promising low cost precursor for the production of activated carbon.

Discriminating and assessing adsorption and biodegradation removal mechanisms during granular activated carbon filtration of microcystin toxins

Wang, H.; Ho, L.; Lewis, D.; Brookes, J.; Newcombe, G.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
1015.25945%
Microcystins are cyanobacterial toxins that are problematic for water authorities due to their resistance to conventional water treatment. Granular activated carbon (GAC) filtration has been shown to be effective in removing microcystin from water using both adsorption and biodegradation removal mechanisms; however, little is known regarding which removal mechanism predominates and to what extent. In this study, microcystin removal due to adsorption and biodegradation in GAC filtration were discriminated and assessed by commissioning three parallel laboratory columns, including a sterile GAC column, a conventional GAC column and a sand column. The results demonstrate that biodegradation is an efficient removal mechanism once it commences and that the rate of biodegradation was dependent upon temperature and initial bacterial concentration. Adsorption of microcystins was prevalent during the initial stages of the GAC columns and was modelled using the homogeneous surface diffusion model (HSDM). The HSDM provided evidence that an active biofilm present on the surface of the conventional GAC hindered adsorption of microcystin compared with the sterile GAC with no active biofilm. Up to 70% removal of microcystin-LR was still observed after 6 months of operation of the sterile GAC column...

Effective transport properties for the pyridine-granular activated carbon adsorption system

Baz-Rodríguez,S. A.; Ocampo-Pérez,R.; Ruelas-Leyva,J. P.; Aguilar-Madera,C. G.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2012 EN
Relevância na Pesquisa
1015.25945%
In this work, the kinetics of pyridine adsorption onto granular activated carbon was studied from the point of view of an up-scaling process by using the method of volume averaging. The pore and surface effective diffusivities were estimated by supposing simple microscale geometries (ordered media of cylinders and spheres) and those of images processed from SEM (Scanning Electron Microscopy) micrographs. In addition, as a rough estimate, the point surface diffusivity is reported. The results revealed that the up-scaled diffusional model satisfactorily interpreted the concentration decay curves and the effective diffusivity was found to be an increasing function of the concentration, mainly due to the contribution of surface diffusion. In general, the diffusivity coefficients involved in the adsorption system are related through the expression molecular diffusivity = 22 ï‚' point surface diffusivity = 5/2 x‚' pore effective diffusivity = 1/12 x ‚' surface effective diffusivity.

Recovery of gold from solutions with ammonia and thiosulfate using activated carbon; Recuperación de oro a partir de disoluciones de amoniaco y tiosulfato utilizando carbón activado

Vargas, C.; Navarro Donoso, Patricio; Araya, Eyleen; Pávez, F.; Alguacil, Francisco José
Fonte: Consejo Superior de Investigaciones Científicas (España) Publicador: Consejo Superior de Investigaciones Científicas (España)
Tipo: Artículo
SPA
Relevância na Pesquisa
801.93375%
The recovery of gold from solutions containing thiosulfate and ammonia using granular activated carbon was studied, evaluating the adsorption and elution stages. The influence of ammonia and thiosulfate concentration and the presence of impurities such as copper and zinc were also evaluated. In the presence of ammonia there was a concentration which maximized the adsorption of gold, while thiosulfate and impurities presence was harmful for the adsorption of gold. During elution, ammonia and thiosulfate concentration, pH regulator and temperature were evaluated. Ammonia favored the process as long as thiosulfate showed a maximum starting from which the elution diminishes. The effect of the pH regulator was very important; If was revealed that when the pH was regulated with caustic ammonia, a synergic effect appeared which favored the elution. Temperature favored the elution process, with activation energy of 9.13 kJ/mol.; Se estudió la recuperación de oro de disoluciones de tiosulfato y amoniaco, utilizando carbón activado en gránulos, evaluando las etapas de adsorción y desorción. En la etapa de adsorción se evaluaron la concentración de amoniaco, de tiosulfato y de impurezas como cobre y cinc. En las condiciones experimentales ensayadas se encontró que...

Removal of copper(II) ion from aqueous solution by high-porosity activated carbon

Milenković,Dragan D; Milosavljević,Milutin M; Marinković,Aleksandar D; Ðokić,Veljko R; Mitrović,Jelena Z; Bojić,Aleksandar Lj
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
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The removal of copper(II) ion from aqueous solution by the granular activated carbon, obtained from hazelnut shells (ACHS) (Corylus avellana L. var. lunga istriana), was investigated. The ACHS was prepared from ground dried hazelnut shells by specific method carbonisation and water steam activation at 950ºC for 2 h. The granular activated carbon produced from hazelnut shells has a high specific surface area (1 452 m²·g-1) and highly developed microporous structure (micropore volume: 0.615 cm³·g-1). In batch tests, the influences of solution pH, contact time, initial metal ion concentration and temperature on the sorption of copper(II) ion on ACHS were studied. The results indicate that sorption of copper(II) ion on ACHS strongly depends on pH values. The adsorption data can be well described by the Langmuir isotherm and Redlich-Peterson model. The monolayer adsorption capacity of the ACHS-copper(II) ion, calculated from the Langmuir isotherms, is 3.07 mmol·g-1. The time-dependent adsorption of copper(II) ion could be described by the pseudo second-order and Elovich kinetics, indicating that the rate-limiting step might be a chemical reaction. The intra-particle diffusion model indicates that adsorption of copper(II) ions on ACHS was diffusion controlled.

Treatability of South African surface waters by activated carbon

Lobanga,KP; Haarhoff,J; van Staden,SJ
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/30/2013 EN
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Natural organic matter (NOM) in water resources for drinking purposes can be removed by different methods, including activated carbon adsorption. Due to the variability of NOM in natural waters, both in terms of its nature and its concentration, a study was undertaken to investigate NOM removal for a wide range of South African surface waters, sampled at different periods, by the use of granular activated carbon (GAC). NOM removal was assessed by measuring the ultraviolet (UV) absorbance at 3 wavelengths, namely, 254 nm (UV254), 272 nm (UV272) and 300 nm (UV300). A comparison of data between the three wavelengths showed that any of the three wavelengths can be used to assess NOM removal by GAC, which is well described by the Freundlich equilibrium equation. A treatment target of 40% removal of initial UV254 absorbance was considered. It was observed that, although the GAC dosage was generally a function of the initial UV254 absorbance, differences existed between waters. This suggests that GAC usage rate is not only a function of the initial UV absorbance but also of the NOM composition, indicating a need for improved NOM characterisation. Comparison between the UV absorbance and dissolved organic carbon (DOC) data suggested that for some waters UV254 absorbance can be used as a rapid substitute for DOC. Finally...