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1.
Biosci Biotechnol Biochem ; 84(1): 17-24, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31566084

RESUMO

Human milk oligosaccharides (HMOs) have drawn attention for their contribution to the explosive bifidobacterial growth in the intestines of neonates. We found that bifidobacteria can efficiently metabolize lacto-N-biose I (LNB), the major building blocks of HMOs, and we have developed a method to synthesize LNB by applying this system. We produced LNB on a kilogram scale by the method. This proved that, among the enterobacteria, only bifidobacteria can assimilate LNB, and provided the data that supported the explosive growth of bifidobacteria in neonates. Furthermore, we were also able to reveal the structure of LNB crystal and the low stability for heating at neutral pH, which has not been clarified so far. In this paper, using bifidobacteria and LNB as examples, I describe the research on oligosaccharide synthesis that was conducted by utilizing a sugar metabolism.Abbreviations: LNB: lacto-N-biose I; GNB: galacto-N-biose; HMOs: human milk oligosaccharides; GLNBP: GNB/LNB phosphorylase; NahK: N-acetylhexosamine 1-kinase; GalT: UDP-glucose-hexose-1-phosphate uridylyltransferase; GalE: UDP-glucose 4-epimerase; SP: sucrose phosphorylase.


Assuntos
Acetilglucosamina/análogos & derivados , Bifidobacterium/metabolismo , Glucosiltransferases/química , Leite Humano/química , Oligossacarídeos/metabolismo , Sacarose/química , Acetilglucosamina/síntese química , Acetilglucosamina/química , Acetilglucosamina/metabolismo , Resinas de Troca de Ânions/química , Bifidobacterium/crescimento & desenvolvimento , Cristalização , Dissacaridases/metabolismo , Microbioma Gastrointestinal/fisiologia , Temperatura Alta , Humanos , Concentração de Íons de Hidrogênio , Recém-Nascido
2.
Chemosphere ; 238: 124583, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31425865

RESUMO

The presence of bromide (Br-) in water results in the formation of brominated disinfection byproducts (DBPs) after chlorination, which are much more cytotoxic and genotoxic than their chlorinated analogs. Given that conventional water treatment processes (e.g., coagulation, flocculation, and sedimentation) fail to remove Br- effectively, in this study, we systematically tested and compared the performance of different anion exchange resins, particularly two novel Br-selective resins, for the removal of Br-. The resins performance was evaluated under both typical and challenging background water conditions by varying the concentrations of anions and organic matter. The overall Br- removal results followed the trend of Purolite-Br ≥ MIEX-Br > IRA910 ≥ IRA900 > MIEX-Gold > MIEX-DOC. Further evaluation of Purolite-Br resin showed Br- removal efficiencies of 93.5 ±â€¯4.5% for the initial Br- concentration of 0.25 mg/L in the presence of competing anions (i.e., Cl-, NO3-, NO2-, SO42-, PO43-, and a mixture of all five), alkalinity and organic matter. In addition, experiments under challenging background water conditions confirmed the selectivity of the resins (i.e. Purolite-Br and MIEX-Br) in removing Br-, with SO42- and Cl- exhibiting the greatest influence upon the resin performance followed by NOM concentration, regardless of the NOM characteristic. After Br- removal, both the subsequent formation of brominated DBPs (trihalomethanes, haloacetic acids, and haloacetonitriles), and the total organic halogens (TOX), decreased by ∼90% under the uniform formation conditions. Overall, Br-selective resins represent a promising alternative for the efficient control of Br-DBPs in water treatment plants.


