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1.
Water Res ; 174: 115600, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32088385

RESUMO

A hierarchically assembled superomniphobic membrane with three levels of reentrant structure was designed and fabricated to enable effective treatment of low surface tension, hypersaline oily wastewaters using direct contact membrane distillation (DCMD). The overall structure is a combination of macro corrugations obtained by surface imprinting, with the micro spherulites morphology achieved through the applied phase inversion method and nano patterns obtained by fluorinated Silica nanoparticles (SiNPs) coating. This resulted in a superomniphobic membrane surface with remarkable anti-wetting properties repelling both high surface tension water and low surface tension oils. Measurements of contact angle (CA) with DI water, an anionic surfactant, oil, and ethanol demonstrated a robust wetting resistance against low surface tension liquids showing both superhydrophobicity and superoleophobicity. CA values of 160.8 ± 2.3° and 154.3 ± 1.9° for water and oil were obtained, respectively. Calculations revealed a high liquid-vapor interface for the fabricated membrane with more than 89% of the water droplet contact area being with air pockets entrapped between adjacent SiNPs and only 11% come into contact with the solid membrane surface. Moreover, the high liquid-vapor interface imparts the membrane with high liquid repellency, self-cleaning and slippery effects, characterized by a minimum droplet-membrane interaction and complete water droplet bouncing on the surface within only 18 ms. When tested in DCMD with synthetic hypersaline oily wastewaters, the fabricated superomniphobic membrane demonstrated stable, non-wetting MD operation over 24 h, even at high concentrations of low surface tension 1.0 mM Sodium dodecyl sulfate and 400 ppm oil, potentially offering a sustainable option for treatment of low surface tension oily industrial wastewater.


Assuntos
Destilação , Purificação da Água , Membranas Artificiais , Óleos , Tensão Superficial , Águas Residuárias
2.
Environ Sci Technol ; 54(4): 2548-2555, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-31971783

RESUMO

This study compares the scaling behavior of membrane distillation (MD) with that of nanophotonics-enabled solar membrane distillation (NESMD). Previous research has shown that NESMD, due to its localized surface heating driven by photothermal membrane coatings, is an energy-efficient system for off-grid desalination; however, concerns remained regarding the scaling behavior of self-heating surfaces. In this work, bench-scale experiments were performed, using model brackish water, to compare the scaling propensity of NESMD with MD. The results showed NESMD to be highly resistant to scaling; a three times higher salt concentration factor (c/c0) was achieved in NESMD compared to MD without any decline in flux. Analyses of the scaling layer on NESMD membranes revealed that salt deposition was 1/4 of that observed for MD. Scaling resistance in NESMD is attributed to its lower operating temperature, which increases the solubility of common scalants and decreases salt precipitation rates. Precipitation kinetics measurements revealed an order of magnitude faster precipitation under heated conditions (62 °C, k = 8.7 × 10-2 s-1) compared to ambient temperature (22 °C, k = 7.1 × 10-3 s-1). These results demonstrate a distinct advantage of NESMD over MD for the treatment of high scaling potential water, where scaling is a barrier to high water recovery.


Assuntos
Destilação , Purificação da Água , Membranas Artificiais , Águas Salinas , Água
3.
Water Res ; 172: 115488, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31951948

RESUMO

The forward osmosis-membrane distillation (FO-MD) hybrid process has shown great promise in achieving zero liquid discharge in the textile industry, recovering valuable dye molecules while producing large amounts of clean water. However, the progress of this technology seems to have stagnated with the direct coupling of commercial asymmetric FO and MD membranes, because water management in the system is found to be rather complicated owing to the processing of the different membranes. Herein, we propose, for the first time, an FO-MD hybrid process using a custom-made self-standing and symmetric membrane and a hydrophobic polytetrafluoroethylene membrane in the FO and MD units, respectively. Three types of operation modes were investigated to systematically study the process performance in the concentration treatment of model textile wastewater; two commercial FO membranes were also tested for comparison. Owing to its low fouling propensity and lack of an internal concentration polarization effect, the water transfer rate of our symmetric FO membrane quickly reaches equilibrium with that in the MD unit, resulting in continuous and stable operation. Consequently, the hybrid process using the symmetric FO membrane was found to consume the least energy, as indicated by its lowest total cost in both lab- and large-scale systems. Overall, our study provides a new strategy for using a symmetric FO membrane in the FO-MD hybrid process and highlights its great potential for use in the treatment of textile wastewater.


