Preparation and characterization of molecularly imprinted silica particles for selective adsorption of naphthalene

A new kind of molecularly imprinted adsorbent for naphthalene was prepared by a covalent/noncovalent hybrid strategy. The monomer-template compound was prepared by the reaction of 3-(triethoxysilyl)propyl isocyanate with β-naphthol to form a thermally cleavable urethane bond. The silica gel was prepared by means of the gelation of monomer-template compound with tetraethoxysilane in ethanol using sol–gel technology. The removal of the template by the cleavage of urethane bond at elevated temperature resulted in the generation of recognition sites which could rebind naphthalene through noncovalent interaction. Binding experiments demonstrated that the imprinted silica particles showed a very fast uptake profile for naphthalene and displayed highly selective recognizing ability for naphthalene over benzene and other PAHs such as anthracene, phenanthrene, pyrene, fluoranthene and triphenylene.     

滤棒长度对卷烟主流烟气中7种有害物质的影响研究

为研究滤棒长度对卷烟主流烟气中一氧化碳（CO）、氢氰酸（HCN）、NNK、氨、苯并[a]芘、苯酚及巴豆醛等7种有害物质的影响,制造出滤棒长度分别为30,27,24,21 mm的4种卷烟,测定其主流烟气中单位焦油的7种有害物质含量。结果表明,卷烟主流烟气中单位焦油苯并[a]芘、巴豆醛、CO的含量随滤棒长度减小而减少;HCN、NNK、NH3、苯酚的含量则有相反的变化规律;而卷烟主流烟气中单位焦油的危害性变化不大。     

活性炭吸附剂的制备及其在选择性降低卷烟主流烟气中氰化氢的应用

采用浸渍法制备低成本活性炭负载过渡金属吸附剂,通过考察活性金属种类和含量、溶剂、活性炭载体种类和颗粒大小等对吸附剂吸附氰化氢性能的影响,优化得到以Cu为活性组分的吸附剂,当Cu质量分数4%时,将制备的吸附剂以二元复合形式添加到卷烟滤嘴中制成中试试样烟,测试发现,与对照成品卷烟相比,试样烟在保持焦油含量基本不变基础上,主流烟气中氰化氢释放量最高可降低71.7%。制备的吸附剂具有较好的稳定性,室温储藏8个月,吸附剂选择性降低主流烟气中氰化氢的效果与新鲜吸附剂一致。     

Graphene‐based molecularly imprinted polymer for separation and pre‐concentration of trace polycyclic aromatic hydrocarbons in environmental water samples

A composite of reduced graphene oxide and pyrene‐imprinted polymer was synthesized and employed as a solid phase for extraction of five selected polycyclic aromatic hydrocarbons (PAHs) from water samples. Gas chromatography‐time of flight/mass spectrometry was employed in the analysis of the extracts. The composite was prepared by a free radical polymerization of methacrylic acid and 4‐vinylpyridine as monomers and ethylene glycol dimethacrylate as a crosslinker. The adsorption studies were carried out through batch binding studies. The binding capacity for the imprinted and non‐imprinted composite was 101.83 and 68.21 µg g^?1, respectively. The adsorption followed the pseudo 2nd order and well fitted the Langmuir isotherm. Mean recoveries ranging from 73% to 105.4% for both spiked deionized water and environmental water samples were obtained when the imprinted composites were employed in solid phase extraction of the PAHs. The composites could be re‐used for five times without a significant loss in recoveries. The proposed method was employed for the analysis of spiked environmental water samples and did not show significant changes in the recoveries showing there were no matrix interferences. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45300.     

Promethazine determination in plasma samples by using carbon paste electrode modified with molecularly imprinted polymer (MIP): Coupling of extraction, preconcentration and electrochemical determination

