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1.
Chemosphere ; 288(Pt 1): 132427, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34600922

RESUMO

As UV-light stabilizers, Bis(4-hydroxy)benzophenone (BBP), are extensively consumed to quench radicals from photooxidation, continuous release of BPs into the environment poses serious threats to the ecology in view of their xenohormone toxicities, and BBP shall be eliminated from water to avoid its adverse effect. Since sulfate radical (SR)-based chemical oxidation techniques have been proven as effective procedures for eliminating organic emerging contaminants, this study aims to develop useful SR-based procedures through activating Oxone for degrading BBP in water. In contrast to the conventional Co3O4, cobalt sulfide (CoS) is particularly proposed as an alternative heterogeneous catalyst for activating Oxone to degrade BBP because CoS exhibits more reactive redox characteristics. As structures of catalysts predominantly control their catalytic activities, in this study, a unique nanoplate-assembled CoS (NPCS) 3D cluster is fabricated via a convenient one-step process to serve as a promising heterogeneous catalyst for activating Oxone to degrade BBP. With NPCS = 100 mg/L and Oxone = 200 mg/L, 5 mg/L of BBP can be completely eliminated in 60 min. The catalytic activity of NPCS towards Oxone activation also significantly surpasses the reference material, Co3O4, to enhance degradation of BBP. Ea of BBP degradation by NPCS-activated Oxone is also determined as a relatively low value of 42.7 kJ/mol. The activation mechanism as well as degradation pathway of BBP degradation by NPCS-activated Oxone was investigated and validated through experimental evidences and density functional theory (DFT) calculation to offer valuable insights into degradation behaviors for developing SR-based processes of BBP degradation using CoS catalysts.


Assuntos
Poluentes Químicos da Água , Benzofenonas , Catálise , Cobalto , Óxidos , Ácidos Sulfúricos , Poluentes Químicos da Água/análise
2.
Bioresour Technol ; 343: 126071, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34606923

RESUMO

One of the potential bioresources for bioethanol production is Napier grass, considering its high cellulose and hemicellulose content. However, the cost of pretreatment hinders the bioethanol produced from being economical. This study examines the effect of hydrothermal process with dilute acid on extruded Napier grass, followed by enzymatic saccharification prior to simultaneous saccharification and co-fermentation (SScF). Extrusion facilitated lignin removal by 30.2 % prior to dilute acid steam explosion. Optimum pretreatment condition was obtained by using 3% sulfuric acid, and 30-min retention time of steam explosion at 190 °C. Ethanol yield of 0.26 g ethanol/g biomass (60.5% fermentation efficiency) was attained by short-term liquefaction and fermentation using a cellulose-hydrolyzing and xylose-assimilating Saccharomyces cerevisiae NBRC1440/B-EC3-X ΔPHO13, despite the presence of inhibitors. This proposed method not only reduced over-degradation of cellulose and hemicellulose, but also eliminated detoxification process and reduced cellulase loading.


Assuntos
Saccharomyces cerevisiae , Xilose , Celulose/metabolismo , Etanol , Fermentação , Hidrólise , Lignina/metabolismo , Saccharomyces cerevisiae/metabolismo , Ácidos Sulfúricos
3.
J Sci Food Agric ; 102(1): 312-321, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34096072

RESUMO

BACKGROUND: Sugarcane straw is an available but largely ignored lignocellulosic biomass to obtain cellulose nanocrystals (CNCs) with highly crystalline, tunable surface chemistries and a wide-ranging adaptability. Herein, we utilized sugarcane straw to obtain pure cellulose via purification processes, followed by subsequent preparation of CNCs via sulfuric acid hydrolysis. The properties of the purified fibers and obtained CNCs were assessed by their composition, morphology, chemical structure, crystallinity and thermal stability. RESULTS: After the purification process, alkali-treated fibers (ATFs) contained 886.33 ± 1.25 g kg-1 cellulose, and its morphological analysis revealed a smooth and slender fibrous structure. The CNCs obtained by treatment with 64 wt% sulfuric acid at 45 °C for 60 min were isolated in a yield of 21.8%, with a diameter and length of 6 to 10 nm and 160 to 200 nm, respectively. Moreover, crystallinity index of these CNCs reached 62.66%, and thermal stability underwent a two-step degradation. Short-term ultrasonication after hydrolysis was employed to enhance isolation of the CNC particles and improve the anionic charge with higher value -38.00 mV. CONCLUSION: Overall, isolation and characterization results indicated the potential for CNCs preparation using sugarcane straw, in addition to offering a fundamental understanding of this material and indicating potential applications. © 2021 Society of Chemical Industry.


Assuntos
Celulose/química , Celulose/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Saccharum/química , Resíduos/análise , Hidrólise , Nanopartículas/química , Caules de Planta/química , Ácidos Sulfúricos
4.
Phys Chem Chem Phys ; 23(35): 19729-19739, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34524307

RESUMO

The fundamental understanding of glucose conversion to 5-ethoxymethylfurfural (EMF) and ethyl levulinate (EL) (value-added chemicals from biomass) in ethanol solution catalyzed by a Brønsted acid is limited at present. Consequently, here, the reaction pathways and mechanism of glucose conversion to EMF and EL catalyzed by a Brønsted acid were studied, using an experimental method and quantum chemical calculations at the B3LYP/6-31G(D) and B2PLYPD3/Def2TZVP level under a polarized continuum model (PCM-SMD). By further verification through GC/MS tests, the mechanism and reaction pathways of glucose conversion in ethanol solution catalyzed by a Brønsted acid were revealed, showing that glucose is catalyzed by proton and ethanol, and ethanol plays a bridging role in the process of proton transfer. There are three main reaction pathways: through glucose and ethyl glucoside (G/EG), through fructose, 5-hydroxymethylfurfural (HMF), levulinic acid (LA), and EL (G/F/H/L/EL), and through fructose, HMF, EMF, and EL (G/F/H/E/EL). The G/F/H/E/EL pathway with an energy barrier of 20.8 kcal mol-1 is considered as the thermodynamic and kinetics primary way, in which the reaction rate of this is highly related to the proton transfer in the isomerization of glucose to fructose. The intermediate HMF was formed from O5 via a ring-opening reaction and by the dehydration of fructose, and was further converted to the main product of EMF by etherification or by LA through hydrolysis. EMF and LA are both unstable, and can partially be transformed to EL. This study is beneficial for the insights aiding the understanding of the process and products controlling biomass conversion in ethanol solution.


Assuntos
Etanol/química , Furaldeído/análogos & derivados , Glucose/química , Modelos Moleculares , Ácidos Sulfúricos/química , Biocombustíveis , Catálise , Teoria da Densidade Funcional , Furaldeído/química , Ácidos Levulínicos/química , Termodinâmica
5.
Carbohydr Polym ; 270: 118361, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34364606

RESUMO

A novel acylation approach suited to rapid bulk thermoplasticization of lignocellulose without solvents was previously demonstrated by the authors in benchtop batch studies. The method relies upon a benzethonium chloride/sulfuric acid functionalizing agent at low concentrations to act as a wetting agent for the wood pulp, similar to an ionic liquid, yet binds to the lignocellulose ester as a flow aid in the final thermoplastic. The present investigation evaluates the approach in a residence time-limited (45-90 s) continuous twin-screw reactor, where intensive mixing and heat were found to yield high acylation. The modified lignocellulose exhibited desired thermoplasticity by being melt moldable without the need for plasticizers and maintained much of the excellent stiffness of cellulose, demonstrating a maximum flexural modulus of 5.4 GPa and tensile modulus of 1.8 GPa. The influence of extrusion conditions on thermoplasticity was examined by a Design of Experiments (DOE) analysis.


Assuntos
Lignina/química , Madeira/química , Acilação , Benzetônio/química , Celulose/química , Temperatura Alta , Líquidos Iônicos/química , Plastificantes/química , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Ácidos Sulfúricos/química , Resistência à Tração
6.
Sensors (Basel) ; 21(16)2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34450950

RESUMO

Simulation is a useful and common technique to evaluate the performance of networks when the implementation of a real scenario is not available. Specifically for Wireless Body Area Networks (WBAN), it is crucial to perform evaluations in environments as close as possible to the real conditions of use. To achieve that, simulations must include different protocol layers involved in WBAN and models close to reality to create realistic simulation environments for e-health applications. To satisfy these needs, this work presents the BNS framework, a flexible tool for WBAN simulations. The proposal is an extension of the Castalia framework, which includes: (1) a new wireless channel model considering real radio-propagation over the human body; (2) an updated implementation of the WBAN MAC protocol in Castalia, with functionalities and requirements in accordance with the IEEE 802.15.6 standard; (3) a new comprehensive and configurable mobility model for simulating intra-WBAN communication; (4) a temperature module based on the Pennes bioheat transfer equation, to model the temperature of a WBAN node based on the activity of the node; and (5) a Healthcare Application Layer that implements data representation and a communication protocol between Personal Health Devices (PHD) following the ISO/IEEE 11073 standard. Three use cases are presented, where WBAN scenarios are simulated and evaluated using the proposed BNS framework. Results show that BNS is a valid and flexible tool to evaluate WBAN solutions through simulation.


Assuntos
Redes de Comunicação de Computadores , Tecnologia sem Fio , Comunicação , Simulação por Computador , Humanos , Naftalenos , Ácidos Sulfúricos
7.
Bioresour Technol ; 340: 125740, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34426233

RESUMO

The prerequisite for cellulosic biochemical production from lignocellulosic materials is efficient enzymatic hydrolysis that is a complicated heterogeneous catalytic process and affected by the complex lignin-cellulose-hemicellulose network. Understanding the main influencing factors for enzymatic hydrolysis is of substantial significance to guide the design of a biorefinery process. An experimental study of the pretreatment indicated that acid pretreatment is preferable for herbaceous feedstocks. Therefore, the classic dilute sulfuric acid pretreatment was utilized to hydrolyze and remove hemicellulose from three representative types of agricultural straws at various intensities. From the enzymatic hydrolysis of residual cellulose perspective, the crystallinity index and enzyme accessibility of the pretreated materials were also mathematically correlated to hemicellulose removals, respectively. For the better insight and understanding of the mathematical logics, the linear and nonlinear kinetic models were therefore compared, and the relationship was established by the five-parameter logistic equations and Allosteric sigmoidal models with well fittings.


Assuntos
Celulose , Ácidos Sulfúricos , Hidrólise , Lignina
8.
Anal Chim Acta ; 1174: 338712, 2021 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-34247739

RESUMO

Based on the sulfuric acid-ultraviolet assay (SA-UV, developed by Albalasmeh et al., 2013), we have further expanded this method for the simultaneous quantification of saccharides (carbohydrates) and proteins by ultraviolet spectrophotometry. The absorbance of saccharides depends on the formation of furfurals by dehydration in the presence of concentrated sulfuric acid, whereas proteins are unaffected and can be quantified by UV active peptide bonds and aromatic amino acid residues. In saccharide/protein mixtures the SA-UV assay offers a good alternative and substitutes the need for two different methods, like the phenol-sulfuric acid (PSA, developed by DuBois et al., 1951) and bicinchoninic acid (BCA, developed by Smith et al., 1985) assays. For the development of this method, we used glucose and BSA as model substrates and performed a method validation in terms of linearity, LOD, LOQ, accuracy, and precision. Simultaneous quantification in glucose/BSA mixtures is possible down to 20 mg/L from 30 µL sample volumes, and even low content mixtures with concentrations down to 2 mg/L can appropriately be quantified from higher volumes by an evaporation technique.


