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Polyethylene degrades slowly when discarded in the environment and exposed to natural weathering. A solution to this problem is the incorporation of additives to accelerate its biodegradation. In the present study, a biodegradable low-density polyethylene (LDPE) blend was obtained by the mixture of LDPE with a biodegrading additive (8% w/w) and the effect of accelerated weathering on biodegradation process was assessed. Chemical, mechanical, thermal, and morphological properties of non-aged and aged samples were studied. Results showed that aging process caused changes on structural characteristics (insertion of functional groups), morphological (appearance of micro-cracks and increased roughness), mechanical (greater stiffness and loss of plasticity) and thermal (lower degree of crystallinity and thermal stability) properties. The presence of biodegrading additive contributed to aging process, since polar functional groups were inserted into additive exposed to soil underwent greater degradation than their non-aged counterparts. CO2 production of aged LDPE blend demonstrated that accelerated weathering influences biodegradation process. In this work, due to availability of O2 gas, aerobic microorganisms can be the main responsible by the material deterioration, leading to production of microbial biomass, CO2 and H2O. Thus, the results of biodegradation (166 days) obtained in this work are promising, once it was reached a natural soil from South Brazil landfill.

Polypropylene (PP) is one of the most widely used polymers in the world, mainly due to its versatility, good properties and low cost. However, as it does not easily degrade in the natural environment, several research projects have been developed in order to increase its biodegradability. The use of pro-degrading additives has been explored, as they promote the polymer degradation process. However, few studies have evaluated the degradation of these materials in natural aqueous environments such as rivers and lakes, which contain large amounts of PP residues. Thus, the present work aims to evaluate the influence of different additives on the degradation process of PP in natural freshwater. Samples from degradation tests were evaluated for 6 months, and their structural, morphological and thermal properties (crystallinity, etc.) were monitored. From the obtained results, it was observed that the additives influenced the degradation of PP. In addition, the enzymatic additive had more promising results since it caused more significant changes in the properties analysed, especially in relation to the morphology and structural characteristics analyses (and consequently the carbonyl index), indicating a greater influence on the degradation process. Thus, the materials studied in this work are an alternative in the field of plastic packaging, reducing the effects caused by plastic waste on the environment.

Polypropylene (PP) has been widely used industrially in several sectors, mainly in the use of packaging of different products. Thus, this has been accumulated in our environment due to the incorrect disposal and its high resistance toward degradation, causing an array of environmental impacts. With this, one alternative that has been explored to minimize the problems intensified by these residues is the use of pro-degrading additives. Therefore, the aim of this work is to evaluate the degradation process of PP blends in soil using enzymatic additive. The soil degradation experiment was done for 6 months; monthly collected samples were checked for alterations on the material properties during that time. The extent of PP degradation with enzymatic additive was compared to an organic additive by techniques of FTIR, TGA, DSC, carbonyl index (CI), and crystallinity. From the obtained results it was observed that the additives influenced the degradation of PP. In addition, the enzymatic additive caused more significant changes in the CI (increase of 3693%), crystallinity (variation of 18.7%), and structural characteristics, indicating a greater influence on the degradation process in relation to the organic additive. In this way, this work has had an important role in the research and development of biodegradable materials with the aim of minimizing the effects induced by plastic waste in the environment.

The preservative Chromate Copper Arsenate (CCA) has been used as an alternative for wood preservation to increase its durability, generating a large volume of effluents at treatment plants and in during the decontamination of treated wood. Due to the presence of high concentrations of toxic elements (Cu, Cr and As) these effluents must be treated before being disposed of. Thus, the aim of this study was to develop an effective wood decontamination method based on the counter-current process, reusing the effluents and rinsing water in each extraction cycle. Additionally, total precipitation of the 3 elements and electric recovery of Cu for the extract of the counter-current process were also studied. Removal of the elements by precipitation produced percentages higher than 98.5%. About 91% of Cu was recovered from the effluent when a current of 5 A was applied for 90 min. The results indicated that the counter-current process was efficient in acid decontamination of CCA-treated wood and the proposed treatments produced an effluent suitable for reuse or disposal, in accordance with environmental legislation. Resumo A utilizacao do preservante CCA (Arseniato de Cobre Cromatado) para preservacao de madeira tem sido uma alternativa para aumentar sua durabilidade, porem gerando grande volume de efluentes, tanto nas usinas de preservacao como em processos de descontaminacao da madeira tratada. Em funcao da presenca de elevadas concentracoes de elementos toxicos (Cu, Cr e As) esses efluentes devem ser tratados antes de serem descartados. O objetivo deste trabalho foi desenvolver o metodo em contracorrente para a descontaminacao da madeira tratada com CCA, em que se avaliou a reutilizacao dos efluentes e das aguas de lavagem para cada ciclo de extracao. Foram estudados ainda a precipitacao total dos elementos Cu, Cr e As e a eletrorrecuperacao de Cu para o primeiro extrato do processo de contracorrente (L1). Foram obtidos percentuais acima de 98,5% de remocao total dos elementos por precipitacao. Cerca de 91% de Cu foi recuperado do efluente quando se aplicou uma corrente de 5 A durante 90 min. Os resultados indicaram que a utilizacao do processo em contracorrente para descontaminacao acida da madeira tratada com CCA mostrou ser eficiente bem como os tratamentos propostos para os efluentes, obtendo-se um efluente adequado para reutilizacao ou descarte de acordo com os padroes da legislacao ambiental ao final dos processos.

This work deals with the production of a high added value ether used as additive in aviation fuel. The ether was synthesized from the iso-amylenes present in the C5, the five-carbon isomer cuts in petroleum distillates and the iso-amyl alcohol found in the fusel oil of the alcohol industry. Qualitative analyses like mass spectrometry and nuclear proton magnetic resonance spectroscopy confirmed the formation and structure of the proposed semi-renewable ether, the high molecular weight di-amyl ether (DAE). Optimization of the reaction parameters resulted in a conversion of the 48%, molar fraction, iso-amylenes when using an adiabatic profile reactor. By using this ether production and purification process, the final product showed 98% w/w of purity. The synthesized di-amyl ether presented physicochemical properties similar to the commercial aviation kerosene. The physicochemical properties evaluation performed in the mixtures of di-amyl ether in aviation kerosene showed relevant improvements, such as reduction of the freezing point and increase of the oxidation reaction rate. The results showed this novel fuel has great potential to be used in gas propulsion turbines in commercial flights and is also strategic for military aircraft.

Zeolites may be easily obtained from coal fly ash by conversion processes based on the similar essential composition of both. Among the existing zeolites, we highlight the Na-P1 which is normally produced by hydrothermal treatment, this zeolite has been synthesized in pressurized reactors at high temperatures. The purpose of this study was to synthesize Na-P1 zeolites under mild conditions using Brazilian coal fly ash. Zeolite Na-P1 was produced simultaneously in pressurized reactors at 150 °C and a glass reactor at 100 °C. Complementary synthesis parameters were also evaluated, such as concentrations of alkali, crystallization time, previous separation of magnetic material from the ashes and effects of seeding on synthesis. The zeolite synthesized in the optimized process (77% Na-P1) was used to remove contaminants from acid mine drainage (AMD). Treatment of this wastewater with 10 g L −1 of synthetic zeolite for 30 min presented high removal of arsenic, nickel, calcium, copper, iron and manganese ions and the partial yet significant removal of ammonium, magnesium, potassium and zinc ions. This performance indicates that the synthetic zeolite has excellent adsorption characteristics and can be an alternative for the treatment of DAM. As such, synthesis under mild conditions in a glass reactor is practical, reducing energy costs and minimizing environmental impacts, with the possibility of reproducing zeolite synthesis on an industrial scale.

An evaluation was made to determine the effect of the glycerides presence resulting from the incomplete conversion of soybean biodiesel produced via alkaline catalysis and ethylic route on engine performance, and emissions in formulations containing 10 and 20% (m/m) of biodiesel used as additives in base diesel with low sulfur content and cetane ratings of 45 and 50. By way of comparison, similar formulations were used with soybean biodiesel methyl route with low concentration of glycerides. Tests on a diesel cycle engine with a mechanical fuel injection system indicated that the presence of glycerides decreases the volatility of biodiesel and increase the cetane number of fuels. The higher the cetane number, the higher the particulate matter emissions and the lower the unburned hydrocarbon emissions. Formulations with cetane number 50 showed higher emissions of particulate matter. The presence of glycerides in biodiesel reduces the fuel's vapor pressure, thereby increasing the cetane number and emissions of particulate matter and lower emissions of unburned hydrocarbons. The specific consumption of fuels formulated with biodiesel increases due to its lower enthalpy of combustion and to the presence of glycerides in fuels formulated with soybean biodiesel produced via the ethanol route.

Information about the mineral and organic fractions of coal is essential for its sustainable use. However, most analytical characterization techniques used could be affected by the presence of organic matter in the matrix. The Brazilian coal contains high levels of sulfur ash (up to 50%), being usually classified as low-rank. In this study, the mineral matter (MM) content in Brazilian coals was obtained from the ash content of samples calcined at moderate (300 °C, 400 °C and 370 °C) and low (< 200 °C) temperatures with oxygen plasma (LTA). The isolate MM could be analyzed without the interference caused by organic matter. The best results for estimating the MM content from thermal treatments at moderate temperatures were obtained at 300 °C (MTAC300 °C). Residual organic and inorganic carbon contents in the ash are recommended for a more accurate MM estimation. LTA analysis indicated MM of 45% to 62% content, similar to values obtained with MTAC300 °C analysis (errors < 9%). In addition, it is possible to estimate the mineral matter content with proposed empirical equations based on easily determined parameters (HTA) with mean relative errors < 10%.

Existing standard test methods for determining forms of sulfur take a long time, consume a significant amount of reagents, and generate waste. Faced with this problem, an alternative screening method is proposed using hydrogen peroxide in acid medium for the desulfurization of coal and estimation of forms of sulfur in Brazilian raw coal. The detailed characterization of the extracts and the solids was performed at different reaction times. Hydrogen peroxide solutions at different concentrations (3, 10, and 30%) were tested in the presence and absence of the HCl or HNO3 (0.1 mol L–1). Best results were obtained using 10% H2O2/0.1 mol L–1 HCl with removals of 88–98% of pyritic sulfur and 3.5–18% of ash present in the coal samples. The concentration of total dissolved iron measured in extracts approaches the maximum concentration of iron expected for total oxidation of pyrite to sulfate at the end of reaction (240 min). Thus, it can be used to estimate the content of pyritic sulfur, with maximum percent erro...

Monitoring light hydrocarbons (LHCs) in coal mines, particularly methane, is important not only because of their implications for global climate change but also for economic and safety reasons. Furthermore, the identification and quantification of LHCs in coal mine air samples and desorbed from confined coal may contribute to a better understanding of coal seam characteristics. The paucity of information about the levels of methane in Brazilian underground coal mines can be attributed to their difficult access and a lack of adequate procedures for correct gas sampling. The aim of this study is to optimize and apply standard gas chromatography procedures to determine LHC levels in the air of coal mines and in confined coal from five mines under operation, three underground (A, B, C) and two surface (D, E) mines, in southern Brazil. The results indicate methane (C1) levels varying from 3 ppm to 27% in the atmosphere of the underground mines. Mine A presented high levels of all LHCs analyzed (C1 to C5), while only C1 and C2 were detected in mine B, and hydrocarbons ranging from C1 to C4 were found in mine C. On the other hand, surface mines presented narrow concentration range for C1 (3 ppm to 470 ppm) and C2–C3, with higher levels observed for puncture explosive points. Among LHCs, methane is desorbed in higher concentrations from confined coals and the presence of C2 was detected in all samples while C3–C5 were only observed in coals from underground mines. These data are consistent with those obtained from the air gas samples collected in the mines under study. Geological events such as faulting and intrusions can accelerate the release of gas or the trapping of large amounts of previously released methane. The LHC emissions from coal mines were found to be highly variable, indicating the need for a comprehensive survey of Brazilian coal mine emissions.

The aim of this study is to determine the kinetics of the Acid Black 1 dye by oxidizing action of ozone and to evaluate the influence of chloride ion contamination on the dye degradation. Pseudo-first order kinetics was observed for both decolorization (620 nm) and aromatic structure (321 nm) degradations. A complete color removal was verified in 25 min ([dye]0 = 1.8 × 10-5 mol L-1), while aromatic structures degraded at slower rates. The presence of chloride ion, the principal impurity of the solid dye reagents, influences significantly the ozonation rate (-42%), even at low chloride concentration (5.6 × 10-4 mol L-1). The most probable mechanism for the chloride suppression effect involves a direct reaction between O3 and Cl- generating HOCl, among other by-products. In despite of that, ozonation could be a competitive degradation process for this dye. O objetivo deste estudo é determinar a cinética degradação do corante Acid Black 1 por ação oxidante do ozônio e avaliar a influência da contaminação de íons cloreto na degradação deste corante. Foram observadas cinéticas de pseudo-primeira ordem, tanto para a degradação das estruturas cromóforas (620 nm), quanto das aromáticas (321 nm). A completa remoção da coloração foi verificada em 25 min ([corante]0 = 1,8 × 10-5 mol L-1), enquanto que as estruturas aromáticas foram degradadas com menor velocidade. A presença de íon cloreto, principal impureza do reagente sólido, influencia significantemente a velocidade de ozonização (-42%), mesmo em baixa concentração (5,6 × 10-4 mol L-1). O mecanismo mais provável para o efeito supressor do íon cloreto envolve a direta reação entre O3 e Cl- gerando HOCl, dentre outros subprodutos. Apesar deste aspecto, a ozonização pode ser um processo de degradação competitivo para este corante.

Em células a combustível1 de eletrólito polimérico sólido o principal componente é o conjunto membrana/eletrodos - MEA (membrane-eletrocde assembly). Os eletrodos de difusão de gás - GDL (gas diffusion layer) são um dos principais constituintes do MEA, sendo um material compósito constituído de camadas difusora e catalítica, formadas por pó de carbono, platina e polímeros - PTFE (politetrafluoretileno) e Nafion - depositados sobre um substrato (papel ou tecido de carbono). Essas camadas apresentam superfícies rugosas e porosas, de caracterização complexa. O objetivo deste trabalho é caracterizar a GDL. A molhabilidade da superfície foi determinada por medidas de ângulo de contato externo pelo método da gota de água. Os ângulos de avanço e recuo foram medidos e usados para estimar a histerese e o ângulo de equilíbrio. A morfologia e a composição foram estudadas usando Microscopia eletrônica de varredura e espectroscopia de energia dispersiva, enquanto que a porosidade foi medida embebendo os substratos com n-heptano e água para quantificar os poros hidrofílicos/hidrofóbicos. O estudo morfológico indicou que a incorporação do PTFE no pó de carbono é uma etapa crítica na fabricação das camadas difusoras. Uma maior quantidade de PTFE resulta no decréscimo da porosidade total e um aumento do percentual de poros hidrofóbicos para ambos os substratos. Os resultados obtidos na determinação dos ângulos de contato apresentaram boa precisão, em especial para os compósitos depositados sobre o tecido de carbono. Os ângulos de contato obtidos para as camadas catalíticas foram inferiores aos das camadas difusoras, provavelmente devido à presença do Nafion, que apresenta caráter hidrofílico minimizado a hidrofobicidade do compósito. Esses resultados confirmaram a complexidade do GDL e a importância de sua caracterização detalhada para a otimização da fabricação do MEA. In polymer electrode fuel cells the main component is the membrane/electrodes assembly (MEA). Gas diffusion electrodes (GDL) are the principal components of the MEA, being a composite material constituted of diffusion and catalyst layers, formed by carbon powder, platinum, PTFE and Nafion polymers deposed over a subtract (carbon paper or cloth). These layers present roughness and porous surfaces of complex characterization. The aim of this work is to characterize GDL. The surface wettability was assessed by drop water external contact angle measurements. The advancing and receding angles were measured and used to estimate the hysteresis and the equilibrium angle. Morphology and composition were studied using scanning electronic microscopy and energy dispersive spectroscopy while porosity was measured by imbibing n-heptane and water into substrates to quantify hydrophilic/hydrofobic pores. Morphologic study indicated that PTFE incorporation into carbon power is a critical step on diffusion layers fabrication. A greater amount of PTFE results in decrease the total porosity and increases the percent of hydrophobic porous for both substrates. The results obtained in angles contact determination present good precision, especially for the composite deposited over carbon cloth. The values obtained for contact angels of the catalyst layers were lower than ones measured over diffusion layer, probably due to the presence of Nafion, which presents a hydrophilic character minimizing the composite hydrophobicity. These results confirmed the complexity of GDL and confirmed the importance of a detailed characterization for MEA assembly optimization.

Advanced oxidation processes are an emerging option to treatment of the painting industry effluents. The aim of this study was to compare the effectiveness of the Fenton and photo-Fenton processes in chemical oxygen demand (COD), total organic carbon (TOC) and phenolic compounds removal from wastewaters generated during alkydic resins manufacture. The optimized treatment conditions are the following: pH 3.0, 15.15 × 10−3 mol L−1 FeSO4 and 0.30 mol L−1 H2O2 for a reaction time of 6 h. photo-Fenton experiments were carried out in the presence of sunlight or artificial radiation and complementary additions of H2O2 were made for all experiments. The best results were obtained with photo-Fenton process assisted with solar radiation, with reductions of 99.5 and 99.1% of COD and TOC levels, respectively. Fenton and photo-Fenton (with artificial irradiation) processes presented lower but not insignificant removals, within 60–80% reduction for both COD and TOC. In addition, an excellent removal (95%) of total phenols was obtained using photo-Fenton process assisted with artificial irradiation. This study demonstrated that the use of photo-Fenton process on alkydic resins wastewater treatment is very promising especially when solar light is used.

The chlorite ion is the principal by-product of the treatment of drinking water by chlorine dioxide. In function of the chlorite salt instability, standard solutions of this ion need standardization by iodometric titration, which is a reliable method although labor intensive and time consuming. An alternative method to standardization of aqueous chlorite solutions, based on its direct UV absorption measurement, was presented. Besides the maximum absorption (260 nm) generally used in other studies, the minimum (239 nm) and isosbestic (248 nm) wavelengths were proposed as supplementary points to chlorite quantification and their molar absorptivity coefficients were estimated (155.2+/-0.6, 104.5+/-1.0 and 69.0+/-1.2 L cm(-1) mol(-1), respectively). The direct spectrophotometric determination of chlorite could be made selectively even in the presence of high concentration of major contaminants (chorine dioxide, chloride and chlorate), being a simple and rapid method, consuming very low volume of sample and generating low quantities of laboratory wastes.

Pararosaniline (C.I. Basic Red 9) is an important dye used in biological and chemical assays, suspected of being carcinogenic. Thus, the environmental and occupational issues related to it are very important. This study aims at investigating the chemical oxidation of pararosaniline dye by ozonation and sonolytic processes. Experimental results indicate that ozonation of pararosaniline solution is more efficient than ultrasonic irradiation alone or in combination with O 3 . The detoxification was assessed by determining acute toxicity and mutagenicity of the ozonized dye solutions. Even for short-term ozonation (15 min) any mutagenic effect was verified although longer treatment periods (120 min) are necessary to obtain high toxicity removal. The results obtained indicate that ozonation is a powerful tool for the treatment of the pararosaniline wastes, even when compared to other advanced oxidation processes as photocatalytic and hydrogen peroxide dye degradation. The kinetics of different pararosaniline degradation techniques are also discussed such an understanding is necessary for the design and application of pararosaniline treatment processes.

Several researchers have reported zeolite synthesis using coal ash for a wide range of applications. However, little attention has been given to green processes, including moderate synthesis conditions, using waste as raw material and effluent reuse or reduction. In this study, Brazilian coal fly ashes were used for integrated synthesis of zeolites 4A and Na–P1 by two different routes and under moderate operating conditions (temperature and pressure). Both procedures produced zeolites with similar conversions (zeolite 4A at 82% purity and zeolite Na–P1 at 57–61%) and high CEC values (zeolites 4A: 4.5 meq Ca2+ g−1 and zeolites Na–P1: 2.6–2.8 meq NH4+ g−1). However, process 1 generated less effluent for the zeolite mass produced (7 mL g−1), with low residual Si and Al levels and 74% of the Si available in the coal fly ash incorporated into the zeolite, while only 55% is used in process 2. For use as a builder in detergents, synthetic zeolite 4A exhibited conformity parameters equal to or greater than those of the commercial zeolite adopted as reference. Treatment of swine wastewater with zeolite Na–P1 resulted in a high removal capacity for total ammoniacal nitrogen (31 mg g−1).

The use and characterization of the first Certified Reference Material (CRM) of Brazilian coal for analytical quality control are presented. All results were determined within the limits of repeatability and reproducibility allowed under the standards. Notable among the characterization parameters was the mineral matter content (45.39%) obtained by an alternative procedure showing a low relative error (-2.1%) compared to the standard technique (low ashing temperature). The possible expanded application of this CRM application in national laboratories, beyond the certificated and reference parameters, has advantages such as lower cost and easy availability, but round robin tests must be performed.