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1.
J Chromatogr A ; 1633: 461627, 2020 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-33128970

RESUMO

A Poly (3,4-ethylenedioxothiophene) (PEDOT)/UiO-66 composite was electrodeposited on an etched stainless-steel wire as head-space solid-phase microextraction (HS-SPME) coating. A robust, well controlled thickness, and uniform coating of metal organic framework composites can be realized by the electrodeposited strategy. The incorporated UiO-66 not only enhanced the uniformity and stability of the composite coating, but also effectively decreased the stacking phenomenon of PEDOT and improved its extraction efficiency, which was over 100 times higher than that of the PEDOT coating without UiO-66. The composite coating was used to enrich seven types of volatile organic compounds (VOCs) in ion-exchange resins, including methyl cyclohexane, benzene, toluene, ortho-xylene, styrene, para-xylene and divinyl-benzene. The results of adsorption isotherm analysis showed that π stacking effect played dominant role between the composite coating and VOCs in the extraction process. The composite coating was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis, respectively. A determination method for seven kinds of VOCs was established by HS-SPME coupled with gas chromatography-flame ionization detection (GC-FID). Under the optimal experimental conditions, the detection linear range (LRs) was 0.09-100 ng mL-1, and the detection limit (LODs) was 0.03-0.06 ng mL-1 (S/N = 3). The method was applied for the migration detection of VOCs in four types of ion-exchange resin, which showed satisfactory recovery (84.5-117.2%).


Assuntos
Técnicas de Química Analítica/métodos , Estruturas Metalorgânicas/química , Compostos Organometálicos/química , Ácidos Ftálicos/química , Polímeros/química , Tiofenos/química , Compostos Orgânicos Voláteis/isolamento & purificação , Adsorção , Benzeno/análise , Benzeno/isolamento & purificação , Cromatografia Gasosa , Ionização de Chama , Resinas de Troca Iônica/química , Limite de Detecção , Microextração em Fase Sólida , Aço Inoxidável/química , Tolueno/análise , Tolueno/isolamento & purificação , Compostos Orgânicos Voláteis/análise , Xilenos/análise , Xilenos/isolamento & purificação
2.
Int J Mol Sci ; 21(21)2020 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-33114195

RESUMO

This study examines the mechanisms of adsorption of anthocyanins from model aqueous solutions at pH values of 3, 6, and 9 by ion-exchange resins making the main component of heterogeneous ion-exchange membranes. This is the first report demonstrating that the pH of the internal solution of a KU-2-8 aromatic cation-exchange resin is 2-3 units lower than the pH of the external bathing anthocyanin-containing solution, and the pH of the internal solution of some anion-exchange resins with an aromatic (AV-17-8, AV-17-2P) or aliphatic (EDE-10P) matrix is 2-4 units higher than the pH of the external solution. This pH shift is caused by the Donnan exclusion of hydroxyl ions (in the KU-2-8 resin) or protons (in the AV-17-8, AV-17-2P, and EDE-10P resins). The most significant pH shift is observed for the EDE-10P resin, which has the highest ion-exchange capacity causing the highest Donnan exclusion. Due to the pH shift, the electric charge of anthocyanin inside an ion-exchange resin differs from its charge in the external solution. At pH 6, the external solution contains uncharged anthocyanin molecules. However, in the AV-17-8 and AV-17-2P resins, the anthocyanins are present as singly charged anions, while in the EDE-10P resin, they are in the form of doubly charged anions. Due to the electrostatic interactions of these anions with the positively charged fixed groups of anion-exchange resins, the adsorption capacities of AV-17-8, AV-17-2P, and EDE-10P were higher than expected. It was established that the electrostatic interactions of anthocyanins with the charged fixed groups increase the adsorption capacity of the aromatic resin by a factor of 1.8-2.5 compared to the adsorption caused by the π-π (stacking) interactions. These results provide new insights into the fouling mechanism of ion-exchange materials by polyphenols; they can help develop strategies for membrane cleaning and for extracting anthocyanins from juices and wine using ion-exchange resins and membranes.


