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1.
J Environ Sci (China) ; 145: 88-96, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38844326

RESUMO

Conventionally, soil cadmium (Cd) measurements in the laboratory are expensive and time-consuming, involving complex processes of sample preparation and chemical analysis. This study aimed to identify the feasibility of using sensor data of visible near-infrared reflectance (Vis-NIR) spectroscopy and portable X-ray fluorescence spectrometry (PXRF) to estimate regional soil Cd concentration in a time- and cost-saving manner. The sensor data of Vis-NIR and PXRF, and Cd concentrations of 128 surface soils from Yunnan Province, China, were measured. Outer-product analysis (OPA) was used for synthesizing the sensor data and Granger-Ramanathan averaging (GRA) was applied to fuse the model results. Artificial neural network (ANN) models were built using Vis-NIR data, PXRF data, and OPA data, respectively. Results showed that: (1) ANN model based on PXRF data performed better than that based on Vis-NIR data for soil Cd estimation; (2) Fusion methods of both OPA and GRA had higher predictive power (R2) = 0.89, ratios of performance to interquartile range (RPIQ) = 4.14, and lower root mean squared error (RMSE) = 0.06, in ANN model based on OPA fusion; R2 = 0.88, RMSE = 0.06, and RPIQ = 3.53 in GRA model) than those based on either Vis-NIR data or PXRF data. In conclusion, there exists a great potential for the combination of OPA fusion and ANN to estimate soil Cd concentration rapidly and accurately.


Assuntos
Cádmio , Monitoramento Ambiental , Poluentes do Solo , Solo , Espectroscopia de Luz Próxima ao Infravermelho , Cádmio/análise , Poluentes do Solo/análise , Solo/química , Espectroscopia de Luz Próxima ao Infravermelho/métodos , China , Monitoramento Ambiental/métodos , Espectrometria por Raios X/métodos , Redes Neurais de Computação , Estudos de Viabilidade
2.
Sensors (Basel) ; 23(18)2023 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-37765764

RESUMO

Traditional methods for obtaining soil heavy metal content are expensive, inefficient, and limited in monitoring range. In order to meet the needs of soil environmental quality evaluation and health status assessment, visible near-infrared spectroscopy and XRF spectroscopy for monitoring heavy metal content in soil have attracted much attention, because of their rapid, nondestructive, economical, and environmentally friendly features. The use of either of these spectra alone cannot meet the accuracy requirements of traditional measurements, while the synergistic use of the two spectra can further improve the accuracy of monitoring heavy metal lead content in soil. Therefore, this study applied various spectral transformations and preprocessing to vis-NIR and XRF spectra; used the whale optimization algorithm (WOA) and competitive adaptive re-weighted sampling (CARS) algorithms to identify feature spectra; designed a combination variable model (CVM) based on multi-layer spectral data fusion, which improved the spectral preprocessing and spectral feature screening process to increase the efficiency of spectral fusion; and established a quantitative model for soil Pb concentration using partial least squares regression (PLSR). The estimation performance of three spectral fusion strategies, CVM, outer-product analysis (OPA), and Granger-Ramanathan averaging (GRA), was discussed. The results showed that the accuracy and efficiency of the CARS algorithm in the fused spectra estimation model were superior to those of the WOA algorithm, with an average coefficient of determination (R2) value of 0.9226 and an average root mean square error (RMSE) of 0.1984. The accuracy of the estimation models established, based on the different spectral types, to predict the Pb content of the soil was ranked as follows: the CVM model > the XRF spectral model > the vis-NIR spectral model. Within the CVM fusion strategy, the estimation model based on CARS and PLSR (CARS_D1+D2) performed the best, with R2 and RMSE values of 0.9546 and 0.2035, respectively. Among the three spectral fusion strategies, CVM had the highest accuracy, OPA had the smallest errors, and GRA showed a more balanced performance. This study provides technical means for on-site rapid estimation of Pb content based on multi-source spectral fusion and lays the foundation for subsequent research on dynamic, real-time, and large-scale quantitative monitoring of soil heavy metal pollution using high-spectral remote sensing images.