Assuntos
Carboidratos , Ácidos Sulfúricos , Proteínas , Espectrofotometria Ultravioleta
9.
J Oleo Sci ; 70(8): 1165-1173, 2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34248095

RESUMO

A mixture of p-toluenesulfonic acid and sulfuric acid (TsOH-H2SO4) was used as a catalyst with a good performance in transesterification of palm oil (PO) with methanol and etherification of crude glycerol with isobutylene (tandem synthesis). For TsOH-H2SO4 catalyzed biodiesel production, the reaction noticeably ran faster in comparison with TsOH or H2SO4 alone and also gave up to 99.9% of the conversion using MeOH/PO molar ratio 9:1 at 80℃, in the period of 4 h. After the whole transesterification process, the crude glycerol phase was separated and then reacted with isobutylene in the etherification process using isobutylene/glycerol molar ratio 9:1 at 80℃, in the period of 5 h reaction time, to give DTBG and TTBG (91.14%). In the case of the etherification in biodiesel, higher selectivity of DTBG and TTBG (99.39%) was obtained in comparison with an absence of biodiesel as the solvent. Furthermore, the catalyst could be reused for 6 cycles of tandem synthesis (transesterification and etherification). The TsOH-H2SO4 catalyst showed a good catalytic performance in tandem synthesis similar to TsOH and it could be recovered for reuse while TsOH could not be recovered. This process offers an attractive route for reuse homogeneous catalyst of tandem synthesis, the main by-product of biodiesel, to tert-butyl glycerol ethers - a value-added in applications as a valuable fuel additive.


Assuntos
Benzenossulfonatos/química , Biocombustíveis , Éteres de Glicerila/síntese química , Ácidos Sulfúricos/química , Alcenos/química , Catálise , Esterificação , Metanol/química , Óleo de Palmeira/química
10.
J Colloid Interface Sci ; 604: 1-14, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34261015

RESUMO

In this work, novel N-doped carbon dots (N-CDs) were synthesized from citric acid and l-serine. The results of fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) show that there are many unsaturated bonds and polar groups in the N-CDs. The inhibition performance of the concerned zero-dimensional nanomaterial for copper was investigated by electrochemical, combining FT-IR, XPS and Raman to investigate the corrosion products. Results indicate that the N-CDs were found to be effective inhibitor with the suppression efficiency as high as 98.5% means after immersed for 24 h, and they interacted with copper substrate by chemical & physical adsorption. Moreover, the related anticorrosion mechanism was explored and elucidated in detail. The purpose of this work is to explore eco-friendly and efficient corrosion inhibitor materials for metal protection.


Assuntos
Carbono , Cobre , Aminoácidos , Corrosão , Espectroscopia de Infravermelho com Transformada de Fourier , Ácidos Sulfúricos
11.
J Org Chem ; 86(15): 10608-10620, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34279102

RESUMO

A novel protocol for the preparation of non-symmetrical 1,2,4,5-tetraoxanes and 1,2,4-trioxanes, promoted by the heterogeneous silica sulfuric acid (SSA) catalyst, is reported. Different ketones react under mild conditions with gem-dihydroperoxides or peroxysilyl alcohols/ß-hydroperoxy alcohols to generate the corresponding endoperoxides in good yields. Our mechanistic proposal, assisted by molecular orbital calculations, at the ωB97XD/def2-TZVPP/PCM(DCM)//B3LYP/6-31G(d) level of theory, enhances the role of SSA in the cyclocondensation step. This novel procedure differs from previously reported methods by using readily available and inexpensive reagents, with recyclable properties, thereby establishing a valid alternative approach for the synthesis of new biologically active endoperoxides.


Assuntos
Tetraoxanos , Catálise , Compostos Heterocíclicos , Dióxido de Silício , Ácidos Sulfúricos
12.
Int J Biol Macromol ; 184: 405-414, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34146558

RESUMO

Cellulose nanocrystals (CNCs) were successfully produced with good nanoscales and dispersibility, using a recycled sulfuric acid (H2SO4) hydrolysis process. This method, at the cost of an overall 25% increase in the hydrolysis time, could significantly reduce the dosage of H2SO4 by approximately 40% without affecting the per-batch yield and performance of CNCs. The obtained CNCs with an average diameter of 6.0-6.5 nm and an average length of 126-134 nm, were successfully applied in the preparation of oil-in-water (O/W) Pickering emulsions via high-pressure homogenization. The emulsions exhibited good storage stability when the concentration of CNC was 1.0 wt%. Further, understanding the wetting behaviors of surface modified CNCs with solvent is critical for the functional designing of Pickering emulsion. Hence, we gained insights into the wetting of hydrophobic and hydrophilic surfaces of sulfate modified CNCs with water and organic solvent (hexadecane) droplets, using molecular dynamic simulation. The results showed that both surfaces had hydrophilic as well as lipophilic properties. Although the sulfate-grafted surface was more hydrophilic than unmodified CNC, substantial local wetting heterogeneities appeared for both solvents. It provides a deeper understanding of the interfacial interactions between modified CNCs and solvent molecules at the molecular level.


Assuntos
Celulose/química , Ácidos Sulfúricos/química , Hidrólise , Simulação de Dinâmica Molecular , Nanopartículas , Reciclagem , Propriedades de Superfície , Molhabilidade
13.
J Oleo Sci ; 70(6): 757-767, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34078757

RESUMO

Ethyl ferulate (EF) is a ferulic acid (FA) derivative with high commercial value. It is not found naturally and is mostly synthesized from FA via esterification with ethanol. The present work aimed to synthesize the EF from γ-oryzanol, a natural antioxidant from rice bran oil via acid-catalyzed transethylation at refluxing temperature of ethanol. The reaction was optimized by central composite design (CCD) under response surface methodology. Based on the CCD, the optimum condition for the synthesis of EF from 0.50 g of γ-oryzanol was as follows: γ-oryzanol to ethanol ratio of 0.50:2 (g/mL), 12.30% (v/v) H2SO4, and a reaction time of 9.37 h; these conditions correspond to a maximum EF yield of 87.11%. Moreover, the optimized transethylation condition was further validated using 12.50 g of γ-oryzanol. At the end of the reaction time, distilled water was added as antisolvent to selectively crystallize the co-products, phytosterol and unreacted γ-oryzanol, by adjusting the ethanol concentration to 49.95% (v/v). The recovery yield of 83.60% with a purity of 98% of EF was achieved. In addition, the DPPH and ABTS assays showed similar antioxidant activities between the prepared and commercial EF.


Assuntos
Antioxidantes/síntese química , Ácidos Cafeicos/síntese química , Fenilpropionatos/química , Antioxidantes/isolamento & purificação , Ácidos Cafeicos/isolamento & purificação , Catálise , Esterificação , Etanol/química , Ácidos Sulfúricos/química
14.
Chemosphere ; 280: 130709, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34162082

RESUMO

Criegee intermediates (CIs) are short-lived carbonyl oxides, which can affect the budget of OH radicals, ozone, ammonia, organic/inorganic acids in the troposphere. This study investigated the reaction of CIs with serine (Ser) in the gas phase by using density functional theory (DFT) calculations and at the gas-liquid interface by using Born-Oppenheimer molecular dynamics (BOMD). The results reveal that the reactivity of the three functional groups of Ser can be ordered as follows: COOH > NH2 > OH. Water-mediated reactions of CIs with NH2 and OH groups of Ser on the droplet follow the proton exchange mechanism. The products, sulfuric acids, ammonia, and water molecules form stable clusters within 20 ns. This study shows that hydroperoxide products can contribute to new particle formation (NPF). The result deepens the understanding of the reaction of CIs with multifunctional pollutants and atmospheric behavior of CIs in polluted areas.


Assuntos
Ozônio , Serina , Óxidos , Ácidos Sulfúricos , Água
15.
Environ Sci Technol ; 55(10): 6665-6676, 2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-33960763

RESUMO

Gaseous sulfuric acid (H2SO4) is a crucial precursor for secondary aerosol formation, particularly for new particle formation (NPF) that plays an essential role in the global number budget of aerosol particles and cloud condensation nuclei. Due to technology challenges, global-wide and long-term measurements of gaseous H2SO4 are currently very challenging. Empirical proxies for H2SO4 have been derived mainly based on short-term intensive campaigns. In this work, we performed comprehensive measurements of H2SO4 and related parameters in the polluted Yangtze River Delta in East China during four seasons and developed a physical proxy based on the budget analysis of gaseous H2SO4. Besides the photo-oxidation of SO2, we found that primary emissions can contribute considerably, particularly at night. Dry deposition has the potential to be a non-negligible sink, in addition to condensation onto particle surfaces. Compared with the empirical proxies, the newly developed physical proxy demonstrates extraordinary stability in all the seasons and has the potential to be widely used to improve the understanding of global NPF fundamentally.