Assuntos
Antocianinas/química , Resinas de Troca Iônica/química , Adsorção , Resinas de Troca Aniônica/química , Resinas de Troca de Cátion/química , Concentração de Íons de Hidrogênio , Estrutura Molecular , Eletricidade Estática
3.
Chemosphere ; 244: 125589, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050353

RESUMO

Radioactive Cs ions are extremely harmful to the human body, causing cancers and other diseases. Treatments were performed on radioactive Cs present in wastewater after use in industrial or medical fields. Prussian blue (PB) has been widely used for the removal of Cs ions from water but its colloidal structure hinders reuse, making it problematic for practical use. To solve this problem, we used a commercial macroporous polymer resin as a PB matrix. To provide an efficient anchor for PB, the surface of the polymer resin was decorated with sodium dodecylbenzenesulfonate to produce a negatively charged surface. The successful chemical binding between the polymer resin and PB prevented leakage of the latter during adsorption and crosslinked structure of the matrix provided regeneration of the adsorbent. The adsorbent maintained its removal efficiency after five repeats of the regeneration process. The PB-based, Cs ion-exchange resin showed excellent selectivity toward Cs ions and good reusability, maintaining its high adsorption capacity.


Assuntos
Benzenossulfonatos/química , Césio/química , Ferrocianetos/química , Resinas de Troca Iônica/química , Poluentes Químicos da Água/química , Adsorção , Humanos , Águas Residuárias/química , Purificação da Água
4.
J Vis Exp ; (146)2019 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-31009012

RESUMO

This method allows the separation of trypanosomes, parasites responsible for animal and human African trypanosomiasis (HAT), from infected blood. This is the best method for diagnosis of first stage HAT and furthermore this parasite purification method permits serological and research investigations. HAT is caused by Tsetse fly transmitted Trypanosoma brucei gambiense and T. b. rhodesiense. Related trypanosomes are the causative agents of animal trypanosomiasis. Trypanosome detection is essential for HAT diagnosis, treatment and follow-up. The technique described here is the most sensitive parasite detection technique, adapted to field conditions for the diagnosis of T. b. gambiense HAT and can be completed within one hour. Blood is layered onto an anion-exchanger column (DEAE cellulose) previously adjusted to pH 8, and elution buffer is added. Highly negatively charged blood cells are adsorbed onto the column whereas the less negatively charged trypanosomes pass through. Collected trypanosomes are pelleted by centrifugation and observed by microscopy. Moreover, parasites are prepared without cellular damage whilst maintaining their infectivity. Purified trypanosomes are required for immunological testing; they are used in the trypanolysis assay, the gold standard in HAT serology. Stained parasites are utilized in the card agglutination test (CATT) for field serology. Antigens from purified trypanosomes, such as variant surface glycoprotein, exoantigens, are also used in various immunoassays. The procedure described here is designed for African trypanosomes; consequently, chromatography conditions have to be adapted to each trypanosome strain, and more generally, to the blood of each species of host mammal. These fascinating pathogens are easily purified and available to use in biochemical, molecular and cell biology studies including co-culture with host cells to investigate host-parasite relationships at the level of membrane receptors, signaling, and gene expression; drug testing in vitro; investigation of gene deletion, mutation, or overexpression on metabolic processes, cytoskeletal biogenesis and parasite survival.


Assuntos
DEAE-Celulose/química , Resinas de Troca Iônica/química , Trypanosoma/isolamento & purificação , Animais , Ânions , Arginase/metabolismo , Sangue/parasitologia , Cromatografia , Feminino , Glucose/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/enzimologia , Camundongos , Pentamidina/farmacologia , Treonina/metabolismo , Trypanosoma/efeitos dos fármacos , Trypanosoma brucei brucei/efeitos dos fármacos
5.
J Environ Sci (China) ; 75: 247-254, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30473290

RESUMO

This research investigated the removal capacity of polymeric sub-micron ion-exchange resins (SMR) for removal of lead, copper, zinc, and nickel from natural waters in competition with natural organic matter (NOM). Polymeric SMR particles were created and tested to ensure that they were adequately dispersed in the solution. They removed little NOM (10% or less) from river water and wastewater, indicating that competition from NOM was not a major concern. SMR were able to remove 82%±0.2% of lead, 46%±0.6% of copper, 55%±20% of zinc, and 17%±2% of nickel from river water spiked with 500µg/L of each. Similarly, in wastewater, they were able to remove 86%±0.1% of lead, 38%±0.8% of copper, 28%±1% of zinc, and 11%±1% of nickel.


Assuntos
Resinas de Troca Iônica/química , Metais/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Metais/química , Poluentes Químicos da Água/química
6.
ACS Infect Dis ; 4(5): 845-859, 2018 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-29460625

RESUMO

Siderophores are a structurally diverse class of natural products common to most bacteria and fungi as iron(III)-chelating ligands. Siderophores, including trihydroxamate ferrioxamines, are used clinically to treat iron overload diseases and show promising activity against many other iron-related human diseases. Here, we present a new method for the isolation of ferrioxamine siderophores from complex mixtures using affinity chromatography based on resin-immobilized FhuD2, a siderophore-binding protein (SBP) from Staphylococcus aureus. The SBP-resin enabled purification of charge positive, charge negative, and neutral ferrioxamine siderophores. Treatment of culture supernatants from Streptomyces violaceus DSM 8286 with SBP-resin provided an analytically pure sample of the salmycins, a mixture of structurally complex glycosylated sideromycins (siderophore-antibiotic conjugates) with potent antibacterial activity toward human pathogenic Staphylococcus aureus (minimum inhibitory concentration (MIC) = 7 nM). Siderophore affinity chromatography could enable the rapid discovery of new siderophore and sideromycin natural products from complex mixtures to aid drug discovery and metabolite identification efforts in a broad range of therapeutic areas.


Assuntos
Proteínas de Bactérias/química , Proteínas de Transporte/química , Compostos Ferrosos/isolamento & purificação , Peptídeos/isolamento & purificação , Sideróforos/química , Streptomyces/química , Proteínas de Transporte/metabolismo , Cromatografia de Afinidade , Desferroxamina/química , Compostos Férricos/química , Humanos , Resinas de Troca Iônica/química , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Sideróforos/metabolismo , Fluxo de Trabalho
7.
Environ Sci Pollut Res Int ; 25(22): 21403-21410, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28337628

RESUMO

Polystyrene divinylbenzene-based ion exchange resins are employed extensively within nuclear power plants (NPPs) and research reactors for purification and chemical control of the cooling water system. To maintain the highest possible water quality, the resins are regularly replaced as they become contaminated with a range of isotopes derived from compromised fuel elements as well as corrosion and activation products including 14C, 60Co, 90Sr, 129I, and 137Cs. Such spent resins constitute a major proportion (in volume terms) of the solid radioactive waste generated by the nuclear industry. Several treatment and conditioning techniques have been developed with a view toward reducing the spent resin volume and generating a stable waste product suitable for long-term storage and disposal. Between them, pyrolysis emerges as an attractive option. Previous work of our group suggests that the pyrolysis treatment of the resins at low temperatures between 300 and 350 °C resulted in a stable waste product with a significant volume reduction (>50%) and characteristics suitable for long-term storage and/or disposal. However, another important issue to take into account is the complexity of the off-gas generated during the process and the different technical alternatives for its conditioning. Ongoing work addresses the characterization of the ion exchange resin treatment's off-gas. Additionally, the application of plasma technology for the treatment of the off-gas current was studied as an alternative to more conventional processes utilizing oil- or gas-fired post-combustion chambers operating at temperatures in excess of 1000 °C. A laboratory-scale flow reactor, using inductively coupled plasma, operating under sub-atmospheric conditions was developed. Fundamental experiments using model compounds have been performed, demonstrating a high destruction and removal ratio (>99.99%) for different reaction media, at low reactor temperatures and moderate power consumption. The role of H2O as an important participant of the oxidation mechanisms in plasma conditions was established. The combination of both processes could represent a simple, safe, and effective alternative for treating spent ion exchange resins with a large reduction of generated gaseous byproducts in fuel cycle facilities where processes that utilize open flames are undesirable.