A promethazine (PMZ) molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized by two different formulations of methacrylic acid-ethylene glycol dimethacrylate (MAA-EGDMA) and vinyl benzene-divinyl benzene (VB-DVB). Then, the MIPs were used to modify the carbon paste electrode (CP). The response difference between MIP-CP and NIP-CP electrodes, containing VB-DVB polymer, was higher than that for MIP-CP and NIP-CP modified with polymer of MAA-EGDMA, indicating the lower nonselective surface adsorption property of the VB-DVB based MIP. The MIP, incorporated in the carbon paste electrode, functioned as selectively recognition element and pre-concentrator agent for PMZ determination. The prepared electrode was used for PMZ measurement by the three steps procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of PMZ. It was shown that the electrode washing, after PMZ extraction, led to enhanced selectivity. Square wave voltammetry (SWV) for PMZ determination by proposed electrode was proved to be better than that of differential pulse voltammetry. Some parameters, effective on the electrode response, were optimized and then a calibration curve was plotted. Two dynamic linear range of 7 × 10⁻⁹ to 4 × 10⁻⁷ and 4 × 10⁻⁷ to 7 × 10⁻⁶ mol L⁻¹ were obtained. The detection limit of the method was calculated equal to 3.2 × 10⁻⁹ mol L⁻¹. This method was used successful for PMZ determination in blood serum sample.     

Quantification of polycyclic aromatic hydrocarbons (PAHs) in the smoke from six woods and comparative study of their distribution

Polycyclic aromatic hydrocarbons (PAHs) are considered as undesirable molecules in smoke. It is important to know the smoke composition applied to meat-based products. PAH extracts of the smoke from five tropical woods were fractionated, analyzed then compared to that of beechwood, a European wood commonly used in the smoking industry of meat-based products. The identification and quantification of the aromatic molecules was carried out with gas chromatography coupled to mass spectrometry (GC/MS).     

Supercritical fluid extraction combined with dispersive liquid-liquid microextraction as a sensitive and efficient sample preparation method for determination of organic compounds in solid samples

The supercritical fluid extraction (SFE) followed by the dispersive liquid-liquid microextraction (DLLME) has been developed for extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. PAHs were employed as model compounds to assess the extraction procedure and were determined by gas chromatography-flame ionization detection (GC-FID). SFE of PAHs was performed at 313 K and 253.2 bar, at static and dynamic times 10 and 30 min, respectively. The extracted PAHs were collected in 1 mL of acetonitrile. Subsequently, 16 μL of chlorobenzene (as extraction solvent) was added to collecting solvent (1.0 mL of acetonitrile). Then, the resulted mixture was injected into 5.0 mL of aqueous solution, rapidly. After centrifugation, the PAHs in the sedimented phase were analyzed by GC-FID. Effects of significant parameters on the extraction in SFE and DLLME methods were investigated. Under the optimum conditions, the calibration plots were linear in the range of 0.4-41.6 mg kg⁻¹ and the limits of detection (LODs) were 0.2 mg kg⁻¹ for all of the analytes. Analysis of PAHs in different solid samples showed that the improved technique has great potential for PAHs analysis in marine sediments. SFE-DLLME leads to high preconcentration factor, easy use of DLLME in solid samples and solving the main problem of SFE that is the extra step (vaporization of large volume of toxic organic solvent) after extraction needed prior to final analysis.     

Trace bensulfuron‐methyl analysis in tap water,soil, and soybean samples by a combination of molecularly imprinted stir bar sorption extraction and HPLC‐UV

A molecularly imprinted stir bar was prepared using bensulfuron‐methyl as the template molecule and methacrylic acid as the functional monomer. The imprinted and nonimprinted stir bars were characterized by scanning electron microscopy, nitrogen sorption porosimetry, thermogravimetric analysis, and differential scanning calorimetry. Extraction time, desorption time and pH value affecting extraction efficiency of the stir bar have been evaluated to achieve the selectively direct preconcentration of the template from aqueous samples. Competitive sorption experiments demonstrated that the imprinted stir bar gave high selectivity and imprinted effect on the template bensulfuron‐methyl compared to the nonimprinted stir bar. Based on S/N of 3, LOD was 0.83 nM. The method showed good recoveries and precision, 92.4% (RSD 1.5%, n = 3) for tap water spiked with 126 ng (100 mL sample), 84.6% (RSD 2.2%, n = 3) for soil spiked with 210 ng (100 g sample) and 73.7% (RSD 2.1%, n = 3) for soybean spiked with 250 ng (5 g sample), suggesting that the imprinted stir bar sorption extraction can be successfully applied to the preconcentration of bensulfuron‐methyl in real samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of a hypercrosslinked,ionic, mesoporous polymer monolith and its application in deep oxidative desulfurization