Assuntos
Águas Residuárias , Purificação da Água , Análise Custo-Benefício , Destilação , Estudos de Viabilidade , Membranas Artificiais , Osmose , Têxteis
4.
Environ Sci Technol ; 54(3): 1867-1877, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31934752

RESUMO

This study reports distillation-based salt removal by Ohmic heating in a hybrid process, in which electrochemical oxidation (EO) and direct contact membrane distillation (DCMD) are performed sequentially. In addition to anodically destructing the organics, the hybrid process also separated the sulfate-based electrolytes from treated water through distillation, without consuming external energy, owing to the temperature of the aqueous sulfate solution being elevated to 70 °C via resistive heating. The hybrid process treated organic compounds in a nonselective fashion, whereas DCMD alone did not completely reject (semi)volatile organics. Integrating EO with DCMD made the hybrid process resistant toward the wetting phenomenon; the process exhibited a steady distillate flux and salt rejection as the initial loading of amphiphilic sodium dodecyl sulfate was increased to 0.3 mM. Anodic persulfate formation from the sulfate and Ohmic heating caused an in situ yield of the sulfate radical in the feed solution; this eliminated membrane fouling, according to the observation that the water flux, which was drastically reduced upon adding alginate, was recovered immediately after an electric current was applied. The hybrid process concurrently decomposed spiked organics and removed naturally present inorganic ions in actual flue gas desulfurization wastewater, without an external supply of electrolyte and heat energy.


Assuntos
Destilação , Purificação da Água , Impedância Elétrica , Calefação , Membranas Artificiais
5.
Chemosphere ; 238: 124684, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524621

RESUMO

A novel biochar composite was fabricated via the pyrolysis of distillers grains treated phosphogypsum for phosphate removal from water. Batch adsorption experiments were performed on the adsorption characteristics of phosphate. Effects of pyrolysis temperature, solution pH, the dosage of adsorbent, ambient temperature on phosphate adsorption were also investigated. The results demonstrated that the optimum initial solution pH for phosphate adsorption was 6.0, and high pyrolysis temperature was favorable for phosphate adsorption. The optimal dosage of biochar was 1.25 g L-1. A pseudo-second-order kinetic model can well explain the adsorption kinetics, indicative of the energetically heterogeneous solid surface of the composite. The maximum phosphate adsorption capacity of the phosphogypsum modified biochar obtained from Langmuir isotherm reached 102.4 mg g-1 which was almost five times that of distillers grains biochar alone (21.5 mg g-1). The mechanism is mainly attributed to electrostatic adsorption, surface precipitation and ligand exchange. The ideal adsorption performance indicated that biochar supported phosphogypsum can be used as high-quality adsorbent for phosphate removal in wastewater treatment.


Assuntos
Sulfato de Cálcio/metabolismo , Carvão Vegetal/metabolismo , Grão Comestível/metabolismo , Fosfatos/análise , Fósforo/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Destilação , Temperatura Alta , Pirólise
6.
Food Chem ; 305: 125511, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31610421

RESUMO

Honey spirit is an alcoholic beverage produced by fermentation followed by distillation of the honey must, which has distinct organoleptic characteristics derived mostly from the raw material used. In order to accurately monitor the quality of the product throughout the distillation process (head, heart and tail stages), FT-RAMAN spectroscopy was applied. Dark honey, light honey and honey obtained following waxes' wash was used to produce honey spirit. The pH, alcoholic strength, methanol content, acetaldehyde content, ethyl acetate content and higher alcohols content were evaluated during the distillation process. The FT-RAMAN technique was used to obtain spectral information for all fractions collected during beverage production. The results suggest that the honey spirit had good quality concerning the volatile composition and methanol was not detected in any sample. FT-RAMAN is promising for the online monitoring of the distillation process in order to improve the final quality of this beverage.


