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1.
Molecules ; 24(15)2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31370148

RESUMO

A novel functional ion-exchange/adsorption metal organic resin (MOR), TEBAC-HKUST-1, was prepared and characterized. Ethanedithiol was used as the grafting agent to introduce thiol groups onto HKUST-1, and 4-vinylbenzyl chloride was then grafted onto SH-HKUST-1 using thiol groups. Finally, the quaternary ammonium functional group was immobilized onto the carrier by performing a quaternization reaction. The structure and property of TEBAC-HKUST-1 MOR were characterized by TGA, N2 adsorption-desorption, FTIR, SEM, and XRD. TEBAC-HKUST-1 MOR was used to remove metal cyanide complexes from wastewater. The adsorption was rapid, and the metal cyanide complexes including Pt(CN)42-, Co(CN)63-, Cu(CN)32-, and Fe(CN)63- were removed in 30 min. TEBAC-HKUST-1 MOR exhibited a high stability in neutral and weak basic aqueous solutions. Furthermore, Pt(II) could be efficiently recovered through two-step elution. The recovery rate of Pt(II) for five cycles were over 92.0% in the mixture solution containing Pt(CN)42-, Co(CN)63-, Cu(CN)32-, and Fe(CN)63-. The kinetic data were best fitted with the pseudo second-order model. Moreover, the isothermal data were best fitted with the Langmuir model. The thermodynamic results show that the adsorption is a spontaneous and exothermic process. TEBAC-HKUST-1 MOR not only exhibited excellent ability for the rapid removal of metal cyanide complexes, but also provided a new idea for the extraction of noble metals from cyanide-contaminated water.


Assuntos
Cianetos/isolamento & purificação , Compostos Organometálicos/química , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Complexos de Coordenação/química , Cianetos/química , Cianetos/toxicidade , Humanos , Concentração de Íons de Hidrogênio , Resinas de Troca Iônica/química , Cinética , Paládio/química , Termodinâmica , Poluentes Químicos da Água
2.
Int J Mol Sci ; 20(14)2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31336637

RESUMO

Electrodialysis and electrodeionization are separation processes whose performance depends on the quality and properties of ion-exchange membranes. One of the features that largely affects these properties is heterogeneity of the membranes both on the macroscopic and microscopic level. Macroscopic heterogeneity is an intrinsic property of heterogeneous ion-exchange membranes. In these membranes, the functional ion-exchange component is dispersed in a non-conductive binder. The functional component is finely ground ion-exchange resin particles. The understanding of the effect of structure on the heterogeneous membrane properties and behavior is thus of utmost importance since it does not only affect the actual performance but also the cost and therefore competitiveness of the aforementioned separation processes. Here we study the electrokinetic behavior of cation-exchange resin particle systems with well-defined geometrical structure. This approach can be understood as a bottom up approach regarding the membrane preparation. We prepare a structured cation-exchange membrane by using its fundamental component, which is the ion exchange resin. We then perform an experimental study with four different experimental systems in which the number of used cation-exchange particles changes from 1 to 4. These systems are studied by means of basic electrochemical characterization measurements, such as measurement of current-voltage curves and direct optical observation of phenomena that occur at the interface between the ion-exchange system and the adjacent electrolyte. Our work aims at better understanding of the relation between the structure and the membrane properties and of how structure affects electrokinetic behavior of these systems.


Assuntos
Cátions/química , Eletricidade , Resinas de Troca Iônica/química , Troca Iônica , Eletroquímica , Concentração de Íons de Hidrogênio , Membranas Artificiais
3.
Int J Biol Macromol ; 138: 681-692, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31344414

RESUMO

We develop a technique for the sorption of inulinase from Kluyveromyces marxianus on the KU-2 matrix cation-exchanger. The most appropriate conditions for immobilization are: 25 °C, pH 4.5, incubation time 1.5 h, protein content during immobilization 10 mg/g of carrier. At higher (20-100 mg/g) concentrations, inulinase forms local high-concentration domains on the ion-exchanger surface, the enzyme is adsorbed on the protein, not on the carrier. 62% of the initial catalytic activity of inulinase is immobilized on KU-2 by the adsorption method. Upon the enzyme immobilization on KU-2, the number of unordered structures in the protein is reduced by ~10%, that points to the compaction of the molecule. Hydrogen bonds are formed only between the sulfo groups of carrier and the protein molecule, without affecting other structures of the cation exchanger. The highest activity of the inulinase immobilized on KU-2 was observed at 70 °C (cf. 50 °C for the native enzyme). Heating of the solution for 60 min in the temperature range of 50-80 °C failed to inactivate completely the immobilized enzyme; the complete loss of its ability to hydrolyze inulin was achieved only after more than 1 h incubation at 90 °C.


Assuntos
Enzimas Imobilizadas , Glicosídeo Hidrolases/química , Resinas de Troca Iônica/química , Adsorção , Biocatálise , Ativação Enzimática , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Hidrólise , Kluyveromyces/enzimologia , Modelos Moleculares , Conformação Proteica , Análise Espectral , Temperatura Ambiente
4.
Sci Total Environ ; 683: 709-718, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31150891

RESUMO

Over the past century, atmospheric nitrogen deposition (Ndep) has increased across the western United States due to agricultural and urban development, resulting in degraded ecosystem quality. Regional patterns of Ndep are often estimated by coupling direct measurements from large-scale monitoring networks and atmospheric chemistry models, but such efforts can be problematic in the western US because of complex terrain and sparse sampling. This study aimed not only to understand Ndep patterns in mountainous ecosystems but also to investigate whether isotope values of lichens and throughfall deposition can be used to determine Ndep sources, and serve as an additional tool in ecosystem health assessments. We measured Ndep amounts and δ15N in montane conifer forests of the Greater Yellowstone Ecosystem using canopy throughfall and bulk monitors and lichens. In addition, we examined patterns of C:N ratios in lichens as a possible indicator of lichen physiological condition. The isotopic signature of δ15N of Ndep helps to discern emission sources, because δ15N of NOx from combustion tends to be high (-5 to +25‰) while NHx from agricultural sources tends to be comparatively low (-40 to -10‰). Summertime Ndep increased with elevation and ranged from 0.26 to 1.66 kg ha-1. Ndep was higher than expected in remote areas. The δ15N values of lichens were typically -15.3 to -10‰ suggesting agriculture as a primary emission source of deposition. Lichen %N, δ15N and C:N ratios can provide important information about Ndep sources and patterns over small spatial scales in complex terrain.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Nitrogênio/análise , Parques Recreativos , Ecossistema , Monitoramento Ambiental/instrumentação , Florestas , Resinas de Troca Iônica/química , Líquens
5.
J Chromatogr A ; 1603: 130-140, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31235330

RESUMO

Zwitterionic chiral ion-exchange selectors (ZWIX) obtained by conjugation of quinine and 2-aminocyclohexanesulfonic acid via a carbamate bond were immobilized on three different silica particle types, viz. 120 Š3 µm fully porous particles (FPP), 200 Š3 µm FPP and 160 Š2.7 µm superficially porous particles (SPP). Selector densities were determined by elemental analysis and the porosities of packed columns measured by inverse size exclusion chromatography with polystyrene standards. Liquid chromatographic tests with a set of chiral zwitterionic, acidic and basic analytes showed that the surface chemistry was successfully transferred to the distinct particle morphologies. The chromatographic performance of the three columns was evaluated by acquiring van Deemter curves. The results showed that the column packed with the SPP particles gives the best performance and kinetic plots further demonstrated that they represent the most favorable compromise in terms of speed, efficiency and pressure drop. Sub-minute separations could be accomplished at much lower pressure drop on the core-shell column, e.g. 2-amino-2-phenylbutyric acid was baseline separated in less than 15 s on a 5 cm long column. The Maxwell effective medium theory with second order approximation was applied to calculate effective diffusion in the mesoporous zones of SPP and FPP, which allowed eventually to deconvolute the individual peak dispersion contributions (ha, hb, hc,m, hc,s, hc,ads). The efficiency gain of the 160 ŠSPP column compared to the 120 ŠFPP (benchmark) column was mainly due to lower eddies (ha), smaller c-term accounting for slow adsorption-desorption kinetics in enantioselective chromatography (hc,ads), and also due to lower stationary mass transfer resistance (hc,s). Enhanced effective diffusion (Deff) in the SPP column contributed to a lower longitudinal diffusion (hb). In contrast, the mobile phase mass transfer coefficient was similar in the two columns leading to comparable hc,m contributions. This study discloses some options for improvement of the efficiency of ZWIX-type chiral columns such as replacing narrow pore (120 Å) by wide pore (200 Å) particles, substituting FPP by SPP and reducing the selector density on the surface.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Resinas de Troca Iônica/química , Adsorção , Cinética , Porosidade , Estereoisomerismo , Temperatura Ambiente
6.
Environ Pollut ; 252(Pt B): 1042-1050, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252101

RESUMO

Aiming at realizing heavy metal recycling and resource utilization, a carbon-based iron catalyst (Fe@C) was synthesized through a resin carbonization method, and adopted for peroxymonosulfate (PMS) activation to remove bisphenol S (BPS), an emerging aquatic contaminant. This study demonstrated that Fe@C exhibited excellent catalytic potential for BPS degradation with a relatively low activation energy (Ea = 29.90 kJ/mol). Kinetic factors affecting the activation performance were thoroughly investigated. The obtained results indicated that Fe@C composite exhibited the superior uniformity with carbon as the framework and granular iron oxide as the coverage. pH increase could cause the inhibitive effect on BPS degradation, while the increasing catalyst loading (0.05-0.5 g/L) was conducive for the catalytic performance of Fe@C, with an optimal PMS concentration at 1.0 mM. A negative influence on BPS degradation was obtained in the presence of SO42-, HCO3- and lower concentration of Cl- (0-20 mM), compared to the promotion at higher concentration of Cl- (>50 mM). Based on the electron spin resonance (ESR) monitoring and radical scavenging results, it is demonstrated that singlet oxygen, a non-radical species, emerged together with ·SO4- and ·OH for BPS degradation. A three-channel catalytic mechanism was verified through typical characterizations. Furthermore, the degradation pathway of BPS was proposed based on the identified intermediates. This novel carbon-based activator for PMS showed notable potential for the waste resin recycling and water decontamination. A novel Fe-based activator carbonized from a saturated resin exhibits excellent performance for Bisphenol S degradation with activated peroxymonosulfate.


Assuntos
Carbono/química , Compostos Férricos/química , Peróxidos/química , Fenóis/análise , Sulfonas/análise , Poluentes Químicos da Água/análise , Catálise , Resinas de Troca Iônica/química , Cinética , Reciclagem
7.
Food Chem ; 292: 260-266, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31054674

RESUMO

The presence of 2-acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)-imidazole (THI) in beverages has raised several concerns regarding its toxicity to humans. The sample preparation and detection of THI in complex matrices is challenging owing to its high water solubility. Here we reported a rapid sample preparation method based on dispersive micro-solid phase extraction (D-µ-SPE) using polymer cation exchange sorbent as sorbent for the extraction of THI from beverage samples. THI was detected by high performance anion exchange chromatography-pulsed amperometric detector (HPAEC-PAD) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The experimental parameters of D-µ-SPE on extraction efficiency were carefully optimized. Under the optimized conditions, high recoveries (83.4-96.1%) and good reproducibility (%RSD ≤ 8.7%) were obtained using D-µ-SPE-HPAEC-PAD and D-µ-SPE-HPLC-MS/MS. Limit of quantification was 75 ng/mL for HPAEC-PAD and 5 ng/mL for HPLC-MS/MS. This work proves the potential application the newly developed method for the quantification of THI in beverages containing caramel color.


Assuntos
Bebidas/análise , Imidazóis/análise , Resinas de Troca Iônica/química , Polímeros/química , Carboidratos/análise , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Imidazóis/isolamento & purificação , Limite de Detecção , Reprodutibilidade dos Testes , Microextração em Fase Sólida , Espectrometria de Massas em Tandem/métodos
8.
Methods Mol Biol ; 1985: 251-277, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31069739

RESUMO

For the early 2000s, chromatographic methods applying chiral stationary phases (CSPs) became the most effective techniques for the resolution of chiral compounds on both analytical and preparative scales. High-performance liquid chromatography (HPLC) employing various types of chiral selectors covalently bonded to silica-based supports offers a state-of-the-art methodology for "chiral analysis." Although a large number of CSPs are available nowadays, the design and development of new "chiral columns" are still needed since it is obvious that in practice one needs a good portfolio of different columns to face the challenging task of enantiomeric resolutions. The development of the unique chiral anion, cation, and zwitterion exchangers achieved by Lindner and his partners serves as an expansion of the range of the efficiently applicable CSPs.In this context this overview chapter discusses and summarizes direct enantiomer separations of chiral acids and ampholytes applying zwitterionic ion exchangers derived from Cinchona alkaloids. Our aim is to provide comprehensive information on practical solutions with focus on the molecular recognition and methodological variables.


Assuntos
Cromatografia Líquida/métodos , Alcaloides de Cinchona/química , Alcaloides de Cinchona/isolamento & purificação , Resinas de Troca Iônica/química , Modelos Químicos , Estereoisomerismo , Água/química
9.
Int J Mol Sci ; 20(10)2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31091791

RESUMO

The electro-kinetic instability in a pressure driven shear flow near an ion exchange membrane is considered. The electrochemical system, through which an electrical potential drop is applied, consists in a polarization layer in contact with the membrane and a bulk. The numerical investigation contained two aspects: analysis of the instability modes and description of the Lagrangian transport of fluid and ions. Regarding the first aspect, the modes were analyzed as a function of the potential drop. The analysis revealed how the spatial distribution of forces controls the dynamics of vortex association and dissociation. In particular, the birth of a counter-clockwise vortex between two clockwise vortices, and the initiation of clusters constituting one or two envelopes wrapping a vortex group, were examined. In regards to the second aspect, the trajectories were computed with the fourth order Runge Kutta scheme for the time integration and with the biquadratric upstream scheme for the spatial and time interpolation of the fluid velocity and the ion flux. The results for the periodic mode showed two kinds of trajectories: the trochoidal motion and the longitudinal one coupled with a periodic transverse motion. For the aperiodic modes, other mechanisms appeared, such as ejection from the mixing layer, trapping by a growing vortex or merging vortices. The analysis of the local velocity field, the vortices' shape, the spatial distribution of the forces and the ion flux components explained these trajectories.


Assuntos
Técnicas Eletroquímicas , Resinas de Troca Iônica/química , Membranas Artificiais , Modelos Teóricos
10.
Water Sci Technol ; 79(5): 820-832, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31025960

RESUMO

This study investigated the applicability of fluorescence excitation-emission matrix spectroscopy (EEMS) to assess total trihalomethane formation potentials (TTHMFPs) and the ability of magnetic ion exchange (MIEX®) resin to reduce TTHMFP. We treated a surface water and secondary wastewater effluent with MIEX mimicking full-scale operation by repeatedly exposing the same resin batch to additional feed water, with batches ranging from 500 to 5,000 resin bed volumes. Results showed that MIEX was more effective at removing or reducing ultraviolet absorbance (UVA254), dissolved organic carbon (DOC), and TTHMFP in surface water than in secondary effluent. The greater UVA254, DOC and TTHMFP removal for surface waters was explained by the stronger affinity of MIEX for terrestrial dissolved organic matter (DOM) compared to microbial DOM. Fluorescence EEMS results showed that the ratio between terrestrial and microbial fluorescent signals of DOM was significantly greater in surface water than in secondary effluent. Fluorescence surrogate parameters were strongly correlated with TTHMFP, namely, fluorescence intensity of humic-like peak C (R2 = 0.98, p < 0.01), protein-like peak T (R2 = 0.96, p < 0.01), and fulvic-like peak A (R2 = 0.87, p < 0.01). Correlations between fluorescence surrogate parameters and TTHMFP were substantially stronger than correlations between DOC and TTHMFP. Overall, the results indicate that fluorescent parameters extracted from EEMS data can be used as quick surrogate parameters to monitor TTHMFP for a diverse group of raw and MIEX-treated waters.


Assuntos
Resinas de Troca Iônica/química , Trialometanos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Troca Iônica , Compostos Orgânicos , Espectrometria de Fluorescência , Trialometanos/análise , Poluentes Químicos da Água/análise
11.
Chemosphere ; 224: 494-501, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30831501

RESUMO

Conventional sorption media are inefficient for phosphorus removal from wastewater due to preference for competing species such as sulphate, nitrate and organics. This work investigates whether the use of hybrid ion exchange resins effectively negates such concerns. Trials were conducted with a hybrid anion exchange (HAIX) media which was preloaded with different background constituents and operated over multiple regeneration cycles to ascertain the likely impacts. The work revealed that whilst the impact of the other constituents was seen in regards to direct competition, the major impact was on reduction of the rate of intraparticle mass transfer through sorption of the constituents onto the base resin thereby reducing the Donnan membrane effect. Comparison of the impact of the background water constituents on the individual components (hybrid resin, base resin, nanoparticles) revealed the importance of the nanoparticle whereby they effectively transform the ion exchange media into a mono component absorber for phosphorus that enables sustained removal even in complex wastewaters.


Assuntos
Resinas de Troca Iônica/química , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Fósforo/análise , Poluentes Químicos da Água/análise , Purificação da Água
12.
Int J Pharm ; 561: 206-218, 2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-30822506

RESUMO

We employed a new dry coating process with mild-intensity vibration to prepare a 100-µm-sized microparticle capable of prolonged release of a drug. To accomplish this without using a binder, a series of laboratory-made acrylic latexes with different glass transition temperatures (Tg) ranging from 30 °C to 80 °C were employed as coating agents, and the effects of Tg and powdering method of the coating agents on coating performance were investigated. The laboratory-made acrylic latexes were powdered by spray-drying (SD) or freeze-drying (FD). Diclofenac sodium (DS)-loaded ion-exchange-resin with particle size ∼100 µm was used as a core particle. The process utilized vibrations with amplitude of 0.5 mm and frequency of 90 Hz to form an ordered mixture composed of the core particles with the loosely-layered coating agents. Subsequently, the coating agents were fixed mechanically on the core particle by impaction of zirconia beads. The coating agents powdered by FD showed higher coating efficiencies than those powdered by SD, irrespective of the differences in Tg values. Among the coating agents powdered by FD, the particles coated at Tg = 60 °C exhibited the most prolonged drug-release, although the coating efficiency was not the highest. In our proposed process utilizing mild vibration, we demonstrated that adjusting the Tg of the coating agents is crucial to the formation of binder-free multiple coating layers for prolonged drug release.


Assuntos
Composição de Medicamentos/métodos , Polímeros/química , Pós/química , Temperatura de Transição , Vibração , Preparações de Ação Retardada/química , Dessecação/métodos , Diclofenaco/química , Liberação Controlada de Fármacos , Resinas de Troca Iônica/química , Látex/química , Tamanho da Partícula , Zircônio/química
13.
J Chromatogr B Analyt Technol Biomed Life Sci ; 1110-1111: 108-115, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30798071

RESUMO

Methionine is an essential sulfur-containing amino acid for organisms. The separation and purification are important for the production of l-methionine from fermentation broth. In this work, the adsorption properties for l-methionine separation of ten macroporous resins were firstly evaluated. Macroporous cation resin D72 showed the best adsorption capacity (52.37 mg/g) and desorption rate (99.12%). The adsorption kinetics of l-methionine on D72 resin followed the pseudo second-order model and adsorption isotherm fitted well to the Sips model, the adsorption process mainly followed a physisorption mechanism. D72 resin packed columns were then used in the batch separation of fermentation broth, the operation parameters were optimized during the dynamic adsorption and desorption experiments. Under the optimized conditions: fermentation broth adjusted to pH = 2, loading flow rate at 2 BV/h, loading volume 55 mL, 1 mol/L NH3·H2O as eluent, elution flow rate at 2 BV/h, column height-diameter ratio at 14:1, excellent recovery and purity of l-methionine (82.37% and 85.69%, respectively) could be achieved.


Assuntos
Cromatografia por Troca Iônica/métodos , Escherichia coli/metabolismo , Resinas de Troca Iônica/química , Metionina/isolamento & purificação , Adsorção , Reatores Biológicos , Fermentação , Metionina/análise , Metionina/química
14.
Water Environ Res ; 91(7): 606-615, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30737846

RESUMO

Nutrient recovery from municipal wastewater was evaluated using anion exchange media loaded with hydrated ferric oxide (HFO) and copper (Cu2+ ) (Dow-HFO-Cu resin) to selectively capture phosphate, followed by clinoptilolite for ammonium removal and recovery. Nutrients were concentrated in the regenerants and recovered as precipitated struvite. Media exchange capacity after multiple ion exchange cycles was determined using permeate from an anaerobic membrane bioreactor (AnMBR) treating synthetic or actual municipal wastewater from a full-scale water reclamation facility. Regeneration through five ion exchange cycles using relatively low concentration regenerant solution (2% NaCl and 0.5% NaOH) resulted in the highest phosphate exchange capacity and phosphate recovery. This regenerant also provided the most consistent ammonium recovery. Column tests treating AnMBR permeate were performed over five ion exchange cycles; Dow-HFO-Cu resin exchange capacities ranged from 1.6 to 2.8 mg PO4 -P/g dry media. A maximum of 94% of the removed phosphate was recovered during regeneration. The rate and extent of regeneration was insensitive to regenerant salt concentrations in the range investigated. Precipitation using a mixture of the spent regeneration brines from the Dow-HFO-Cu resin and clinoptilolite columns produced low molar ratios of Mg:NH4 :PO4 , suggesting that the recovered product was not pure struvite. PRACTITIONER POINTS: Ion exchange-precipitation for the removal and recovery of PO 4 3 - and NH4 + from AnMBR permeate is a promising technology. 2% NaCl + 0.5% NaOH regeneration solution provided the most consistent exchange performance for both phosphate and ammonium recovery. Regenerated Dow-HFO-Cu resin exchange capacity was consistently less than the virgin resin, likely due to copper leaching during regeneration. Molar ratios in the precipitates suggested that the precipitated material was not pure struvite.


Assuntos
Compostos de Amônio/isolamento & purificação , Resinas de Troca Iônica/química , Fosfatos/isolamento & purificação , Gerenciamento de Resíduos/métodos , Zeolitas/química , Anaerobiose , Reatores Biológicos , Membranas Artificiais
15.
J Pharm Biomed Anal ; 166: 379-386, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30711807

RESUMO

In this work, hypercrosslinked strong anion-exchange polymer resins (HXLPP-SAX) were synthesized and evaluated as solid-phase extraction (SPE) sorbents for extracting fluoroquinolones (FQs) in milk samples. These particles were prepared using a protocol that was facile and cost-effective by combining hypercrosslinking reactions and quaternisation reactions in one step. After the synthesis, the morphological properties and anion-exchange, adsorption, and selectivity performances of the HXLPP-SAX resins were characterized and evaluated. It was shown that the polymers were monodisperse microspheres, with the mean diameters of 2-4 µm, ion-exchange capacity (IEC) of 0.311 meq/g, and specific surface area more than 1000 m2/g. The resins applied as SPE sorbents possessed high selectivity in the extraction of amphoteric compounds (enoxacin and enrofloxacin as the representatives) followed by HPLC-UV analysis, as compared to commercially available strong anion-exchange sorbents (Oasis MAX). The SPE-HPLC-UV method was fully validated and exhibited good linearity (10-2000 ng/g, R2 ≥ 0.997), low limits of detection (2.8-5.1 ng/g), good recoveries (85.8%-117.9%, RSDs ≤ 7.1%) and precisions (intra-day RSDs ≤ 7.7% and inter-day RSDs ≤ 9.4%). Then the method was performed the selective enrichment of six FQs (enoxacin, norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, and sparfloxacin) in milk samples. The present results demonstrated that the proposed resins exhibited a promising potential for the enrichment and determination of FQ residues in milk samples as well as in other samples with complex matrices.


Assuntos
Reagentes para Ligações Cruzadas/química , Fluoroquinolonas/análise , Resinas de Troca Iônica/química , Leite/química , Drogas Veterinárias/análise , Adsorção , Animais , Cromatografia Líquida de Alta Pressão , Resinas de Troca Iônica/síntese química , Limite de Detecção , Reprodutibilidade dos Testes , Extração em Fase Sólida , Espectrofotometria Ultravioleta
16.
Environ Toxicol Chem ; 38(2): 321-328, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30620786

RESUMO

We assessed the relationship between the diffusive gradient in thin film (DGT) technique using the new ion-exchange resin Ambersep GT74 and the uptake of mercury (Hg) by a model plant cultivated on metal-contaminated agricultural soils under greenhouse conditions. Based on the total Hg content, 0.37 to 1.17% of the Hg passed to the soil porewater from the solid phase, and 2.18 to 9.18% of the Hg is DGT-available. These results were confirmed by calculating the R value (the ratio of the concentrations of bioavailable Hg measured by DGT and soil solution), which illustrated the strong bonding of Hg to the solid phase of soil and its extremely low mobility. Only inorganic Hg2+ species were found in the metal-contaminated agricultural soils, as determined by a high-performance liquid chromatography-cold vapor atomic fluorescence spectrometry speciation analysis. The Hg was distributed in Miscanthus × giganteus organs in the following order for all sampling sites: roots (55-82%) >> leaves (8-27%) > stems (7-16%) > rhizomes (4-7%). Environ Toxicol Chem 2019;38:321-328. © 2018 SETAC.


Assuntos
Monitoramento Ambiental/métodos , Mercúrio/análise , Poaceae/metabolismo , Poluentes do Solo/análise , Solo/química , Disponibilidade Biológica , Transporte Biológico , Cromatografia Líquida de Alta Pressão , Resinas de Troca Iônica/química , Mercúrio/metabolismo , Modelos Biológicos , Poluentes do Solo/metabolismo
17.
Chem Soc Rev ; 48(2): 463-487, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30603760

RESUMO

Water pollution is a global problem threatening the entire biosphere and affecting the life of many millions of people around the world. Not only is water pollution one of the foremost global risk factors for illness, diseases and death, but it also contributes to the continuous reduction of the available drinkable water worldwide. Delivering valuable solutions, which are easy to implement and affordable, often remains a challenge. Here we review the current state-of-the-art of available technologies for water purification and discuss their field of application for heavy metal ion removal, as heavy metal ions are the most harmful and widespread contaminants. We consider each technology in the context of sustainability, a largely neglected key factor, which may actually play a pivotal role in the implementation of each technology in real applications, and we introduce a compact index, the Ranking Efficiency Product (REP), to evaluate the efficiency and ease of implementation of the various technologies in this broader perspective. Emerging technologies, for which a detailed quantitative analysis and assessment is not yet possible according to this methodology, either due to scarcity or inhomogeneity of data, are discussed in the final part of the manuscript.


Assuntos
Metais Pesados/química , Purificação da Água/métodos , Adsorção , Precipitação Química , Grafite/química , Resinas de Troca Iônica/química , Estruturas Metalorgânicas/química , Metais Pesados/isolamento & purificação , Nanotubos de Carbono/química , Ultrafiltração , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
18.
Environ Sci Pollut Res Int ; 26(4): 3803-3813, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30539396

RESUMO

Based on soluble starch and acrylamide by performing graft polymerization in aqueous solution and hydrolysis step, a low-cost ion exchange resin has been synthesized to remove the heavy metal ions of Cr3+ and Ni2+. The hydrolysis progresses by adding NaOH to convert -CONH2 to -COONa, and the adsorption experiments confirmed that the functional group to adsorb heavy metals is -COO-, rather than -CONH2. During the determination of heavy metal adsorption, the Na+ concentration diffused by SR-16 into the solution was also analysed to investigate the ion exchange process. The composition and morphology of SR-16 was characterized by FT-IR, SEM, elemental analyser and EDS, and the results showed that SR-16 has an excellent adsorption capacity to the removal of heavy metal pollution; the adsorption mechanism of SR-16 could be explained by ion exchange progress with -COONa attached on the network structure.


Assuntos
Acrilamida/química , Resinas de Troca Iônica/química , Resinas de Troca Iônica/síntese química , Amido/química , Adsorção , Difusão , Hidrólise , Metais Pesados/análise , Modelos Teóricos , Polimerização , Propriedades de Superfície , Poluentes Químicos da Água/análise
19.
Spectrochim Acta A Mol Biomol Spectrosc ; 210: 126-135, 2019 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-30453188

RESUMO

The objective of the study is to obtain the modified zeolite powders and to apply these materials as active fillers in the dental composites with the remineralizing potential. Three different synthesis pathways were applied to receive LTA-type (Linde A-type) zeolites. All zeolites were subjected to the ion exchange process and mineralization of surface with hydroxyapatite (HA) layer. As a result a calcium form and surface modified form of these materials were prepared. The effectiveness of each modification process was confirmed by X-ray Diffractometry, Infrared and Raman Spectroscopy. Materials were also characterized by Scanning Electron Microscopy, Energy Dispersive Spectroscopy and nitrogen adsorption/desorption measurements. The remineralizing potential was specified as an ability to release calcium ions during the incubation in saline with the use of Inductively Coupled Plasma-Mass Spectrometry. The obtained zeolite fillers were placed in the organic matrix to create photopolymerizable composites with potential dental applications. The homogeneity of the filler distribution in polymeric matrix was checked by the Raman spectra mapping. Composites containing calcium form of zeolites as well as zeolites with the HA layer proved to have the ability to release calcium ions during incubation in saline in the amount comparable to calcium phosphates-filled composites or even higher than dental glass-filled composites. The ability to release calcium ions, together with good mechanical properties and mass stability testify the suitability of prepared composites in potential dental applications.


Assuntos
Cálcio/química , Resinas de Troca Iônica/química , Zeolitas/química , Força Compressiva , Durapatita/química , Resinas de Troca Iônica/síntese química , Teste de Materiais , Microscopia Eletrônica de Varredura , Solubilidade , Espectrometria por Raios X , Espectrofotometria Infravermelho , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Difração de Raios X , Zeolitas/síntese química
20.
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
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