Assuntos
Poluentes Atmosféricos , Material Particulado , Poluentes Atmosféricos/análise , China , Monitoramento Ambiental , Tamanho da Partícula , Material Particulado/análise , Rios , Ácidos Sulfúricos
16.
Chemosphere ; 281: 130806, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34004519

RESUMO

The degradation of tartrazine in the presence of cobalt activated Oxone® (potassium peroxymonosulfate) was investigated at different initial pH values. Aluminum pillared clay had the role of a support for catalytically active cobalt oxide species. The degradation of tartrazine and the formation of a mixture of degradation products were monitored using the Ultraviolet-Visible (UV-Vis) spectroscopy and gas chromatography-mass spectrometry (GC-MS). The exact qualitative composition of this mixture and the determination of the most probable mechanism of degradation (the primary goal) were obtained using GC-MS. Besides, the main reaction pathway (reaction with SO4˙- radical anion) and secondary pathways were proposed depending on the pH value. At pH = 6 the reaction with HO˙ radical was proposed. At pH = 11 decarboxilation was suggested as the first step of the secondary proposed reaction pathway. The combination of results acquired from the deconvolution of UV-Vis spectra and the theoretical UV-Vis spectra of degradation products, whose occurrence was predicted by quantum-chemical calculations, was proven to be beneficial for the identification of tartrazine degradation products and for defining UV-Vis predictors of particular degradation steps. An additional contribution of this paper, from the reactivity aspect, was the establishment of the critical structural demand for the radical degradation of any diazo compound. The existence of a hydrogen atom bound to a diazo group was found to be the essential prerequisite for the radical cleavage of diazo compounds.


Assuntos
Tartrazina , Poluentes Químicos da Água , Concentração de Íons de Hidrogênio , Oxirredução , Ácidos Sulfúricos , Raios Ultravioleta , Poluentes Químicos da Água/análise
17.
Int J Biol Macromol ; 181: 824-834, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33836194

RESUMO

Currently, there are few studies on acid-soluble pectin from okra, especially in biological activity for antioxidant and anti-inflammatory. In this study, the antioxidant properties of acid-soluble okra pectin components and their anti-inflammatory were explored. Firstly, two acid-soluble okra pectic fractions, namely crude acid-soluble okra pectin (CAOP) and acid-soluble okra pectin (AOP), were obtained and exhibited structural and compositional variation. The two pectic fractions contained a low degree of esterification (42.0-46.5%) and a relatively high uronic acid content (31.6-37.3%). AOP was composed of galacturonic acid (79.1 mol/%), galactose (4.3 mol/%), rhamnose (14.5 mol/%) and xylose (2.1 mol/%), and the molecular weight was 92.8 kDa. Morphological and thermal properties of acid-soluble okra pectin components were also investigated. Compared to CAOP, AOP expressed better antioxidant activity, and suppressed the NO production in LPS-induced RAW 264.7 macrophages. All the above results indicated that AOP had the potential to act as a natural antioxidant or a functional anti-inflammatory food, which would broaden the development and utilization of okra resources.


