Adsorption in Jar-Test system: a study of the physico-chemical interactions of the chitosan biopolymer with the textile dye DO 2GL

The incorrect disposal of contaminated effluents from textile industries is a major contribution to their environmental impact. We aimed to use the chitosan biopolymer from industrial sources as a potential adsorbent agent. The experiments were performed in Jar-Test simulating an industrial scale treatment. Both pH and mass variations were analyzed. Our UV spectra results showed that all datasets fitted to the Langmuir model, indicating the formation of monolayers. Kinetics studies confirmed that adsorption follows a pseudo-second order model, in addition to a chemisorption pattern during adsorption. Kinetics studies also demonstrated intraparticle diffusion, which confirmed a strong adsorbate/adsorbent interaction with the dye. The Jar-Test proved to be an efficient system to simulate treatment of effluents on an industrial scale, thus ranking chitosan powder as a good adsorbent and eligible to future large-scale applications.Keywords: chitosan, intraparticle diffusions, chemisorption, isotherms, kinetics

Incêndios de petróleo e pretoquímicos: biorremediação de áreas afetadas

From oilrigs extraction to transport and distribution of petrochemicals, there is always the risk of accidents resulting in fires. In such cases, the release of aqueous film forming foams (AFFF) are a usual practice. These compounds are comprised of compounds containing fluorine-carbon, which contribute to their fire extinguishing capabilities when released in large amounts. Tons of AFFF are released into the environment during emergencies and thus causing long term harnessing of the environment even long after the fire is extinguished, since such substances end up in water bodies. Fluorine and carbon bonds are highly resistant to degradation and therefore have long environmental persistence. Biodegradation pathways of organic halogens are quite specific and slow. In this study, we determined the potential microbiota in different biodegradation AFFF mixtures of hydrocarbons, and studied the biotransformation of compounds in the formulation of AFFF. Thus, it was possible to better understand the impact of fluorinated compounds into the environment. A wide variety of techniques was applied, involving a combination of mass spectrometry techniques to determine the biotransformation pathways of perfluorcarbonados components; respirometric techniques to study the biodegradability of AFFF in association with petroleum hydrocarbons; bio-assays to determine the phyto-toxicity of AFFF; and molecular biology techniques for metagenomic analyzes evaluating changes in the profile of soil microbial communities after AFFF was introduced in the medium. It was observed that petroleum hydrocarbons during application of fire foams fluorocarbon influenced the overall biotransformation process, altering the metabolism of the microbial communities. In general, the fluorocarbon biotransformation is slower by a mutual interference between AFFF and BTEX, but the CO2 production is increased by the effect of the perfluorinated surfactant combined with the ...Dos poços e plataformas de petróleo ao transporte e distribuição de petroquímicos, sempre há o risco de acidentes que resultam em incêndios. Nesses casos são muitas vezes utilizadas espumas formadoras de filme aquoso (AFFF), pois compostos fluorados em grandes quantidades nas misturas das AFFFs contribuem com a capacidade extintora de incêndio. Em situações de emergência, toneladas de AFFF são liberadas no ambiente e, portanto, podem afetar em longo prazo o ambiente mesmo depois do incêndio ser apagado, pois contém substâncias que escoam para corpos d'água. Os flúor-carbonados são altamente resistentes à biodegradação e, por isso, têm prolongada persistência ambiental. As vias de biodegradação dos organo-halogenados são bastante específicas e lentas. Nesse estudo foi determinado o potencial de biodegradação de diferentes microbiotas sobre misturas da AFFF em hidrocarbonetos, e estudado o processo de biotransformação dos compostos presentes na formulação da AFFF. Pela combinação de metodologias foi possível conhecer melhor sobre o impacto dos compostos flúor-carbonados no ambiente. Foram realizados estudos com a técnica de espectrometria de massa, para determinar as vias de biotransformação dos componentes perfluorcarbonados; técnicas respirométricas, para estudar a biodegradabilidade da AFFF em associação com hidrocarbonetos de petróleo; bioensaios com plantas, para determinar a toxicidade da AFFF; e técnicas de biologia molecular, para análise metagenômica de alteração no perfil da comunidade microbiana de solo após a introdução da AFFF ao meio. Os hidrocarbonetos de petróleo influenciaram, durante a aplicação de espumas de incêndio, o processo de transformação de fluorcarbonados, alterando o metabolismo de comunidades microbianas. Em geral, a biotransformação de fluorcarbonados foi mais lenta por uma interferência mútua entre BTEX e AFFF, mas a produção de CO2 foi maior pelo...Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Screening the toxicity and biodegradability of petroleum hydrocarbons by a rapid colorimetric method

Crude oil and petroleum products have a wide variety of hazardous components with high toxicity and low biodegradability. Certain dyes change their colors by intercepting electron transfer reactions during the transformation processes. This study applied resazurin and 2,6-dichlorophenol-indophenol indicators for a rapid screening biodegradation capability and toxicity response to various petroleum products such as motor oil, diesel, gasoline, and phenol. Colorimetry tests were performed in test tubes, and the absorbance values were measured over time. We observed different discoloration profiles after degradation tests using Bacillus subtilis inoculum. Phytotoxicity assays were also performed to compare colorimetric screening assays with a conventional toxicity testing with plants (seed germination). The results indicated that biotransformation of oils can increase its overall toxicity. Intermediate byproducts can be formed through biodegradation and thereby increase the toxicity of oils. The assessment of acute toxicity has shown that phenol is extremely toxic to petroleum-biodegrading microbial communities. Low molecular-weight gasoline was considered biodegradable, but it also exhibited a high acute toxic effect, mainly due to its high solubility and the presence of more volatile compounds that can penetrate cells and potentially damage cellular structures.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Assessing Bacillus subtilis biosurfactant effects on the biodegradation of petroleum products

Microbial pollutant removal capabilities can be determined and exploited to accomplish bioremediation of hydrocarbon-polluted environments. Thus, increasing knowledge on environmental behavior of different petroleum products can lead to better bioremediation strategies. Biodegradation can be enhanced by adding biosurfactants to hydrocarbon-degrading microorganism consortia. This work aimed to improve petroleum products biodegradation by using a biosurfactant produced by Bacillus subtilis. The produced biosurfactant was added to biodegradation assays containing crude oil, diesel, and kerosene. Biodegradation was monitored by a respirometric technique capable of evaluating CO2 production in an aerobic simulated wastewater environment. The biosurfactant yielded optimal surface tension reduction (30.9 mN m(-1)) and emulsification results (46.90 % with kerosene). Biodegradation successfully occurred and different profiles were observed for each substance. Precise mathematical modeling of biosurfactant effects on petroleum degradation profile was designed, hence allowing long-term kinetics prediction. Assays containing biosurfactant yielded a higher overall CO2 output. Higher emulsification and an enhanced CO2 production dataset on assays containing biosurfactants was observed, especially in crude oil and kerosene.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Photocatalytic Degradation of Phenol by Thermal Titanium Dioxide Thin Layer Electrodes

Electrochemical processes in industrial effluents have been studied as a means to obtain higher efficiency in wastewater treatment. Heterogeneous photocatalysis appears as a low-cost alternative through the use of lower wattage lamps and thermal TiO2 films. Photocatalysis became a clean process for water treatment due to hydroxyl radicals generated on semiconductor surface. Such radicals are able to degrade several organic compounds. This study used different electrodes and analytical methods for degradation of phenol molecules to reduce treatment costs, improve efficiency, and identify compounds formed during the decomposition of phenolic molecules. Thermal growth of TiO2 film was observed on the titanium electrode in rutile form. Application of an electrical potential on the Ti/TiO2 working electrode increases efficiency in reducing concentration of phenol after photocatalytic treatment. Still, high energy radiation (UVC) showed best degradation rates in photolytic process. Different compounds formed during the degradation of phenol were also identified in the UVC-PE treatment

Biodegradation and toxicological evaluation of lubricant oils

The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei), arugula seeds (Eruca sativa) and lettuce seeds (Lactuca sativa), with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil) for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES