Heterogeneous photocatalytic degradation of reactive dyes in aqueous TiO(2) suspensions: Decolorization kinetics

This work assesses the photocatalytic (TiO(2)/UV) degradation of a simulated reactive dye bath (Black 5, Red 239, Yellow 17, and auxiliary chemicals). Color removal was monitored by spectrophotometry. Mineralization was determined by DOC analyses. Photocatalytic, photolytic, and adsorption experiments were performed, showing that adsorption was negligible. After 30 min of irradiation, it was achieved 97% and 40% of color removal with photocatalysis and photolysis, respectively. No mineralization occurred within 30 min. A kinetic model composed of two, first-order in-series reactions was used. The first photocatalytic decolorization rate constant was k(1) = 2.6 min(-1) and the second k(2) = 0.011 min(-1). The fast decolorization of Reactive Black 5 dye is an indication that the number of azo and vinylsulfone groups in the dye molecule maybe a determining factor for the increased photolytic and photocatalytic color removal and degradation rates. (C) 2008 Elsevier B.V. All rights reserved.

Avaliação da hidrólise alcalina da quitina e elaboração de filmes de quitosana para aplicação na adsorção do corante têxtil reativo preto 5

Nesta pesquisa, diferentes amostras de quitosana foram produzidas por diferentes condições de hidrólise alcalina da quitina. A partir das amostras de quitosana foram produzidos filmes,sendo estes aplicados na adsorção do corante têxtil reativo preto 5 e os resultados foram comparados com os dos seus respectivos pós. Os valores das massas molares da quitosana aumentaram em função do aumento do diâmetro da quitina e diminuíram com o aumento da relação de solução NaOH:quitina, da concentração de NaOH e tempo de reação, e ficaram na faixa de 100 a 200 kDa. Um comportamento inverso foi observado para o grau de desacetilação da quitosana, e seus valores variaram de 65 a 95%. Quanto aos filmes biopoliméricos elaborados, os que apresentaram melhores valores quanto as suas propriedades mecânicas e de permeabilidade ao vapor de água foram os filmes produzidos com quitosana de mais elevada massa molar e menor grau de desacetilação. A fim de avaliar o comportamento dos filmes em processos de adsorção, estes foram aplicados na remoção do corante reativo preto 5 (RB5) em diferentes condições de pH (4, 6 e 8). Após, foram escolhidos quatro filmes de quitosana (FQ), com diferentes graus de desacetilação e massas molares, que foram comparados com as quitosanas na forma de pó (PQ) no estudo de adsorção. Este foi realizado sob diversas condições experimentais (pH, temperatura e taxa de agitação) através das isotermas de equilíbrio, da termodinâmica e da cinética. Análises de interação e ciclos de adsorção-dessorção também foram realizados. Verificou-se que PQ e FQ com grau de desacetilação de 95% e massa molar de 100 kDa foram os adsorvente mais adequados, apresentando mais de 99% de remoção do corante RB5 em pH 4,0. Para ambos, PQ e FQ, o modelo de Langmuir foi o mais adequado para representar os dados de equilíbrio. As capacidades máximas de adsorção foram 654,3 e 589,5 mg g-1 para PQ e FQ, respectivamente, obtidos a 298 K. O processo de adsorção foi espontâneo, favorável e exotérmico. A adsorção de RB5 para PQ e FQ seguiu o modelo cinético de Elovich,e ocorreram interações eletrostáticas do PQ-RB5 e do FQ-RB5. Os filmes de quitosana foram reutilizados três vezes, enquanto que a quitosana em pó não pode ser reutilizada.

Aquatic Toxicity Of Dyes Before And After Photo-fenton Treatment.

This study evaluated the ecotoxicity of five dyes to freshwater organisms before and during their photo-Fenton degradation. EC50 (48h) of the five tested dyes ranged from of 6.9 to >1000mgL(-1) for Daphnia similis. In the chronic tests IC50 (72h) varied from 65 to >100mgL(-1) for Pseudokirchneriella subcapitata and IC50 (8 days) from 0.5 to 410mgL(-1) for Ceriodaphnia dubia. Toxicity tests revealed that although the applied treatment was effective for decolorization of the dye, the partial mineralization may be responsible for the presence of degradation products which can be either more toxic than the original dye, as is the case of Vat Green 3 and Reactive Black 5, lead to initially toxic products which may be further degraded to non toxic products (acid Orange 7 and Food Red 17), or generate non toxic products as in the case of Food Yellow 3. The results highlighted the importance of assessing both acute and chronic toxicity tests of treated sample before effluent discharge.

Degradação de corantes reativos pelo sistema ferro metálico/peróxido de hidrogênio

In this work the degradation of aqueous solutions of reactive azo-dyes is reported using a combined reductive/advanced oxidative process based in the H2O2/zero-valent iron system. At optimized experimental conditions (pH 7, H2O2 100 mg L-1, iron 7 g L-1) and using a continuous system containing commercial iron wool, the process afforded almost total discolorization of aqueous solutions of three reactive azo-dyes (reactive orange 16, reactive black 5 and brilliant yellow 3G-P) at a hydraulic retention time of 2.5 min. At these conditions the hydrogen peroxide is almost totally consumed while the released total soluble iron reaches a concentration compatible with the current Brazilian legislation (15 mg L-1).

Descoloração redutiva de corantes azo e o efeito de mediadores redox na presença do aceptor de elétrons sulfato

We investigated the impact of sulphate and the redox mediator Anthraquinone-2,6-disulfonate (AQDS) on the decolorization of the azo dyes Congo Red (CR) and Reactive Black 5 (RB5). In anaerobic reactors free of extra sulphate dosage, the color removal efficiency decreased drastically when the external electron donor ethanol was removed. In presence of an extra dosage of sulphate, CR decolourisations were 47.8% (free of AQDS) and 96.5% (supplemented with AQDS). The decolourisations achieved in both reactors with RB5 were lower than the ones found with CR. Finally, the biogenic sulphide contribution on azo dye reduction was negligiable.

Sintese e aplicação de filmes biocomponentes nanoestruturados de 'TI'/'TI''O IND.2'/'W''O IND.3' por template e 'SI'/'TI''O IND.2'/'PT' por heterojunção em conversão de energia solar e remediação ambiental

Pós-graduação em Química - IQ

Photoelectrochemical Hydrogen Generation and Concomitant Organic Dye Oxidation under TiO2 Nanotube

The present work describes the photoelectrochemical hydrogen generation during a photodegradation of an organic compound. For this, it was chosen the reactive black 5 dye as a model of organic pollutant and its oxidation under TiO2 nanotube in a two compartment cell. The photoelectrocatalysis is conducted in 0.1 mol L-1 Na2SO4 pH 6 medium under photoanode biased at +1.0 V (SCE) and activated by UV and visible light using 150W Xe-Arc lamp (Oriel) and 125 W Hg lamp (Osram). The concomitant hydrogen production was monitored at cathodic compartment using a Pt cathode. Using optimized condition of Na2SO4 0.1 mol L-1 pH 6 as supporting electrolyte, applied potential of +1.0V it was verified 100% of discoloration and 72% of TOC removal of 1.0 x 10(-5) mol L-1 Reactive Black 5 dye after 120 min of treatment (rate constant of 10.6 x10(-2) min(-1)). The concomitant hydrogen generation was 44% in this condition.

Aquatic toxicity of dyes before and after photo-Fenton treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Melhoria do processo de tingimento numa empresa têxtil

Dissertação de mestrado em Engenharia e Gestão da Qualidade

Application of carbon composite adsorbents prepared from coffee waste and clay for the removal of reactive dyes from aqueous solutions

A novel carbon composite was prepared from a mixture of coffee waste and clay with inorganic:organic ratio of 1.3 (CC-1.3). The mixture was pyrolysed at 700 °C. Considering the application of this adsorbent for removal of anionic dyes, the CC-1.3 was treated with a 6 mol L^-1 HCl for 24 h to obtain ACC-1.3. Fourier transform infrared (FTIR), N₂ adsorption/desorption curves, scanning electron microscope (SEM) and powder X-ray diffractometry (XRD) were used for characterisation of CC-1.3 and ACC-1.3 carbon adsorbents. The adsorbents were effectively utilised for removal of reactive blue 19 (RB-19) and reactive violet 5 (RV-5) textile dyes from aqueous solutions. The maximum amounts of RB-19 dye adsorbed at 25 °C are 63.59 (CC-1.3) and 110.6 mg g^-1 (ACC-1.3), and 54.34 (CC-1.3) and 94.32 mg g^-1 (ACC-1.3) for RV-5 dye. Four simulated dye-house effluents were used to test the application of the adsorbents for treatment of effluents.

Síntese de derivados de adenina e guanina

Tese de Doutoramento em Ciências (Especialidade em Química)

Influence of inflammation on total energy expenditure in hemodialysis patients.

Background and Objectives: Studies show that inflammation can contribute to an increase in resting energy expenditure in patients with chronic kidney disease; however, findings about total energy expenditure (TEE) have not been reported. The aim of this study was to evaluate the effects of inflammation on TEE and physical activity energy expenditure in hemodialysis (HD) patients.Design: This was a cross-sectional study.Setting: This study was conducted from Hopital Edouard Herriot, Lyon, France.Patients: This study included 24 HD patients and 18 healthy subjects.Main Outcome Measure: TEE and step counts were measured over a 7-day period by the SenseWear Pro2 Armband in 24 HD patients (15 patients with C-reactive protein,5 mg/L, aged 67.0 +/- 6 14.7 years, and 9 with C-reactive protein >5 mg/L, aged 69.0 +/- 6 18.0 years) and compared with 18 healthy subjects (62.3 +/- 6 15.3 years).Results: Mean estimated TEE measured with SenseWear Pro2 Armband was significantly lower (25.5 +/- 4.1 kcal/kg/day) in patients with inflammation when compared with those without inflammation (32.0 +/- 6.7 kcal/kg/day) and with healthy subjects (31.8 +/- 6 7.0 kcal/kg/day) (P = .012). There was a difference in the physical activity (step counts) between patient groups (P < .05). Healthy subjects and patients without inflammation walked more (8,107 +/- 5,419 and 6,016 +/- 3,752 steps/day, respectively) as compared with patients with inflammation (2,801 +/- 2,754 steps/day, P = .001).Conclusion: Our findings suggest that patients with inflammation have a lower TEE when compared with healthy subjects and patients without inflammation. TEE is influenced by physical activity because patients with inflammation appear to be less active. (C) 2011 by the National Kidney Foundation, Inc. All rights reserved.

Detection of Hepatitis B Virus Antigens in Paraffin-embedded Liver Specimens from the Amazon Region, Brazil

Hepatic viscerotomy of paraffin-preserved old specimens, collected in the period from 1934 to 1967, were analyzed by immunohistochemical assays to detect hepatitis B, hepatitis D, dengue and yellow fever virus antigens. The material belongs to the Yellow Fever Collection, Department of Pathology, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil and the cases were diagnosed at that time according to clinical aspects and histopathological findings reporting viral hepatitis, yellow fever, focal necrosis and hepatic atrophy. From the 79 specimens, 69 were collected at the Labrea Region and the other 10 in different other localities in the Amazon Region. The five micra thick histological slices were analyzed for the presence of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) by immunoperoxidase technique. An immunofluorescence assay was applied to the detection of hepatitis D, yellow fever and dengue virus antigens. Nine (11.4%) histological samples were HBsAg reactive and 5 (6.3%) were HBcAg reactive. The oldest reactive sample was from 1934. Viral antigens related to the other pathologies were not detected in this study. Our results confirm that the methodology described may be used to elucidate the aetiology of hepatitis diseases even after a long time of conservation of the specimens.

Effect of age at disease onset in the clinical profile of spondyloarthritis: a study of 1424 Brazilian patients

Objectives To analyse demographic and clinical variables in patients with disease onset before and after 40, 45 and 50 years in a large series of Brazilian SpA patients. Methods A common protocol of investigation was prospectively applied to 1424 SpA patients in 29 centres distributed through the main geographical regions in Brazil. The mean age at disease onset was 28.56 +/- 12.34 years, with 259 patients (18.2%) referring disease onset after 40 years, 15.1 (10.6%) after 45 years and 81 (5.8%) after 50 years. Clinical and demographic variables and disease indices (BASDAI, BASFI, BASRI, MASES, ASQoL) were investigated. Ankylosing spondylitis was the most frequent disease (66.3%), followed by psoriatic arthritis (18%), undifferentiated SpA (6.7%), reactive arthritis (5.5%), and enteropathic arthritis (3.5%). Results Comparing the groups according to age of disease onset, those patients with later onset presented statistical association with female gender, peripheral arthritis, dactylitis, nail involvement and psoriasis, as well as negative statistical association with inflammatory low hack pain, alternating buttock pain, radiographic sacroiliitis, hip involvement, positive familial history, HLA-B27 and uveitis. BASDAI, BASFI and quality of life, as well as physicians and patient's global assessment, were similar in all the groups. Radiographic indices showed worse results in the younger age groups. Conclusion There are two different clinical patterns in SpA defined by age at disease onset: one with predominance of axial symptoms in the group with disease onset <= 40 years and another favouring the peripheral manifestations in those with later disease onset.

Post-surgical follow-up (by ELISA and immunoblotting) of cured versus non-cured cystic echinococcosis in young patients

The study was designed to determine comparatively the prognostic value of immunoblotting and ELISA in the serological follow-up of young cystic echinococcosis (CE) patients exhibiting either a cured or a progredient (non-cured) course of disease after treatment. A total of 54 patients (mean age 9 years, range from 3 to 15 years) with surgically, radiologically and/or histologically proven CE were studied for a period up to 60 months after surgery. Additionally, some of the patients underwent chemotherapy. Based on the clinical course and outcome, as well as on imaging findings, patients were clustered into 2 groups of either cured (CCE), or non-cured (NCCE) CE patients. ELISA showed a high rate of seropositivity 4 to 5 years post-surgery for both CCE (57.1%) and NCCE (100%) patients, the difference found between the two groups was statistically not significant. Immunoblotting based upon recognition of AgB subcomponents (8 and 16 kDa bands) showed a decrease of respective antibody reactivities after 4 years post-surgery. Only sera from 14.3% of CCE patients recognized the subcomponents of AgB after 4 years, while none (0%) of these sera was still reactive at 5 years post-surgery. At variance, immunoblotting remained positive for AgB subcomponents in 100% of the NCCE cases as tested between 4 and 5 years after surgical treatment. Immunoblotting therefore proved to be a useful approach for monitoring post-surgical follow-ups of human CCE and NCCE in young patients when based upon the recognition of AgB subcomponents.