This study aimed to develop PSU membranes by adding different concentrations (zero, 0.5, 1.0, and 1.5 wt.%) of graphene nanoplatelets (GNP) during synthesis to evaluate the influence of GNP on ...membrane permeability, retention capacity, mechanical and chemical resistance, structure, and membrane chemistry. All produced membranes had a hydrophilic character, which reduced with the increase in GNP content (72.4° to 84.4°) and a decrease in thickness (200.8 µm to 109.3 µm). Adding GNP did not affect the membranes' mechanical properties and chemical resistance. GNP addition increased the compaction time (from 5.35 h to 35.62 h) and reduced membrane permeability (from 6.78 L∙m
−2
∙h
−1
∙bar
−1
to 0.10 L∙m
−2
∙h
−1
∙bar
−1
) of pure water. The obtained membranes were classified as ultrafiltration membranes, with an egg albumin retention rate (45 kDa) above 80 %. A greater retention of egg albumin was observed with the highest amount of GNP (1.5 wt.%). Adding GNP stabilized the polymeric matrix (PSU) properties, including increased chemical and mechanical resistance, interaction between the polymer and the nanofiller, and hydrophobic characteristics with a smaller thickness. This study contributed to Brazilian research in membrane synthesis, promoting the investigation of outstanding materials in the field of nanotechnology, in particular, the use of GNP as an additive in the preparation of mixed matrix membranes for water treatment.
The objective of this study was to develop non-supported and PET-supported chitosan membranes that were cross-linked with glutaraldehyde, then evaluate their physical–chemical, morphological, and ...mechanical properties, and evaluate their performance in the separation of ethanol/water and limonene/linalool synthetic mixtures by hydrophilic and target-organophilic pervaporation, respectively. The presence of a PET layer did not affect most of the physical-chemical parameters of the membranes, but the mechanical properties were enhanced, especially the Young modulus (76 MPa to 398 MPa), tensile strength (16 MPa to 27 MPa), and elongation at break (7% to 26%), rendering the supported membrane more resistant. Regarding the pervaporation tests, no permeate was obtained in target-organophilic pervaporation tests, regardless of membrane type. The support layer influenced the hydrophilic pervaporation parameters of the supported membrane, especially in reducing transmembrane flux (0.397 kg∙m−2∙h−1 to 0.121 kg∙m−2∙h−1) and increasing membrane selectivity (611 to 1974). However, the pervaporation separation index has not differed between membranes (228 for the non-supported and 218 for the PET-supported membrane), indicating that, overall, both membranes had a similar performance. Thus, the applicability of each membrane is linked to specific applications that require a more resistant membrane, greater transmembrane fluxes, and higher selectivity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This study was carried out to evaluate the agronomic potential of elephant grass biomass (
Pennisetum purpureum
Schum) biochar obtained through slow pyrolysis using a semi-continuous pilot screw ...reactor in the absence of a carrier gas, and under different conditions. The biomass was pyrolyzed with temperature ranging between 400 and 600 °C. The products (biogas/biochar/bio-oil) yields were evaluated. With increasing temperature, there was a decrease in biochar yield, however, the bio-oil yield was relatively constant. Different physicochemical properties of the biochar were evaluated, and the biochar was incubated in the soil for 60 days. After the incubation period the mixture of soil and biochar underwent analysis to determine soil fertility. The biochar produced presented an elevated content of micro and macronutrients, as well as high pH. Agronomic tests showed that biochar presented great potential to be used as an auxiliary liming agent, and as a fertilizer.
The use of artificial lighting in a total or supplementary way is a current trend, with growing interest due to the increase in the global population and climate change, which require high-yield, ...quality, and fast-growing crops with less water and a smaller carbon footprint. This experiment aimed to evaluate the effect of light-emitting diode (LED) lighting on the production of basil, mustard, and red cabbage seedlings under controlled artificial conditions and in a greenhouse as a supplementary lighting regime. Under controlled conditions, the experiment was conducted with basil seedlings, comparing LED light with two wavelengths (purple and white light). In a greenhouse, mustard and red cabbage seedlings were evaluated under natural light (regular photoperiod) and with supplementary purple lighting of 3 h added to the photoperiod. The variables assessed were aerial fresh mass (AFM), aerial dry mass (ADM), root dry mass (RDM), plant length (PL), and leaf area (LA). Basil seedlings grown under purple light showed greater length and AFM than those grown under white light, with no effect on the production of secondary metabolites. In the greenhouse experiment, red cabbage seedlings showed an increase in AFM, ADM, and DRM with light supplementation, with no effect on LA. AFM showed no statistical difference in mustard seedlings, but the productive parameters LA, ADM, and DRM were higher with supplementation. None of the evaluated treatments influenced the production of phenolic compounds and flavonoids in the three species evaluated. Light supplementation affected red cabbage and mustard seedlings differently, promoting better development in some production parameters without affecting the production of phenolic compounds and flavonoids in either plant. Thus, light supplementation or artificial lighting can be considered a tool to enhance and accelerate the growth of seedlings, increasing productivity and maintaining the quality of the secondary metabolites evaluated. Thus, this technology can reduce operational costs, enable cultivation in periods of low natural light and photoperiod, and cultivate tropical species in temperate environments in completely artificial (indoor) conditions.
This study aimed to evaluate the extraction of Corymbia citriodora (Hook.) K.D.Hill and L.A.S.Johnson essential oil by steam distillation under reduced pressure. Yield and composition of the ...essential oils obtained at different system pressures were analyzed. System pressure had a significant influence on essential oil yield, resulting in a reduction of 78.6% when the pressure was reduced from 690 Torr to 240 Torr. There were also changes in essential oil composition, with an increase in citronellol content (oxygenated monoterpene). However, the major compound (citronellal) remained at a high content in all tests. Regarding the extracted mass of the major compounds (citronellal, citronellol), there was a significant reduction for all when the system pressure was reduced. Although the reduction in the pressure of the system caused a reduction in oil yield, it was possible to carry out the steps of extraction and purification of the major compound simultaneously. Reduced pressure extraction may decrease process time, increasing its efficiency and reducing costs in the extraction of essential oils.
The production of seedlings is one of the main activities for implementing agricultural crops. Many factors are involved in producing quality seedlings, including nutrition, health, genetics, and ...climatic factors such as temperature, humidity, and light. To evaluate the effect of light supplementation, a study was conducted using supplementary artificial light to produce lettuce and cauliflower seedlings. Sowing was carried out in styrofoam trays under a floating irrigation system. Part of the experiment containing the two species, received treatment with LED light for an additional 4 h per day, in addition to solar radiation (10 h∙day−1). The remaining seedlings received only solar radiation (without supplementation). After 37 days, the seedlings’ biometric (leaf area, root length, aerial dry mass, and root dry mass) and biochemical parameters (phenolic compounds, flavonoids, chlorophyll a/b, and total chlorophyll) were analyzed. The data showed that the complementary light enhanced the performance in all the biometric parameters evaluated in the experiment for lettuce and cauliflower. The biochemical parameters in lettuce were also higher in seedlings with light supplementation. For cauliflower, supplementary light did not differ from the natural photoperiod for biochemical parameters except for a reduction in the levels of total phenolic compounds. Considering the enhanced biometric and biochemical parameters and greater dry weight and leaf area of the seedlings grown with supplemental light, using such a tool can optimize seedling development, possibly reducing production time in the nursery and providing greater productivity.
Abstract The development potential of byproducts from wastes of grape processing can be a promising alternative due to environmental questions. Moreover, there is the possibility of using this ...material in the development of products with added value. In this study, the wastes of grape skin (GSk), grape seed (GSe), and defatted grape seed with skin fragments (DGS) from ‘Ives noir’ grape (Vitis labrusca L.), grown under organic farming conditions, had their chemical composition and physical-chemical properties evaluated. Parameters of chemical composition, contents of phenolic compounds, total anthocyanins, flavonoids, and minerals, the antioxidant capacity, and water sorption capacity were evaluated. The wastes of grape were also analyzed by FTIR and TG/DTG. All residues had a high fiber content (54.1 - 74.3 wt.%), the DGS waste had the highest contents of phenolic compounds as flavonoids, and the GSk waste had the highest content of total anthocyanins. Antioxidant capacity values were higher in the ABTS+ method, with no statistical difference. On the other hand, in the DPPH antioxidant assay, the DGS and GSe wastes had higher antioxidant activity; these wastes also had greater thermal stability. The GSk waste had the highest water sorption capacity. The results show that the wastes from grape processing have the potential to be reused in applications with more value added.
Rosemary essential oil has many compounds suitable for use in the food, cosmetics and pharmaceuticals industries. This study aimed to evaluate vacuum fractional distillation to separate and purify ...components of rosemary oil, also to observe the distillation patterns. The light terpenes (α-pinene, myrcene, camphene) were removed at the top of the column, while the oxygen containing components (verbenone, borneol, linalool, geraniol) remained at the bottom. The concentrations of some minor compounds increased more than ten times (borneol, geraniol) compared with the raw oil. There was no evidence of thermal degradation in any of the experiments. Therefore, vacuum fractional distillation may be an interesting process to upgrade rosemary essential oil.
Whey is a byproduct of the dairy industry, obtained during the manufacture of cheese and casein. It is a promising feedstock for the food industry due to the functional and nutritional properties of ...its proteins. Ultrafiltration (UF), associated with diafiltration (DF), has been used in the industry to produce whey protein concentrates. This technology allows for a selective concentration of the proteins. The objective of this work was to concentrate and purify whey protein using UF and DF, also proposing a modeling scheme to maximize the process profit. The results obtained were used to estimate the parameters of a theoretical model aiming to optimize the UF/DF process. The protein content, according to the data from the simulation, would reach 98.6 wt.%, representing a final profit of US$ 81.00 per kilogram of product. Experimentally, to produce a product with a protein content of 70.0 wt.% (42 kg·m
−3
), up to 40 L of effluent can be produced. The results of the theoretical model reported that 67 L of effluent is generated when a product with a protein content of 98.6 wt.% (59 kg·m
−3
) is obtained. In this sense, despite the increase in effluent generation, the UF-DF coupled process, according to the model, may increase protein content to 98.6 wt.%, greatly increasing process profitability relative to a modest increase in effluent treatment cost.
Abstract Whey, a by-product of dairy industry, is a feedstock widely employed in the production of biodegradable films. However, these films present some limitations when considering the performance ...of synthetic polymers, especially biological transformation by decomposition. This work aimed to evaluate the effects of chitosan addition to whey-based films to improve films physical-chemical properties and resistance to microbial degradation. The results showed that there was an interaction effect between the chitosan concentration and the storage time for the physical-chemical properties of elongation at break and opacity. There was statistical difference among the formulations; however, for the moisture content and film thickness, there was no interaction effect between the formulation and the storage time. The films with 1.5 and 3.0 wt.% chitosan presented a yellowish hue, characteristic of the polysaccharide; this could also be detected by SEM analysis. The films presented an excellent biodegradability, being decomposed in about 8 days. Considering all chitosan contents tested had similar performances, the chitosan content of 0.15 wt.% was the one with the better cost-benefit relation.
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