Assuntos
Bebidas Alcoólicas/análise , Destilação/métodos , Mel/análise , Análise Espectral Raman , Qualidade dos Alimentos
7.
Chemosphere ; 238: 124572, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31422312

RESUMO

The wastewaters from distilleries of winemaking by-products, a scarcely studied type of vinasse, were treated by white-rot fungal strains from species Irpex lacteus, Ganoderma resinaceum, Trametes versicolor, Phlebia rufa and Bjerkandera adusta. The main objectives of this study were to evaluate fungal performance during vinasse biodegradation, their enzyme patterns and ecotoxicity evolution throughout treatment. Despite all strains were able to promote strong (>80%) dephenolization and reduction of total organic carbon (TOC), P. rufa was less affected by vinasse toxicity and exhibit better decolorization. In batch cultures at 28 °C and pH 4.0, the first phase of P. rufa biodegradation kinetics was characterized by strong metabolic activity with simultaneous depletion of TOC, phenolics and sugars. The main events of second phase are the increase of peroxidases production after the peak of laccase activity, and strong color removal. At the end of treatment, it was observed highly significant (p < 0.001) abatement of pollution parameters (83-100% removal). Since water reclamation and reuse for e.g. crop irrigation is a priority issue, vinasse ecotoxicity was assessed with bioindicators representing three different phylogenetic and trophic levels: a marine bacterium (Aliivibrio fischeri), a freshwater microcrustacean (Daphnia magna) and a dicotyledonous macrophyte (Lepidium sativum). It was observed significant (p < 0.05) reduction of initial vinasse toxicity, as evaluated by these bioindicators, deserving special mention an almost complete phytotoxicity elimination.


Assuntos
Aliivibrio fischeri/crescimento & desenvolvimento , Coriolaceae/metabolismo , Daphnia/crescimento & desenvolvimento , Lepidium sativum/crescimento & desenvolvimento , Polyporales/metabolismo , Trametes/metabolismo , Águas Residuárias/química , Águas Residuárias/toxicidade , Aliivibrio fischeri/metabolismo , Animais , Biodegradação Ambiental , Daphnia/metabolismo , Destilação , Biomarcadores Ambientais/efeitos dos fármacos , Lacase/metabolismo , Lepidium sativum/metabolismo , Peroxidases/metabolismo , Fenóis/metabolismo , Filogenia
8.
Food Chem ; 303: 125405, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466029

RESUMO

The study aimed at evaluating the influence of fermented sugarcane molasses ageing on lees and the distillation process used for the production of rums. Molasses were freshly fermented or 3-months lees aged. Batch (PS: Pot Still) or continuous (CS: Coffey Still) distillation was carried out resulting in four different rum distillates. Gas chromatography and 3D-fluorescence enabled to differentiate rum distillates chemical composition according to the distillation process, regardless of the ageing on lees of fermented molasses. Differences in fluorescent PARAFAC components and volatile acids, acetals and carbonyls contents revealed the predominance of the physicochemical processes driven at the liquid-vapor interface of fermented molasses, generated by the distillation systems. Notwithstanding the distilling conditions, the long chain fatty ester content was significantly higher in the 3-months lees aged condition. Multivariate analysis highlighted that CS rum distillates were chemically more homogeneous than those obtained by PS that preserved the lees effect.


Assuntos
Bebidas Alcoólicas/análise , Destilação/métodos , Manipulação de Alimentos/métodos , Melaço/análise , Saccharum/química , Cromatografia Gasosa , Fermentação , Fatores de Tempo
9.
Water Res ; 168: 115149, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31604175

RESUMO

Strategically important elements are those that are vital to advanced manufacturing, low carbon technologies and other growing industries. Ongoing depletion and supply risks to these elements are a critical concern, and thus, recovery of these elements from low-grade ores and brines has generated significant interest worldwide. Among the strategically important elements, this paper focuses on rare earth elements (REEs), the platinum-group metals and lithium due to their wide application in the advanced industrial economics. We critically review the current methods such as precipitation, ion exchange and solvent extraction for extracting these elements from low-grade ores and brines and provide insight into the technical challenges to the practical realisation of metal extraction from these low-grade sources. The challenges include the low concentration of the target elements in brines and inadequate selectivity of the existing methods. This review also critically analyzes the potential applicability of an integrated clean water production and metal extraction process based on conventional pressure-driven membrane and emerging membrane technologies (e.g., membrane distillation). Such a process can first enrich the strategically important elements in solution for their subsequent recovery along with clean water production.