Assuntos
Resinas de Troca de Ânions/química , Brometos/análise , Trialometanos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Desinfecção/métodos , Floculação , Halogenação , Troca Iônica
3.
Chemosphere ; 238: 124633, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31454747

RESUMO

Three different source waters were investigated using virgin and pre-used anion exchange resins, coagulation, and ion exchange combined with coagulation (IEX&Coagulation). The hydrophobicity, size distribution and charge of natural organic matter (NOM) were used to evaluate its removal. Dissolved organic carbon (DOC) removal by pre-used IEX resin was 67-79%. A consistent ratio of different hydrophobicity fractions was found in the removed DOC, while the proportion and quantity of the molecular weight fraction around 1 kDa was important in understanding the treatability of water. For pre-used resin, organic compounds were hypothesised to be restricted to easily accessible exchange sites. Comparatively, virgin resin achieved higher DOC removals (86-89%) as resin fouling was absent. Charge density and the proportion of the hydrophobic fraction were found to be important indicators for the specific disinfection byproduct formation potential (DBP-FP). Treatment of raw water with pre-used resin decreased the specific DBP-FP by between 2 and 43%, while the use of virgin resin resulted in a reduction of between 31 and 63%. The highest water quality was achieved when the combination of IEX and coagulation was used, reducing DOC and the specific DBP-FP well below that seen for either process alone.


Assuntos
Compostos Orgânicos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Resinas de Troca de Ânions/química , Floculação , Interações Hidrofóbicas e Hidrofílicas , Troca Iônica
4.
Prep Biochem Biotechnol ; 49(10): 1020-1032, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31407965

RESUMO

Proteolytic degradation is a serious problem that complicates downstream processing during production of recombinant therapeutic proteins. It can lead to decreased product yield, diminished biological activity, and suboptimal product quality. Proteolytic degradation or protein truncation is observed in various expression hosts and is mostly attributed to the activity of proteases released by host cells. Since these clipped proteins can impact pharmacokinetics and immunogenicity in addition to potency, they need to be appropriately controlled to ensure consistency of product quality and patient safety. A chromatography step for the selective removal of clipped proteins from an intact protein was developed in this study. Poly(ethylenimine)-grafted anion- exchange resins (PolyQUAT and PolyPEI) were evaluated and compared to traditional macroporous anion-exchange and tentacled anion-exchange resins. Isocratic retention experiments were conducted to determine the retention factors (k') and charge factors (Z) were determined through the classical stoichiometric displacement model. High selectivity in separation of closely related clipped proteins was obtained with the PolyQUAT resin. A robust design space was established for the PolyQUAT chromatography through Design-Of-Experiments (DoE) based process optimization. Results showed a product recovery of up to 63% with purity levels >99.0%. Approximately, one-log clearance of host cell protein and two-logs clearance of host cell DNA were also obtained. The newly developed PolyQUAT process was compared with an existing process and shown to be superior with respect to the number of process steps, process time, process yield, and product quality.


Assuntos
Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/métodos , Polietilenoimina/química , Proteínas/isolamento & purificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
5.
Anal Chim Acta ; 1079: 220-229, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387715

RESUMO

We developed temperature-responsive mixed-mode columns packed with poly(N-isopropylacrylamide) (PNIPAAm)-modified beads and poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS)-modified beads in various ratios. The PNIPAAm-modified silica beads and PAMPS-modified silica beads were prepared by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid, respectively. We confirmed polymer modification of the silica beads by CHN elemental analysis, FTIR, zeta-potential measurements, and SEM. To determine the column separation efficiency, we examined the elution behaviors of cold medicine active ingredients and monoamines from each column. Analyte separation occurred on columns with PNIPAAm to PAMPS ratios of 1:20 and 1:10, whereas a column containing only PNIPAAm-modified beads did not retain the analytes. The analytes were retained on the columns through hydrophobic and electrostatic interactions with PNIPAAm and PAMPS, respectively. The separation performance improved with increasing column temperature because of dehydration of PNIPAAm and enhancement of hydrophobic interactions at elevated temperatures. The mixed-mode columns will be useful for separating basic bioactive compounds because the retention of analytes can be modulated by changing the column temperature and the composition.


Assuntos
Resinas Acrílicas/química , Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/instrumentação , Polímeros/química , Ácidos Sulfônicos/química , Alcaloides/análise , Aminas/análise , Cromatografia por Troca Iônica/métodos , Compostos Heterocíclicos de Anéis Fundidos/análise , Dióxido de Silício/química , Temperatura Ambiente
6.
Int J Mol Sci ; 20(14)2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31311111

RESUMO

To ameliorate the trade-off effect between ionic conductivity and water swelling of anion exchange membranes (AEMs), a crosslinked, hyperbranched membrane (C-HBM) combining the advantages of densely functionalization architecture and crosslinking structure was fabricated by the quaternization of the hyperbranched poly(4-vinylbenzyl chloride) (HB-PVBC) with a multiamine oligomer poly(N,N-Dimethylbenzylamine). The membrane displayed well-developed microphase separation morphology, as confirmed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Moreover, the corresponding high ionic conductivity, strongly depressed water swelling, high thermal stability, and acceptable alkaline stability were achieved. Of special note is the much higher ratio of hydroxide conductivity to water swelling (33.0) than that of most published side-chain type, block, and densely functionalized AEMs, implying its higher potential for application in fuel cells.


Assuntos
Resinas de Troca de Ânions/química , Fontes de Energia Elétrica , Membranas Artificiais , Álcalis/química , Benzilaminas/química , Reagentes para Ligações Cruzadas/química , Interações Hidrofóbicas e Hidrofílicas , Transporte de Íons , Polivinil/química
7.
Anal Bioanal Chem ; 411(14): 3103-3113, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30972471

RESUMO

13C metabolite tracer and metabolic flux analyses require upfront experimental planning and validation tools. Here, we present a validation scheme including a comparison of different LC methods that allow for customization of analytical strategies for tracer studies with regard to the targeted metabolites. As the measurement of significant changes in labeling patterns depends on the spectral accuracy, we investigate this aspect comprehensively for high-resolution orbitrap mass spectrometry combined with reversed-phase chromatography, hydrophilic interaction liquid chromatography, or anion-exchange chromatography. Moreover, we propose a quality control protocol based on (1) a metabolite containing selenium to assess the instrument performance and on (2) in vivo synthesized isotopically enriched Pichia pastoris to validate the accuracy of carbon isotopologue distributions (CIDs), in this case considering each isotopologue of a targeted metabolite panel. Finally, validation involved a thorough assessment of procedural blanks and matrix interferences. We compared the analytical figures of merit regarding CID determination for over 40 metabolites between the three methods. Excellent precisions of less than 1% and trueness bias as small as 0.01-1% were found for the majority of compounds, whereas the CID determination of a small fraction was affected by contaminants. For most compounds, changes of labeling pattern as low as 1% could be measured. Graphical abstract.


Assuntos
Isótopos de Carbono/análise , Cromatografia por Troca Iônica/métodos , Cromatografia de Fase Reversa/métodos , Espectrometria de Massas/métodos , Estudos de Validação como Assunto , Resinas de Troca de Ânions/química , Isótopos de Carbono/normas , Interações Hidrofóbicas e Hidrofílicas , Pichia/química , Padrões de Referência , Selênio/química
8.
J Chromatogr A ; 1597: 187-195, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-30922722

