Produção de biodiesel via transesterificação etílica com zeólitas básicas

Soybean oil transesterification with ethanol was carried out in a batch reactor using USY zeolites modified with barium and strontium (15 wt.%) as catalysts. A series of three catalytic cycles were performed for each zeolite without any loss of activity. The biodiesel product was analyzed by HPLC and FT-Raman, and the catalysts by pyridine and CO2 adsorption. Ba/USY provided higher conversions (> 97%) than Sr/USY (< 75%). The increased catalytic activity of Ba/USY was attributed to two different effects: a larger number of basic sites; and a lower interaction between barium species and HUSY BrØnsted sites.

Rheological and thermal characteristics of wheat gluten biopolymers plasticized with glycerol

The objective this work was to obtain bioplastics from mixtures of wheat gluten and glycerol by two different processes and evaluate their respective rheological properties. The mixtures and their respective bioplastics were obtained through direct batch mixing under approximately adiabatic and isothermal conditions. The bioplastics showed high values for the storage (G') and loss (G") moduli, suggesting a stronger protein network formed in both processes. The temperature onset and the percentage of weight loss to be estimated were found to be near in both bioplastics. The bioplastics have demonstrated to be materials of interesting potential of use as biodegradable barrier materials.

Biodegradação de paclobutrazol por Pseudomonas spp. em sistemas de solo saturados

Paclobutrazol is growth regulator of plants that has low mobility in soil and therefore has accumulated. The objective of this study was to investigate the paclobutrazol biodegradation in two soils from the São Francisco River Valley. The biodegradation experiments were conducted in batch using paclobutrazol and paclobutrazol added glycerol. The experiments were performed in sterile and nonsterile conditions using a mixed culture of Pseudomonas. The concentration of paclobutrazol was determined by high performance liquid chromatography. The biodegradation reached 43% in 14 days of experiments with only paclobutrazol and 70% in 28 days of experiments that contained glycerol and paclobutrazol.

Remoção de íons Pb2+ de solução de bateria automotiva por caulinita modificada com óxido de manganês

Nine absorbents were prepared using a mixture of Amazonian kaolinite and MnO2 at three temperatures (600, 700 and 900 ºC) in order to retain Pb2+ ions contained in the battery solutions. The batch experiments carried out with the batteries used water for 3 h and the kinetic isotherm was fitted with the pseudo-second order Lagergren equation. Findings show that synthesized adsorbents AD4, AD5 and AD7 performed well in reducing the Pb2+ ion content from 0.36 to 0.00 mg g-1. The better performance for removing the Pb2+ ions occurred for adsorbents synthesized in the temperature range from 600 to 700 ºC.

Degradação de poluentes emergentes por processos Fenton e foto-Fenton

A continuous photochemical treatment system was developed for aiming the treatment of aqueous solutions containing relevant micro-pollutants (microcystin-LR, sulfamethoxazole and 17-b estradiol). The continuous photo-Fenton process provided high degradation efficiency. However, contact time between samples and the irradiated region is short relative to total treatment time, indicating that observed changes are predominantly due to the Fenton process. Higher degradation efficiency was observed in systems operated using two treatment cycles, the first involving a batch Fenton process and the second a continuous photo-Fenton treatment.

Aproveitamento da glicerina proveniente da produção de biodiesel na obtenção de híbrido de caulinita para adsorção de Cr3+

The aim of this work was to contribute to the creation of new ways of treating wastewater contaminated with Cr3+, based on solid-liquid adsorption. An adsorbent material was prepared by functionalization of kaolinite with glycerin biodiesel by-product. This material was tested for adsorption performed using a batch method, and results showed that inclusion of glycerin in the structure of kaolinite led to a significant increase in the capacity of Cr3+ adsorption. This contributes to the allocation of by-product of biodiesel and to the treatment of effluents from tanneries.