3.
Environ Sci Technol ; 56(9): 5786-5795, 2022 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-35404044

RESUMO

Dioxins in the sintering flue gas are usually removed through integrated elimination technologies by carbonaceous catalysts. However, the regeneration of the used catalyst is poorly investigated, leading to the risk of leakage of dioxins. Herein, the influences of cyclic regenerations on the dioxin removal performance of a catalyst (V2O5/AC) were investigated systematically with dibenzofuran (DBF) as a model pollutant. It was demonstrated that the adsorption capacity and oxidation activity of catalysts significantly declined after several regeneration cycles due to the decreasing external specific surface area and V5+, respectively. Compared with 79.12% DBF directly emitted from a regenerator during N2 regeneration, the emission of DBF was only 29.93% with the modification of the regeneration process through O2 addition and temperature adjustment. The possible regenerated products were also analyzed to disclose the transformation behaviors of DBF. The regeneration mechanisms of DBF followed the transformation pathway of dibenzofuranol, benzofuran, anhydride species, and ultimately to CO2 and H2O. Moreover, the accumulated heavy aromatics on the surface could be decomposed by introducing O2. This research provides a comprehensive understanding of dioxin transformation behavior and a theoretical basis for efficient control of dioxin removal in the whole integrated removal technologies.


Assuntos
Dioxinas , Dibenzodioxinas Policloradas , Adsorção , Catálise , Temperatura
4.
J Anal Appl Pyrolysis ; 163: 105481, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-36540305

RESUMO

The disposable masks generated in the battle against COVID-19 has attracted wide attention in the world. Pyrolysis can convert the masks into useful chemicals and fuels. In this work, the masks are pyrolyzed at temperatures of 400-580 °C and the volatiles generated are cracked without or with catalysts at 440-580 °C. The catalysts used include metal oxides (Al2O3, kaolin, Fe2O3, CeO2, TiO2) and molecular sieves (HZSM5, HY, ß(25H), ß(60H)). The yields and composition of gas and liquid products are studied in detail where the tetrahydrofuran (THF) soluble compounds are defined as the liquid product and the n-hexane soluble compounds are defined as the oil. The liquid product and the oil were identified by GC-MS and quantified by GC. Results indicate that 440 °C is sufficient for the masks' pyrolysis and the yields of gas, liquid product and oil are 23.4, 74.7 and 42.1 wt%, respectively. About 30% of the liquid product are C6-C35 hydrocarbons while about 70% are C36-C70 hydrocarbons trapped in the GC column (termed as column residue). The gas products are mainly C5, propylene and butene, accounting for 54.8%, 22.8% and 14.5% of the total gas product, respectively. Cracking of volatiles over various catalysts converts the liquid product mainly to propylene, butene and smaller organic gases. TiO2, HY and ß(60H) are good catalysts, especially ß(60H), which increases the yield of gas product to 86.5 wt% with 73.0% being ethylene, propylene and butene at 580 °C.

5.
Anal Bioanal Chem ; 413(23): 5685-5694, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34345950

RESUMO

A continuous-flow microchip enabling high-accuracy DNA analysis was developed. Serial consecutive analysis for multiple amplified DNA samples was demonstrated. The sample segments were continuously introduced to the microchip from the PCR device which was interfaced to the microchip through capillary tubing. Electrokinetic co-injection of the DNA samples with size marker enabled reproducible and reliable injection of the DNAs into the gel-filled separation channel providing accurate size determination of the DNA samples. Cross-contamination between serially introduced DNA samples was minimized by plugging a washing solution segment following the previous sample segment between two sample plugs. Using this microchip, continuous separation of multiple samples was performed without any inconvenient and labor-intensive sample preparation steps such as sample mixing, staining, and gel loading which are necessary for conventional gel electrophoresis. It has taken about 4 min to separate single DNA sample and taken 37 min for three serially injected samples which implies that this microchip can be a platform device for fast as well as highly accurate DNA analysis.


Assuntos
DNA/análise , Eletroforese em Microchip/métodos , Desenho de Equipamento , Limite de Detecção , Reação em Cadeia da Polimerase/métodos
6.
Angew Chem Int Ed Engl ; 58(22): 7273-7277, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-30882984

RESUMO

Methods that provide real-time information are essential to resolve transients occurring at dynamic interfaces. Now a powerful method is presented that enables the time- and potential-resolved characterization of liquid and gaseous products of electrochemical reactions shortly after their formation. To demonstrate its extraordinary potential, the electrochemical real time mass spectrometry (EC-RTMS) approach is used to determine the products of the CO2 reduction reaction (CO2 RR) during potential step or sweep experiments on pristine and in situ anodized copper. The enhanced formation of several C2+ products over C1 products is tracked directly after copper anodization, with unprecedented temporal resolution. This new technique creates exciting new opportunities for resolving processes that occur at short timescales and eventually for guiding the design of new, robust catalysts for selective electrosynthesis under dynamic operation.

7.
J Biol Chem ; 292(12): 5128-5143, 2017 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-28053093

RESUMO

The Jeotgalicoccus sp. peroxygenase cytochrome P450 OleTJE (CYP152L1) is a hydrogen peroxide-driven oxidase that catalyzes oxidative decarboxylation of fatty acids, producing terminal alkenes with applications as fine chemicals and biofuels. Understanding mechanisms that favor decarboxylation over fatty acid hydroxylation in OleTJE could enable protein engineering to improve catalysis or to introduce decarboxylation activity into P450s with different substrate preferences. In this manuscript, we have focused on OleTJE active site residues Phe79, His85, and Arg245 to interrogate their roles in substrate binding and catalytic activity. His85 is a potential proton donor to reactive iron-oxo species during substrate decarboxylation. The H85Q mutant substitutes a glutamine found in several peroxygenases that favor fatty acid hydroxylation. H85Q OleTJE still favors alkene production, suggesting alternative protonation mechanisms. However, the mutant undergoes only minor substrate binding-induced heme iron spin state shift toward high spin by comparison with WT OleTJE, indicating the key role of His85 in this process. Phe79 interacts with His85, and Phe79 mutants showed diminished affinity for shorter chain (C10-C16) fatty acids and weak substrate-induced high spin conversion. F79A OleTJE is least affected in substrate oxidation, whereas the F79W/Y mutants exhibit lower stability and cysteine thiolate protonation on reduction. Finally, Arg245 is crucial for binding the substrate carboxylate, and R245E/L mutations severely compromise activity and heme content, although alkene products are formed from some substrates, including stearic acid (C18:0). The results identify crucial roles for the active site amino acid trio in determining OleTJE catalytic efficiency in alkene production and in regulating protein stability, heme iron coordination, and spin state.


Assuntos
Alcenos/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Peroxidases/metabolismo , Staphylococcaceae/enzimologia , Sequência de Aminoácidos , Domínio Catalítico , Cristalografia por Raios X , Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/genética , Ácidos Graxos/metabolismo , Hidroxilação , Modelos Moleculares , Mutação , Peroxidases/química , Peroxidases/genética , Alinhamento de Sequência , Staphylococcaceae/química , Staphylococcaceae/genética , Staphylococcaceae/metabolismo , Especificidade por Substrato
8.
Molecules ; 23(4)2018 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-29642602

RESUMO

Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.


Assuntos
Lignina/química , Adsorção , Biomassa , Floculação , Solubilidade
9.
Molecules ; 22(12)2017 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-29240680

RESUMO

Azo compounds have high exothermic characteristics and low thermal stability, which have caused many serious thermal accidents around the world. In general, different locations (e.g., equatorial or polar regions) have different UV intensities. If the azo compound exists in an inappropriately stored or transported condition, the decrease in thermal stability may cause a thermal hazard or ageing. 2,2'-Azobis(2,4-dimethyl)valeronitrile (ADVN) is investigated with respect to the thermal stability affected by UV exposure at 0, 6, 12, and 24 h. When ADVN is exposed to 24 h of UV (100 mW/m² and 254 nm), T0 is not only advanced, but the mass loss is also increased during the main decomposition stage. In addition, the apparent activation energy and integral procedural decomposition temperature (IPDT) of ADVN exposed to 24 h of UV is calculated by kinetic models. Therefore, the prevention mechanism, thermal characteristics, and kinetic parameters are established in our study. We should isolate UV contacting ADVN under any situations, avoiding ADVN being aged or leading to thermal runaway. This study provided significant information for a safer process under changing UV exposure times for ADVN. Furthermore, the research method may serve as an important benchmark for handling potentially hazardous chemicals, such as azo compounds described herein.