Assuntos
Gases/análise , Resinas de Troca Iônica/química , Pirólise , Resíduos Radioativos , Gerenciamento de Resíduos/métodos , Radioisótopos de Césio , Radioisótopos de Cobalto , Radioisótopos do Iodo , Troca Iônica , Centrais Nucleares , Oxirredução , Gases em Plasma , Radioisótopos de Estrôncio , Resíduos/análise
8.
Molecules ; 23(1)2017 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-29271942

RESUMO

Hot pressurized liquid extraction has been used to obtain polyphenols; however, its operating conditions can generate hydroxymethylfurfural, a potential human carcinogen. The addition of ethanol can reduce process temperatures and retain extraction efficiencies, but the ethanol may reduce the recovery of polyphenols in the subsequent purification stage, affecting the antioxidant properties of the extracts. This study evaluates a combined hot pressurized liquid extraction-resin purification process to obtain polyphenol extracts from spent ground coffee reduced in hydroxymethylfurfural. A multifactorial design was developed to determine the combined effect of the extraction (ethanol content: 0-16% and temperature: 60-90 °C) and purification (ethanol: 60-80%) conditions on some chemical properties of the extracts. The highest recovery of polyphenols (~8 mg GAE/g dry coffee solids) and reduction of hydroxymethylfurfural (95%) were obtained at 90 °C and 16% of ethanol during extraction and 80% of ethanol during purification. These operating conditions retained the antioxidant capacity of the crude extract between 60% and 88% depending on the determination method and recovered 90, 98, and 100% of 4-feruloylquinic acid, epicatechin, and 5-feruloylquinic acid, respectively after purification. The combined process allows differential polyphenols' recovery and enhances the safety of the extracts. Our computational chemistry results ruled out that the overall selectivity of the integrated process was correlated with the size of the polyphenols.


Assuntos
Antioxidantes/isolamento & purificação , Catequina/isolamento & purificação , Coffea/química , Ácidos Cumáricos/isolamento & purificação , Extração Líquido-Líquido/métodos , Sementes/química , Etanol/química , Análise Fatorial , Furaldeído/análogos & derivados , Furaldeído/química , Humanos , Resinas de Troca Iônica/química , Extratos Vegetais/química , Pressão
9.
Artigo em Inglês | MEDLINE | ID: mdl-28683396

RESUMO

The black garlic juice is popular for its nutritive value. Enrichment of antioxidants is needed to make black garlic extract an effective functional ingredient. Five macroporous resins were evaluated for their capacity in adsorbing antioxidants in black garlic juice. XAD-16 resin was chosen for further study due to its high adsorption and desorption ratios. Pseudo-second-order kinetics (qe=625µmol Trolox equiv/g dry resin, k2=0.0001463) and Freundlich isotherm models (ΔH=-10.1547kJ/mol) were suitable for describing the whole exothermic and physical adsorption processes of the antioxidants from black garlic juice on XAD-16 resin. The antioxidants and phenolics were mostly enriched in 40% ethanol fraction by XAD-16 resin column chromatography. The black garlic extract and its fractions could protect erythrocytes against AAPH-induced hemolysis in dose-dependent manners. The pretreatment of AAPH-damaged erythrocytes with 40% ethanol fractions (2.5mg/mL) significantly decreased the hemolysis ratios from 53.58% to 3.79%. The 40% ethanol fraction possessing strong intracellular antioxidant activity could be used as a functional food ingredient.


Assuntos
Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Alho/química , Hemólise/efeitos dos fármacos , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Adsorção , Antioxidantes/análise , Antioxidantes/química , Cromatografia por Troca Iônica/instrumentação , Cromatografia por Troca Iônica/métodos , Eritrócitos/efeitos dos fármacos , Humanos , Resinas de Troca Iônica/química , Extratos Vegetais/análise , Extratos Vegetais/química
10.
J Hazard Mater ; 334: 256-266, 2017 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-28419932

RESUMO

Heavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu2+, Pb2+, Cd2+ and Zn2+) was studied from aqueous phase to oil phase (493, 523, 548, and 573K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu2+ (96%, isotherm 573K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb2+ and Cd2+ was the same in the OIL, with maximum values of 5.7×10-3 (mol/l) and 5.0×10-3 (mol/l) at 573K, respectively. By contrast, concentration of Zn2+ ion showed a slight increase with increasing temperature due to electrostatic forces between Zn2+ and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn2+, was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents.


Assuntos
Quelantes/química , Decapodiformes , Contaminação de Alimentos , Resinas de Troca Iônica/química , Metais Pesados/isolamento & purificação , Óleos/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Animais , Cromatografia Gasosa-Espectrometria de Massas , Hidrólise , Metais Pesados/química , Eletricidade Estática , Temperatura , Poluentes Químicos da Água/química
11.
Chemosphere ; 175: 365-372, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28236706

RESUMO

D201 resin and P507 extractant diluted with sulfonated kerosene were used to respectively separate vanadium and scandium, and impurity ions from hydrochloric acid leaching solution of red mud. More than 99% of vanadium was selectively adsorbed from the hydrochloric acid leaching solution under the conditions of pH value of 1.8, volume ratio of leaching solution to resin of 10, and flow rate of 3.33 mL/min. Maximum extraction and separation of scandium was observed from the acid leaching solution at an aqueous pH value of 0.2. More than 99% of scandium can be selectively extracted using 15% P507, 5% TBP at the aqueous solution/organic phase (A/O) ratio of 10:1 for 6 min. The loaded organic phase was washed with 0.3 mol/L sulfuric acid, wherein most impurities were removed. After the process of desorption or stripping, precipitation, and roasting, high-purity V2O5 and Sc2O3 were obtained. Finally, a conceptual flow sheet was established to separate and recover vanadium and scandium from red mud hydrochloric acid leaching solution.


Assuntos
Ácido Clorídrico/química , Resíduos Industriais , Resinas de Troca Iônica/química , Escândio/isolamento & purificação , Solventes/química , Vanádio/isolamento & purificação , Concentração de Íons de Hidrogênio , Troca Iônica , Soluções , Ácidos Sulfúricos/química , Compostos de Vanádio/isolamento & purificação
12.
Curr Pharm Des ; 23(2): 328-337, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27774905

RESUMO

BACKGROUND: Estrogens and their synthetic analogues are widely used as pharmaceuticals. Upon oral administration these drugs are eventually excreted via urine. The persistence of these pharmaceuticals and inefficient removal by water treatment lead to accumulation in surface water and effluents with negative effects for aquatic life and human health. METHODS: In this study, the uptake of estradiol by a combined magnetic ion exchange resin - ultrafiltration process (MIEX-UF) was investigated. This is a relatively common process used in drinking water treatment for the removal of natural organic matter. However, uptake of micropollutants, such as steroidal pharmaceuticals, may occur as a side effect of water treatment due to the high affinity for polymeric materials. To elucidate the mechanism governing estradiol partitioning between water, resin and membrane, the influence of different parameters, such as pH, humic acid concentration and membrane molecular-weight-cut-off (MWCO) was studied. RESULTS: Humic acid concentration and pH affected estradiol uptake most. At pH 11 the most significant increase of estradiol uptake was observed for MIEX-UF process (30 ng/g corresponding to 80%) compared with individual UF (17 ng/g corresponding to 12%). The presence of humic acid slightly reduced estradiol uptake at pH 11 (about 55%) due to competition for the ion exchange binding sites. CONCLUSION: Results demonstrated that the uptake of estradiol, which is amongst the most potent EDCs detected in surface water, in the MIEX-UF process can reach significant quantities (30 ng/g of resin) leading to uncontrolled accumulation of this micropollutant during drinking water treatment. This study gives a novel contribution in the understanding the mechanism of the unanticipated accumulation of pharmaceuticals, such as estradiol, in the drinking water treatment process.


Assuntos
Estradiol/isolamento & purificação , Troca Iônica , Campos Magnéticos , Ultrafiltração/métodos , Purificação da Água/métodos , Água/química , Estradiol/química , Humanos , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Resinas de Troca Iônica/química
13.
Bioprocess Biosyst Eng ; 38(3): 421-8, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25199811

RESUMO

Bioconversion of DL-2-amino-Δ(2)-thiazoline-4-carboxylic acid (DL-ATC) catalyzed by whole cells of Pseudomonas sp. was successfully applied for the production of L-cysteine. It was found, however, like most whole-cell biocatalytic processes, the accumulated L-cysteine produced obvious inhibition to the activity of biocatalyst and reduced the yield. To improve L-cysteine productivity, an anion exchange-based in situ product removal (ISPR) approach was developed. Several anion-exchange resins were tested to select a suitable adsorbent used in the bioconversion of DL-ATC for the in situ removal of L-cysteine. The strong basic anion-exchange resin 201 × 7 exhibited the highest adsorption capacity for L-cysteine and low adsorption for DL-ATC, which is a favorable option. With in situ addition of 60 g L(-1) resin 201 × 7, the product inhibition can be reduced significantly and 200 mmol L(-1) of DL-ATC was converted to L-cysteine with 90.4 % of yield and 28.6 mmol L(-1 )h(-1) of volumetric productivity. Compared to the bioconversion without the addition of resin, the volumetric productivity of L-cysteine was improved by 2.27-fold using ISPR method.


Assuntos
Cisteína/biossíntese , Cisteína/isolamento & purificação , Resinas de Troca Iônica/química , Pseudomonas/crescimento & desenvolvimento
14.
Anal Bioanal Chem ; 406(25): 6095-103, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24948092

RESUMO

This article provides a condensed introduction to principles of chiral separation, gives a historic overview of the genesis of the most important concepts regarding chiral stationary phase (CSPs), and summarizes the state of the art in a concise manner. Some recent developments in the field of polysaccharide CSPs are outlined. Finally, the article focusses on the new concept of zwitterionic chiral stationary phases and their application profile and peculiarities. Some other trends in column technology, including sub-2 µm and core-shell CSP particles and the emerging field of (UP)SFC, are briefly discussed.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Resinas de Troca Iônica/química , Peptídeos/isolamento & purificação , Polissacarídeos/química , Proteínas/isolamento & purificação , Peptídeos/química , Proteínas/química , Estereoisomerismo
15.
J Water Health ; 11(4): 692-9, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24334843

RESUMO

We compared extracts and toxicities of organic compounds (OCs) in drinking water concentrated by composite XAD-2/8 resin (mixed with an equal volume of XAD-2 and XAD-8 resins) with those extracted by single XAD-2 (non-polar) and XAD-8 (polar) resins. Drinking water was processed from raw water of the Han River and the Yangtze River in Wuhan section, China. The extraction efficiency of all resins was controlled at 30%. The types of extracted OCs were detected by gas chromatography-mass spectrometry, and the cytotoxicity and genotoxicity were assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and comet assays, respectively, in human hepatoma HepG2 cells. Our results showed that XAD-2/8 extracted a larger variety of OCs, compared with XAD-8 and XAD-2. The cytotoxicity and genotoxicity of extracted OCs were in the order of XAD-8> XAD-2/8> XAD-2 at almost all tested concentrations after 24 h treatment (P < 0.05). Our findings suggest that single XAD resin selectively extracts either polar or non-polar OCs, which would lead to over- or under-estimation of the toxicity of drinking water. Nevertheless, composite resin extracts both polar and non-polar OCs, and could be utilized as a useful extraction technique to evaluate the level and toxicity of OCs in drinking water.


Assuntos
Água Potável/química , Resinas de Troca Iônica/química , Compostos Orgânicos/química , Rios/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , China , Cromatografia Gasosa-Espectrometria de Massas , Células Hep G2 , Humanos
16.
Water Res ; 47(11): 3827-34, 2013 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-23648287

RESUMO

The performance of ion exchange (IX) resin for organics removal from wastewater was assessed using advanced characterisation techniques for varying doses of IX. Organic characterisation using liquid chromatography with a photodiode array (PDA) and fluorescence spectroscopy (Method A), and UV254, organic carbon and organic nitrogen detectors (Method B), was undertaken on wastewater before and after magnetic IX treatment. Results showed partial removal of the biopolymer fraction at high IX doses. With increasing concentration of IX, evidence for nitrogen-containing compounds such as proteins and amino acids disappeared from the LC-OND chromatogram, complementary to the fluorescence response. A greater fluorescence response of tryptophan-like proteins (278 nm/343 nm) for low IX concentrations was consistent with aggregation of tryptophan-like compounds into larger aggregates, either by self-aggregation or with polysaccharides. Recycling of IX resin through multiple adsorption steps without regeneration maintained the high level of humics removal but there was no continued removal of biopolymer. Subsequent membrane filtration of the IX treated waters resulted in complex fouling trends. Filtration tests with either polypropylene (PP) or polyvinylidene fluoride (PVDF) membranes showed higher rates of initial fouling following treatment with high IX doses (10 mL/L) compared to filtration of untreated water, while treatment with lower IX doses resulted in decreased fouling rates relative to the untreated water. However, at longer filtration times the rate of fouling of IX treated waters was lower than untreated water and the relative fouling rates corresponded to the amount of biopolymer material in the feed. It was proposed that the mode of fouling changed from pore constriction during the initial filtration period to filter cake build up at longer filtration times. The organic composition strongly influenced the rate of fouling during the initial filtration period due to competitive adsorption processes, while at longer filtration times the rate of fouling appeared to depend upon the amount of biopolymer material in the feed water.


Assuntos
Filtração/instrumentação , Resinas de Troca Iônica/química , Membranas Artificiais , Polipropilenos , Purificação da Água/instrumentação , Purificação da Água/métodos , Adsorção , Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas , Compostos Orgânicos/isolamento & purificação , Polivinil , Espectrometria de Fluorescência , Águas Residuárias , Qualidade da Água
17.
Chem Commun (Camb) ; 49(4): 409-11, 2013 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-23187977

RESUMO

A straightforward synthesis of comb-polypeptides of repeated peptide sequences was developed. These polypeptides were obtained by ROP of defined NCA without any post-polymerization grafting. The key to this strategy relies on the preparation of pure NCA bearing a peptide sequence on its side chain, by an original solid supported methodology.


Assuntos
Peptídeos/síntese química , Aminoácidos/química , Anidridos/química , Resinas de Troca Iônica/química , Estrutura Molecular , Peptídeos/química , Polimerização
18.
Anal Chim Acta ; 738: 1-12, 2012 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-22790694

RESUMO

In recent years the use of monolithic polymers in separation science has greatly increased due to the advantages these materials present over particle-based stationary phases, such as their relative ease of preparation and good permeability. For these reasons, these materials present high potential as stationary phases for the separation and purification of large molecules such as proteins, peptides, nucleic acids and cells. An example of this is the wide range of commercial available polymer-based monolithic columns now present in the market. This review summarizes recent developments in the synthesis of monolithic polymers for separation science, such as the incorporation of nanostructures in the polymeric scaffold as well as the preparation of hybrid structures. The different methods used in the surface functionalization of monolithic columns are also reviewed. Finally, we critically discuss the recent applications of this column technology in the separation of large molecules under different chromatographic mode.


Assuntos
Cromatografia Líquida/instrumentação , Peptídeos/análise , Polímeros/síntese química , Proteínas/análise , Separação Celular/instrumentação , Cromatografia de Afinidade/instrumentação , Cromatografia em Gel/instrumentação , Cromatografia por Troca Iônica/instrumentação , Cromatografia Líquida/métodos , Cromatografia de Fase Reversa/instrumentação , Interações Hidrofóbicas e Hidrofílicas , Resinas de Troca Iônica/química , Microscopia Eletrônica de Varredura , Nanopartículas/química , Propriedades de Superfície
19.
Environ Sci Technol ; 46(14): 7811-7, 2012 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-22703385

RESUMO

Alternative technologies to disinfect drinking water such as ultraviolet (UV) disinfection are becoming more widespread. The benefits of UV disinfection include reduced risk of microbial pathogens such as Cryptosporidium and reduced production of regulated drinking water disinfection byproducts (DBPs). The objective of this research was to determine if mammalian cell cytotoxicity and genotoxicity varied in response to different chlorination protocols with and without polychromatic medium pressure UV (MPUV) and monochromatic low pressure UV (LPUV) disinfection technologies. The specific aims were to analyze the mammalian cell cytotoxicity and genotoxicity of concentrated organic fractions from source water before and after chlorination and to determine the cytotoxicity and genotoxicity of the concentrated organic fractions from water samples treated with UV alone or UV before or after chlorination. Exposure of granular activated carbon-filtered Ohio River water to UV alone resulted in the lowest levels of mammalian cell cytotoxicity and genotoxicity. With combinations of UV and chlorine, the lowest levels of cytotoxicity and genotoxicity were observed with MPUV radiation. The best combined UV plus chlorine methodology that generated the lowest cytotoxicity and genotoxicity employed chlorination first followed by MPUV radiation. These data may prove important in the development of multibarrier methods of pathogen inactivation of drinking water, while limiting unintended toxic consequences.


Assuntos
Cloro/toxicidade , Desinfetantes/toxicidade , Desinfecção/métodos , Água Potável/química , Testes de Toxicidade/métodos , Raios Ultravioleta , Animais , Células CHO , Morte Celular/efeitos dos fármacos , Ensaio Cometa , Cricetinae , Resinas de Troca Iônica/química , Mutagênicos/toxicidade , Ohio , Projetos Piloto , Rios/química , Qualidade da Água
20.
Chemosphere ; 88(7): 895-902, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22560977

RESUMO

An activated carbon (AC) containing a high concentration (374mgg(-1)) of Fe was prepared by carbonization of an ion-exchange resin. To examine its chemical reactivity as a catalyst to decompose 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), the decomposition parameters of temperature and time were varied under air or N(2). Decomposition at 350°C was achieved within 15min under air and 30min under N(2), and the efficiency of PCB-153 decomposition was 99.7% and 98.0%, respectively. An analysis of inorganic chloride ions revealed that PCB-153 was mineralized effectively during the decomposition. The Brunauer-Emmett-Teller (BET) surface area and pore volume of the AC were measured to assess the adsorption capacity before and after the decomposition. The differences between decomposition under air and N(2) reflected the differences in the BET surface and pore volume measurements. A decomposition pathway was postulated, and the reactive characteristics of chlorine atoms loaded on the benzene rings followed the order of para>meta>ortho, which agrees with the calculated results from a density functional theory study.


Assuntos
Poluentes Atmosféricos/química , Carvão Vegetal/química , Resinas de Troca Iônica/química , Ferro/química , Bifenilos Policlorados/química , Catálise , Temperatura
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