In this study, we used a facile and scalable strategy to produce a hypercrosslinked, ionic, mesoporous polymer monolith (HCIMPM). On the basis of structure‐directing polymeric crosslinking, the interconnected nanonetwork was formed through the in situ crosslinking of the homopolymer poly(vinyl imidazole) via a quaternization reaction, and its textural properties could be effectively adjusted by the block copolymer poly(ethylene oxide)‐block‐poly(propylene oxide)‐block‐poly(ethylene oxide)(PEO₂₀PPO₇₀PEO₂₀). The maximum specific surface area and pore volume were 212 m²/g and 1.08 cm³/g, respectively. Furthermore, the synthetic framework could be functionalized via the loading of PW₁₂ through ion exchange. The obtained HCIMPM with PW₁₂O₄₀^3? (PW‐HCIMPM) was applied in the oxidative desulfurization, and approximately 100% sulfur removal could be achieved in the model oil with hydrogen peroxide (30 wt %) as an oxidant. Moreover, the solid catalyst could be recovered readily and recycled at least six times without a significant decrease in the desulfurization efficiency. As for real diesel, we also observed that almost all of the original sulfur compounds could be converted in 120 min. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46280.     

Synthesis and characterization of novel copper/polyaniline nanocomposite and application as a catalyst in the Wacker oxidation reaction

Copper nanoclusters were synthesized by a chemical reduction of an aqueous copper salt solution by sodium borohydride. A polyaniline nanocomposite containing copper nanoclusters was prepared by polymerizing a monomer aniline hydrochloride solution containing the copper nanoclusters using ammonium persulfate as an oxidizing agent. The synthesized nanocomposite was characterized using various techniques such as UV‐visible spectroscopy, FTIR spectroscopy, X‐ray diffraction (XRD), and transmission electron microscopy (TEM). The presence of copper was confirmed by XRD and the size of the copper clusters was found to be ～53 nm, which is in good agreement with that obtained from the TEM. The synthesized nanocomposite was used to serve as a catalyst in a Wacker oxidation reaction for the conversion of 1‐decene to 2‐decanone in the presence of molecular oxygen. The formation of 2‐decanone was confirmed using GC‐MS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2412–2417, 2003     

Synthesis of a novel fluorene-based conjugated polymer with pendent bulky caged adamantane moieties and its application in the detection of trace DNT explosives

A novel fluorene-based conjugated polymer with phenylene spacers and steric bulky adamantane moieties in side chains has been synthesized by palladium-catalyzed Suzuki coupling reactions. This design strategy offers several advantages for the detection of trace 2,4-dinitrotoluene (DNT) vapor. The incorporation of the two groups into polymer side chains could retain an effective conjugation length and prevent the π-stacking of polymer chains. The detection of DNT vapor indicated that the polymer displayed higher fluorescence quenching sensitivity toward the explosives in films compared to reference polymers. The fluorescence quenching efficiency of the fluorescent polymer achieved 33.3% in 10 s and 71.1% in 60 s. The pathways or cavities generated by the two spacers are beneficial for the rapid diffusion of explosive vapor into the film interiors and increase the fluorescence quenching efficiency of the film.     

Synthesis of a novel sulfonated poly(amide‐imide) and its application in preparation of ultrafiltration PES membranes as a modifier

Sulfonated poly(amide‐imide) (SPAI) copolymer was synthesized, characterized, and blended into poly(ether sulfone) (PES)/dimethylacetamide casting solutions to prepare ultrafiltration membranes. Different weight ratios of the copolymer (0–10 wt %) were mixed in the PES casting solution. The analyses of contact angle and attenuated total reflection‐Fourier transform infrared spectra were used to study hydrophilicity and physicochemical properties of the membrane surface, respectively. The membranes were further characterized by scanning electron microscopy images, ultrafiltration performance, and fouling analyses. The outcomes showed that addition of the SPAI in the PES matrix improved considerably the membranes hydrophilicity. Moreover, with increasing SPAI concentration, the porosity, flux recovery ratio, and pure water permeability of the modified membranes were improved. The pure water flux was increased from 3.6 to 12.4 kg/m² h by increasing 2 wt % SPAI. The antifouling property of the modified PES membranes against bovine serum albumin, tested by a dead‐end filtration setup revealed that bovine serum albumin rejection of the obtained membrane was also enhanced and the antifouling properties of the blending membranes were improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46477.     

