A B S T R A C TThe use of alternative materials for environmental decontamination has been intensively studied. In this study, the capacity of banana peels treated with sodium hydroxide (NaOH), hydrochloric acid (HCl), and phosphoric acid (H 3 PO 4 ) to adsorb Pb (II) was evaluated. The physical and chemical changes on the banana peels after chemical treatment were evaluated by infrared spectroscopy and scanning electron microscopy. Batch adsorption experiments were carried out as a function of pH, time, metal concentration, and temperature; desorption tests were also performed. Pb (II) concentrations were determined by flame atomic absorption spectrometry. An increase in the adsorption capacity of the modified and natural peels was observed in the pH range of 3-5, and pH 5 was adopted for further experiments. The adsorption system reached equilibrium in 300 min, and its kinetics followed the pseudo-second-order equation. From adsorption isotherms, it was observed considerable enhance on adsorption capacity of banana peels, especially with treated with NaOH. Besides, the negative Gibbs free energy variation values showed that the Pb (II) adsorption was spontaneous. Moreover, the improvement in the Pb (II) desorption for the modified peels was observed, indicating that the proposed material can be reutilized.

Os rejeitos contendo metais pesados, originados de atividades industriais e mineradoras, podem ocasionar danos ao meio ambiente e à saúde humana. Mesmo o cromo, considerado um metal essencial, quando encontrado em altas concentrações, pode ser prejudicial, razão pela qual, o objetivo deste trabalho foi investigar a eficiência de tratamentos químicos em casca, bagaço e casca com bagaço de laranja, com o intuito de tratar efluentes aquosos contaminados por cromo (III). A modificação referese a alteração da estrutura química dos resíduos de laranja com hidróxido de sódio e ácido cítrico. Foram realizados ensaios em sistemas de batelada contendo cromo, sendo que as concentrações foram determinadas através da utilização de um espectrofotômetro de absorção atômica com chama. Analisouse a adsorção em função do pH, tempo de contato, concentração do metal, capacidade de dessorção e fatores termodinâmicos. As modificações foram constatadas no infravermelho pelo surgimento de um pico em 1730 cm-1 , o qual se refere aos grupos carboxilatos. O tempo necessário para o sistema de adsorção atingir o equilíbrio foi de cerca de 500 minutos e a cinética segue um comportamento descrito pela equação de pseudo-segunda ordem. Avaliou-se a adsorção em relação aos modelos de Langmuir e Freundlich, sendo o modelo de Freundlich o que se aplicou melhor ao processo. O valor da capacidade máxima de adsorção foi de 75,64 mg.g-1 para a casca modificada com NaOH. Além de aumentar as propriedades adsorventes, o sistema tornou-se mais espontâneo energeticamente após o tratamento químico, verificado pelos baixos valores da energia de Gibbs. Palavras-chave: Adsorção. Cromo. Resíduos de laranja. Modificação química.

Early and delayed treatment with low-dose ASA can reduce the morphofunctional damage of colonic myenteric neurons caused by murine T. cruzi infection.

The consequences of using aspirin (ASA) for the pathogenesis of Chagas disease are unclear. This study evaluated the effects of treatment of Chagas disease with ASA on the esophageal nitrergic myenteric neuron population and esophageal wall in mice. We observed that treatment of chagasic infection with ASA protects the esophageal myenteric neurons from the atrophy caused by the Trypanosoma cruzi infection. The mice were infected with 1300 trypomastigotes of Y strain T. cruzi intraperitoneally. Part of infected mice was treated with ASA from fifth to twelfth day after inoculation. Our data support the hypothesis that eicosanoids given during the acute phase of the chagasic infection may act as immunomodulators aiding the transition to and maintenance of the chronic phase of the disease. Besides, ASA treatment did not provoke alterations in the esophageal wall and the myenteric neurons in infected mice.

Patients with Chagas' disease may develop dysfunctions of oesophageal and colonic motility resulting from the degeneration or loss of the myenteric neurons of the enteric nervous system. Studies have shown that the use of aspirin, also known as acetylsalicylic acid (ASA), influences the pathogenesis of the disease. However, this remains controversial. The aim of this study was to evaluate the consequences of treatment with low doses of aspirin during the chronic phase of Chagas' disease on oesophageal function. Twenty male Swiss mice, 60 days of age, were used. The animals were infected with Y strain of Trypanosoma cruzi, injected intraperitoneally. Aspirin was given at a dose of 50 mg/kg to some of the infected animals, from the 55th to 63rd day after inoculation on consecutive days, and from the 65th to 75th day on alternate days. We investigated food passage of time, wall structure and nitrergic neuronal population of the distal oesophagus. Our data revealed that the use of low doses of aspirin in chronic Chagas' disease caused an increase in the number of nitrergic neurons and partially prevented hypertrophy of the oesophagus. In addition, the aspirin administration impeded Chagas' diseases associated changes in intestinal transit time. Thus treatment with aspirin in the chronic phase of Chagas' disease changes the natural history of the disease and raises the possibility of using it as a new therapeutic approach to the treatment of this aspect of Chagas' disease pathology.