Assuntos
Metais Terras Raras , Destilação , Metais , Água
10.
Chemosphere ; 238: 124641, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31466001

RESUMO

Seawater reverse osmosis (SWRO) brine contain many valuable resources. In this study, fractional-submerged membrane distillation crystallizer (F-SMDC) was used to recover sodium sulfate (Na2SO4) from SWRO brine. The concentration/temperature gradient (CG/TG) in the reactor enhanced water recovery utilizing MD and Na2SO4 crystallization via a crystallizer. Crystals were not obtained at the bottom section of the F-SMDC due to: firstly, calcium sulfate crystallization occurring on the membrane surface; and secondly, low temperature-sensitivity solubility component such as NaCl exerting a negative influence. In order to obtain supersaturation, a sulfate-rich scenario was created in the reactor through the addition of the following three components: Na2SO4, MgSO4 and (NH4)2SO4. When Na2SO4 and MgSO4 were added, a larger concentration was observed at the top section, resulting in a low concentration gradient (CG) ratio, i.e. around 1.7. Conversely, the addition of (NH4)2SO4 achieved faster Na2SO4 crystallization (VCF 1.42) at the bottom section with a greater CG ratio of more than 2.0. Total water recovery ratio of 72% and 223.73 g Na2SO4 crystals were successfully extracted from simulated SWRO brine using laboratory scale F-SMDC.


Assuntos
Destilação/métodos , Sais/química , Sulfatos/isolamento & purificação , Cristalização , Membranas Artificiais , Osmose , Água do Mar/química , Solubilidade , Temperatura Ambiente
11.
Chemosphere ; 239: 124696, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726529

RESUMO

Brine disposal is a major drawback for seawater desalination. Membrane distillation (MD) is an emerging technology to treat a high saline water including brine disposal instead of reverse osmosis, multi-stage flash and multi-effect distillation. This study investigated a pilot scale of a spiral-wound air gap MD (AGMD) module and evaluated its efficiency. A pilot-scale AGMD module with design production capacity of 10 m3/d was operated. Experiments with varying flow velocity showed increasing trend of water vapor flux as flow velocity increases. The temperature is one of the significant points in maximizing water permeate vapor flux in MD. Increasing temperature from 65 °C to 75 °C in evaporator channel has increased flux from 0.59 to 1.15 L/m2/h. Under various conditions, specific thermal energy consumption (STEC) and gained output ratio (GOR) was used to analyze energy efficiency. The pilot plant showed high GOR value in spite of a limited heating and cooling source available at the site. The highest GOR achieved was 3.54 with STEC of 182.78 kWh/m3. This study provides an overview of operation experience and its data analysis related to temperature, concentration, flow rate and energy supply.


Assuntos
Destilação/métodos , Membranas Artificiais , Sais/análise , Purificação da Água/métodos , Destilação/instrumentação , Temperatura Alta , Osmose , Projetos Piloto , Água do Mar/química , Água/química
12.
Zhongguo Zhong Yao Za Zhi ; 44(18): 4000-4008, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31872737

RESUMO

Agarwood is a traditional and precious medicinal material and natural spice in China and other southeast Asian countries.As the head of all spices,agarwood has many pharmacological activities such as analgesia,antidiarrheal,anti-inflammatory and antibacterial effects. Due to its high price and scarce resources,there were just a few previous studies on it,mainly focusing on the chemical compositions of the agarwood essential oil and solvent extract mixture. The components of agarwood oils obtained by supercritical extraction and steam distillation were analyzed by using Gas Chromatography-Mass Spectrometer( GC-MS),and then the agarwood oils compositions and contents were compared between the traditional extraction method and the recently emerging supercritical extraction method. Antioxidant experiments of scavenging DPPH,ABTS,hydroxyl radical,total reducing power and MIC experiments of five kinds of tester strains such as staphylococcus aureus were combined to illustrate the differences between these two kinds of agarwood oils in terms of antioxidant and bacteriostatic activities. The results showed that the main components of agarwood oil were sesquiterpenoids( 68. 68%) in steam distillation extraction method,but sesquiterpenoids( 23. 78%) and chromones( 29. 42%) in supercritical extraction method. Fourteen common components included benzyl acetone,α-santalol,γ-eudesmol,agarospirol and guaiol etc. The antioxidant activity and inhibitory MIC of agarwood oils in supercritical extraction method were better than those in steam distillation method,and the inhibitory effect of agarwood oil on the growth of bacillus subtilis was found for the first time.


Assuntos
Antibacterianos/química , Antioxidantes/química , Destilação/métodos , Óleos Voláteis/química , Óleos Vegetais/química , Antibacterianos/farmacologia , Antioxidantes/farmacologia , China , Óleos Voláteis/farmacologia , Óleos Vegetais/farmacologia , Vapor , Thymelaeaceae/química , Madeira/química
13.
Environ Sci Pollut Res Int ; 26(32): 33607-33620, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31587163

RESUMO

This study aimed to improve the pore size, porosity, and hydrophobicity of polyvinylidene fluoride (PVDF) membranes for desalination by vacuum membrane distillation (VMD). New membranes were prepared via etching PVDF/calcium carbonate (CaCO3) composite membranes using hydrochloric acid (HCl), depending on the chemical reaction of CaCO3 and HCl. Etched membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), contact angle (CA), atomic force microscope (AFM), and scanning electron microscopy (SEM). The results showed that CaCO3 of composite membranes was completely reacted by 1.5 mol/L HCl after composite membranes had been etched 90 min. The crystallinity of etched membranes was the same as that of PVDF/CaCO3 composite membranes, and no new functional groups appeared in etched membranes, which indicated that etched membranes had good chemical stability. The surface roughness increased and led to the increase of contact angle, which means the hydrophobicity of etched membranes was enhanced. As a result, the increment of permeation flux had been improved in a VMD process. It was found that the maximum flux of etched membrane was enhanced and up to 1.65 times of composite membrane when the concentration of sodium chloride (NaCl) solution was 5.0 wt%, and the maximum flux reached up to 30.9 kg m-2 h-1.


Assuntos
Ácido Clorídrico/química , Membranas Artificiais , Polivinil/química , Carbonato de Cálcio/química , Destilação , Interações Hidrofóbicas e Hidrofílicas , Microscopia Eletrônica de Varredura , Porosidade , Cloreto de Sódio , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Chem Biodivers ; 16(11): e1900357, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31573145

RESUMO

The ginger extract obtained with supercritical CO2 fluid was purified by molecular distillation (MD), and the chemical compositions, antioxidant and cytotoxic activities of ginger extract and its distillates were investigated. Analysis revealed that the ginger extract was rich in terpene hydrocarbons, along with oxygenated terpenes and other non-volatile compounds. The MD distillates were prepared in a series of stages and the active compounds like terpenes and gingerols could be separated by MD. The major compounds of the distillates purified by MD at 40 °C, 80 Pa and 60 °C, 80 Pa were terpene hydrocarbons. Additional distillates obtained by MD at 80 °C, 80 Pa and 100 °C, 60 Pa were predominated by terpene hydrocarbons and oxygenated terpenes. Until the operating conditions of MD reached 150 °C and 2 Pa, some non-volatile compounds were concentrated in the final distillate. Moreover, antioxidant activities and the cytotoxic effects on three human cancer cells in final MD distillate were superior to other extracts, and this phenomenon could be mainly supported by the phenols. The MD could be used to prepare ginger distillates with better antioxidant and cytotoxic activities.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Antioxidantes/farmacologia , Compostos de Bifenilo/antagonistas & inibidores , Dióxido de Carbono/química , Gengibre/química , Picratos/antagonistas & inibidores , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Antioxidantes/química , Antioxidantes/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Destilação , Ensaios de Seleção de Medicamentos Antitumorais , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Extratos Vegetais/isolamento & purificação , Células Tumorais Cultivadas
15.
Environ Sci Technol ; 53(22): 13506-13513, 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31625726

RESUMO

Membrane distillation (MD) is a promising alternative approach for desalination, especially for high-salinity brines. Its application has been limited by its high operational cost because of the energy consumption required for hydraulic circulation and heating the entire circulating feed. Localized heating of the feed by Joule heating diminishes energy consumption, but the potential charging on the electrothermal material surface causes water splitting and membrane degradation in high-salinity environments. Herein, a novel reverse Joule-heating air gap MD method was designed in which an electrothermal material was placed at the air gap, isolating itself from saline water. Even though the Joule-heating layer was at the air gap side, 90.56% of heat flowed into the saline water for heating the feed. The opposite temperature gradient in the membrane matrix as opposed to conventional MD-mitigated membrane wetting was caused by capillary condensation. This novel electrothermal-driven MD configuration is worthy to be introduced into applications.


Assuntos
Destilação , Purificação da Água , Membranas Artificiais , Salinidade , Molhabilidade
16.
Environ Sci Technol ; 53(20): 11801-11809, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31535854

RESUMO

We report in this study a scalable and controllable approach for fabricating robust and high-performance superhydrophobic membranes for membrane distillation (MD). This novel approach combines electro-co-spinning/spraying (ES2) with chemical vapor welding and enables the formation of robust superhydrophobic (r-SH) membranes that are mechanically strong, highly porous, and robustly superhydrophobic. Compared with superhydrophobic membranes obtained using surface deposition of fluorinated nanoparticles, the r-SH membranes have more robust wetting properties and higher vapor permeability in MD. MD scaling experiments with sodium chloride and gypsum show that the r-SH membrane is highly effective in mitigating mineral scaling. Finally, we also discuss the mechanism of scaling resistance enabled by superhydrophobic membranes with a highlight on the roles of the surface-bound air layer in reducing the crystal-membrane contact area, nucleation propensity, and ion-membrane contact time.


Assuntos
Destilação , Purificação da Água , Membranas Artificiais , Porosidade , Molhabilidade
17.
Molecules ; 24(18)2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31540154

RESUMO

Essential oils and hydrosols of two cultivars of muscadine grapes (Muscadinia rotundifolia (Michx.) Small.) were obtained by hydro-distillation of flowers and berry skins. Twenty-three volatile compounds were identified in essential oils from the muscadine flowers, and twenty volatiles in their corresponding hydrosols. The composition of volatiles in berry skins differed significantly from that of the vine flowers. The antioxidant potential of investigated essential oils and hydrosols was evaluated using five in vitro assays: DPPH (2,2-diphenyl-1-picrylhydrazyl) method, TEAC (Trolox equivalent antioxidant capacity), FRAP (Ferric reducing antioxidant power), CUPRAC (cupric ion reducing antioxidant capacity), and NO (nitric oxide radical scavenging assay). The essential oils from the flowers of both cultivars showed the strongest antioxidant power, whereas the hydrosols were the significantly less active. All investigated essential oils showed very weak antibacterial activities against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. However, the essential oils from the flowers of both cultivars showed moderate antifungal activities against Candida albicans, which were stronger for the oil from "Carlos" (white muscadine cultivar). To the best of our knowledge, this is the first report on obtaining and characterizing essential oils and hydrosols from muscadine grapes. This study demonstrated the variations in aromatic compounds accumulated in flowers and mature berry skins of muscadine grapes, and evaluated their possible antioxidant and antimicrobial activities. The presented results will be the base for future research, focused on a better understanding of the molecular and regulatory mechanisms involved in aromatic compound biosynthesis and accumulation in muscadine grapes.


