Chemistry and Environment

Textile industries produce effluents rich in dyes throughout its production chain. In this study, kinetic experiments were carried using the dead and treated biomass of Aspergillus niger for indigo carmine removal from the synthetic aqueous solutions of this dye. A kinetic run with activated carbon was also carried for comparison. The obtained results suggest that non-treated fungal biomass has been capable of remove 95% of carmine indigo from the aqueous solutions. This removal was similar to that obtained with activated carbon. The results also indicate that acid treatments considerably improve the kinetic of the dye removal, but they are not influenced the maximum adsorptive capacity of the adsorbent. Moreover, saline and alkaline treatments decreased both the maximum capacity and the kinetic of adsorption.

In the present work, advanced oxidation processes, Fe2+/H2O2 and UV/H2O2, and direct photolysis (UV light) have been applied in the decolorization of two synthetic wastewater containing indigo and azo dyes and laundry effluent. Individual aqueous solutions containing 20 mg/L indigo carmine and congo red dyes (43 µmol/L and 29 µmol/L, respectively) and textile laundry wastewater at pH 3 were subjected to different experimental conditions in the oxidation reactions at room temperature (27 ºC). Color and COD removals were evaluated for each oxidation systems. The results showed that the utilized processes are able to successfully decolorize the wastewaters. Complete bleaching was achieved by Fenton and UV/H2O2. Also, kinetics investigations revealed that the decolorization follows pseudo-first order kinetic with respect to the dye concentration.

Liquid phase adsorptive separations are found in several industrial applications such as the recovery of p‐xylene from its isomers. In this study, the headspace experimental technique was used to measure pure and multicomponent adsorption equilibria of liquid xylenes in Y zeolite. Data for pure‐component equilibrium were determined at temperatures between 80 and 120°C and correlated using the Extended Langmuir model. The parameters for pure components estimated from the correlated data showed good agreement with data reported in previous studies and relatively low deviations when compared to the experimental data dispersion. Using the pure‐component data, two models were tested for multicomponent (binary and quaternary) equilibrium correlation: Ideal Adsorbed Solution (IAS) model and Extended Langmuir Multicomponent model. The results from the IAS model did not conform well to the experimental results, indicating the existence of significant nonidealities in the system. The Extended Langmuir model predicted values generally in good agreement with the binary and quaternary experimental data measured using the Headspace technique.

RESUMO Este estudo investigou a eficiência da remoção de nitrato em meio aquoso usando adsorção em argilas montmorilonitas comerciais, comparativamente a uma resina aniônica comumente usada nessa operação. Algumas dessas argilas foram intercaladas como o íon hexadeciltrimetilamônio para avaliação. Áreas superficiais específicas, capacidades de troca catiônica e espectros de infravermelho médio foram obtidos para caracterização das argilas. Testes preliminares indicaram a nanoargila funcionalizada com aminopropiltrietoxisilano e octadecilamina como a mais eficiente na adsorção de nitrato, conquanto não tenha superado em eficiência a resina aniônica comercial também testada. Curvas cinéticas e isotermas de equilíbrio de adsorção de nitrato em fase aquosa na nanoargila e na resina comercial foram determinadas e modeladas para comparação, como também para seleção de modelos representativos e para estimativa de propriedades termodinâmicas dos sistemas estudados. Todos os ensaios foram re...

This study investigates the potential use of amino-functionalized silica gel as an adsorbent for the recovering of congo red dye from aqueous solution. The effects of pH, contact time, and temperature were determined and evaluated. Equilibrium isotherms were also studied. The adsorption kinetics was modeled by pseudo-first order and pseudo-second order. Furthermore, desorption of congo red was preliminarily studied. The pH range from 4.5 to 7.0 was favorable for the adsorption of congo red onto amine modified silica at 25ºC. Higher adsorption capacity was obtained at 50ºC. Langmuir and Freundlich models were fitted to the adsorption equilibrium data. The best fittings were obtained with the pseudo-second order and Langmuir model for kinetics and equilibrium, respectively. Desorption studies suggest that ion exchange might be the major mode of adsorption. KOH solution was the best desorbing agent for recovering the adsorbed dye.

VII Encontro de Pesquisa e Pós-Graduação (VII ENPPG) / VII Encontro de Iniciação Científica e Tecnológica (VII ENICIT) / I Simpósio de Inovação Tecnológica (I SIMPIT) ... ADSORÇÃO DE FENOL E NITROFENÓIS EM SOLUÇÃO AQUOSA USANDO BAGAÇO DE COCO (cocos ...

Uma das grandes preocupacoes da sociedade moderna refere-se ao impacto ambiental causado pela liberacao de metais pesados oriundos de diversas atividades industriais no meio ambiente. Os efluentes contendo metais pesados devem receber tratamentos adequados antes de sua disposicao nos corpos hidricos, a fim de se evitar o desequilibrio ambiental, haja vista que os metais pesados como o cobre e o zinco nao sao biodegradaveis. O uso da adsorcao no tratamento de efluentes industriais contendo metais pesados tem se mostrado bastante atrativo, pois apresenta alta seletividade e eficiencia, baixo custo relativo e certa facilidade operacional. Neste contexto, utilizou-se no presente trabalho como adsorvente um gel a base de quitosana e goma de cajueiro para remover ions Cu 2+ e Zn 2+ de efluentes aquosos sinteticos destes metais. Realizaram-se estudos de equilibrio de adsorcao e de dessorcao das biomassas, submetidas a diferentes tratamentos quimicos. Na primeira etapa, observou-se que o modelo da isoterma de Henry foi a que melhor se ajustou aos dados de experimentais de equilibrio. Na dessorcao, observou-se que a biomassa tratada com HCl 0,05 mol.L -1 foi a que apresentou maior percentual de dessorcao, aproximadamente 80%, podendo-se viabilizar a dessorcao como uma alternativa eficiente na regeneracao do adsorvente utilizado no tratamento de aguas industriais contendo ions de metais pesados.