Two‐stage stabilizer addition protocol as a means to reduce the size and improve the uniformity of polymer beads in suspension polymerization

A two‐stage stabilizer addition protocol is suggested for reducing the size and improving the uniformity of polymer beads resulting from conventional suspension polymerization. The stabilizer load was divided into an initial charge and a secondary addition. The use of a low concentration of stabilizer in the initial charge served to assist drop rupture while avoiding significant reduction in drop size and production of too many satellite droplets. The secondary addition time of stabilizer occurred just before the onset of the growth stage when drops were vulnerable to coalescence but robust against break up due to their high viscosity. The secondary addition of stabilizer served to provide stability to monomer drops during the growth stage and as a result the drops underwent limited coalescence. This resulted in the formation of smaller and more uniform polymer beads in comparison to beads obtained by conventional suspension polymerization at the same overall concentration of stabilizer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45671.     

Synthesis and application of sodium 2‐acrylamido‐2‐methylpropane sulphonate/N‐vinylcaprolactam/divinyl benzene as a high‐performance viscosifier in water‐based drilling fluid

Aiming at good thickening ability and temperature resistance in water‐based drilling fluid, a novel copolymer viscosifier (SDKP) of sodium 2‐acrylamido‐2‐methylpropane sulfonate (NaAMPS) with N‐vinylcaprolactam (NVCL) and cross‐linking divinylbenzene (DVB) was prepared by micellar radical polymerization. The composition and molecular structure of optimal SDKP under the optimum reaction conditions was characterized by FT‐IR, ¹H‐NMR, and elemental analysis, and the molecular weight was determined by GPC. Thermal gravimetric analysis showed that the SDKP was even stable when the temperature was not higher than 330 °C. The performance of SDKP as viscosifier for aqueous, brines, and saturated brine bentonite drilling fluid was evaluated before and after aging tests at 230 °C for 16 h. The evaluation results indicated that the SDKP had excellent thickening ability, thermal resistant, and salt tolerance. HTHP rheology test showed that the SDKP containing drilling fluids displayed a thermo‐thickening effect in temperature range of 150 to 180 °C, which was beneficial to increase the viscosity and strength of fluids at high temperatures. Shear test showed that the SDKP illustrated a similar shear thinning to xanthan gum. ESEM observations demonstrated that the continuous three‐dimensional network was formed in the SDKP aqueous and brines solution, which was probably the main reason for its excellent thickening properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44140.     

Synthesis of PAA-g-PNIPAM well-defined graft polymer by sequential RAFT and SET-LRP and its application in preparing size-controlled super-paramagnetic Fe3O4 nanoparticles as a stabilizer

A series of well-defined double hydrophilic graft copolymers, poly(acrylic acid)-g-poly(N-isopropylacrylamide) (PAA-g-PNIPAM), was employed as a novel water-soluble coating for constructing superparamagnetic iron oxide nanoparticles. The copolymer was synthesized via a three-step procedure: firstly, a well-defined hydrophobic PtBA-based backbone, poly(tert-butyl 2-((2-chloropropanoyloxy)-methyl)acrylate)-co-poly(tert-butyl acrylate), (PtBCPMA₁₉-co-PtBA₁₈), was prepared through RAFT copolymerization of a new trifunctional acrylic monomer, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate and tert-butyl acrylate; secondly, taking this backbone as a macroinitiator to initiate SET-LRP of N-isopropylacrylamide resulted in well-defined (poly(tert-butyl 2-((2-chloropropanoyloxy)methyl)-acrylate)-co-poly(tert-butyl acrylate))-g-poly(N-isopropylacrylamide) ((PtBCPMA-co-PtBA)-g-PNIPAM) amphiphilic graft copolymers with relatively narrow polydispersities (M_w/M_n ≤ 1.31); thirdly, handling (PtBCPMA-co-PtBA)-g-PNIPAM in acidic conditions afforded PAA-g-PNIPAM graft copolymers. The resulting PAA-g-PNIPAM copolymers were directly utilized as a polymeric stabilizer in the preparation of superparamagnetic Fe₃O₄ nanoparticles. The particle size can be readily tuned in the range of 12.1–23.2 nm by varying the amount of PAA-g-PNIPAM copolymer or the length of PNIPAM side chain. Besides, the structure and properties of prepared Fe₃O₄/polymer nanocomposites were characterized by XRD, FT-IR, TGA, TEM, and magnetic measurement in detail.