Assuntos
Antibacterianos/química , Antifúngicos/química , Antioxidantes/química , Flores/química , Óleos Voláteis/química , Vitis/química , Antibacterianos/farmacologia , Antifúngicos/farmacologia , Antioxidantes/farmacologia , Destilação , Frutas/química , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Óleos Voláteis/farmacologia , Extratos Vegetais/química
18.
Water Res ; 165: 114982, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31473356

RESUMO

In this study, an omniphobic membrane was fabricated by electrospraying fluorinated zinc oxide (ZnO) nanoparticles (NPs) mixed with polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) on the surface of an organosilane functionalized polyvinylidene difluoride (PVDF) membrane. Our results revealed that the functionalized ZnO NPs membrane exhibited a rough hierarchical re-entrant morphology with low surface energy which allowed it to achieve high omniphobic characteristics. It was observed that the addition of 30% ZnO (w/w of PVDF-HFP) was found to be optimal and imparted a high repulsive characteristic. The optimized PVDF/ZnO(30)/FAS/PVDF-HFP referred as cPFP-30Z membrane exhibited a high contact angle values of 159.0 ±â€¯3.1°, 129.6 ±â€¯2.2°, 130.4 ±â€¯4.1° and 126.1 ±â€¯1.2° for water, sodium dodecyl sulfate (SDS) saline solution (0.3 mM SDS in 3.5% NaCl), ethanol, and vegetable oil, respectively. The low surface energy and high surface roughness (Ra) of optimised membrane was assessed as 0.78 ±â€¯0.14 mN m-1 and 1.37 µm, respectively. Additionally, in contrast with the commercial PVDF membrane, the cPFP-30Z membrane exhibited superior anti-wetting/anti-fouling characteristics and high salt rejection performance (>99%) when operated with a saline oil solution (0.015 v/v) and SDS (0.4 mM) feed solutions.


Assuntos
Nanopartículas , Purificação da Água , Óxido de Zinco , Destilação , Membranas Artificiais , Polivinil , Água do Mar , Tensão Superficial
19.
Environ Sci Technol ; 53(20): 11869-11876, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31545033

RESUMO

Concentration polarization (CP) occurs in almost all membrane-based separation processes. In this study, the concentration profile of the dissolved salt has been accurately characterized using a previously developed laser-based spectrophotometric method which had a spatial resolution of 4.5 µm. The objective of the current work was to probe the concentration profile of the solute and analyze the impact of operating parameters, such as feed concentration, hydrodynamic conditions, and feed temperature, on the solute concentration profile in the boundary layer. This study also examined the validity of the conventional approach, where semi-empirical models are used to estimate the boundary layer thickness (BLT) and concentration polarization coefficient (CPC)-based on experimental results. Nusselt correlations were developed specifically for the membrane cell and validated through experimental observations at the operating conditions used in this study. A key finding of this study is that the conventional approach of estimating the effect of CP severely underpredicts the BLT and CPC. The results of this study highlight the need to develop new methods to estimate the BLT and CPC as the conventional approach of using semi-empirical Nusselt and Sherwood correlations does not agree with experimental observations obtained for a membrane distillation system employed in this study.


Assuntos
Destilação , Membranas Artificiais , Membranas , Soluções , Temperatura Ambiente
20.
Environ Sci Pollut Res Int ; 26(29): 30452-30462, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31444717

RESUMO

This study investigates the feasibility of recovery of phosphorus via struvite precipitation from a synthetic anaerobically treated distillery spent wash by optimizing the process using a chemical equilibrium model, namely Visual MINTEQ. Process parameters such as Mg2+, [Formula: see text], and [Formula: see text] ion concentrations and pH were used as inputs into the model. Increasing the molar ratio of [Formula: see text] from 0.8:1 to 1.6:1 at pH 9 led to an increase in phosphate recovery from 88.2 to 99.5%. The model and experimental results were in good agreement in terms of phosphate recovery, indicating that the Visual MINTEQ model can be used to pre-determine the process parameters for struvite synthesis. Increasing the concentration of calcium ion adversely affected the synthesis and purity of struvite, whereas the presence of melanoidins had no significant impact. This study demonstrates that phosphorus recovery through struvite precipitation is a sustainable approach to reclaim phosphorus from high-strength industrial wastewater.


Assuntos
Fosfatos/isolamento & purificação , Estruvita/química , Eliminação de Resíduos Líquidos/métodos , Precipitação Química , Destilação , Indústria Alimentícia , Concentração de Íons de Hidrogênio , Magnésio/química , Modelos Químicos , Fósforo/química , Fósforo/isolamento & purificação , Águas Residuárias/química
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