Assuntos
Compostos Azo/química , Nitrilas/química , Processos Fotoquímicos , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Ambiente Controlado , Isomerismo , Cinética , Temperatura , Termodinâmica , Raios Ultravioleta
10.
Int J Food Sci Nutr ; 67(7): 789-96, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27381473

RESUMO

Food and agricultural industries generate substantial quantities of phenolic-rich by-products that could be valuable natural sources of antioxidants. The aim of this study was to identify and quantify the phenolic compounds and radical scavenging activities of two by-products (pomace and lees) from Vitis vinifera L. cv Pinot noir. We found a different distribution of phenolic classes (flavanols, flavonols, phenolic acids and stilbenes) and singular scavenging activity against free radicals (hydroxyl, superoxide and peroxyl radicals). The major class of phenolics in pomace was flavanols and in lees was flavonols, with catechin (117.9 ± 2.5 µg g(-1)) and quercetin (42.4 ± 1.2 µg g(-1)) being the most abundant individual compounds. We also found high potential on scavenging activity against superoxide radicals in pomace (80% of scavenging activity) and radical peroxyl (67% scavenging activity). These results show the possibility of using Pinot noir by-products as promising additives or as a source for the development of new products in different segments of the food and cosmetic industries.


Assuntos
Antioxidantes/análise , Frutas/química , Fenóis/análise , Vitis/química , Catequina/análise , Cromatografia Líquida de Alta Pressão , Flavonoides/análise , Flavonóis/análise , Hidroxibenzoatos/análise , Quercetina/análise , Estilbenos/análise , Espectrometria de Massas em Tandem
11.
J Sep Sci ; 38(9): 1552-60, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25707736

RESUMO

Pearls have been widely used as a traditional medicine, in cosmetics, and as a health food supplement in China since ancient times. However, the identification and quality assessment of pearl powder have been challenging tasks because of the similar morphological features and chemical composition of its common adulterants, especially conch powders. In this study, ultra-performance liquid chromatography was combined with pre-column derivatization to rapidly quantify 14 amino acids in pearl powder and its analogues. Based upon the quantification results, a quality criterion of a total amino acid content of not less than 1.10% was proposed for pearl powder. Principal component analysis indicated that leucine and phenylalanine were the amino acids characteristic for distinguishing between pearls and nacres. The area ratio of leucine to phenylalanine was demonstrated to be an effective diagnostic marker to discriminate freshwater cultured pearls, natural seawater pearls, and nacres. The proposed method, involving both the qualitative and quantitative aspects, was subsequently applied to quality assessment of pearl powders purchased commercially in various parts of China; eight out of 18 batches were deemed authentic and unadulterated. In the future, this analytical process should play a significant role in standardizing and providing quality control to the pearl powder market.


Assuntos
Aminoácidos/análise , Exoesqueleto/química , Pinctada , Animais , Cromatografia Líquida de Alta Pressão , Pós
12.
Electrophoresis ; 35(9): 1368-74, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24452905

RESUMO

In the current work, a fast and reliable CE method for characterizing of six hindered amine light stabilizers (HALS), technical products commonly employed as UV-stabilizing agents for various polymeric materials, is presented. These compounds can be monomeric or oligomeric species whereby there is no or only limited information available concerning purity or actual structural composition of the respective stabilizer. Using a BGE based on formic acid with 10% acetonitrile, different constituents of several HALS could be separated by CE and identified employing QTOF/MS detection. In the case of Cyasorb 3529, ten different oligomers were discovered and possible structures were suggested based on exact mass measurements. The majority of the elucidated structures is not fully congruent with the information provided by the manufacturers. Furthermore, in the case of Chimassorb 119 and Tinuvin 770 impurities or unreacted compounds remaining from the manufacturing process could be identified. Besides performing such basic characterizations of technical grade HALS, the presented method is also shown to be suitable for a reliable identification of these stabilizers in real polymer samples.