Assuntos
Abelmoschus/química , Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Pectinas/farmacologia , Ácidos Sulfúricos/química , Animais , Sobrevivência Celular/efeitos dos fármacos , Fenômenos Químicos , Camundongos , Pectinas/química , Espectroscopia de Prótons por Ressonância Magnética , Células RAW 264.7 , Solubilidade , Temperatura , Difração de Raios X
18.
J Org Chem ; 86(20): 14016-14027, 2021 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33750133

RESUMO

A new method was developed for the synthesis of 4-chalcogenyl-1H-isochromen-1-ones through the 6-endo-dig electrophilic cyclization of 2-alkynylaryl esters and diorganyl dichalcogenides under ultrasound irradiation. The reactions were performed under mild conditions, using Oxone as a green oxidant to promote the cleavage of the chalcogen-chalcogen bond in diorganyl diselenides and ditellurides to generate electrophilic species in situ. A total of 25 compounds were selectively obtained after 30-70 min, in good to excellent yields (74-95%). This procedure was extended to prepare 5H-selenopheno[3,2-c]isochromen-5-ones. Additionally, for the first time, the 4-chalcogenyl-1H-isochromen-1-ones were used as substrates in the thionation reaction, using Lawesson's reagent and microwave irradiation under solvent-free conditions, obtaining the thio derivatives in yields of up to 99% in only 15 min.


Assuntos
Estrutura Molecular , Catálise , Ciclização , Solventes , Ácidos Sulfúricos
19.
Waste Manag ; 125: 192-203, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33706256

RESUMO

The growing demand for lithium-ion batteries will result in an increasing flow of spent batteries, which must be recycled to prevent environmental and health problems, while helping to mitigate the raw materials dependence and risks of shortage and promoting a circular economy. Combining pyrometallurgical and hydrometallurgical recycling approaches has been the focus of recent studies, since it can bring many advantages. In this work, the effects of incineration on the leaching efficiency of metals from EV LIBs were evaluated. The thermal process was applied as a pre-treatment for the electrode material, aiming for carbothermic reduction of the valuable metals by the graphite contained in the waste. Leaching efficiencies above 70% were obtained for Li, Mn, Ni and Co after 60 min of leaching even when using 0.5 M sulfuric acid, which can be linked to the formation of more easily leachable compounds during the incineration process. When the incineration temperature was increased (600-700 °C), the intensity of graphite signals decreased and other oxides were identified, possibly due to the increase in oxidative conditions. Higher leaching efficiencies of Mn, Ni, Co, and Li were reached at lower temperatures of incineration (400-500 °C) and at higher leaching times, which could be related to the partial carbothermic reduction of the metals.


Assuntos
Incineração , Lítio , Fontes de Energia Elétrica , Reciclagem , Ácidos Sulfúricos
20.
Sci Rep ; 11(1): 2877, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33536529

RESUMO

Acidification of drinking water to a pH between 2.5 and 3.0 is widely used to prevent the spread of bacterial diseases in animal colonies. Besides hydrochloric acid (HCl), sulfuric acid (H2SO4) is also used to acidify drinking water. Here we examined the effects of H2SO4-acidified drinking water (pH = 2.8) received from weaning (postnatal day 21) on the behavior and gut microflora of 129S6/SvEv mice, a mouse strain commonly used in transgenic studies. In contrast to HCl-acidified water, H2SO4-acidified water only temporarily impaired the pole-descending ability of mice (at 3 months of age), and did not change the performance in an accelerating rotarod test. As compared to 129S6/SvEv mice receiving non-acidified or HCl-acidified drinking water, the gut microbiota of 129S6/SvEv mice on H2SO4-acidified water displayed significant alterations at every taxonomic level especially at 6 months of age. Our results demonstrate that the effects of acidified drinking water on the behavior and gut microbiota of 129S6/SvEv mice depends on the acid used for acidification. To shed some light on how acidified drinking water affects the physiology of 129S6/SvEv mice, we analyzed the serum and fecal metabolomes and found remarkable, acidified water-induced alterations.


Assuntos
Infecções Bacterianas/veterinária , Água Potável/química , Microbioma Gastrointestinal/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Ácidos Sulfúricos/administração & dosagem , Animais , Infecções Bacterianas/prevenção & controle , Infecções Bacterianas/transmissão , Água Potável/administração & dosagem , Fezes/microbiologia , Concentração de Íons de Hidrogênio , Masculino , Metaboloma/efeitos dos fármacos , Metabolômica , Camundongos , Modelos Animais , Teste de Desempenho do Rota-Rod
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