MCM-41 and MCM-48 with niobium were successfully synthesized using 1-tetradecyl-3-methylimidazolium chloride (C
14
MICl) as a structure-directing agent. The best Si/Nb molar ratio was chosen (Si/Nb = ...20) and the CALB enzyme was immobilized in situ in the synthesized Nb-MCM. SEM micrographs showed the formation of very regular spherical agglomerates with a diameter between 0.25 and 0.75 μm. The material presented a surface area of 954 and 704 m
2
/g and a pore volume of 0.321 and 0.286 cm
3
/g, for Nb-MCM-41 and Nb-MCM-48, respectively. Also, both materials showed a pore size of 2.261 nm. The number of recycles obtained for the CALB enzyme immobilized in Nb-MCM-41 and Nb-MCM-48 was 26 recycles with a residual activity of 49.62% and 16 recycles with a residual activity of 53.01%, respectively. For both materials, enzymatic activity remained stable for 5 months of storage at room temperature and refrigeration. The supports were able to catalyze the esterification reaction at 40, 60, and 80 °C, showing industrial application in reactions that require high temperatures. This methodology allows the preparation of new highly active and selective enzyme catalysts using niobium and C
14
MICl. Also, the new materials can provide greater viability in processes, ensuring a longer service life of catalysts.
Graphical abstract
Oil emulsified in water is one of the most difficult mixtures to treat due to the good stability of emulsions, so there is a growing demand for more efficient methods for separating immiscible ...oil/water mixtures. In this context, the focus of this study was to obtain an adsorbent for the selective treatment of a simulated oily wastewater. To this aim, a modified hydrotalcite sample with hydrophobic and magnetic characteristics was prepared and characterized. Initially, the effect of sodium dodecyl sulfate (SDS) amount on the adsorbent characteristics was evaluated (266-800 mg
SDS
g
−1
LDH
). The hydrophobic hydrotalcite (LDH-SDS) containing 533 mg
SDS
g
−1
LDH
(LDH-SDS2) presented a higher interlayer space where the surfactant molecules were arranged perpendicular to the lamellae, allowing better access to the hydrotalcite pores and facilitating the selective adsorption of oil compounds. Moreover, the synergistic association of hydrophobic properties with super-wetting and effective adhesion oil to Fe
3
O
4
favoured the selective adsorption of the simulated oily wastewater onto the hydrophobic and magnetic hydrotalcite (LDH-MSDS), facilitating the post-treatment separation. The kinetic analysis demonstrated that the adsorption equilibrium was attained in 120 min and the pseudo-second order model was the most suitable for predicting the removal of total organic carbon (TOC) from the simulated oily wastewater. The Langmuir model described very well the equilibrium experimental data, with a maximum adsorption capacity for TOC removal using LDH-MSDS of 659.9 mg g
−1
. Therefore, the modified hydrotalcite prepared in this study showed intrinsic characteristics that make it a promising adsorbent for the selective treatment of oily wastewaters.
MCM-48 mesoporous support was synthesized with the ionic solid 1-tetradecyl-3-methylimidazolium chloride (C
14
MICl) as a structure-directing agent for in situ immobilization of
Candida antarctica
B ...(CALB). The MCM-48C
14
MICl support showed characteristics of mesoporous material of interest, with a pore size of 20.30 and 73.41 A for the support without and with the enzyme, respectively. The elongation of the carbonic chain of the ionic solid directly influenced the increase in the specific area and pore volume of the material. In addition, the decrease in the specific area and pore volume for support with the enzyme showed the effectiveness of immobilization in situ. It was possible to obtain the ideal levels for the best activities of esterification of the enzyme with optimization of a mathematical model. The optimized variables were 0.31 g of enzyme and 3.35% of ionic solid with a maximum esterification activity of 392.92 U/g and 688% of yield. The support showed residual activity above 50% when stored under refrigeration for 75 days. At 60 and 80 °C, the enzyme immobilized on the support retained more than 80 and 40% of its residual activity, respectively. In addition, the support presented the possibility of reuse for up to 10 cycles with residual activity of approximately 50%. The support synthesized in the present study presents a great industrial opportunity for the immobilization and use of the CALB enzyme.
Zeolites are microporous materials with tetrahedral three-dimensional structure; such structure allows the transfer of material through its pores, but small pores prejudice such transfer. One way to ...overcome these problems is the development of materials combining microporous and mesoporous structures. This study reports the synthesis at room temperature of hierarchical materials, ZSM-5/MCM-48, ZSM-35/MCM-48, ZSM-5/MCM-41 and ZSM-35/MCM-41, from ZSM-5 and ZSM-35 seeds, using ionic liquid (1-hexadecyl-3-methylimidazolium) as supramolecular template. Infrared spectroscopy and attenuated total reflectance analyses confirmed the formation of the materials through the presence of bands at 1220 and 1070 cm
−1
. SAXS analyses showed that most of the materials have surface fracture dimensions (3 ≤
α
< 4), except the sample MCM 41/ZSM 5, having a mass fractal structure. Signals in the high-angle region correlated with XRD analysis, confirming the formation of the materials. TGA analysis shows that ionic liquid decomposition occurs at higher temperatures when the ionic liquid is within the material. Finally, the results obtained by textural analysis via N
2
adsorption agreed with data reported in the literature.
This study aimed to evaluate the effects of adding probiotic culture (Bifidobacterium animalis subsp. Lactis Bb-12) and prebiotics (fructooligosaccharide - FOS) to yoghurt formulations stored at 4°C ...for 28 days, using an experimental design (independent variables: (0-3% of FOS and probiotic starter cultures 0-3%). The pH, acidity, fat, syneresis, protein, ºBrix, sugars, FOS and probiotic bacteria count were analyzed. The probiotic- and prebiotic-added yoghurt formulations showed lower acidity, syneresis and glucose than the control yoghurt and compared to formulations containing probiotic and prebiotic separately. The 3% probiotic and prebiotic formulation showed a lower loss of concentration of FOS, and after 28 days presented 1.5g of FOS per 100g (0.3% kestose, 0.7% nystose, 0.5% fructosyl-nystose). Furthermore, the addition of prebiotics exerted a protective effect on probiotic bacteria, enhancing their survival.
RESUMO: Este estudo teve como objetivo avaliar os efeitos da adição de cultura probiótica (Bifidobacterium animalis subsp. Lactis Bb-12) e prebióticos (fructooligosacarídeo - FOS) a formulações de iogurte armazenadas a 4°C por 28 dias, utilizando um planejamento experimental (variáveis independentes: (0-3% de FOS e cultura probiótica starter 0-3%). Foram analisados pH, acidez, gordura, sinérese, proteína, ºBrix, açúcares, FOS e contagem de bactérias probióticas. As formulações de iogurte adicionado de probiótico e prebiótico apresentaram menor acidez, sinérese e glicose quando comparados ao iogurte controle e também em comparação com as formulações contendo probiótico e prebiótico sozinhas. A formulação com 3% de probiótico e prebiótico apresentou menor perda de concentração de FOS e, após 28 dias, apresentou 1,5g de FOS por 100g (0,3% de kestose, 0,7% de nystose , 0,5% de fructosil-nistose). Além disso, a adição de prebióticos exerceu um efeito protetor sobre as bactérias probióticas e aumentou a sua sobrevivência.
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•Benzyl cinnamate production was optimized by enzymatic esterification.•The lipase NS 8011 showed efficiency and stability until the 13th cycle.•Benzyl cinnamate showed antioxidant ...activity and toxicity against Artemia salina.