Assuntos
Indústria Química , Eletroforese Capilar/métodos , Reagentes de Laboratório/química , Espectrometria de Massas/métodos , Piperidinas/química , Acetonitrilas , Aminas , Benzofenonas/química , Ácidos Decanoicos/química , Formiatos , Plásticos/normas
13.
Electrophoresis ; 35(20): 2965-71, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25043527

RESUMO

The current work describes the development of a CZE method with quadrupole QTOF-MS detection and UV detection for the quantitation of Cyasorb 3529, a common hindered amine light stabilizer (HALS), in polymer materials. Analysis of real polymer samples revealed that the oligomer composition of Cyasorb 3529 changes during processing, a fact hampering the development of a straightforward method for quantitation based on calibration with a Cyasorb 3529 standard. To overcome this obstacle in-depth investigations of the oligomer composition of this HALS using QTOF-MS and QTOF-MS/MS had to be performed whereby 22 new oligomer structures, in addition to the ten structures already described, were identified. Finally, a CZE method for quantitative analysis of this HALS was developed starting with a comprehensive characterization of a Cyasorb 3529 standard using CZE-QTOF-MS, subsequently allowing the correct assignment of most Cyasorb 3529 oligomers in an electropherogram with UV detection. Employing the latter detection technique and hexamethyl-melamine as internal standard, peak areas obtained for the melamine could be correlated with those from the triazine ring, the UV-absorbing unit present in the HALS. This approach finally allowed proper quantitation of the single oligomers of Cyasorb 3529, an imperative for the quantitative assessment of this HALS in real polymer samples.


Assuntos
Eletroforese Capilar/métodos , Piperidinas/análise , Protetores contra Radiação/análise , Espectrofotometria Ultravioleta/métodos , Espectrometria de Massas em Tandem/métodos , Triazinas/análise , Piperidinas/química , Triazinas/química
14.
Food Res Int ; 186: 114317, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38729709

RESUMO

Lipids play a pivotal role in the nutrition of preterm infants, acting as a primary energy source. Due to their underdeveloped gastrointestinal systems, lipid malabsorption is common, leading to insufficient energy intake and slowed growth. Therefore, it is critical to explore the reasons behind the low lipid absorption rate in formulas for preterm infants. This study utilized a simulated in intro gastrointestinal digestion model to assess the differences in lipid digestion between preterm human milk and various infant formulas. Results showed that the fatty acid release rates for formulas IF3, IF5, and IF7 were 58.90 %, 56.58 %, and 66.71 %, respectively, lower than human milk's 72.31 %. The primary free fatty acids (FFA) and 2-monoacylglycerol (2-MAG) released during digestion were C14:0, C16:0, C18:0, C18:1n-9, and C18:2n-6, in both human milk and formulas. Notably, the higher release of C16:0 in formulas may disrupt fatty acid balance, impacting lipid absorption. Further investigations are necessary to elucidate lipid absorption differences, which will inform the optimization of lipid content in preterm infant formulas.


Assuntos
Digestão , Fórmulas Infantis , Recém-Nascido Prematuro , Leite Humano , Leite Humano/química , Leite Humano/metabolismo , Humanos , Fórmulas Infantis/química , Recém-Nascido , Ácidos Graxos/análise , Ácidos Graxos/metabolismo , Lipídeos/análise , Ácidos Graxos não Esterificados/análise , Ácidos Graxos não Esterificados/metabolismo , Metabolismo dos Lipídeos , Trato Gastrointestinal/metabolismo , Modelos Biológicos , Monoglicerídeos/metabolismo , Monoglicerídeos/análise , Gorduras na Dieta/metabolismo , Gorduras na Dieta/análise
15.
Chem Asian J ; 19(6): e202301128, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38323702

RESUMO

In this study, a zero-gap flow-through microfluidic reactor was constructed for the degradation of tetracycline and norfloxacin in water using a porous Ti/RuO2-IrO2@Pt electrode as the anode and porous titanium plate as the cathode. The operation parameters included electrolyte type, electrolyte concentration, current density, initial concentration of pollutants and pH, were investigated. The degradation efficiency and energy consumption were calculated and compared with traditional electrolyzer. In the zero-gap flow-through microfluidic reactor, 100 % of both tetracycline and norfloxacin can be decomposed in 15 min, and high mineralization rate were achieved under the optimized reaction condition. And the reaction was consistent with pseudo-first-order kinetics with k value of 0.492 cm-1 and 1.010 cm-1, for tetracycline and norfloxacin, respectively. In addition, the energy consumption was 28.33 kWh ⋅ kg-1 TC and 8.36 kWh ⋅ kg-1 NOR, for tetracycline and norfloxacin, respectively, which was much lower than that of traditional electrolyzer. The LC-MS results showed that tetracycline underwent a series of demethylation, dehydration and deamination reactions, and the norfloxacin went through ring opening reaction, decarboxylation and hydroxylation reaction, and finally both produced CO2 and H2O.

16.
ChemSusChem ; : e202400535, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38728590

RESUMO

In the past decade, organic electrosynthesis has emerged as an atom- and energy-efficient strategy for harvesting renewable electricity that provides exceptional control over the reaction parameters. A profound and fundamental understanding of electrochemical interfaces becomes imperative to advance the knowledge-based development of electrochemical processes. The major strategy toward an efficient electrochemical system is based on the advancement in material science for electrocatalysis. Studies on the complex interplay among electrode surface, electrolyte, and transformation intermediates have only recently started to emerge. It involves acquiring atomic-scale insights into the electrochemical double layer, for which the identity and concentration of composing ions play a crucial role. In this study, we present how the identity and concentration of alkali cations impact the selectivity of aldehyde functionality electroreduction. As a case-study transformation, we set the electrochemical conversion of 5-hydroxymethylfurfural (HMF), a promising biomass-derived feedstock for the sustainable production of polymer or fuel precursors. Our findings reveal a consistent trend of the selectivity shift towards 2,5-bis(hydroxymethyl)furan (BHMF) as a function of cation size and concentration, rationalized by specific cation adsorption at the glassy carbon (GC), followed by the increase in the electrode surface charge density.

17.
Polymers (Basel) ; 16(13)2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-39000734

RESUMO

Tetra pak packaging is one of the most frequently used types of packaging in the food industry. The recycling of the tetra pak packaging waste presents a difficult task because of its multi-layered, multi-component structure. In this study, the degradation of tetra pak packaging in subcritical (SubCW) and supercritical (SCW) water was investigated. The experiments were carried out in one (SCW) or two stages (SubCW and SCW), whereby the influence of the reaction temperature and time on the yield and composition of the products obtained was investigated. The maximum oil phase yield achieved in a one-stage and a two-stage degradation process was 60.7% and 65.5%, respectively. The oil and gas phases were composed of different types of hydrocarbons. Higher temperature and longer time led to higher amounts of saturated aliphatic hydrocarbons in both the oil and gas phases. The aqueous phase contained sugars (glucose, fructose) and sugar derivatives (levulinic acid, glyceraldehyde, furfurals). Based on these results, the degradation pathway of waste tetra pak packaging in SubCW and SCW was proposed. The results of the study show that the degradation of waste tetra pak packaging with SubCW and SCW is a promising recycling process.