Beef tallow is a promising alternative as a non-edible raw material for biodiesel production, due to its lower price compared to vegetable oils such as soybean oil. The problem of using beef tallow as a raw material for biodiesel is its high acidity level, found as a consequence of hydrolysis and oxidation reactions. These degradation processes are significant in the presence of high levels of humidity and temperature, which are usually found in the storage conditions. In this study, the influence of synthetic and natural antioxidants on the oxidation stability of beef tallow was evaluated using Rancimat tests and by monitoring their acid and peroxide values over 148 days of storage in an oven. The studied synthetic and natural (cashew nut shell liquid, CNSL) antioxidants were effective to prevent oxidation of beef tallow on storage conditions. Biodiesel samples were produced from samples of beef tallow with and without antioxidants. The biodiesel samples produced from beef tallow containing BHT presented the best induction period values. The biodiesel samples produced from beef tallow containing technical CNSL (0.5 wt%) met the requirement of oxidation stability at 110 °C determined by the Brazilian specification.

No presente estudo foram avaliados os dados da qualidade de água da Lagoa da Parangaba, Fortaleza, Ceará, com o intuito de determinar as relações ea influência dos fatores determinantes na qualidade da água, através de técnicas de estatística multivariada. ...

Several different plant extracts have been evaluated with respect to their antimicrobial effects against oral pathogens and for reduction of gingivitis. Given that a large number of these substances have been associated with significant side effects that contraindicate their long-term use, new compounds need to be tested. The aim of this study was to assess the short-term safety and efficacy of a Lippia sidoides ("alecrim pimenta")-based essential oil mouthrinse on gingival inflammation and bacterial plaque. Fifty-five patients were enrolled into a pilot, double-blinded, randomized, parallel-armed study. Patients were randomly assigned to undergo a 7-day treatment regimen with either the L. sidoides-based mouthrinse or 0.12% chlorhexidine mouthrinse. The results demonstrated decreased plaque index, gingival index and gingival bleeding index scores at 7 days, as compared to baseline. There was no statistically significance difference (p>0.05) between test and control groups for any of the clinical parameters assessed throughout the study. Adverse events were mild and transient. The findings of this study demonstrated that the L. sidoides-based mouthrinse was safe and efficacious in reducing bacterial plaque and gingival inflammation.

Carvacrol and dimeric chalcones are the respective bioactive components of Lippia sidoides and Myracrodruon urundeuva, popular medicinal plants of Northeastern Brazil with proven antimicrobial and antiinflammatory properties. Periodontal disease is associated with inflammation and microbiological proliferation, thus the study aimed to investigate the effect of a topical gel based on carvacrol and chalcones in the experimental periodontal disease (EPD) in rats. Animals were treated with carvacrol and/or chalcones gel, immediately after EPD induction, three times a day for 11 days. Appropriate controls were included in the study. Animals were weighed daily. They were killed on day 11, the mandibles dissected and alveolar bone loss was measured. The periodontium were examined at histopathology and the neutrophil influx into the gingiva was assayed using myeloperoxidase activity. The bacterial flora were assessed through culture of the gingival tissue. Alveolar bone loss was significantly (p < 0.05) inhibited by combined carvacrol and chalcones gel, compared with the vehicle and non-treated groups. The treatment with the combined gel reduced tissue lesion at histopathology, decreased myeloperoxidase activity in gingival tissue and inhibited the growth of oral microorganisms as well as the weight loss. Carvacrol and chalcones combination gel has a beneficial effect upon EPD in this model.

Citral (CIT), which contains the chiral enantiomers, neral (cis) and geranial (trans), is the majority monoterpene from Lippia alba and Cymbopogon citratus. The present study aimed to evaluate CIT for antinociceptive and anti-inflammatory activities in rodents. Antinociceptive and anti-inflammatory effects were studied by measuring nociception through acetic acid and formalin tests, while inflammation was verified by inducing peritonitis and paw edema with carrageenan. All tested doses of CIT had significant protection (p<0.001) against acetic acid (0.8%) induced nociceptive behavior and the effects were also similar to morphine while formalin induced nociception was significantly protected (p<0.05) only at higher dose (200 mg/kg) of CIT in the first phase of the test. CIT significantly reduce (p<0.001) nociceptive behavior emanating from inflammation in second phase at all the doses.The pretreatment with CIT (100 and 200 mg/kg) significantly reduced the paw edema induced by carrageenan. Moreover, systemic treatment with CIT (100 and 200 mg/kg) significantly reduced (p<0.001) the leukocyte migration in the carrageenan-induced migration to the peritoneal cavity. Our investigation shows that CIT possess significant central and peripheral antinociceptive effects. It was also verified an anti-inflammatory activity. All together these results suggest that CIT might represent important tool for treatment of painful conditions.