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Common carbon-blacks have shown insufficient stability as cathodic catalyst supports for proton exchange membrane fuel cells (PEMFCs). In this regard, alternative supports have been proposed and, specifically graphene or reduced graphene oxide (rGO), have attracted special attention. Herein, a set of electrocatalysts using reduced graphene oxide (rGO) as support is synthetized by a modified polyol method. The influence of Pt loading on the support is studied and compared with conventional supports, considering Pt particle morphologies and oxygen reduction reaction (ORR) performance in rotating disk electrode (RDE). Despite Pt average particle size typically increases with the Pt loading, 30 wt% of Pt on rGO is the optimal Pt loading, yielding the highest ORR activity among the rGO-supported electrocatalysts. These results show that both Pt loading and type of support greatly impact on the morphology and electrochemical performance of Pt nanoparticles.

Planet Earth is facing accelerated global warming due to greenhouse gas emissions from human activities. The United Nations agreement at the Paris Climate Conference in 2015 highlighted the importance of reducing CO2 emissions from fossil fuel combustion. Hydrogen is a clean and efficient energy carrier and a hydrogen-based economy is now widely regarded as a potential solution for the future of energy security and sustainability. Although hydrogen can be produced from water electrolysis, economic reasons dictate that most of the H2 produced worldwide, currently comes from the steam reforming of natural gas and this situation is set to continue in the foreseeable future. This production process delivers a H2-rich mixture of gases from which H2 needs to be purified up to the ultra-high purity levels required by fuel cells (99.97%). This driving force pushes for the development of newer H2 purification technologies that can be highly selective and more energy efficient than the traditional energy intensive processes of pressure swing adsorption and cryogenic distillation. Membrane technology appears as an obvious energy efficient alternative for producing the ultra-pure H2 required for fuel cells. However, membrane technology for H2 purification has still not reached the maturity level required for its ubiquitous industrial application. This review article covers the major aspects of the current research in membrane separation technology for H2 purification, focusing on four major types of emerging membrane technologies (carbon molecular sieve membranes; ionic-liquid based membranes; palladium-based membranes and electrochemical hydrogen pumping membranes) and establishes a comparison between them in terms of advantages and limitations.

The recognition of the effects of fossil fuel consumption resulted in several agreements, legislation, and projects focusing on the minimization of impacts caused. Biomass is a versatile energy source. Eucalyptus is a fast-growing crop, mainly used by the pulp and paper industry. Torrefaction is a thermochemical conversion process that can improve biomass fuel properties, enabling its use in the energy sector. However, correct management of biomass is crucial for the sustainability of this process. Torrefaction can also be used to eliminate some elements that can hinder subsequent conversion processes. One example is chlorine, which, during combustion or gasification processes, can form hydrochloric acid that leads to corrosion of metal surfaces. In this context, this research aimed to determine the temperature at which chlorine is eliminated during torrefaction process. For this purpose, several tests were performed at different temperatures and residence times. All samples were analyzed before and after the process, and were characterized by proximate and elemental analysis, calorimetry, and chlorine titration. The analysis showed that, even for the lowest torrefaction temperature used, chlorine content was already below the detection value, showing that, even at lower temperatures, thermal treatment is an efficient technique for the elimination of chlorine from biomass.

This work addresses the effect of using thermochromic paints in residential buildings. Two different thermochromic paint types were considered: One that changes properties through a step transition at a certain temperature, and another that changes properties in a gradual/linear manner throughout a temperature range. The studied building was a two-floor villa, virtually simulated through a digital model with and without thermal insulation, and considering thermochromic paints applied both on external walls and on the roof. The performance assessment was done through the energy use for heating and cooling (in conditioned mode), as well as in terms of the indoor temperature (in free-floating mode). Three different cities/climates were considered: Porto, Madrid, and Abu Dhabi. Results showed that energy savings up to 50.6% could be reached if the building is operated in conditioned mode. Conversely, when operated in free-floating mode, optimally selected thermochromic paints enable reductions up to 11.0 °C, during summertime, and an increase up to 2.7 °C, during wintertime. These results point out the great benefits of using optimally selected thermochromic paints for obtaining thermal comfort, and also the need to further develop stable and cost-effective thermochromic pigments for outdoor applications, as well as to test physical models in a real environment.

Phenol was detected for the first time in the mononitrobenzene production process by benzene adiabatic nitration, supporting the theory that proposes phenol as the precursor of nitrophenols, unwanted byproducts. For that, analytical procedures (based in liquid and gas chromatographic techniques) have been developed and improved that aim to detect these chemical species both in the industrial nitration process as well as in laboratory tests at different reaction conditions. The obtained results confirmed the proposed and accepted mechanism for the nitrophenols formation during benzene nitration, showing that phenol is indeed the nitrophenolic byproducts precursor. Moreover, it is shown the phenol's high reactivity even at smooth reaction conditions (namely low temperature and low sulfuric acid concentration), which explains the difficulty of detecting this compound within the reaction medium using the analytical techniques applied for monitoring benzene nitration process. In this study, it was also discovered that 4-mononitrophenol had higher affinity into the aqueous acid phase when compared to the other nitrophenolic byproducts (2-mononitrophenol; 2,4-dinitrophenol; 2,6-dinitrophenol; and 2,4,6-trinitrophenol) that have more affinity into the organic phase. Phenol distribution between both reaction phases was found to be similar to the majority of the nitrophenols, i.e., it is present in higher concentration in the organic phase.

This is the first review presenting and discussing Burkholderia sacchari as a bacterial chassis. B. sacchari is a distinguished polyhydroxyalkanoates producer strain, with low biological risk, reaching high biopolymer yields from sucrose (0.29 g/g), and xylose (0.38 g/g). It has great potential for integration into a biorefinery using residues from biomass, achieving 146 g/L cell dry weight containing 72% polyhydroxyalkanoates. Xylitol (about 70 g/L) and xylonic acid [about 390 g/L, productivity 7.7 g/(L.h)] are produced by the wild-type B. sacchari. Recombinants were constructed to allow the production and monomer composition control of diverse tailor-made polyhydroxyalkanoates, and some applications have been tested. 3-hydroxyvalerate and 3-hydroxyhexanoate yields from substrate reached 80% and 50%, respectively. The genome-scale reconstruction of its metabolic network, associated with the improvement of tools for genetic modification, and metabolic fluxes understanding by future research, will consolidate its potential as a bioproduction chassis.

A series of TiO 2 composites loaded with 0.5–4 wt.% of reduced graphene oxide (rGO) was prepared through a combined sol-gel method and solvothermal treatment. The composites were characterized by scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), the Brunauer-Emmett-Teller (BET) method and diffuse reflectance spectroscopy (DRS). The photocatalytic performance of the prepared materials was evaluated by methylene blue discoloration in aqueous medium. The TiO 2 -rGO 1% composite led to an increase of ca. 11% in the pseudo-first-order rate constant, however, further increasing in rGO contents led to a decrease in the photocatalytic activity. When present in a high content, reduced graphene oxide can act as a recombination center, rather than providing a pathway for charge transfer and preventing recombination of electron-hole pairs. Subsequently, the TiO 2 -rGO 1% was immobilized in a vinyl-base paint and evaluated for the purification of air containing 1 ppm v of nitrogen oxide (NO). The results showed that the NO conversion was 25% and the selectivity for the transformation of NO into nitrates and nitrites was 50%. The same paint containing bare TiO 2 presented an NO conversion of 35% and selectivity of 40%. Although, the abatement of NO by the composite was lower, the selectivity for ionic compounds was higher, indicating that the presence of rGO is important for the decomposition of NO under more oxidized compounds.

This study aimed to evaluate the synthesis and application of heterogeneous catalysts based on heteropolyacids for 5-hydroxymethylfurfural (HMF) production from glucose. Initially, assays were carried out in order to establish the most favorable catalyst synthesis conditions. For such purpose, calcination temperature (300 or 500 °C), type of support (Nb2O5 or Al2O3), and active phase (H3PW12O40—HPW or H3PMo12O40—HPMo) were tested and combined based on Taguchi’s L8 orthogonal array. As a result, HPW-Nb2O5 calcined at 300 °C was selected as it presented optimal HMF production performance (9.5% yield). Subsequently, the reaction conditions capable of maximizing HMF production from glucose using the selected catalyst were established. In these experiments, different temperatures (160 or 200 °C), acetone-to-water ratios (1:1 or 3:1 v/v), glucose concentrations (50 or 100 g/L), and catalyst concentrations (1 or 5% w/v) were evaluated according to a Taguchi’s L16 experimental design. The conditions that resulted in the highest HMF yield (40.8%) consisted of using 50 g/L of glucose at 160 °C, 1:1 (v/v) acetone-to-water ratio, and catalyst concentration of 5% (w/v). Recycling tests revealed that the catalyst can be used in four runs, which results in the same HMF yield (approx. 40%).

Hollow fiber membrane contactors with microporous polypropylene (PP) and composite polytetrafluoroethylene/polyethersulfone (PTFE/PES) were used for carbon dioxide (CO2) removal from a gas mixture. The composite membranes exhibited higher efficiency than the microporous membranes, which was related to prevention of pore wetting due to the PTFE present in the top layer of the membrane. For both type of contactors, it was investigated the influence of liquid flow rate, temperature and kind of absorbent on the CO2 removal. A better performance of CO2 transfer into the liquid phase was observed by increasing the liquid flow rate, by using a reacting absorbent (sodium hydroxide) and by decreasing the liquid temperature.

Bark from Eucalyptus globulus, a side-stream of pulp and paper industry, is a source of bioactive polyphenols that are extractable with 80/20 (v/v) ethanol/water. In this work, downstream processing of this extract was performed by ultrafiltration (UF) assessing for the first time (i) the influence of membrane type and transmembrane pressure (TMP) on the flux and permeate composition; (ii) the analysis of flux and resistances using the resistance-in-series model; (iii) permeate flux and cake build up modeling; and finally (iv) the feasibility of concentration by UF. Four membranes were selected: polyamide composite GE – 1 kDa (GE 1), polyethersulfone PLEAIDE – 5 kDa (P 5), polyvinylidenefluoride JW – 30 kDa (JW 30), and polysulfone EW – 60 kDa (EW 60). The effect of TMP on the permeation flux was evaluated, and total solids (TS), total phenolic compounds (TPC), proanthocyanidins (Pac) and formaldehyde condensed tannins (fcT) were quantified in the permeates. Data analysis showed that the experiments were performed in a region not controlled by pressure. P 5 and JW 30 membranes are more susceptible to fouling than the GE 1 and EW 60. In spite of the lowest cut-off of GE 1 membrane, it presented the lowest retention to TS, TPC and Pac, demonstrating that membrane material plays a significant role in separation. Finally, a model using classical cake-filtration theory and the surface-renewal concept successfully predicted the permeate flux and cake build up. A trade-off between permeate flux, the resistance and the retentions to TPC and Pac was established. The selected TMP was 3 bar for EW 60 (retentions: TPC 14%, Pac 30%) and 5 bar for JW 30, P 5 and GE 1 (retentions: TPC 66%, 66% and 58%; Pac 87%, 88% and 58%, respectively).

The aim of this study was to develop methodologies and experimental procedures to determine textile parameters required in numerical approaches of heat and mass transfer through textiles. Privileging techniques usually available in textile/clothing laboratories, experimental approaches were defined that allow to estimate all required parameters, while taking into consideration water presence in the fibres and hence the effect of fibres hygroscopic properties. Numerical models usually require values of textile thickness, fibre fraction, and tortuosity, as well as knowledge of the boundary conditions, e.g. convective heat and mass transfer coefficients. To calculate these parameters, thickness, weight, and volume of textile samples were measured, whereas convective and textile evaporative resistances were determined by indirect measurements. Results were obtained for four distinct textile samples (made of wool, cotton, and a mixture of materials), of different hydrophilic nature. When the obtained parameters were incorporated in a numerical model and numerical predictions of temperature and humidity were compared with experimental data obtained during measurements of fabric evaporative resistance, it was shown that the predictions were accurate; this lends support to the developed methods and approaches. Since an uncertainty in the measured parameters can compromise the accuracy of numerical predictions, a sensitivity analysis was conducted to study the influence of deviations in the model input parameters and of assumptions regarding water presence in the fibres, on the predictions of heat and mass transfer rates. The results show that a deviation in textile weight and thickness as well as the assumption of no water retained in fibres during their characterisation, have a significant effect on the predicted heat transfer and water distribution over time. Moreover, a deviation in the total evaporative resistance, convective evaporative resistance, and sorption rate factor has great influence on the heat flux obtained in the initial period of testing.

The flow in a Confined Impinging Jets (CIJs) mixer was studied with Planar Laser Induced Fluorescence. Two key aspects influencing the flow regimes and mixing quality were studied: the impact of the jets' Reynolds number (Re) in the range 50 < Re < 600; and the effect of the jets' flow imbalance, maintaining the flow rate of one of the injectors fixed and varying the other. Mixing mechanisms and scales are studied from the acquired flow images, and the mixing degree is quantified from the calculation of the Intensity of Segregation (Danckwerts, 1952). In balanced flow conditions, i.e., equal volumetric feeding rates, when the best mixing performance is observed, three flow regimes are observed: for Re < 103 the flow is steady with complete segregation of the two feeding jet streams; for Re = 104 the flow tends to an oscillatory periodic laminar flow regime; for Re > 104 the flow evolves to a self-sustained chaotic laminar regime with strong mixing dynamics. With the increase of Re it is observed the formation of smaller mixing scales in the flow and an increase on the mixing quality. The visualized mixing scales are compared with theoretical models existing in the literature for the estimation of the striation thickness, leading to the conclusion that, in the studied flow regimes, the statistical theory of turbulent diffusion does not provide a realistic physical description of the flow. Furthermore, the jets' mass flow imbalance is shown to always influence negatively the mixing quality. This is observed even when the flow imbalance results in the increase of the flow rate of one of the jets, increasing the amount of energy supplied to the system for dissipation. Results of this work show that the mechanism of eddy engulfment promoted by the two chaotically oscillating impinging jets, in the laminar regime, is a key aspect in mixing by CIJs.

In the present study, the sugar cane juice from COCAFE Mill, was clarified using tubular ceramic membranes (α-Al2O3/TiO2) with pore size of 0.1 and 0.3 µm, and membrane area of 0.005 m2. Experiments were performed in batch with sugar cane juice, in a pilot unit of micro and ultrafiltration using the principle of tangential filtration. The sugar cane juice was settled for one hour and the supernatant was treated by microfiltration. After that, the MF permeate was ultrafiltered. The experiments of micro and ultrafiltration were carried out at 65ºC and 1 bar. The ceramic membranes were able to remove the colloidal particles, producing a limpid permeated juice with color reduction. The clarification process with micro- followed by ultrafiltration produced a good result with an average purity rise of 2.74 units, 99.4% lower turbidity and 44.8% lighter color in the permeate.

A mathematical model to predict the dissolution of salt particles suspended in a brine flow is provided. The model consists of a system of three partial differential equations (PDE) based on mass conservation of salt dissolved in the fluid phase, on mass conservation of salt particles in the solid phase and on the overall conservation of energy. A fluid flow experimental unit was built to determine the kinetics of the dissolution of salt particles in a brine flow. Fluid samples free from particled solid material retrieved through the flow line at several predefined points were collected to determine salt dissolution profile. The global convective mass transfer coefficient was evaluated based on the experimental data. Simulations validated the mathematical model and relative deviations between experimental data and simulations were less than 10%.

n-Decane is a saturated long-chain hydrocarbon, belonging to the family of the volatile organic compounds (VOCs), which is persistently present in indoor air of several industrial closed facilities. Due to the VOCs environmental impact, all efforts that have been made during the last decades to degrade this kind of air pollutants are extremely important. Accordingly, the present paper reports n-decane photooxidation studies carried out in an annular photoreactor under simulated solar irradiation and employing a catalytic bed made of cellulose acetate monoliths coated with a photocatalytic paint. The influence of the feed flow rate, n-decane concentration, relative humidity, and incident irradiance on the n-decane degradation kinetics was assessed. Within this work, n-decane photodegradations higher than 90% were achieved, depending on the experimental conditions. Additionally, a phenomenological reaction rate model of the n-decane photocatalytic oxidation was proposed and assessed. The proposed model assumes that n-decane and water molecules compete for different active sites on the catalyst surface. Finally, despite the high n-decane photodegradation achieved, reaction by-products were identified and, based on these compounds, a reaction mechanism was formulated.

Due to growing electricity demand, cheap renewable energy sources are needed. Fuel cells are an interesting alternative for generating electricity since they use hydrogen as their main fuel and release only water and heat to the environment. Although fuel cells show great flexibility in size and operating temperature (some models even operate at low temperatures), the technology has the drawback for hydrogen transportation and storage. However, hydrogen may be produced from methanol steam reforming obtained from renewable sources such as biomass. The use of methanol as raw material in hydrogen production process by steam reforming is highly interesting owing to the fact that alcohol has the best hydrogen carbon-1 ratio (4:1) and may be processed at low temperatures and atmospheric pressures. They are features which are desirable for its use in autonomous fuel cells. Current research develops a mathematical model of an isothermal methanol steam reforming reactor and validates it against experimental data from the literature. The mathematical model was solved numerically by MATLAB® and the comparison of its predictions for different experimental conditions indicated that the developed model and the methodology for its numerical solution were adequate. Further, a preliminary analysis was undertaken on methanol steam reforming reactor project for autonomous fuel cell.

The biosorption process with algae is usually carried out with a concomitant alginate leaching process. Alginate is identified as the main functional group, responsible for generating the most active sites. Biomass chemical and thermal pretreatment is an alternative process for reducing organic leaching. Experiments with different pH rates were performed to analyze the leaching process of pretreated (contact time: 24, 48 and 72 hours) and non-pretreated biomass of Sargassum filipendula. The concentrations of calcium, magnesium, sodium and potassium ions, as well as total organic carbon, were determined to evaluate the biomass sorption capacity. Capacities of native and pretreated biomass to remove the heavy metal ions Cr and/or Ni from solutions of different concentrations were compared. The ion competition effect on removal capacity was studied. The biosorbent had a higher affinity with chromium ion.

This work reviews the state-of-the-art nanostructured photoelectrodes for use in dye-sensitized solar cells. The influence of the photoelectrode structure in the DSC performance is analyzed. The nanostructured photoelectrodes can be classified into: (1) nanoparticles with high surface areas for efficient dye loading; (2) 1D nanostructures such as nanotubes and nanowires that offer direct electron transport pathways towards the collecting substrate; (3) 3D hierarchically ordered photoelectrodes that combine large pores for efficient electrolyte diffusion, large particles for effective light scattering but also small particles needed to achieve high surface areas; (4) 3D template-based techniques that create highly conductive macroporous scaffolds to produce structures with different length scales for electrolyte diffusion (macro and mesopores) and dye loading (micro and nanopores); and finally (5) hybrid TiO2/graphene nanostructures able to suppress electron recombination in the semiconductor/electrolyte interface, increasing the electron mobility and extraction and also able to enhance light absorption, ultimately increasing the DSC performance.

Nowadays, the production of hydrogen has received increased attention due to its important industrial applications and to its promising potential as an alternative energy source. The use of hydrogen in fuel cell applications requires a high purity. In this work, hydrogen purification from mixtures that also contain CO2, CO, CH4, and N2 was performed by Pressure Swing Adsorption (PSA) with CuBTC as adsorbent (supplied by KRICT). The equilibrium adsorption of each pure gas was measured and fixed-bed adsorption experiments were carried out. The same column, employed for the fixed-bed breakthrough curves, was used to carry out experiments of a 4-step PSA cycle. A mathematical model of multicomponent adsorption in fixed bed was developed. This model was validated against the results obtained in breakthrough experiments and PSA tests, presenting a good prediction of the experimental data. Therefore, this model can be used as a base for the design of optimized PSA cycles.

This paper aimed to monitor the nitrogen compounds and total phosphorous in the Maringá Stream watershed in order to investigate the spatial and temporal variations in the water quality. For this, samplings were collected from seven sites during the period from October 2008 to September 2009. The results indicated the most critical stretches of water pollution with the inflow of the discharges from a sewage treatment plant of the city. Also it is important to highlight the influence of diffuse pollution coming from agricultural runoff and wastewater from fishing lakes, on the water quality.

A meso oscillatory flow reactor (OFR) was successfully applied for the precipitation of hydroxyapatite (HAp) nanoparticles. Mixing efficiency of the mesoreactor operated batchwise in a vertical tube was evaluated at constant power density, by monitoring variation of hue values upon mixing both spatially and temporally. The best operating conditions for fast mixing and a more homogeneous reaction medium were verified for f = 0.83 Hz and x0 = 4.5 mm. HAp precipitation was then carried out under these conditions at 37 °C for different mixing Ca/P molar ratios. HAp nanoparticles with a mean size (d50) of about 67 nm and a narrow size distribution were obtained. Furthermore, the obtained results show the advantages of the meso-OFR over a stirred tank batch reactor due to the production, about four times faster, of smaller and more uniform HAp nanoparticles. © 2013 American Institute of Chemical Engineers AIChE J, 2013, This work was supported by the Portuguese Foundation for Science and Technology (SFRH/BD/42992/2008) through the MIT-Portugal Program, Bioengineering Systems Focus Area. The authors are thankful to Dr Jorge Ferreira from LNEG (Laboratorio Nacional de Energia e Geologia, Portugal) for carrying out the X-ray measurements and his help with the interpretation of results.

Microbial fuel cells (MFCs) are a promising technology for electricity production from a variety of materials, such as natural organic matter, complex organic waste or renewable biomass, and can be advantageously combined with applications in wastewater treatment. The problem with MFCs is that they are technically still very far from attaining acceptable levels of power output, since the performance of this type of fuel cells is affected by limitations based on irreversible reactions and processes occurring both on the anode and cathode side. However, in the last years, there has been a growing amount of work on MFCs which managed to increase power outputs by an order of magnitude. The present review article discusses a number of biological and engineering aspects related to improvement of MFC performance including the effect of important parameters, such as pH, temperature, feed rate, shear stress and organic load. The recent progresses on scale-up MFC are summarized and the different modelling approaches to describe the different biological and transport phenomena in MFCs are also provided.

Advanced oxidation processes (AOPs) have been increasingly applied to emergent pollutants degradation. Although, homogeneous reaction by classical Fenton enables amoxicillin degradation, high iron catalyst concentrations are needed, raising environmental concerns. This work proposed an innovative and cheap solution to degrade amoxicillin by combining microwave with Fenton’s reaction. The main operational parameters were optimized step-by-step (hydrogen peroxide and ferrous ion concentration and microwave power). Amoxicillin oxidation was significantly improved over classical Fenton’s reaction. In fact, in less than 5 min (P = 162 W, [H2O2]0 = 2.35 mg L−1, [Fe2+]0 = 95 μg L−1) amoxicillin was no longer detected in the reaction system. A semi-empirical kinetic model was proposed to predict the two-stage decay curves at any conditions within the studied parameters and the adequacy of the model was statistically evaluated.

The large volume of sugar cane vinasse generated by alcohol distillation motivated current treatment to reduce vinasse volume by a concentration process and to eliminate pollutants in the wastewater. The vinasse concentration by the coagulation/flocculation process favored the use of the thickened sludge either for fertilizing purposes or for biogas production. The photocatalysis treatment of the clarified vinasse mineralized pollutants and reduced toxicity, with subsequent water reuse. The first series of coagulation/flocculation experiments were carried out in a jar-test apparatus at room temperature with samples of 200 mL and several coagulant concentrations. In the second series of experiments, photocatalysis tests were performed on the clarified vinasse obtained by coagulation/flocculation under conditions optimized in the first series of experiments. The photocatalysis tests were performed for five consecutive days with UV irradiation, using TiO2-P25 as photocatalyst. Significant reduction of toxicity, consistent with the reduction in chemical oxygen demand (COD), was found when the photocatalysis treatment subsequent to coagulation/flocculation process was employed. Further, 98% reduction of turbidity and 87% reduction of color were obtained by the coagulation/flocculation process. Coupled to the photocatalysis process, significant reductions in absorbance, toxicity and COD (80%) were also achieved.

Adsorption equilibrium isotherms for propane and propylene on a new 13X zeolite from CECA were measured at three temperatures (323, 373, 423 K) up to 5 bar. Maximum capacities of 3.47 and 3.08 mol/kg were found for propylene and propane, respectively. These values are significantly higher than those reported in literature. Adsorption isotherms were fitted with Toth equation. Heats of adsorption were calculated as a function of loading from experimental data with Van’t Hoff equation leading to 53 kJ/mol and 35 kJ/mol for propylene and propane, respectively; values were also obtained from fitting with Toth equation. Single and binary breakthrough curves were measured and simulated with a mathematical model for fixed bed adsorbers. A 5-step VSA cycle was also simulated to produce 99.5% propylene from a 25:75 propane/propylene mixture; experimental validation confirms a good prediction. Propylene was obtained with a purity of 99.54%, a recovery of 85% and a productivity of 1.46 molC3H6/kgads/h.

Adequate water management is crucial to increase stability and durability of Polymer Electrolyte Membrane Fuel Cells. In this paper, a test rig suitable for water balance and nitrogen crossover studies was built around a hydrogen‐air segmented cell and used to indirectly assess flooding or drying conditions in specific zones of the active cell area. In particular, the anode of the segmented cell was operated in recirculation mode with continuous water removal. Current density distribution (CDD) diagrams were obtained for different anode operating parameters, namely, the recirculated gas flow rate, anode pressure, and time between purges. Water accumulation at the electrodes was assessed from CDD diagrams and confirmed using water balance and flow‐patterns calculations. It was concluded that lower recirculation flow rates led to flooding due to decreased water removal capabilities at the anode. For higher recirculation flow rates, drying was observed in one zone of the cell but homogeneous CDD in the other. Finally, the use of partially segment bipolar plates was proposed to increase the in‐plane electrical resistance between adjacent segments. The partial segmentation increased the segment to segment in‐plane electrical resistance between 14 and 21% and decreased the through‐plane to in‐plane resistance ratio by 17%.

This study investigated the optimization of time of coagulation, flocculation, and sedimentation of the chemical coagulant, aluminum sulfate and natural coagulant, Tannin. It was performed an economic analysis of the process, checked the removal efficiency of color, turbidity, COD, and treatment characterization using metals, BOD5, and total solids. The tests were conducted in Jar Test, using different mixing and sedimentation times. The time required to provide the rapid and slow mixing were 2 and 20 minutes, respectively, for the investigated coagulants, with optimum concentration of 400 mg L-1 for Tannin and 600 mg L-1 for Aluminum Sulfate. For the analyzed parameters, the percentage of removal, according to the best optimization test were 93.12, 99.06 and 99.29% for COD, color, and turbidity, respectively, using the coagulant aluminum sulfate, and 94.81, 99.17 and 99.65% for COD, color and turbidity, respectively, using the coagulant Tannin.

The use of single wall nanohorns (SWNH) as electrocatalyst support has proved to increase the performance of polymer electrolyte membrane-based fuel cells. In order to investigate in more detail such behavior, the electrochemical characterization of SWNH based electrodes was performed. The use of SWNH in vapour phase high temperature direct methanol fuel cells (HT-DMFC) was also addressed. Cyclic voltammetry experiments have indicated a higher electrochemical activity towards methanol electro-oxidation and a higher tolerance to carbonaceous species accumulation for a SWNH based electrode than for carbon black and commercial corresponding ones. Carbon black electrode presented a better performance than SWNH one for oxygen reduction reaction at low current densities while, at higher overvoltages, SWNH electrode performed better. The exact role of the improved performance of SWNH based electrodes is yet not clear but may be related to a higher water vapour adsorption or electrode morphology. Vapour phase HT-DMFC operation showed the improved performance of the SWNH electrode in agreement with previous works and with the electrochemical characterization performed during this work; despite the higher ohmic resistance observed in comparison with the carbon black based electrode. Moreover, SWNH based electrode showed improved fuel cell stability during longer operation times.

Due to several factors caused by urban and industrial growth worldwide, water supply problems have become increasingly complex, with difficult and costly solutions. The use of membrane filters is one of the newest unit operation options being incorporated into the water and sewage treatment process. This work involves the study of the production of a polymeric asymmetric porous membrane to be used in the removal of possible abiotic or biological contaminants remaining after the post-treatment of drinking water, as well as the assessment of the membrane life span. The phase inversion process was used to produce the membrane, using a polymer solution consisting of polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA), and NN-Dimethylformamide as a solvent. KCl salts were incorporated as additive, and a polyester polypropylene sheet was used as support. The membrane was tested in a transverse flow module. The tests demonstrated that the membrane presented an effective barrier to abiotic contaminants, with an average flux of 342 kg h-1 m-2 and life span of 48h

A general hybrid semi-parametric process control framework is proposed in this study. The motivation was the integration of different levels of knowledge systems into a general hybrid semi-parametric control structure, of which the general linear controller or the PID controller are, for instance, particular cases. Several hybrid semi-parametric control structure variants and tuning methods are benchmarked in relation to a simulated bioprocess control problem, namely closed-loop control of the biomass concentration through manipulation of the substrate feeding rate, coupled with the closed-loop control of the dissolved oxygen concentration through the stirring velocity. The results demonstrate that (i) due to the hybrid approach the control loop can be closed without any additional identification experiments; (ii) the incorporation of different types of knowledge can enhance the controller performance, when compared to structures without a priori knowledge; (iii) knowledge incorporation seems to facilitate the tuning of the controller; and (iv) the control action can be analyzed in relation to structural information incorporated into the hybrid controller.

In this work an iron MOF, MIL-100(Fe) is proposed as a plausible adsorbent to carry out C3/C4 separation by adsorption. The adsorption equilibrium of pure propane, propylene and isobutane over MIL-100(Fe) was studied by means of a magnetic suspension balance in a wide range of temperature and pressure (323–423 K and 0–500 kPa). Propane and propylene present nearly linear isotherms at high temperature, while isobutane present steeper isotherms at low pressures, showing higher adsorption capacity than that of propane and propylene in most of the studied range. Multicomponent fixed-bed adsorption experiments confirmed the preferential adsorption of isobutane over propane and propylene, with an adsorption separation factor of 3. A non-isothermal, non-adiabatic, bidisperse mass transfer model that describes satisfactorily the single and multicomponent breakthrough experiments is proposed.

This study aimed to track the spatial and temporal variations of toxic chemical compounds, such as the metals Al, Cd, Pb, Cu, Cr, Mn, Zn and the pesticide glyphosate, in Maringá stream and in a stretch of Pirapó river. The results pointed out that, in the case of metals, one of the possible sources of these elements is associated to agricultural activities. For glyphosate, were not found concentrations above those established by the Brazilian Water Quality Legislation (CONAMA 357/2005). Concerning this, we emphasized that the impact caused by the agrochemical on water quality should be evaluated considering the adverse effects to the environment caused by its degradation, that produces recalcitrant and surfactant compounds that may be even more toxic for humans and aquatic environment.

Cu-BTC MOF is an appealing candidate to carry out propane/propylene separation by adsorption due to its high adsorption capacity and propylene selectivity. In this work a new sample of Cu-BTC, synthesised and shaped into spheres by the Korean Research Institute of Chemical Technology (KRICT) is studied for this commitment. The sample under evaluation presents the highest propylene specific adsorption capacity known up to date for a shaped material (up to 8 mol kg −1 of dry adsorbent at 323 K). A mathematical model is proposed that adequately describes breakthrough experiments. This model has also been used to simulate an experimental 5-step VSA cycle conceived to produce polymer grade propylene. Although this cycle presents low recoveries, the validated model can be used as a base for VPSA design.

This paper studies alternative catalysts to ammonium sulfate for curing urea-formaldehyde (UF) resins. When using a latent catalyst like ammonium sulfate, hexamine is formed as by-product of curing reaction. It is believed that hexamine hydrolysis may contribute to formaldehyde release during the life-time of wood-based panels produced with UF resins. Orthophosphoric acid, on the other hand, catalyzes resin cure without by-product formation and was compared to ammonium sulfate. The pot-life of adhesives with both catalysts was evaluated at 40 °C with a Brookfield rheometer. Mechanical resistance tests performed with ABES (Automated Bonding Evaluation System) showed that orthophosphoric acid effectively catalyzes UF resin cure. Particleboards were produced using both catalysts and the most important properties evaluated, according to European Standards: formaldehyde content, internal bond, moisture content, thickness swelling and density. Particleboards cured with orthophosphoric acid and stored under forceful conditions of humidity and temperature presented similar internal bond and lower formaldehyde content than those produced with ammonium sulfate.

Stand-alone graphene-based films were prepared from graphene oxide (GO) nanoplatelets and their use as counter-electrodes (CEs) in dye-sensitized solar cells (DSCs) was investigated. The graphene-based CEs were produced by spray deposition of GO and chemically reduced GO, followed by thermal annealing under an inert atmosphere. These GO-based CEs were shown to have similar transparency as a reference CE made of Pt. Consistent with impedance data from symmetrical half-cells, DSCs assembled with such GO-based CEs exhibited relative efficiencies of ca. 75% comparatively to the reference Pt CE. The possibility of obtaining transparent (transmittance higher than 80%) and reasonable catalytic films for DSCs (energy conversion efficiency of 2.64%) from GO nanoplatelets was demonstrated. The need for reduction of the graphene oxide nanoplatelets prior to deposition was not observed, allowing for a simplified CE manufacturing process. However, further work is still needed to equal or surpass the performance of Pt CEs.

A new effective sealing method was developed for application in dye-sensitized solar cells. The sealing method employs a cord of a low temperature fusing glass frit paste that bounds the entire perimeter of the substrate. The glass precursor was heated to its melting point assisted by a laser beam, allowing the two substrates of the cell to be completely sealed. In the present work, the feasibility of this laser assisted glass paste sealing process is investigated and the best laser operating conditions are determined. Different tests were performed to the sealed samples at optimized sealing conditions and conclusions drawn. The glass-sealed samples were compared with results from conventional sealing based on commercial thermoplastics sealants. The results obtained from leakage, temperature and strength tests showed that the glass-sealing technique is better than the conventional method.

Over the past few years, antibiotics have been considered emerging pollutants due to their continuous input and persistence in the aquatic ecosystem even at low concentrations. They have been detected worldwide in environmental matrices, indicating their ineffective removal from water and wastewater using conventional treatment methods. To prevent this contamination, several processes to degrade/ remove antibiotics have been studied. This review addresses the current state of knowledge concerning the input sources, occurrence and mainly the degradation and removal processes applied to a specific class of micropollutants, the antibiotics. In this paper, different remediation techniques were evaluated and compared, such as conventional techniques (biological processes, filtration, coagulation, flocculation and sedimentation), advanced oxidation processes (AOPs), adsorption, membrane processes and combined methods. In this study, it was found that ozonation, Fenton/photo-Fenton and semiconductor photocatalysis were the most tested methodologies. Combined processes seem to be the best solution for the treatment of effluents containing antibiotics, especially those using renewable energy and byproducts materials.

In this work, we present simulation-based predictions of the absolute hydration energy for several simple polar molecules with different functional groups, as well as for more complex multifunctional molecules. Our calculations were performed using the thermodynamic integration methodology where electrostatic and non-polar interactions were treated separately, allowing for a stable transition path between the end-points of the integration. An appropriate methodology for the analytical integration of the simulation data was applied. We compare the performance of three popular molecular mechanics force fields: TraPPE. Gromos and OPLS-AA for the description of solute atoms in MSPC/E water. It is observed that these force fields generally perform well for the simpler molecules, but are less accurate when multifunctional molecules are considered.

In this work, mutual solubilities of two [PF6]-based ionic liquids (ILs) with water and their thermophysical properties, namely, melting properties of pure ILs and densities and viscosities of both pure and water-saturated ILs, were determined. The selected Its comprise 1-methyl-3-propylimidazolium and 1-methyl-3-propylpyridinium cations combined with the anion hexafluorophosphate. Mutual solubilities with water were measured in the temperature range from (288.15 to 318.15) K. From the experimental solubility data dependence on temperature, the molar thermodynamic functions of solution, such as Gibbs energy, enthalpy, and entropy of the ILs in water were further derived. In addition, a simulation study based on the COSMO-RS methodology was carried out. For both pure ILs and water-equilibrated samples, densities and viscosities were determined in the temperature interval between (303.15 and 373.15) K. The isobaric thermal expansion coefficients for pure and water-saturated ILs were calculated based on the density dependence on temperature.