18.
Chemosphere ; 339: 139664, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37506889

RESUMO

The relative rate method was employed to investigate the kinetics of the Cl-initiated reactions of 1-chlorobutane (1-CB) and 2-chlorobutane (2-CB) over 263-363 K, and the measured rate coefficients at room temperature are (1.04 ± 0.24) × 10-10 and (5.84 ± 0.27) × 10-11 cm3 molecule-1 s-1, respectively. The Arrhenius equations for the title reactions were derived to be k1-CB + Cl (T = 263-363 K) = (2.77 ± 0.72) × 10-11 exp [(422 ± 79)/T] and k2-CB + Cl (T = 263-363 K) = (1.40 ± 0.32) × 10-11 exp [(415 ± 70)/T] cm3 molecule-1 s-1, respectively. The products were analysed qualitatively using gas chromatography-mass spectrometry (GC-MS), and the reaction mechanism was proposed for the reactions. The rate coefficients for the title reactions were calculated computationally over the temperature range of 200-400 K using canonical variational transition state theory with appropriate tunnelling corrections at CCSD(T)/6-311++G(2d,2p)//BHandHLYP/6-311++G(2d,2p) level of theory to complement our experimentally measured kinetic parameters. The experimental and theoretical data obtained were used to evaluate the impact of the studied molecules in the troposphere.


Assuntos
Cloro , Temperatura , Cloro/química , Cinética
19.
J Agric Food Chem ; 70(24): 7586-7593, 2022 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-35695390

RESUMO

This study presents the first ultra-high performance supercritical fluid chromatography-diode array detector (UHPSFC-DAD) assay for simultaneous quantitation of secoiridoids, iridoids, xanthones, and xanthone glycosides in Gentiana lutea L. Separation was reached within 12 min on an Acquity UPC2 BEH 2-EP column using CO2 and methanol with 5.5% water as mobile phases. Method validation for nine selected marker compounds (gentisin, isogentisin, swertiamarin, sweroside, gentiopicroside, loganic acid, amarogentin, gentioside, and its isomer) confirmed the assay's sensitivity, linearity, precision, and accuracy. The practical applicability was proven by the analysis of 13 root specimens and 10 commercial liquid preparations (seven liqueurs and three clear spirits). In all root batches, the secoiridoid gentiopicroside dominated (2.1-5.6%) clearly over all other metabolites. In the liqueurs, the metabolite content and distribution were extremely variable: while gentiopicroside was the main compound in four liqueurs, sweroside dominated in one preparation and loganic acid in two others. In contrast, measurable amounts of the metabolites were not detected in any of the examined clear spirits.


Assuntos
Cromatografia com Fluido Supercrítico , Bebidas , Cromatografia Líquida de Alta Pressão/métodos , Gentiana , Extratos Vegetais , Raízes de Plantas
20.
Environ Sci Pollut Res Int ; 29(38): 57758-57772, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35352231

RESUMO

Detection of residual organic and inorganic species in water bodies, including drinking water, has led to developing strategies for their removal. Here, we report a very efficient method of removing Cr(VI), organic dye, and antibiotic from water using a type-II heterojunction based on Sn3O4/SnS2 solar photocatalyst. The toxic Cr(VI) species are reduced by photocatalytic methodology, while methylene blue (MB) dye and ciprofloxacin (CIP) antibiotics are removed by photocatalytic degradation. The structural, compositional, morphological, and optical properties of the hydrothermally synthesized photocatalyst have been studied. Under sunlight exposure, more than 99.9% of Cr(VI) is reduced within 60 min at a reaction rate of 0.066 min-1. While 99.6% of MB and 90% of CIP degradation are achieved in 90 min and 120 min, corresponding to photocatalytic degradation rates of 0.043 min-1 and 0.019 min-1, respectively. The total organic carbon after degradation corresponded to 85.1% for MB and 72.4% for CIP mineralization. The observed photocatalytic degradation is attributed to in situ generation of reactive oxygen species (ROS), e.g., superoxide radicals and hydroxyl radicals. The role of ROS towards photocatalytic degradation of MB and CIP, respectively, was confirmed from ROS scavenging studies. The MB and CIP degradation mechanism has been discussed by analyzing their degradation products.


Assuntos
Azul de Metileno , Nanocompostos , Compostos de Estanho/química , Antibacterianos , Catálise , Cromo/química , Ciprofloxacina , Azul de Metileno/química , Nanocompostos/química , Espécies Reativas de Oxigênio , Luz Solar , Água
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