RESUMO

Ion exchangers of high binding capacity and uptake rate are desired for high performance purification of proteins by ion exchange chromatography. For this purpose, we have herein developed a new anion exchanger by grafting N,N-Dimethylaminopropyl acrylamide (DMAPAA) onto Sepharose FF by atom transfer radical polymerization. Six DMAPAA-grafted Sepharose FF resins of the same grafting density but different chain lengths (ionic capacities, ICs) were prepared, and named as FF-pDMAPAAn (n denotes IC value, 65-831 mmol/L). Bovine serum albumin (BSA) adsorption and its chromatography were studied to evaluate the anion exchange resins. It was found that the equilibrium protein adsorption capacity (qm) increased rapidly from 91 mg/mL at IC = 65 mmol/L till reaching a peak value (368 mg/mL) at IC = 458 mmol/L and then decreased slightly with further increasing IC (chain length) to 831 mmol/L. The uptake rate, De/D0, defined as the ratio of effective diffusion coefficient (De) to free diffusivity of the protein (D0), also presented similar changes as a function of IC. Namely, De/D0 increased from 0.25 to 2.45 in the IC range of 65 to 458 mmol/L, kept almost unchanged from 458 to 573 mmol/L and then decreased slightly with further increase of IC to 831 mmol/L. Therefore, FF-pDMAPAA458 presented the best performance of the six resins for BSA adsorption, possessing very high qm and De/D0 values (368 mg/mL and 2.45, respectively). The resin was thus extensively characterized in the effect of ionic strength and column chromatography. The qm and De/D0 of FF-pDMAPAA458 were much higher than other anion exchangers reported in literatures and kept over 230 mg/mL and 2.3, respectively, at salt concentrations up to 100 mmol/L. Therefore, the dynamic binding capacity of the FF-pDMAPAA458 column was remarkably higher than Q Sepharose FF and other two typical polymer-grafted anion exchangers reported in literatures in the salt concentration range, and kept as high as 180-220 mg/mL in the superficial flow velocity rang of 150-1350 cm/h. Taken together, the results demonstrated that FF-pDMAPAA resins of appropriate ionic capacities are promising for high-performance protein chromatography.


Assuntos
Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/métodos , Proteínas/química , Sefarose/química , Acrilamida/química , Adsorção , Cromatografia por Troca Iônica/instrumentação , Íons/química , Cinética , Concentração Osmolar , Polietilenoimina/química , Soroalbumina Bovina/química
9.
J Chromatogr A ; 1596: 117-123, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30904170

RESUMO

Four covalently-bonded hyperbranched anion exchangers based on poly(styrene-divinylbenzene) (PS-DVB) substrate with different structure of the functional layer were prepared using mono- and dianionic amino acids such as glycine, ß-alanine, aspartic acid, and glutamic acid in the internal part of the functional layer. Selectivity of all anion exchangers toward weakly retained organic acids was investigated at different temperatures in order to evaluate the effect of the number of carboxylic groups in the functional layer and its hydrophilicity on the separation. It was found that dianionic amino acids used in the first modification cycle of hyperbranching provide the best resolution for mono- and divalent organic acids, which makes the number of carboxylic groups in the structure of amino acid a key factor in the separation of such analytes with covalently-bonded hyperbranched anion exchangers, while the role of amino acid hydrophilicity is not that significant. Stationary phases prepared using aspartic and glutamic acids provided baseline resolution for quinic, glycolic, acetic, lactic, formic, and galacturonic acids, which are not resolved to baseline with modern commercially available anion exchangers; the increase of temperature was found to be favorable for improving the resolution even further.


Assuntos
Aminoácidos Dicarboxílicos/química , Aminoácidos/química , Resinas de Troca de Ânions/química , Aminoácidos/isolamento & purificação , Cromatografia por Troca Iônica , Interações Hidrofóbicas e Hidrofílicas , Compostos Orgânicos/química , Poliestirenos/química , Temperatura Ambiente
10.
Chemosphere ; 223: 39-47, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30763914

RESUMO

In this paper, a series of mono-functional and bifunctional anion exchange resins with different kinds of trialkylammonium groups were synthesized and used for adsorption of nitrate from aqueous solution. The obtained resins were systematically characterized by scanning electron microscopy, Fourier transform infrared spectrometry and pore size distribution. Adsorptive behaviors and mechanisms were investigated by batch experiments. The nitrate could be preferentially adsorbed in the presence of chloride, sulfate and humic acid by longer-chain trialkylamine modified resins. Especially, the L20 resin with the triethylammonium functional group was demonstrated to possess high selectivity toward nitrate with the highest distribution coefficient among all tested resins. For both single and bi-solutes systems, the adsorption isotherm data could be well fitted with the Langmuir model, while the experimental kinetic data was well described by both pseudo first-order and second-order kinetic model. The L20 resin could be reused after many adsorption-desorption cycles with most of its virgin adsorption capacity for advanced wastewater treatment, indicating its great potential for the selective and efficient removal of nitrate from large amounts of municipal wastewater or surface water.


Assuntos
Resinas de Troca de Ânions/química , Nitratos/química , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Resinas de Troca de Ânions/síntese química , Cinética , Nitratos/isolamento & purificação , Porosidade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
11.
Environ Sci Pollut Res Int ; 26(33): 34233-34247, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30617880

RESUMO

Removal and recovery of phosphorus (P) from sewage are essential for sustainable development of P resource. Based on the water quality determination of sludge dewatering filtrate from a wastewater treatment plant in Beijing, this study investigated the adsorption and regeneration characteristics of P by magnetic anion exchange resin (MAEX). The experiments showed that the P adsorption capacity of MAEX could reach a maximum of 2.74 mg/mL when initial P concentration was 25 mg/L and dosage of MAEX was 8 mL/L. The P adsorption on MAEX resin was suitable for large temperature range (283-323 K). However, the adsorption capacity was reduced in various degrees due to the interference of different anions (Br-, SO42-, Cl-, NO3-, HCO3-, CO32-) and organic compounds (bovine serum albumin, humic acid). Kinetics studies indicated that the P adsorption process followed the pseudo-second-order model. The MAEX resin had a rapid P adsorption rate and the P adsorption capacity at 30 min could reach 97.7-99.3% of qe. Increase of temperature was favorable to P adsorption on MAEX, and the adsorption isotherm data fitted to Langmuir model more than Freundlich model. Meanwhile, the thermodynamics parameters were calculated; it was shown that the adsorption process was an endothermic reaction. Desorption and regeneration experiments showed that NaHCO3 was a suitable regenerant, and the P adsorption capacity could reach 90.51% of the original capacity after 10 times of adsorption-desorption cycles; this indicated that MAEX resin has an excellent regeneration performance and thus has a very good application prospect of P removal and recovery. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that ion exchange, charge attraction, and hydrogen bonding affected the removal of P by the MAEX resin. The vibrating sample magnetometer (VSM) analysis revealed that MAEX resin was a kind of soft magnetic materials with good magnetism.


Assuntos
Resinas de Troca de Ânions/química , Fósforo/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Adsorção , Ânions , Pequim , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Troca Iônica , Cinética , Fenômenos Magnéticos , Magnetismo , Esgotos , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Termodinâmica , Águas Residuárias
12.
J Chromatogr A ; 1589: 65-72, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30598288

RESUMO

Three covalently-bonded poly(styrene-divinylbenzene)-based (PS-DVB) hyperbranched anion exchangers prepared using primary amines with carboxylic, sulfonic or 2-hydroxyethyl substituents in the internal part of the functional layer were studied and compared for evaluating the effect of amines substituents on the chromatographic performance of the stationary phases. The hyperbranched coating was created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE) and amination with primary amine; glycine, taurine (2-aminoethanesulfonic acid) or ethanolamine were used in the first cycle, and 4 more cycles were conducted with methylamine (MA). The influence of the structure and type of primary amine used in the first cycle on the retention and selectivity toward inorganic anions, short-chain carboxylic acids, and polyphosphates was investigated using hydroxide eluent. The effect of temperature on the separation of organic acids was also studied for all stationary phases, which revealed the possibility to control and improve resolution for some pairs of analytes.


Assuntos
Ácidos/química , Aminas/química , Resinas de Troca de Ânions/química , Compostos Orgânicos/química , Aminação , Cromatografia por Troca Iônica , Temperatura Ambiente
13.
J Chromatogr A ; 1585: 121-130, 2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30503698

RESUMO

Complex adsorption kinetics behaviors of proteins in mixtures hampers chromatographic process development and complicates model-based prediction of separation. We investigated the adsorption characteristics of mixtures comprised of a larger protein (secretory immunoglobulins or thyroglobulin) and a smaller protein (serum albumin or green fluorescence protein) on the small-pore anion exchanger Q Sepharose FF. Confocal laser scanning microscopy measurements revealed that binding of the large protein was extremely slow and eventually stopped completely after the adsorption front penetrated just a few µm into the particle. Binding capacities after 24 h of incubation were nevertheless around 35 mg/mL of particle which is relatively high when considering that only a fraction of the particle was saturated, suggesting that locally-high bound protein concentrations are attained in a layer close to the particle surface. During mixture adsorption, the bound protein layer also significantly hindered diffusion of the smaller proteins into the particles resulting in about three times slower adsorption kinetics compared to single component adsorption. The combined effects of restricted diffusion and protein binding explain why flow-through purification of these mixtures with the small-pore resin Q Sepharose FF is effective under practical conditions. In this resin, diffusion of secretory immunoglobulins (or thyroglobulin) is restricted in the small pores so that despite their intrinsically greater affinity for the resin, much less binds compared to small proteins. Using the large-pore resin POROS 50 HQ results in faster transport, but also in more binding of secretory immunoglobulins (or thyroglobulin) compared to smaller protein impurities, preventing effective flow-through purification.


Assuntos
Resinas de Troca de Ânions/química , Proteínas/isolamento & purificação , Adsorção , Difusão , Cinética , Proteínas/química , Sefarose/química
14.
Anal Sci ; 35(3): 347-350, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30344207

RESUMO

We propose the creation of reusable indicator-sorbed-solids, using anion-exchange resins or kaolin as supports, with the aim to reduce chemical use towards green analytical chemistry. Indicators (phenolphthalein, thymol blue and butterfly pea flower extract as a natural indicator) sorbed on a solid support, were employed in acid-base titration, in both homogenous aqueous and heterogenous aqueous organic phases. Applications of the developed techniques to some real samples, such as vinegar, colored fruit juice and vegetable oil, have been demonstrated.


Assuntos
Resinas de Troca de Ânions/química , Análise de Alimentos/métodos , Química Verde/métodos , Indicadores e Reagentes/química , Caulim/química , Titulometria/métodos , Ácido Acético/análise , Adsorção , Sucos de Frutas e Vegetais/análise , Óleos Vegetais/análise
15.
Sci Total Environ ; 655: 571-580, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30476837

RESUMO

Cyanobacterial blooms are becoming a serious challenge across the globe due to changing climate and rainfall patterns as a consequence of human activities. In the present study, the fundamental interactions involved during the removal of Microcystin-LR (MCLR), one of the most commonly occurring cyanobacterial toxins, were investigated by employing strongly basic anion exchange (IX) resins. Several factors including the stoichiometric coefficients, competitive fractions and solute affinities were determined under various concentrations of inorganic ions and natural organic matter. The results indicated that suphates were the most competitive fractions with high affinity (α (affinity coefficient) values ~ 9) followed by nitrates (α ~ 4.7) and NOM fractions (α ~ 4.5, p < 0.05). The Equivalent Background Concentration Mode (EBC), that arises from the Ideal Adsorption Solution Theory (IAST), indicated a competitive fraction of ~2 µeq/L NOM, which approximates to <10% of the initial NOM concentrations, indicating a small fraction of the NOM resulting in the competitive effect. Further, studies with natural surface waters indicated that the MCLR uptake could be modeled using the IAST-EBC model and the IX resin could simultaneously removal of >90% of NOM, inorganic ions and MCLR at resin dosages of 3.6 meq/L or higher.


Assuntos
Resinas de Troca de Ânions/química , Microcistinas/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Substâncias Húmicas/análise , Microcistinas/análise , Poluentes Químicos da Água/análise
16.
J Sci Food Agric ; 99(1): 117-123, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29808577

RESUMO

BACKGROUND: Activated almonds are raw almonds that have been soaked in water for 12-24 h at room temperature, sometimes followed by a 24 h drying period at low temperature (50 ± 5 °C). This treatment is thought to enhance the nutrient bioavailability of almonds by degrading nutrient inhibitors, such as phytic acid or d-myo-inositol hexaphosphate (InsP6 ), through the release of phytase or passive diffusion of InsP6 into the soaking water. Over a wide pH range, InsP6 is a negatively charged compound that limits the absorption of essential nutrients by forming insoluble complexes with minerals such as iron and zinc. It is hypothesized that hydrating the seed during soaking triggers InsP6 degradation into lower myo-inositol phosphates with less binding capacity. RESULTS: Anion-exchange chromatography coupled with tandem mass spectrometry was used to quantify myo-inositol mono-, di-, tris-, tetra-, penta-, and hexaphosphates (InsP1-6 ) in raw pasteurized activated almonds. At least 24 h of soaking at ambient temperature was required to reduce InsP6 content from 14.71 to 14.01 µmol g-1 . CONCLUSIONS: The reduction in InsP6 is statistically significant (P < 0.05) after 24 h of activation, but only represents a 4.75% decrease from the unsoaked almonds. © 2018 Society of Chemical Industry.


Assuntos
Fosfatos de Inositol/análise , Nozes/química , Prunus dulcis/química , 6-Fitase/metabolismo , Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/instrumentação , Cromatografia por Troca Iônica/métodos , Manipulação de Alimentos , Fosfatos de Inositol/isolamento & purificação , Proteínas de Plantas/metabolismo , Prunus dulcis/enzimologia , Espectrometria de Massas em Tandem/métodos
17.
J Chromatogr A ; 1586: 62-71, 2019 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-30579640

RESUMO

A weakly basic anion exchange resin with hydroxylated tertiary amine groups was successfully synthesized and used for the first time in an adsorption study for glycerin in fatty acid methyl esters (FAME). A kinetic study of glycerin adsorption on the resin demonstrated that the resin exhibited a rapid initial adsorption behavior, and the correlation coefficients (r22) of the pseudo-second order reaction model were all greater than 0.98, which indicated the existence of hydrogen bonds through sharing electrons between glycerin and active sites on the resin. The whole process of glycerin adsorption onto the resin was a combination mechanism involving hydrogen bond sorption and intraparticle diffusion. The thermodynamic experiments showed that the glycerin adsorption onto the resin was a spontaneous exothermic process accompanied with a gradual decrease in entropy. In addition to intraparticle diffusion, the adsorption behaviors of the resin for glycerin also involved hydrogen bond forces between the OH in the glycerin molecule and N atom in the N(CH3)2 group, glycerin intermolecular hydrogen bond attraction, the dipole bond forces between glycerin and the N(CH3)2 group (90.96%) in the resin, and the dipole bond forces between glycerin and several of the N(CH3)3+ groups (9.04%) in the resin.


Assuntos
Aminas/química , Resinas de Troca de Ânions/química , Ésteres/química , Ácidos Graxos/química , Glicerol/isolamento & purificação , Adsorção , Glicerol/análise , Glicerol/química , Ligações de Hidrogênio , Concentração de Íons de Hidrogênio , Termodinâmica
18.
Waste Manag ; 81: 61-70, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30527044

RESUMO

Refractory organic matters (ROM) are the dominant organic matters in the membrane bioreactor -treated MSW landfill leachate, which are usually resistant to microbial degradation. Advanced membrane systems, which are expensive and generally for drinking water treatment, have to be used to make the final effluent meet discharge requirements. Anion exchange approach might be another option to remove ROM from leachate. In this study, the adsorption isotherms and kinetics were performed to illustrate the adsorption mechanism of anion exchange resins, 717 and D301R-Cl, for removing ROM from leachate. The results demonstrated that the adsorption isotherms for both resins were best represented by Langmuir model. The measured adsorption capacities of the 717 and D301-Cl resins were 39.84 and 35.84 mg COD g-1 dry resin, respectively. The adsorption kinetics of ROM onto both resins followed a pseudo-second-order model and the measured rate constants were 0.00278 and 0.00236 g mg-1 min-1 for the 717 and D301R-Cl resins, respectively. Additionally, intra-particle diffusion analysis indicated that the adsorption of ROM was controlled by both film and intra-particle diffusions. Based on the UV/Vis spectra and fluorescence EEM analysis, the UV humic-like substances were preferentially adsorbed on both resins, although more on D301R-Cl resin than 717 resin. Furthermore, column studies showed that the adsorption of ROM on both 717 and D301R-Cl resins can be divided into two phases: monolayer adsorption and multilayer adsorption, while the desorption demonstrated similar pattern but different efficiency due to the unique property of resin. The results suggested that the resins could remove ROM from leachate efficiently, while the practical progress needs to be further optimized.


Assuntos
Resinas de Troca de Ânions/química , Resíduos Sólidos/análise , Poluentes Químicos da Água/química , Adsorção , Instalações de Eliminação de Resíduos
19.
ACS Appl Mater Interfaces ; 10(48): 41747-41756, 2018 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-30456944

RESUMO

Large quantities of organic ion-exchange resins are used worldwide for water decontamination and polishing. Fouling by microorganisms and decomposition products of natural organic matter severely limits the lifetime of these resins. Much research has thus been invested in polymer-based antifouling coatings. In the present study, poly(4-styrenesulfonate) (PSS) and a co-polymer of PSS and a zwitterionic group were used to spontaneously coat commercial Dowex 1X8 anion-exchange resin. UV-visible spectroscopy provided a precise measure of the kinetics and amount of PSS sorbed onto or into resin beads. When challenged with Chlamydomonas reinhardtii algae, uncoated resin was rapidly fouled by algae. Coating the resin with either the homopolymer of PSS or the co-polymer with zwitterion eliminated fouling. Using narrow- and wide-molecular-weight distribution PSS, a cutoff molecular weight of about 240 repeat units was found, above which PSS was unable to diffuse into the resin. Thus, only one monolayer of added PSS was sufficient to confer a highly desirable antifouling property on this resin while consuming less than 0.1% of the exchanger capacity. Radioactive sulfate ions were used to probe the kinetics of (self)exchange, which were virtually unaffected by the PSS coating. This resin treatment is a fast, ultra-low-cost step for potentially enhancing the lifetime of ion exchangers.


Assuntos
Resinas de Troca de Ânions/química , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Resinas Sintéticas/química
20.
J Chromatogr A ; 1574: 27-35, 2018 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-30228008

RESUMO

For the first time, the possibility of the use of liquid anion exchangers in dispersive liquid-liquid microextraction for the direct extraction of some inorganic anions (nitrite, nitrate, and iodide) was evaluated. In this technique, chloroform containing a liquid anion exchanger (trioctylamine) was used as extractant. The mixture of the extractant and disperser solvent (acetonitrile) was injected into the acidic sample solution. The protonated trioctylamine formed a water-insoluble salt with the inorganic anions (analytes). After the phase separation and stripping of the analytes from the extractant, the analytes were determined by liquid chromatography with UV detection. Various parameters affecting the extraction efficiency were investigated. Under the optimum conditions, broad linear dynamic ranges, with determination coefficients (r2) higher than 0.998, and enrichment factors between 94 and 244 were obtained. The limits of detection and quantification were in the range of 0.1-0.5 and 0.4-1.7 µg L-1, respectively. Also, the values of intra- and inter-day relative standard deviations were 3.5-5.8% and 5.5-7.8%, respectively. Various real water samples including sea, tap, river, spring and mineral water were analyzed by the method. The method was sensitive, simple, inexpensive and capable of the simultaneous extraction and determination of the selected inorganic anions.


Assuntos
Ânions/isolamento & purificação , Monitoramento Ambiental/métodos , Microextração em Fase Líquida/métodos , Água/química , Acetonitrilos/química , Resinas de Troca de Ânions/química , Ânions/química , Clorofórmio/química , Cromatografia Líquida , Limite de Detecção , Rios/química , Solventes/química
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