Otimização da esterificação de ácido hexanóico com n-butanol empregando lipase (Termomyces lanuginosus) imobilizada em gelatina

The application of Lipozyme (Termomyces lanuginosus) immobilized in gelatin gel in aliphatic ester synthesis was investigated taking the esterification of hexanoic acid with n-butanol as a model reaction. Conditions were optimized by factorial design and the highest conversion was obtained under the following conditions: molar ratio alcohol: acid of 2:1, reaction time of 48 h and biocatalyst weight of 7.0 g. Under these conditions the esterification yield was around 98 %. The operational stability of the immobilized lipase was assessed and results showed that after 12 batch runs, the enzyme showed no significant loss of activity.

Síntese, caracterização e atividade fotocatalítica de catalisadores nanoestruturados de TiO2 dopados com metais

Titanium dioxide nanostructured catalysts (nanotubes) doped with different metals (silver, gold, copper, palladium and zinc) were synthesized by the hydrothermal method in order to promote an increase in their photocatalytic activity under visible light. The catalysts were characterized by X-ray diffraction, diffuse reflectance spectroscopy, transmission electron microscopy and specific area and pore volume determination. The materials' photocatalytic activity was evaluated by rhodamine B decomposition in a glass batch reactor. Under UV radiation, only nanotubes doped with palladium were more active than the TiO2 P25, but the samples doped with silver, palladium and gold exhibited better results than the undoped samples under visible light.

Remoção de cromo (VI) de soluções aquosas utilizando o compósito magnético calcinado hidrotalcita-óxido de ferro: estudo cinético e de equilíbrio termodinâmico

In this work, hydrotalcite, a layered double hydroxide, had its ion exchange properties combined with the magnetic properties of iron oxide to produce a magnetic adsorbent, HT-Fe 500. These magnetic composites can be used as adsorbents for anionic contaminants in water and subsequently removed from the medium by a simple magnetic process. Removal of chromium (VI) from aqueous solutions using HT-Fe 500 was achieved using batch adsorption experiments. The adsorption capacity, calculated with the Langmuir-Freundlich model showed to be dependent on temperature, reaching values of 25.93 and 48.31 mg g-1, respectively, for temperatures of 25 and 30 ºC.

Determinação rápida de hidroquinona usando análise por injeção em batelada (BIA) com detecção amperométrica

A fast analytical method for determination of hydroquinone in pharmaceutical formulations employing batch injection analysis (BIA) with amperometric detection using a boron-doped diamond electrode is described. The supporting electrolyte was a 0.1 mol L-1 H2SO4 solution (the single reagent used for analysis). The method showed good repeatability (RSD of 0.45%, n=20), wide linear range (from 10 to 2000 µmol L-1, R=0.9999), low detection limit (0.016 µmol L-1) and satisfactory recovery values (91-96%). Accuracy of the method was evaluated by comparative analyses using high-performance liquid-chromatography. The ability to replace the electronic pipette by disposable syringes (injection procedure) in BIA systems was also shown.

Imobilização de lacase de Aspergillus sp. em quitosana e sua aplicação na bioconversão de fenóis em reatores de leito fixo

The immobilization of laccase on chitosan by cross-linking and application of the immobilized laccase in the bioconversion of phenolic compounds in batch and fixed bed reactors were studied. The process for immobilization of enzyme was optimized using a rotational central composite design. The optimized conditions to generate immobilized laccase with maximal activity were determined to be a glutaraldehyde concentration of 1.0% (v/v), a pH of 6.0, an immobilization time of 5.0 hours and an enzyme concentration of 5.2 g L-1. In packed bed reactors, the activity of the immobilized enzyme is maintained for a longer time in the bioconversion of 2,6-dimethoxyphenol than in the bioconversion of syringaldazine.