In this work was optimized the production of benzyl cinnamate by enzymatic catalysis using the immobilized lipase NS88011 and to evaluate its biological properties. The optimized condition for this system was 1:3 (acid:alcohol) molar ratio, 59 °C, biocatalyst concentration 4.4 mg.mL−1 for 32 h, with a yield of 97.6 %. The enzyme stability study showed that the enzyme remains active and yields above 60 % until the 13th cycle (416 h), presenting a promising half-life. In the determination of the antioxidant activity of the ester, an inhibitory concentration necessary to inhibit 50 % of the free radical 2,2-diphenyl-1-picryl-hydrazyl DPPH (IC50) of 149.8 mg.mL−1 was observed. For acute toxicity against bioindicator Artemia salina, lethal doses (LD50) of 0.07 and 436.7 μg.mL−1 were obtained for the ester and cinnamic acid, showing that benzyl cinnamate had higher toxicity, indicating potential cytotoxic activity against human tumors.
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•Treatment of a real swine wastewater was studied with continuous flow EC.•Current density is the most important process variable for both Al and Fe electrodes.•Removal of turbidity ...and TP using Al and Fe electrodes.
Electrocoagulation (EC) is a process of hydroxides generating by passing electric current through electrodes of aluminum and/or iron, to remove impurities in some effluent. Thus, this study investigated the EC process for turbidity and total phosphorus (TP) removal of swine wastewater. For this purpose, two central composite rotatable design (CCRD) 22 were applied aiming at investigating the effects of current density (CD) (16.3–57.5mA/cm2) and the hydraulic retention time (HRT), where different times were evaluated for the aluminum electrode (31.8–88.2mL/min) and for iron electrode (61.8–118.2mL/min). The removals of turbidity using aluminum and iron electrodes were of 91%. For aluminum electrode the removals of TP were 93% and for iron were 96%. The central composite rotatable design showed that the current density (DC) is the most important process variable for both electrode materials (Al and Fe) evaluated, since the removal efficiency was enhanced with increasing CD. The hydraulic retention time (HRT) had no significant effect. For aluminum electrode the energy and electrode consumption was of 2.2–15.3kWh/L and of 0.56–2.01g, respectively. For iron electrode the energy and electrode consumption was of 2.1–17.2kWh/L and of 0.74–2.77g. EC could be considered a promisor post-treatment effluent of the anaerobic digestion for the simultaneous removal of turbidity and TP. In the conditions of HRT and CD of this study, the iron electrode presented best removals efficiencies in relation to aluminum electrode.
Sol-gel technique aiming enzymatic immobilization in situ with ionic liquids as additives is poorly studied. In this process, the addition of the enzyme is carried out in the synthesis of the ...support. The characteristics of ionic liquids, such as low vapor pressure, thermal stability, and non-flammability, make them strong candidates for use as immobilization additives. The objective of the present study was to immobilize the
Candida antarctica
B lipase by the sol-gel technique using ionic liquids as additives. The optimum points determined for ionic liquids 1-butyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium bromide, and 1 hexadecyl-3-methylimimidazolium were 0.30, 0.27, and 0.22 g/mL of enzyme and 1.60, 1.52, and 1.52% of additive, respectively. The amount of enzyme and ionic liquids used in aerogel immobilization was the same as the optimized values in the xerogel immobilization process (for each ionic liquid). Ionic liquids proved to be good additives in the enzymatic immobilization process. Xerogel, regardless of the ionic liquid, presented a greater number of use cycles and better thermal stability compared to aerogel.
O uso de planilhas de ensino-aprendizagem no ensino presencial ou remoto fornece ao aluno uma nova perspectiva de ensino. Auxilia no desenvolvimento da capacidade de avaliar as possibilidades e ...variáveis do estudo em diferentes situações, uma vez que a planilha é de fácil utilização e muito versátil. O objetivo do presente estudo foi demostrar de maneira simplificada como montar uma planilha utilizando os softwares Microsoft Excel ou LibreOffice Calc para a determinação do fluxo de calor em placa plana (telhado) com os efeitos da radiação na superfície externa utilizando o método numérico da Bisseção. O exercício proposto engloba diferentes disciplinas dos cursos de Engenharia e a planilha se torna uma aliada positiva para a explicação e compreensão dos assuntos abordados. Foram mostrados todos os passos que devem ser seguidos para a montagem e realização do exercício e foi obtido um fluxo de calor de 29,4335 W/m² nas condições propostas e 71 iterações foram necessárias.
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