Divinylbenzene Copolymer Research Articles

Aminophosphonic groups grafted onto the structure of macroporous styrene–divinylbenzene copolymer: preparation and studies on the antimicrobial effect

This paper has investigated the preparation, characterization and antimicrobial effect of two new compounds. α-Aminophosphonic acid groups were grafted onto the structure of a styrene-6.7% divinylbenzene (S-6.7% DVB) copolymer. The compounds bearing the N–C–P skeleton in α-aminophosphonic acids groups were synthesized following a “one-pot” modified Kabachnik–Fields reaction performed with three components (polymeric amine, aldehyde and phosphorous acid) in tetrahydrofuran at 55 °C. The presence of 2 novel products: aminobenzylphosphonic acid (BzAmPhonic) and aminopropylphosphonic acid (PrAmPhonic) grafted on (S-6.7% DVB) copolymer was indicated by characterization using FT-IR spectroscopy, EDX, TGA, measurement of the phosphorus content and the degree of functionalization with pendant α-aminophosphonic acid group. It was proved that novel products have an antimicrobial effect in vitro after 1 h of contact against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Bacillus cereus (B. cereus), Pseudomonas aeruginosa (P. aeruginosa) and a species of yeast Candida albicans (C. albicans). The best antibacterial activity was obtained by the PrAmPhonic sample. We were interested in obtaining new polymeric functionalized compounds endowed with very good antimicrobial properties. The main advantage of the novel antibacterial agents synthesized in this work is that they can be easily recovered in order not to contaminate the environment.

Microencapsulated oleic–capric acid/hexadecane mixture as phase change material for thermal energy storage

Thermal energy storage systems provide efficiency in order to have better utilization of energy sources while protecting the environment. Thermal energy storage can be classified as sensible and latent heat storage. The storage of latent heat allows a greater density of energy storage with a narrow temperature range during phase change. Phase change materials (PCMs) are important novel materials, which are used as the storage of thermal energy as latent heat, and can provide utilization of waste heat energy. In this study, the capric acid and oleic acid mixture containing hexadecane were encapsulated as the core with styrene–divinylbenzene copolymer shell by emulsion polymerization technique. Thermal properties of fatty acid microcapsules were characterized by differential scanning calorimetry and thermogravimetric analysis and also their morphology and structure were examined by scanning electron microscopy, polarized optical microscopy and Fourier transform infrared spectroscopy (FT-IR), respectively. The heat storage property of microencapsulated PCM was tested in a horizontal air flow channel system equipped with a flat heating plate, air fan and air flow sensors. The microencapsulated PCM was prepared successfully, and results of the analysis presented that this material is promising candidate for potential heating and cooling system applications.

Tandem column isolation of zirconium-89 from cyclotron bombarded yttrium targets using an automated fluidic platform: Anion exchange to hydroxamate resin columns

The development of a tandem column purification method for the preparation of high-purity 89Zr(IV) oxalate is presented. The primary column was a macroporous strongly basic anion exchange resin on styrene divinylbenzene co-polymer. The secondary column, with an internal volume of 33 μL, was packed with hydroxamate resin. A condition of inverted selectivity was developed, whereby the 89Zr eluent solution for the primary column is equivalent to the 89Zr load solution for the secondary column. The ability to transfer 89Zr from one column to the next allows two sequential column clean-up methods to be performed prior to the final elution of the 89Zr(IV) oxalate. This approach assures delivery of high purity 89Zr product and assures a 89Zr product that is eluted in a substantially smaller volume than is possible when using the traditionally-employed single hydroxamate resin column method. The tandem column purification process has been implemented into a prototype automated fluidic system. The system is configured with on-line gamma detection so column effluents can be monitored in near-real time. The automated method was tested using seven cyclotron bombarded Y foil targets. It was found that 95.1 ± 1.3% of the 89Zr present in the foils was recovered in the secondary column elution fraction. Furthermore, elution peak analysis of several 89Zr elution profile radiochromatograms made possible the determination of 89Zr recovery as a function of volume; a 89Zr product volume that contains 90% of the mean secondary column elution peak can be obtained in 0.29 ± 0.06 mL (representing 86 ± 5% of the 89Zr activity in the target). This product volume represents a significant improvement in radionuclide product concentration over the predominant method used in the field. In addition to the reduced 89Zr product elution volume, titrations of the 89Zr product with deferoxamine mesylate salt across two preparatory methods resulted in mean effective specific activity (ESA) values of 279 and 340 T Bq·mmole−1 and mean bindable metals concentrations ([MB]) of 13.5 and 16.7 nmole·g−1. These ESA and [MB] values infer that the 89Zr(IV) oxalate product resulting from this tandem column isolation method has the highest purity reported to date.

Hyperbranched mixed-mode anion-exchange polymeric sorbent for highly selective extraction of nine acidic non-steroidal anti-inflammatory drugs from human urine

This paper describes the poly(divinylbenzene) (PDVB) supported synthesis of quaternized hyperbranched macromolecules (QHMs) and its use as a highly selective, high-capacity mixed-mode anion-exchange (MAX) sorbent. In detail, the aminated PDVB support was firstly synthesized by copolymerization of divinylbenzene and 2-(diethylamino)ethyl methacrylate via Pickering emulsion polymerization. The QHMs were then grafted on PDVB by a divergent synthesis involving consecutive reactions of resorcinol diglycidyl ether with methylamine (N, N-dimethylethanolamine for terminal epoxides), which brought in a high density of quaternary ammonium functionalities. The changes of specific surface area (SBET), pore volume and ion exchange capacity (IEC) with generation number reveal that the QHMs have been grown successfully within the large meso-channels of the porous aminated PDVB. The best compromise between the SBET, pore volume and IEC was obtained at the 4th generation (G4). Due to the highest IEC (0.47 meq/g), the G4-QHMs was successfully applied for mixed-mode solid phase extraction (SPE) of acidic non-steroidal anti-inflammatory drugs (NSAIDs). An efficient approach based on the mixed-mode SPE coupled with HPLC-UV was developed for highly selective extraction and cleanup of nine NSAIDs (tolmetin, TLM; ketoprofen, KEP; naproxen, NAP; flurbiprofen, FLB; diclofenac, DIC; indomethacin, INM; ibuprofen, IBP; mefenamic acid, MFA; tolfenamic acid, TFA) in human urine samples. Under the optimized conditions, the method exhibited satisfactory recoveries ranging from 81.9% to 104.0% with relative standard deviation (RSD) values below 8.5%, good sensitivity (0.004–0.009 μg mL−1 limit of detection) and good linearity (coefficient of determination, R2 > 0.997, 0.01–0.2 μg mL−1 for NAP, 0.05–1.0 μg mL−1 for FLB, DIC, INM, MFA, TFA, 0.1–2.0 μg mL−1 for TLM, KEP, IBP). The hyperbranched MAX sorbent is superior to Oasis HLB and comparable to Oasis MAX in obtaining clean chromatographic profiles. Our results demonstrate the potential application of the hyperbranched MAX for complex sample analysis.

Исследование сорбционно-газохроматографического определения полихлорированных бифенилов в маслах

Проведено исследование использования многослойных сорбционных колонок, в состав которых включены сорбенты различной природы (силикагель, полихром-1, полисорб-1, флорисил или оксид алюминия), для извлечения смеси полихлорированных бифенилов (ПХБ), содержащей ди-, три-, тетра-, пента-, гекса- и гептахлорбифенилы, из трансформаторного и растительного масел. Показано, что наиболее подходящим является использование колонок с полихромом-1, в этом случае требуется меньший расход элюента, степень извлечения одинаковая для всех групп конгенеров ПХБ и составляет 80%. Минимальное определяемое содержание смеси ПХБ при анализе в условиях ГХ-ЭЗД составило 0.002%.

Passive air sampling of flame retardants and plasticizers in Canadian homes using PDMS, XAD-coated PDMS and PUF samplers

Passive air samplers (PAS) were evaluated for measuring indoor concentrations of phthalates, novel brominated flame retardants (N-BFRs), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs). Sampling rates were obtained from a 50-day calibration study for two newly introduced PAS, polydimethylsiloxane (PDMS) or silicone rubber PAS (one with and one without a coating of styrene divinyl benzene co-polymer, XAD) and the commonly used polyurethane foam (PUF) PAS. Average sampling rates normalized to PAS surface area were 1.5 ± 1.1 m3 day−1 dm−2 for both unsheltered PDMS and XAD-PDMS, and 0.90 m3 ± 0.6 day−1dm−2 for partially sheltered PUF. These values were derived based on the compound-specific sampling rates measured here and in the literature for the PAS tested, to reasonably account for site-specific variability of sampling rates.PDMS and PUF were co-deployed for three weeks in 51 homes located in Ottawa and Toronto, Canada. Duplicate PUF and PDMS samplers gave concentrations within 10% of each other. PDMS and PUF-derived air concentrations were not statistically different for gas-phase compounds. PUF had a higher detection of particle-phase compounds such as some OPEs. Phthalate and OPE air concentrations were ∼100 times higher than those of N-BFRs and PBDEs. Concentrations were not systematically related to PM10, temperature or relative humidity.We conclude that both PAS provide replicable estimates of indoor concentrations of these targeted semi-volatile organic compounds (SVOCs) over a three-week deployment period. However, PUF is advantageous for collecting a wider range of compounds including those in the particle phase.

Prospects for Using Weakly Dissociated Ion Exchange Resins in Special Water Treatment Systems at VVER-Based Nuclear Power Plants for Reducing the Volume of Radioactive Waste Generated

Minimizing the amount of liquid radioactive waste generated during operation of nuclear power plants is among the important problems that have to be solved to enhance the nuclear power industry safety and economic indicators. For this purpose, it is proposed that the ion-exchange materials applied in the active water treatment systems of new power units equipped with VVER-type reactors be used only once (without regenerating them). In so doing, measures should be taken to dramatically reduce the consumption of ion-exchange resins by using materials having a higher ion-exchange capacity than the currently used universal ion-exchange resins. In addition, it is necessary to improve the ion-exchange treatment technology to achieve a higher extent of filling sorbents with the target components, primarily, with radionuclides to be buried. In this context, the properties of weakly dissociated ion-exchange resins made on the basis of acrylic acid and divinylbenzene copolymers are considered. The selected line of research is theoretically substantiated, and the results from laboratory investigations on treating model flows are presented, including those for elaborating the regeneration modes of weakly dissociated ion-exchange resins, the use of which makes it possible to fix biologically dangerous components in mineral-like structures with the minimal amount of compounds to be buried. It is shown that sequential subjecting of alkali flows contaminated with radionuclides to ionexchange treatment in the carbonaceous resin–sulfonic cation resin system results in that the solution becomes dealkalized under the effect of carbonaceous resin, after which cesium radionuclides are removed by means of sulfonic cation resin. Such redistribution of functions helps to decrease the concentration of alkali-metal and ammonium ions that compete with 134, 137Cs radionuclides for sorption vacations, due to which the sorbent to be buried is filled with radioactive substances to the maximal extent, thus resulting in a smaller amount of generated radioactive waste.

Application of Polymethacrylic Acid Imprinted Quartz Crystal Microbalance Sensor for Detection of 3-Carene in Mango

This paper aims to develop a selective molecularly imprinted polymer (MIP) layer combined with quartz crystal microbalance sensor for the detection of 3-Carene, a significant aroma compound of mango. The proposed sensor is prepared from the co-polymer of methacrylic acid and divinylbenzene, and it is imprinted with 3-Carene. The MIP template was synthesized and deposited onto the quartz crystal microbalance platform by proper functionalizing the gold electrode using 2-propene 1- thiol. The developed MIP material is characterized by fourier transform infra-red, scanning electron microscope, and atomic force microscope techniques. The sensor offers very good selectivity and sensitivity (1–1000 ppm) of 0.11 Hz/ppm to 3-Carene from its structural analogies. The limit of detection and the limit of quantitation of the sensor are found to be 0.8 and 1.4 ppm, respectively. The performance of the sensor offers satisfactory reproducibility and repeatability to 3-Carene. Moreover, the response of the sensor has been correlated to the standard gas- chromatography-mass spectrometry data to detect 3-Carene in Langda and Chausa mango.

Adsorption Characteristics of U ranium (VI) Ion on Cryptand Synthetic Resin Adsorbent

Cryptand resins were synthesized by mixing 1-aza-18-crown-6 macrocyclic ligand with styrene divinylbenzene copolymer having 1%, 2%, 5%, and 10% crosslink by a substitution reaction. These synthetic resins were confirmed by chlorine content, elementary analysis, SEM, surface area, and IR-spectrum. As the results of the effects of pH, crosslink of synthetic resin, and dielectric constant of a solvent on uranium ion adsorption for resin adsorbent, the uranium ion showed high adsorption at pH 3 or over. Adsorption selectivity for the resin in methanol solvent was the order of uranium (UO2 2+) ＞calcium (Ca2+) ＞neodymium (Nd3+) ion, adsorbability of the uranium ion was the crosslink in order of 1%, 2%, 5%, and 10% and it was increased with the lower dielectric constant.

Chromium adsorption into a macroporous resin based on vinylpyridine–divinylbenzene copolymers: thermodynamics, kinetics, and process dynamic in a fixed bed column

The synthesis of the poly(4-vinylpyridine-co-ethylvinylbenzene) resin is investigated and its performance to remove Cr(VI) from aqueous solutions is evaluated as a function of pH using batch and fixed bed column adsorptions. The rate of Cr(VI) removal is observed to increase as the pH solution shifts to acidic conditions due to an enhanced protonation of the 4-vinylpyridine group in the polymer, which favors its electrostatic attraction with Cr(VI) oxyanions. This finding is supported with Density Functional Theory (DFT) calculations, revealing that the interaction between $${\text{CrO}}_{4}^{{2 - }}$$ (predominant species at pH < 6) and protonated 4VP is more favorable than a bond formed with $${\text{HCrO}}_{4}^{ - }$$ species (pH > 6) due to a higher charge delocalization arising in the O atoms. Experimental isotherms are approximated with the Langmuir and Radke-Prausnitz adsorption models. This former approach generates the best fitting to the data, whereby it was incorporated into a nonlinear transient model to account for the Cr(VI) adsorption in a fixed bed, and evaluating its capacity to predict experimental adsorption data. The model enables to infer that the resin presents a fast kinetic for Cr(VI) sorption, and the Cr(VI) intra-particle diffusion across the adsorbent pores is the rate-determining step for sorption.

A Two-Step Bioconversion Process for Canolol Production from Rapeseed Meal Combining an Aspergillus niger Feruloyl Esterase and the Fungus Neolentinus lepideus.

Rapeseed meal is a cheap and abundant raw material, particularly rich in phenolic compounds of biotechnological interest. In this study, we developed a two-step bioconversion process of naturally occurring sinapic acid (4-hydroxy-3,5-dimethoxycinnamic acid) from rapeseed meal into canolol by combining the complementary potentialities of two filamentous fungi, the micromycete Aspergillus niger and the basidiomycete Neolentinus lepideus. Canolol could display numerous industrial applications because of its high antioxidant, antimutagenic and anticarcinogenic properties. In the first step of the process, the use of the enzyme feruloyl esterase type-A (named AnFaeA) produced with the recombinant strain A. niger BRFM451 made it possible to release free sinapic acid from the raw meal by hydrolysing the conjugated forms of sinapic acid in the meal (mainly sinapine and glucopyranosyl sinapate). An amount of 39 nkat AnFaeA per gram of raw meal, at 55 °C and pH 5, led to the recovery of 6.6 to 7.4 mg of free sinapic acid per gram raw meal, which corresponded to a global hydrolysis yield of 68 to 76% and a 100% hydrolysis of sinapine. Then, the XAD2 adsorbent (a styrene and divinylbenzene copolymer resin), used at pH 4, enabled the efficient recovery of the released sinapic acid, and its concentration after elution with ethanol. In the second step, 3-day-old submerged cultures of the strain N. lepideus BRFM15 were supplied with the recovered sinapic acid as the substrate of bioconversion into canolol by a non-oxidative decarboxylation pathway. Canolol production reached 1.3 g/L with a molar yield of bioconversion of 80% and a productivity of 100 mg/L day. The same XAD2 resin, when used at pH 7, allowed the recovery and purification of canolol from the culture broth of N. lepideus. The two-step process used mild conditions compatible with green chemistry.

Applications of Ion Exchange Resin in Oral Drug Delivery Systems

Ion Exchange Resins (IER) are insoluble polymers having styrene divinylbenzene copolymer backbone that contain acidic or basic functional groups and have the ability to exchange counter ions with the surrounding aqueous solutions. From the past many years they have been widely used for purification and softening of water and in chromatographic columns, however recently their use in pharmaceutical industry has gained considerable importance. Due to the physical stability and inert nature of the resins, they can be used as a versatile vehicle to design several modified release dosage forms The ionizable drug is complexed with the resin owing to the property of ion exchange. This resin complex dissociatesin vivo to release the drug. Based on the dissociation strength of the drug from the drug resin complex, various release patterns can be achieved. Many formulation glitches can be circumvented using ion exchange resins such as bitter taste and deliquescence. These resins also aid in enhancing disintegrationand stability of formulation. This review focuses on different types of ion exchange resins, their preparation methods, chemistry, properties, incompatibilities and their application in various oral drug delivery systems as well as highlighting their use as therapeutic agents.

Immobilization of cyanobacteria and microalgae on polyethylenimine-based sorbents

Immobilization of phototrophic microogranisms: microalgae (MA) and cyanobacteria (CB) on polyethylenimine (PEI)-based sorbents was studied. For this purpose, 3 insoluble porous polymeric materials were synthesized by cross-linking of PEI with epichlorohydrine and immobilization of PEI on the surface of styrene–divinylbenzene copolymer. The sorbent on the basis of cross-linked PEI was also alkylated with hexadecyl bromide to achieve hydrophobicity of its surface. The analysis of kinetics and efficiency of immobilization assessed for the model MA and CB cultures revealed the significant difference in the sorption activity of different types of sorbents depending on their synthesis procedure, chemical composition and hydrophilic-hydrophobic properties of polymeric surface. The hydrophobic sorbent obtained by immobilization of PEI on the surface of styrene–divinylbenzene copolymer characterized by very low sorption activity towards CB and MA cells. The highest immobilization efficiency of phototrophic cells was achieved for the hydrophilic sorbent on the basis of PEI cross-linked with epichlorohydrine, which provided the attachment of 50–70% of cells during 3 h of incubation. The hydrophobic sorbent based on alkylated cross-linked PEI effectively immobilized CB cells, while the colonization of the polymer surface by MA cells was very scarce. The noticed effect is explained by difference in prokaryotic (CB) and eukaryotic (MA) types of surface structures organization. Assessment of photosynthetic activity of immobilized MA cells by pulse-modulated fluorometry showed that hydrophobic sorbents had no toxic effect on the cells, while toxicity of hydrophilic cross-linked PEI-based sorbent was observed only after long-term cultivation ofphototrophic cells with this sorbent.

Sensitive Detection of α-Conotoxin GI in Human Plasma Using a Solid-Phase Extraction Column and LC-MS/MS.

α-conotoxin GI, a short peptide toxin in the venom of Conus geographus, is composed of 13 amino acids and two disulfide bonds. It is the most toxic component of Conus geographus venom with estimated lethal doses of 0.029–0.038 mg/kg for humans. There is currently no reported analytical method for this toxin. In the present study, a sensitive detection method was developed to quantify GI in human plasma using a solid-phase extraction (SPE) column (polystyrene–divinyl benzene copolymer) combined with liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in the multiple reaction monitoring (MRM) mode. The plasma samples were treated with a protein precipitating solvent (methanol: acetonitrile = 50:50, v/v). GI in the solvent was efficiently extracted with an SPE column and was further separated by a Grace Alltima HP C18 (50 × 2.1 mm, 5 μm) column at a flow rate of 0.4 mL/min. Water (with 2% methanol) acetonitrile (with 0.1% acetic acid) was selected as the mobile phase combination used in a linear gradient system. α-Conotoxin GI was analyzed by an API 4000 triple quadrupole mass spectrometer. In the method validation, the linear calibration curve in the range of 2.0 to 300.0 ng/mL had correlation coefficients (r) above 0.996. The recovery was 57.6–66.8% for GI and the internal standard. The lower limit of quantification (LLOQ) was 2 ng/mL. The intra- and inter-batch precisions were below 6.31% and 8.61%, respectively, and the accuracies were all within acceptance. GI was stable in a bench-top autosampler through long-term storage and freeze/thaw cycles. Therefore, this method is specific, sensitive and reliable for quantitative analysis of α-conotoxin GI in human plasma.

Synthesis of porous polymer based solid amine adsorbent: Effect of pore size and amine loading on CO2 adsorption

A series of porous polymers was synthesized by a suspension polymerization of divinylbenzene (DVB) and ethylene glycol dimethyl acrylate (EGDMA), which was further functionalized with polyethyleneimine (PEI) for CO2 capture. The results showed that the synthesized DVB and EGDMA (DE) copolymers were an effective support for loading PEI because of its larger pore size and specific surfaces area. It was found that DE (30, 10) loaded with 30wt% PEI exhibited a higher CO2 adsorption amount of 3.28mmol/g at 25°C under dry condition. The CO2 adsorption capacity would decline gradually as the temperature continuously raised, for the reaction between CO2 and amine groups was an exothermic reaction. The kinetics study showed that Avrami kinetic model could accurately describe the whole CO2 adsorption process, suggesting that both physical adsorption and chemical adsorption were involved with the CO2 adsorption process. The intraparticle diffusion and Boyd’s film diffusion models were applied to investigate the CO2 diffusion mechanism, the intraparticle diffusion model could well distinguish the rate-limiting step during CO2 adsorption process. This solid amine adsorbent could be regenerated with nitrogen stream at 75°C, and it kept stable CO2 adsorption capacity after eight adsorption-desorption cycles. All these features indicated that this porous polymer based adsorbent has a high potential for CO2 capture and separation from flue gas.

Analysis and testing of bisphenol A, bisphenol A diglycidyl ether and their derivatives in canned dog foods

An analytical method was developed for the simultaneous determination of bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE) and their derivatives, BADGE·2H2O, BADGE·H2O, BADGE·HCl·H2O, BADGE·2HCl and BADGE·HCl, in canned animal food commodities using reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection. The samples were cleaned up using solid-phase extraction (SPE) with hydrophobic polystyrene–divinylbenzene (PS/DVB) copolymer sorbent. The performance characteristics confirmed that the method used was in accordance with the EU validation criteria. The recovery values ranged from 62 to 97%. The repeatability (CVr) and within-laboratory reproducibility (CVW) values ranged from 2.3 to 9.7% and from 2.8 to 10.8%, respectively, while the limit of detection (LOD) and the limit of quantification (LOQ) values ranged from 5 to 10 µg/kg and from 5 to 15 µg/kg, respectively. The method was successfully used to evaluate the levels of 7 bisphenols in 24 of the canned dog foods retailed on the Slovenian market. BADGE·2H2O was found in all the samples tested, with values ranging from 16 to 540 µg/kg, while BPA was found in 96% of the samples tested and ranged from <5 to 208 µg/kg. The contribution of BADGE·H2O and BADGE·HCl·H2O was minor, while no traces of BADGE, BADGE·2HCl or BADGE·HCl were detected. Epoxy phenolic coatings were identified in the cans tested by the Fourier transform infrared spectroscopy (FTIR) analysis. Given the temporary human tolerable daily intake (TDI) value of 4 µg/kg b.w./day recently laid down by the European Food Safety Authority (EFSA), these results, especially those for the BPA in canned dog foods, merit further attention and investigation.

Highly tunable porous organic polymer (POP) supports for metallocene-based ethylene polymerization

Porous organic Polymers (POPs) can not only exhibit high specific surface area and pore volume, but also tunable pore size distribution. Herein, copolymers of 2-hydroxyethylmethylacrylate (HEMA) and divinylbenzene (DVB) with specific pore structure were synthesized via a dispersion polymerization strategy, and then immobilized metallocene catalysts with well-defined pore structure were obtained on the produced POP supports. The nitrogen sorption and Gel permeation chromatography (GPC) results demonstrate that the pore structure of the immobilized metallocene catalyst is highly dependent on the pore structure of the POPs, and the pore structure of metallocene catalysts or the POPs has a significant influence on the molecular chain growth of the produced polyethylene. By tuning the distribution of the active species scattered in the micro- and the narrow meso-pore range (roughly ≤4nm), the chain growth of the polyolefin can be tailored effectively during the polymerization process, although differential scanning calorimetry (DSC) and temperature rising elution fractionation (TREF) results show that the chemical composition distributions (CCDs) of produced PE from the POPs-supported metallocene catalysts are not determined by polymerization activity or molecule chain length, but mainly by the active site species scattered in the supported catalysts. Scanning electron micrograph (SEM) shows that the produced polyethylene has highly porous fabric which consists of nanofiber and spherical beads of micron dimension.

Detection of theaflavins in black tea using a molecular imprinted polyacrylamide-graphite nanocomposite electrode

In this work, we report a facile and convenient approach for the synthesis of a molecular imprinted electrode for detecting total theaflavin (TF), an important chemical constituent of black tea. The proposed electrode is prepared from co-polymer of acrylamide and divinylbenzene along with graphite and it is imprinted with TF. The molecular imprinted polymer (MIP) is characterized by fourier transform infra-red (FTIR) and field emission scanning electron microscope (FESEM) techniques. Cyclic voltammetric and differential pulse voltammetry analysis were performed in order to study the performance of the electrode. The MIP electrode is found to have a good detection limit of 14μΜ (S/N=3) and a linear range of 20–100μΜ. The electrode also showed an excellent selectivity and sensitivity to TF from its structural analogues. The analytical performance of the MIP electrode has been observed to be reasonably good and has adequate repeatability and reproducibility. The proposed electrode is employed to determine the TF content in black tea samples by correlating with HPLC data using partial least square regression technique and a prediction accuracy of 94% is obtained.

Acidic phosphoryl podands as components of extraction chromatography material for selective extraction of promethium-147

A number of new acidic phosphoryl podands with different substituents in the phosphoryl groups and different polyether chain structure are synthesized. They are used to obtain impregnation-type sorbents. A copolymer of styrene and divinyl benzene (LPS-500 grade) is used as a matrix for sorbent manufacturing. The effect of the structure and amount of supported phosphoryl podand, as well as of the concentration and nature of the acid in the initial solution of rare metals on extraction-chromatographic separation of La3+, Nd3+, Pm3+, and Sm3+ in the dynamic mode, is studied. It is found that the developed sorbents are superior with regard to efficiency of separation of these elements from weakly acidic media to the known counterparts synthesized on the basis of the conventionally used extractants: di(2-ethylhexyl)phosphoric acid and N,N,N′,N′-tetra-n-octyldiglycolamide. The possibility of practical application of the obtained sorbents for selective extraction and purification of promethium-147 from a number of associated rare-earth metals from technological solutions of PO Mayak is shown.

Performance of poly(styrene-co-divinylbenzene) functionalized with different aminophosphonate pendant groups, in the removal of phenolic compounds from aqueous solutions

AbstractIn the present work, we describe the synthesis and characterization of styrene-6.7%-divinylbenzene copolymers functionalized with aminophosphonate groups by “one-pot” reactions. Different aminophosphonate groups were grafted on the copolymer with the aim of obtaining adsorbents for removal of phenolic compounds from aqueous solutions. Adsorption experiments were carried out in batch system. The phenolic compounds studied were phenol and 2,4,6-trimethyl-phenol. The best adsorption capacity was observed in the case of polymeric adsorbents functionalized with aminophosphonate groups inpara-position of the aromatic nucleus for both phenol and 2,4,6-trimethyl-phenol. In comparison, the copolymers with the functional groups inortho-position and respectively inmeta-position were slightly less efficient. The differences in adsorption efficiency may be explained taking into account the structure of the adsorption active centers. The possible explanation is that the active functional groups responsible for the adsorption process, grafted inortho-ormeta-position could be affected by possible steric hindrance effects. The difference between the adsorption capacities of the polymers of the same series, are rather small and depending on the nature of the radical found in the structure of the aminophosphonate: isopropylamine or isobuthylamine.