Remoção de compostos fenólicos de soluções aquosas utilizando carvão ativado preparado a partir do aguapé (Eichhornia crassipes): estudo cinético e de equilíbrio termodinâmico

Activated carbon was produced from the water hyacinth (CAA) by impregnation with ZnCl2 (1:2), followed by pyrolysis at 700 ºC, under N2. CAA was used for the adsorption of phenol, m-cresol and o-cresol from aqueous solutions, using batch adsorption. The effects of contact time, pH, temperature and concentration on sorption were investigated. Adsorption capacity, calculated using the Langmuir model proved to be dependent on temperature, reaching values of 163.7, 130.2 and 142.3 mg g-1 for phenol, m-cresol and o-cresol, respectively, at 45 ºC. Thermodynamic data at the solid-liquid interface suggests an endothermic, spontaneous and environmentally-friendly process.

Removal of Pb(II) ions and malachite green dye from wastewater by activated carbon produced from lemon peel

In the present study, a high-surface area activated carbon was prepared by chemical activation of lemon peel with H3PO4 as the active agent. Then, the adsorption behavior of Malachite green dye and Pb(II) ions on the produced activated carbon was studied. Batch process was employed for sorption kinetics and equilibrium studies. Experimental data were fitted to various isotherm models. According to the Langmuir model, the maximum adsorption capacities of Malachite green dye and Pb(II) ions were found to be 66.67 and 90.91 mg g-1, respectively, at room temperature. Kinetic studies showed the adsorption process followed a pseudo second-order rate model. The sorption kinetics were controlled by intra-particle diffusion. The results indicated that the produced activated carbon can be economically and effectively used as an adsorbent for the removal of Malachite green dye and Pb(II) ions from wastewaters.

Preparation and evaluation of magnetic chitosan particles modified with ethylenediamine and Fe(III) for the removal of Cr(VI) from aqueous solutions

The adsorption of Cr(VI) in aqueous solution by magnetic particles of crosslinked chitosan-ethylenediamine-Fe(III) (MPCh-EDA-FeCL) was studied in a batch system. Fe3+ in the MPCh-EDA-FeCL permitted that adsorption of Cr(VI) occurred with maximum efficiency between pH 3 and 11. The maximum adsorption capacity at pH 7.0 was 81.04 mg g-1 at 25 ºC. The adsorption kinetic process was described by the pseudo-second-order model. Thermodynamic parameters indicated spontaneous, exothermic and chemical adsorption nature. The adsorbent was successively regenerated using a 0.1 mol L-1 NaOH solution. Results were satisfactory for treatment of wastewater from the electroplating industry.

Design and implementation of a multipurpose reactor for scale-up studies

In the theoretical part, the different polymerisation catalysts are introduced and the phenomena related to mixing in the stirred tank reactor are presented. Also the advantages and challenges related to scale-up are discussed. The aim of the applied part was to design and implement an intermediate-sized reactor useful for scale-up studies. The reactor setting was tested making one batch of Ziegler–Natta polypropylene catalyst. The catalyst preparation with a designed equipment setting succeeded and the catalyst was analysed. The analyses of the catalyst were done, because the properties of the catalyst were compared to the normal properties of Ziegler–Natta polypropylene catalyst. The total titanium content of the catalyst was slightly higher than in normal Ziegler–Natta polypropylene catalyst, but the magnesium and aluminium content of the catalyst were in the normal level. By adjusting the siphonation tube and adding one washing step the titanium content of the catalyst could be decreased. The particle size of the catalyst was small, but the activity was in a normal range. The size of the catalyst particles could be increased by decreasing the stirring speed. During the test run, it was noticed that some improvements for the designed equipment setting could be done. For example more valves for the chemical feed line need to be added to ensure inert conditions during the catalyst preparation. Also nitrogen for the reactor needs to separate from other nitrogen line. With this change the pressure in the reactor can be kept as desired during the catalyst preparation. The proposals for improvements are presented in the applied part. After these improvements are done, the equipment setting is ready for start-up. The computational fluid dynamics model for the designed reactor was provided by cooperation with Lappeenranta University of Technology. The experiments showed that for adequate mixing with one impeller, stirring speed of 600 rpm is needed. The computational fluid dynamics model with two impellers showed that there was no difference in the mixing efficiency if the upper impeller were pumping downwards or upwards.