Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 93
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Small ; 20(29): e2400477, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38402438

RESUMO

Utilizing the ionic flux to generate voltage output has been confirmed as an effective way to meet the requirements of clean energy sources. Different from ionic thermoelectric (i-TE) and hydrovoltaic devices, a new hydrothermal chemical generator is designed by amorphous FeCl3 particles dispersing in MWCNT and unique ferric chloride or water gate. In the presence of gate, the special ion behaviors enable the cell to present a constant voltage of 0.60 V lasting for over 96 h without temperature difference. Combining the differences of cation concentration, humidity and temperature between the right and left side of sample, the maximum short-circuit current and power output can be obtained to 168.46 µA and 28.11 µW, respectively. The generator also can utilize the low-grade heat to produce electricity wherein Seebeck coefficient is 6.79 mV K-1. The emerged hydrothermal chemical generator offers a novel approach to utilize the low-grade heat, water and salt solution resources, which provides a simple, sustainable and low-cost strategy to realize energy supply.

2.
Nanotechnology ; 35(50)2024 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-39332441

RESUMO

The advancement of various energy conversion and storage technologies hinges on the development of efficient and stable electrocatalysts for the oxygen reduction reaction (ORR). In this study, we report the enhancement of carbon cloth (CC) for robust ORR through an FeCl3intercalation reaction. Utilizing a thermal annealing method, FeCl3was intercalated into the graphite structure on the surface of CC, resulting in the creation of numerous defects and the incorporation of Fe species. These newly introduced defects play a pivotal role in activating the ORR via a two-electron pathway. The presence of Fe species further stabilizes the catalytic activity, leading to efficient and stable ORR performance. Our findings highlight the significance of defect engineering and Fe species incorporation in carbon-based materials for improved ORR catalysis and pave the way for the development of advanced electrocatalysts for energy-related applications.

3.
Environ Res ; 259: 119513, 2024 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-38950815

RESUMO

To investigate the effect of stalk type on the metallization degrees in FeCl3-derived magnetic biochar (MBC), MBC was synthesized via an impregnation-pyrolysis method using six different stalks. The Fe0 content in MBC significantly influenced its magnetic properties and ostensibly governed its catalytic capabilities. Analysis of the interaction between stalks and FeCl3 revealed that the variation in metallization degrees, resulting from FeCl2 decomposition (6.1%) and stalk-mediated reduction (20.7%), was directly responsible for the observed differences in MBC metallization. The presence of oxygen-containing functional groups and fixed carbon appeared to promote metallization in MBC induced by reduction. A series of statistical analyses indicated that the cellulose, lignin, and hemicellulose content of the stalks were key factors contributing to differences in MBC metallization degrees. Further exploration revealed that hemicellulose and cellulose were more effective than lignin in enhancing metallization through FeCl2 decomposition and reduction. Constructing stalk models demonstrated that the variance in the content of these three biomass components across the six stalk types could lead to differences in the metallization degree attributable to reduction and FeCl2 decomposition, thereby affecting the overall metallization degree of MBC. A prediction model for MBC metallization degree was developed based on these findings. Moreover, the elevated Si content in some stalks facilitated the formation of Fe2(SiO4), which subsequently impeded the reduction process. This study provides a theoretical foundation for the informed selection of stalk feedstocks in the production of FeCl3-derived MBC.


Assuntos
Carvão Vegetal , Cloretos , Compostos Férricos , Pirólise , Carvão Vegetal/química , Compostos Férricos/química , Cloretos/química , Lignina/química , Celulose/química , Polissacarídeos
4.
J Environ Manage ; 367: 121873, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39059309

RESUMO

Efficient nitrogen removal in constructed wetlands (CWs) remains challenging when treating agricultural runoff with a low carbon-to-nitrogen ratio (C/N). However, using biochar, iron ore, and FeCl3-modified biochar (Fe-BC) as amendments could potentially improve total nitrogen (TN) removal efficiency in CWs, but the underlying mechanisms associated with adding these substrates are unclear. In this study, five CWs: quartz sand constructed wetland (Control), biochar constructed wetland, Fe-BC constructed wetland, iron ore constructed wetland, and iron ore + biochar constructed wetland, were built to compare their treatment performance. The rhizosphere microbial community compositions and their co-occurrence networks were analyzed to reveal the underlying mechanisms driving their treatment performance. The results showed that iron ore was the most efficient amendment, although all treatments increased TN removal efficiency in the CWs. Ammonia-oxidizing, heterotrophic denitrifying, nitrate-dependent anaerobic ferrous oxidizing (NAFO), and Feammox bacteria abundance was higher in the iron ore system and led to the simultaneous removal of NH4+-N, NO3--N, and NO2--N. Visual representations of the co-occurrence networks further revealed that there was an increase in cooperative mutualism (the high proportion of positive links) and more complex interactions among genera related to the nitrogen and iron cycle (especially ammonia-oxidizing bacteria, heterotrophic denitrifying bacteria, NAFO bacteria, and Feammox bacteria) in the iron ore system, which ultimately contributed to the highest TN removal efficiency. This study provides critical insights into how different iron ore or biochar substrates could be used to treat agricultural runoff in CWs.


Assuntos
Carvão Vegetal , Ferro , Nitrogênio , Áreas Alagadas , Nitrogênio/metabolismo , Carvão Vegetal/química , Ferro/química , Ferro/metabolismo
5.
Molecules ; 29(13)2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38999150

RESUMO

Functionalized imidazo[1,2-α]pyridines are important scaffolds in pharmaceuticals. Herein, we present an efficient 3-sulfonylmethylation protocol for imidazo[1,2-α]pyridines by sodium sulfinates in DMA and H2O (2:1) via an FeCl3-catalyzed three-component coupling reaction. Various sulfonylmethyl imidazo[1,2-α]pyridines were thus afforded in high yields with excellent functional group tolerance. A plausible oxidation-addition mechanism was proposed.

6.
J Environ Sci (China) ; 139: 473-482, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38105070

RESUMO

Microplastic pollution has become one of the most concerned focuses in the world. Among many treatment methods, photocatalysis is considered to be one of the most environmentally friendly methods. In this work, the photodegradation behavior of polyamide microplastics is studied by using polyamide 6 PA6) as model microplastics and FeCl3 as catalyst. It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl3 is irradiated in water. The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl3 aqueous solution, indicating that it is promising to use this new method to solve the problem of PA6 type microplastics. In addition, the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS), which provides a new insight for the study of polymer degradation mechanism.


Assuntos
Nylons , Plásticos , Microplásticos , Cromatografia Líquida , Espectrometria de Massas em Tandem/métodos , Metais
7.
Chemistry ; 29(57): e202301736, 2023 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-37439586

RESUMO

An efficient, simple and general protocol for the selective hydration of terminal alkynes into the corresponding methyl ketones has been developed by using a cheap, easy-to-synthesise and sustainable FeIII -based eutectic mixture [FeCl3 ⋅ 6H2 O/Gly (3 : 1)] as both promoter and solvent for the hydration reaction, working: i) under mild (45 °C) and bench-type reaction conditions (air); and ii) in the absence of ligands, co-catalysts, co-solvents or toxic, non-abundant and expensive noble transition metals (Au, Ru, Pd). When the final methyl ketones are solid/insoluble in the eutectic mixture, the hydration reaction takes place in 30 min, and the obtained methyl ketones can be isolated by simply decanting the liquid FeIII -DES, allowing the direct isolation of the desired ketones without VOC solvents. By using this straightforward and simple isolation protocol, we have been able to recycle the FeIII -based eutectic mixture system up to eight consecutive times. Furthermore, the FeIII -eutectic mixture is able to promote the selective and efficient formal oxidation of internal alkynes into 1,2-diketones, with the possibility of recycling this system up to three consecutive times. Preliminary investigations into a possible mechanism for the oxidation of the internal alkynes seem to indicate that it proceeds through the formation of the corresponding methyl ketones and α-chloroketones.

8.
J Environ Manage ; 344: 118403, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37364494

RESUMO

Stormwater treatment and reuse can alleviate water pollution and scarcity while current sand filtration systems showed low treatment performance for stormwater. For enhancing E. coli removal in stormwater, this study applied the bermudagrass-derived activated biochars (BCs) in the BC-sand filtration systems for E. coli removal. Compared with the pristine BC (without activation), the FeCl3 and NaOH activations increased the BC carbon content from 68.02% to 71.60% and 81.22% while E. coli removal efficiency increased from 77.60% to 81.16% and 98.68%, respectively. In all BCs, the BC carbon content showed a highly positive correlation with E. coli removal efficiency. The FeCl3 and NaOH activations also led to the enhancement of roughness of BC surface for enhancing E. coli removal by straining (physical entrapment). The main mechanisms for E. coli removal by BC-amended sand column were found to be hydrophobic attraction and straining. Additionally, under 105-107 CFU/mL of E. coli, final E. coli concentration in NaOH activated BC (NaOH-BC) column was one order of magnitude lower than those in pristine BC and FeCl3 activated BC (Fe-BC) columns. The presence of humic acid remarkably lowered the E. coli removal efficiency from 77.60% to 45.38% in pristine BC-amended sand column while slightly lowering the E. coli removal efficiencies from 81.16% and 98.68% to 68.65% and 92.57% in Fe-BC and NaOH-BC-amended sand columns, respectively. Moreover, compared to pristine BC, the activated BCs (Fe-BC and NaOH-BC) also resulted in the lower antibiotics (tetracycline and sulfamethoxazole) concentrations in the effluents from the BC-amended sand columns. Therefore, for the first time, this study indicated NaOH-BC showed high potential for effective treatment of E. coli from stormwater by the BC-amended sand filtration system compared with pristine BC and Fe-BC.


Assuntos
Areia , Purificação da Água , Escherichia coli , Cynodon , Purificação da Água/métodos , Abastecimento de Água , Chuva , Hidróxido de Sódio , Carvão Vegetal/química , Filtração/métodos
9.
Molecules ; 28(6)2023 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-36985479

RESUMO

In this study, high-performance modified biochar/alginate composite bead (MCB/ALG) adsorbents were prepared from recycled agricultural waste corncobs by a high-temperature pyrolysis and KOH/FeCl3 activation process. The prepared MCB/ALG beads were tested for the adsorption of methylene blue (MB) dye from wastewater. A variety of analytical methods, such as SEM, BET, FTIR and XRD, were used to investigate the structure and properties of the as-prepared adsorbents. The effects of solution pH, time, initial MB concentration and adsorption temperature on the adsorption performance of MCB/ALG beads were discussed in detail. The results showed that the adsorption equilibrium of MB dye was consistent with the Langmuir isothermal model and the pseudo-second-order kinetic model. The maximum adsorption capacity of MCB/ALG-1 could reach 1373.49 mg/g at 303 K. The thermodynamic studies implied endothermic and spontaneous properties of the adsorption system. This high adsorption performance of MCB/ALG was mainly attributed to pore filling, hydrogen bonding and electrostatic interactions. The regeneration experiments showed that the removal rate of MB could still reach 85% even after five cycles of experiments, indicating that MCB/ALG had good reusability and stability. These results suggested that a win-win strategy of applying agricultural waste to water remediation was feasible.

10.
Chemistry ; 28(7): e202104002, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34859514

RESUMO

Conventional syntheses of 1,2-trans-ß-d- or α-l-glycosidic linkages rely mainly on neighboring group participation in the glycosylation reactions. The requirement for a neighboring participation group (NPG) excludes direct glycosylation with (1→2)-linked glycan donors, thus only allowing stepwise assembly of glycans and glycoconjugates containing this type of common motif. Here, a robust glycosylation protocol for the synthesis of 1,2-trans-ß-d- or α-l-glycosidic linkages without resorting to NPG is disclosed; it employs an optimal combination of glycosyl N-phenyltrifluroacetimidates as donors, FeCl3 as promoter, and CH2 Cl2 /nitrile as solvent. A broad substrate scope has been demonstrated by glycosylations with 12 (1→2)-linked di- and trisaccharide donors and 13 alcoholic acceptors including eight complex triterpene derivatives. Most of the glycosylation reactions are high yielding and exclusively 1,2-trans selective. Ten representative, naturally occurring triterpene saponins were thus synthesized in a convergent manner after deprotection of the coupled glycosides. Intensive mechanistic studies indicated that this glycosylation proceeds by SN 2-type substitution of the glycosyl α-nitrilium intermediates. Importantly, FeCl3 dissociates and coordinates with nitrile into [Fe(RCN)n Cl2 ]+ and [FeCl4 ]- , and the ferric cationic species coordinates with the alcoholic acceptor to provide a protic species that activates the imidate, meanwhile the poor nucleophilicity of [FeCl4 ]- ensures an uninterruptive role for the glycosidation.


Assuntos
Saponinas , Triterpenos , Glicosídeos , Glicosilação , Estereoisomerismo , Trissacarídeos
11.
Environ Geochem Health ; 43(9): 3343-3350, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33661450

RESUMO

In this study, soil washing is applied for the remediation of heavy-metal (Pb, Cu and Zn) contaminated paddy soil located near an abandoned mine area. FeCl3 washing solutions were used in bench-scale soil washing experiments at concentrations in the range of 0.1 to 1 M. The strong acid, HCl was also used in this study for comparison. The washing process was performed at room temperature, mixing at 200 RPM for 1 h and a liquid to solid ratio of 2. A sequential extraction technique was performed to evaluate the chemical fractions of Pb in the soils. The soil washing effectiveness was evaluated and compared against regulations applicable to residential districts (Korean warning standards). The soil washing results showed that the heavy metal concentrations were reduced with increasing concentrations of FeCl3. Moreover, the lowest heavy metal concentrations were obtained with a 1 M FeCl3 washing solution. In the case of Pb removal, a 0.3 M FeCl3 washing solution was required to comply with the Korean warning standard of 200 mg/kg. The lowest Pb concentration of 117 mg/kg was obtained with 1 M FeCl3. Similar washing results were also obtained with HCl. The initial total concentrations for Cu and Zn were below the Korean warning standards of 150 and 300 mg/kg, respectively. Consequently, the reduction in Cu and Zn from the contaminated paddy soil using FeCl3 washing solutions was rather limited. The sequential extraction results showed that the exchangeable and weak acid-soluble fractions of Pb were significantly reduced upon FeCl3 washing.


Assuntos
Metais Pesados , Poluentes do Solo , Poluição Ambiental , Metais Pesados/análise , Solo , Poluentes do Solo/análise
12.
Bioorg Chem ; 97: 103691, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32143019

RESUMO

In spite of their various pharmacological properties the anti-inflammatory potential of benzo[c]phenanthridines remained underexplored. Thus, for the first time PDE4 inhibitory potential of 11,12-dihydro benzo[c]phenanthridine/benzo[c]phenanthridine was assessed in vitro. Elegant synthesis of these compounds was performed via a multi-step sequence consisting of a Pd-catalyzed unusual construction of 4-allyl isocoumarin ring and FeCl3-mediated intramolecular regio- as well as site-selective arene-allyl cyclization as key steps. The overall strategy involved Sonogashira coupling followed by isocoumarin and isoquinolone synthesis, then chlorination and subsequent cyclization to afford a range of 11,12-dihydro derivatives. One of these dihydro compounds was converted to the corresponding benzo[c]phenanthridine that showed concentration dependent inhibition of PDE4B affording an initial hit molecule. The SAR study suggested that 11,12-dihydro analogs were less potent than the compound having unsaturation at the same part of the ring.


Assuntos
Fenantridinas/síntese química , Fenantridinas/farmacologia , Inibidores da Fosfodiesterase 4/síntese química , Inibidores da Fosfodiesterase 4/farmacologia , Animais , Derivados de Benzeno/síntese química , Derivados de Benzeno/química , Derivados de Benzeno/farmacologia , Catálise , Linhagem Celular , Técnicas de Química Sintética , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/química , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Ciclização , Humanos , Isocumarinas/síntese química , Isocumarinas/química , Simulação de Acoplamento Molecular , Paládio/química , Fenantridinas/química , Inibidores da Fosfodiesterase 4/química
13.
Mol Divers ; 24(1): 107-117, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30843127

RESUMO

A regioselective three-component reaction of α,ß-unsaturated aldehydes, cyclic 1,3-dicarbonyls and 6-aminouracils in the presence of FeCl3·6H2O as catalyst under microwave irradiation has been demonstrated. Three-component reaction of α,ß-unsaturated aldehydes like cinnamaldehyde/crotonaldehyde, cyclic 1,3-diketones such as 2-hydroxy-1,4-naphthaquinone/dimedone and 6-aminouracils provides regioselective pyrimidine-fused tetrahydropyridines tethered with cyclic 1,3-diketones. On the other hand, replacing cyclic 1,3-diketones by 4-hydroxycoumarin and keeping all other conditions the same provided a two-component pyrimidine-fused pyridines. The salient features of this methodology are operational simplicity, short reaction time, good-to-moderate yields of the products, easy purification method and regioselective products having medicinally important heterocyclic rings such as pyrimidine, tetrahydropyridine or pyridine.


Assuntos
Técnicas de Química Sintética , Micro-Ondas , Piridinas/síntese química , Pirimidinas/química , Pirrolidinas/síntese química , Estrutura Molecular , Análise Espectral
14.
Bioelectromagnetics ; 41(1): 52-62, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31802523

RESUMO

We established three types of thrombosis models to explore the effects of the static magnetic field (SMF) on thrombosis in rats and mice with three different MF intensities. In the carrageenan-induced thrombosis model in rats, the SMF treatments reduced the black tail length of rats, extracorporeal thrombus, and the mass of wet and dry thrombus, and improved the coagulation index value. In FeCl3 -induced arterial thrombosis model in rats, the SMF treatment showed some anti-thrombotic effects. More specifically, the SMF treatment affected rodent blood pressure, plasma plasminogen activator inhibitor, tissue-type plasminogen activator, thrombus mass, and thrombus protein content. In the adrenaline-induced thrombosis model in mice, the SMF treatment had certain effects on the diameter and blood flow velocity of mouse auricle microcirculation in fine veins and arteries. Overall, the highest MF intensities we tested, 20-150 mT, showed a trend of anti-thrombotic effect, indicating that the moderate-intensity SMF might serve as a potential treatment for clot-related diseases in the future. Bioelectromagnetics. 2020;41:52-62 © 2019 Bioelectromagnetics Society.


Assuntos
Campos Magnéticos/efeitos adversos , Trombose/prevenção & controle , Animais , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Carragenina/metabolismo , Epinefrina/metabolismo , Frequência Cardíaca , Compostos de Ferro/metabolismo , Masculino , Camundongos , Microcirculação , Ativadores de Plasminogênio/metabolismo , Ratos , Ratos Sprague-Dawley , Ativador de Plasminogênio Tecidual/metabolismo
15.
Ecotoxicol Environ Saf ; 182: 109388, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31299477

RESUMO

Iron in excess can have toxic effects on living organisms. In China, the freshwater crayfish Procambarus clarkii is a source of aquatic food with high-quality protein and has significant commercial value. P. clarkii shows oxidative stress on exposure to heavy metals, and antioxidant enzymes, such as ubiquitination enzymes and proteasomes, play important roles in oxidative stress. To understand the antioxidant defense system of P. clarkii, we analyzed the hepatopancreas transcriptomes of P. clarkii after stimulation with FeCl3. In total, 5199 differentially expressed genes (DEGs) were identified (2747 upregulated and 2452 downregulated). GO analysis revealed that these DEGs belonged to 16 cellular component, 16 molecular function, and 19 biological process subcategories. A total of 1069 DEGs were classified into 25 categories by using COG. Some antioxidant defense pathways, such as "Ubiquitin mediated proteolysis" and "Glutathione metabolism," were identified using KEGG. In addition, quantitative real time-PCR (qRT-PCR) substantiated the up-regulation of a random selection of DEGs including antioxidant and immune defense genes. We obtained information for P. clarkii transcriptome databases and new insights into the responses of P. clarkii hepatopancreas to heavy metals.


Assuntos
Antioxidantes/metabolismo , Astacoidea/efeitos dos fármacos , Compostos Férricos/toxicidade , Hepatopâncreas/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Animais , Astacoidea/genética , China , Perfilação da Expressão Gênica , Hepatopâncreas/metabolismo , Estresse Oxidativo/genética , Distribuição Aleatória , Reação em Cadeia da Polimerase em Tempo Real
16.
J Environ Manage ; 238: 296-306, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30852406

RESUMO

This work developed an innovative activated carbon (ICAC) derived from orange peels (OP) through chemical activation using FeCl3. The traditional activated carbon (PCAC) that was prepared through K2CO3 activation served as a comparison. Three adsorbents (ICAC, PCAC, and OP) were characterized by various techniques, these being: Brunauer-Emmett-Teller (BET) surface area analysis, thermo-gravimetric analysis, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. They were applied to remove diclofenac from aqueous solution applying batch experiments, in order to investigate the characteristics of adsorptive kinetics, isotherms, and thermodynamics. Results indicated that the SBET values were in the following order: 457 m2/g (PCAC) > 184 m2/g (ICAC) > 3.56 m2/g (OP). The adsorption process reached a fast equilibrium, with activating energies being 27.6 kJ/mol (ICAC), 16.0 kJ/mol (OP), and 11.2 kJ/mol (PCAC). The Langmuir adsorption capacities at 30 °C exhibited the decreasing order: 144 mg/g (ICAC) > 6.44 mg/g (OP) > 5.61 mg/g (PCAC). The thermodynamic parameters demonstrated a signal dissimilarity between biosorbent (ΔG° <0, ΔH° <0, and ΔS° <0) and activated carbon samples (ΔG° <0, ΔH° >0, and ΔS° >0). The presence of iron (FeOCl, γ-Fe2O3, and FeOOH) on the surface of ICAC played a determining role in efficiently removing diclofenac from solution. The excellent adsorption capacity of ICAC toward diclofenac resulted presumably from the contribution of complicated adsorption mechanisms, such as hydrogen bonding, ion-dipole interaction, π-π interaction, pore filling, and possible Fenton-like degradation. Therefore, FeCl3 can serve as a promising activating agent for AC preparation with excellent efficiency in removing diclofenac.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Adsorção , Anti-Inflamatórios , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
17.
J Environ Sci (China) ; 78: 267-275, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30665645

RESUMO

Microplastics have caused great concern worldwide recently due to their ubiquitous presence within the marine environment. Up to now, most attention has been paid to their sources, distributions, measurement methods, and especially their eco-toxicological effects. With microplastics being increasingly detected in freshwater, it is urgently necessary to evaluate their behaviors during coagulation and ultrafiltration (UF) processes. Herein, the removal behavior of polyethylene (PE), which is easily suspended in water and is the main component of microplastics, was investigated with commonly used Fe-based salts. Results showed that although higher removal efficiency was induced for smaller PE particles, low PE removal efficiency (below 15%) was observed using the traditional coagulation process, and was little influenced by water characteristics. In comparison to solution pH, PAM addition played a more important role in increasing the removal efficiency, especially anionic PAM at high dosage (with efficiency up to 90.9%). The main reason was ascribed to the dense floc formation and high adsorption ability because of the positively charged Fe-based flocs under neutral conditions. For ultrafiltration, although PE particles could be completely rejected, slight membrane fouling was caused owing to their large particle size. The membrane flux decreased after coagulation; however, the membrane fouling was less severe than that induced by flocs alone due to the heterogeneous nature of the cake layer caused by PE, even at high dosages of Fe-based salts. Based on the behavior exhibited during coagulation and ultrafiltration, we believe these findings will have potential application in drinking water treatment.


Assuntos
Água Potável/química , Plásticos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Floculação , Ferro/química , Membranas Artificiais , Plásticos/análise , Ultrafiltração/métodos , Poluentes Químicos da Água/análise
18.
Chem Pharm Bull (Tokyo) ; 66(9): 901-906, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30175750

RESUMO

Ginsenoside Rb1 is an important saponin of ginseng(s); however, Rb1, with 3-O- and 20-O-sugar moieties, has low bioavailability. Here, we report the derivatization of ginsenoside Rb1 to completely generate six types of highly bioactive minor ginsenoside Rg3 and its derivatives by FeCl3 catalysis, the reaction conditions are similar to enzymatic reaction conditions. In FeCl3 catalysis, the only 20-O-sugar-moiety of ginsenoside Rb1 was decomposed into the minor ginsenosides Rk1 and Rg5 with newly produced C-20 ethylene bands; but also hydrolyzed into 20(S)-Rg3 and 20(R)-Rg3; subsequently the C-24(25) ethylene bands of 20(S)-Rg3 and 20(R)-Rg3 were hydrated to 20(S)-25-OH-Rg3 and 20(R)-25-OH-Rg3. After separation of reaction mixture from 34 g ginsenoside-Rb1 by silica-gel-column, the 3.3 g sample I of TLC top-band consisting of Rg5 and Rk1, 8.7 g sample II of TLC middle-band consisting of 20(S)-Rg3 and 20(R)-Rg3, 3.5 g sample III of TLC bottom-band consisting of unknown product-I and -II including 20(S)-25-OH-Rg3, were obtained. The sample III consisting of unknown product-I and -II was purified by crystallization, and identified to 20(S)-25-OH-Rg3 and 20(R)-25-OH-Rg3 by HPLC-Evaporative Light Scattering Detector (ELSD) and NMR. Therefore, six types of minor-ginsenosides Rk1, Rg5, 20(S)-Rg3, 20(R)-Rg3, 20(S)-25-OH-Rg3 and 20(R)-25-OH-Rg3 were successfully prepared from ginsenoside Rb1 by FeCl3 catalysis. FeCl3 has low toxicity and is inexpensive, and the reaction conditions are similar to enzymatic reaction conditions; thus, this method is applicable to the development of ginseng-based drugs.


Assuntos
Cloretos/química , Compostos Férricos/química , Ginsenosídeos/química , Catálise , Cristalização , Ginsenosídeos/síntese química , Hidrólise , Peso Molecular
19.
Molecules ; 22(9)2017 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-28892005

RESUMO

An efficient and practical protocol has been developed to synthesize dihydropyrimidinones and dihydropyrimidinethiones through FeCl3∙6H2O/TMSBr-catalyzed three-component cyclocondensation under microwave irradiation. This approach features high yields, broad substrate scope, short reaction time, mild reaction conditions, operational simplicity and easy work-up, thus affording a versatile method for the synthesis of dihydropyrimidinones and dihydropyrimidinethiones.


Assuntos
Técnicas de Química Sintética , Micro-Ondas , Piridinas/síntese química , Pirimidinonas/síntese química , Tionas/síntese química , Catálise , Cloretos/química , Compostos Férricos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Compostos de Trimetilsilil/química
20.
Environ Monit Assess ; 189(8): 387, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28695403

RESUMO

In this study, the reclamation of clean water from spent filter backwash water (SFBW) was investigated through pilot-scale experiments. The pilot plant consisted of pre-sedimentation, coagulation, flocculation, clarification, and ultrafiltration (UF). Two coagulants of PAFCl and FeCl3 were investigated with respect to their performance on treated SFBW quality and UF membrane fouling. At the optimum dose of PAFCl and FeCl3 turbidity removal of 99.6 and 99.4% was attained, respectively. PAFCl resulted in an optimum UV254, TOC, and DOC removal of 80, 83.6, and 72.7%, respectively, and FeCl3 caused the removal of those parameters by 76.7, 80.9, and 65.9%, respectively. PAFCl removed hydrophilic and transphilic constituent better than FeCl3, but FeCl3 had, to some extent, higher affinities to a hydrophobic fraction. It was concluded that PAFCl showed a better coagulation performance in most cases and caused a lower membrane fouling rate compared to FeCl3. Finally, the treated SFBW with both coagulant-UF systems met the drinking water standards.


Assuntos
Purificação da Água/métodos , Cloretos/química , Água Potável/química , Monitoramento Ambiental , Compostos Férricos/química , Floculação , Ultrafiltração , Água/química , Poluentes da Água/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA