Solution-blow spun PLA/SiO2 nanofiber membranes toward high efficiency oil/water separation

With the ever frequent of industrial organic solvent emissions and oil spillages, the development of high efficiency oil/water separation materials has attracted extensive attention. Here, PLA-based nanofiber membranes modified with metal oxides (SiO₂, TiO₂, Al₂O₃, and CeO₂) are fabricated through blow spinning the mixed solution of polylactic acid (PLA) and metal oxide nanoparticles (NPs). Results shows that the addition of SiO₂ NPs significantly increases the hydrophobicity of the membranes, while maintaining the excellent superoleophilicity. The PLA/SiO₂ nanofiber membranes demonstrate a higher separation performance than pure PLA, PLA/TiO₂, PLA/Al₂O₃, and PLA/CeO₂ nanofiber membranes with high separation efficiency (~100%) and permeation flux (17,800 L m⁻² h⁻¹ for n-heptane), as well as prominent oil adsorption capacity (19.9 g/g for n-hexane). The successful fabrication of metal oxides modified PLA nanofiber membranes with high separation and adsorption ability, and excellent durability hold great application potential in the field of oily wastewater treatment.     

Preparation and characterization of poly-carboxymethyl-β-cyclodextrin superplasticizer

A new superplasticizer of poly-carboxymethyl-β-cyclodextrin (PCM-β-CD) was prepared by ring-opening polymerization of epoxy chloropropane and CM-β-CD using sodium hydroxide as initiator. The structure of PCM-β-CD was characterized by FTIR and NMR as well as GPC. The performances of the CM-β-CD were tested by measuring paste luidity, setting time, adsorption and zeta-potential. The result showed the performances of PCM-β-CD closed to the control polycarboxylate superplasticizer (PCs) used in this study, especially the fluidity loss is smaller and the setting time is longer than the PCs. The reason might be the synergism of the steric hindrance with the hollow truncated cone and the electrostatic repulsion from –COO^? groups. The mechanism of dispersion and retardation by PCM-β-CD was elucidated based on the results of adsorption properties and zeta‐potential of the cement particles. The study offers a new approach to synthesize superplasticizer based on β-CD and an alternative to concrete engineering.     

β-Cyclodextrin Based Molecularly Imprinted Solid Phase Extraction for Class Selective Extraction of Priority Phenols in Water Samples

Molecular imprinted polymer (MIP MAA-β-CD) with 2,4-dichlorophenol (2,4-DCP) and methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) as the template molecule and the functional monomer, respectively, was prepared and used in molecular imprinted-solid phase extraction (MISPE) for the extraction of phenols (2,4-dichlorophenol, 2-chlorophenol, 4-chloro-3-methylphenol, 4-chlorophenol, 2,4,6-trichlorophenol, and 2-nitrophenol) from water samples. The MISPE method was optimized prior to the determination using gas chromatography coupled with a flame ionization detector (GC-FID). Under the optimized conditions, the MIP MAA-β-CD sorbent showed good linearity (0.01-12 mgL^?1), low limits of detection (0.14-0.75 µgL^?1), and good repeatability (RSD 2.3-3.6%, n = 3). Good recoveries were obtained in the range of 97-115% for tap water and between 88-103% for river water. The developed MIP MAA-β-CD SPE was then compared with other adsorbents. The unique properties of β-CD and presence of imprinted cavities explains the higher extraction recoveries obtained for phenols when using MIP MAA-β-CD SPE.     

Electrocatalytic reduction of 1,2-diiodoethane by anions of supramolecular complex of (β-CD)2/C60 in DMF solution

The homogeneous electrocatalytic reduction of 1,2-diiodoethane by anions of the supramolecular complex of (β-CD)₂/C₆₀ in DMF solution is reported. The results show that the trianion of (β-CD)₂/C₆₀ exhibits electrocatalytic behavior towards the reduction of 1,2-diiodoethane, whereas the dianion is unable to reduce the diiodoethane. The second-order catalytic rate constant in DMF solution was determined to be 3.1 × 10⁵ M⁻¹ s⁻¹ by analysis of voltammetric responses under pseudo-first-order conditions with respect to (β-CD)₂/C₆₀. The results suggest that the host β-cyclodextrin molecules have little effect on the electrocatalytic ability of the encapsulated C₆₀ toward organic halides.     

Preparation and sorption studies of microsphere copolymers containing β-cyclodextrin and poly(acrylic acid)

Microsphere polymeric materials containing β-cyclodextrin (β-CD) and poly(acrylic acid) (PAA) with tunable morphologies were prepared in order to improve their sorption characteristics in aqueous solution. The microsphere polymeric materials were prepared using a (water/oil) micro-emulsion-evaporation technique to condense β-cyclodextrin (β-CD) with PAA at various comonomer ratios and mixing speeds. The β-CD microsphere copolymers were characterized using FTIR, TGA, DSC, SEM, elemental (C and H) microanalyses, and solid state ¹³C-NMR spectroscopy. The sorption properties of the polymeric materials at 295 K in aqueous solution containing p-nitrophenol (PNP) were studied using a dye-based method with UV–Vis spectrophotometry at pH 4.6 and 10.3. The sorption isotherms of copolymer/PNP systems were evaluated with various isotherm models (e.g., Langmuir, BET, Freundlich, and Sips). The Sips isotherm showed the best overall agreement with the experimental results and the sorption parameters provided estimates of the sorbent surface area (12.0–331 m²/g) and the sorption capacity (Q_m = 0.359–2.20 mmol/g at pH = 4.6; Q_m = 0.070–0.191 mmol/g at pH = 10.3) for the microsphere copolymer/PNP systems in aqueous solution. The nitrogen adsorption properties of the microporous copolymers in the solid state were obtained at 77K with BET surface areas ranging from 0.275 to 4.47 m²/g. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Reaction kinetics in reactive extraction for chiral separation of α-cyclohexyl-mandelic acid enantiomers with hydroxypropyl-β-cyclodextrin

This paper reports on determination of the intrinsic reaction kinetics in reactive extraction of α-cyclohexyl-mandelic acid (α-CHMA) enantiomers with hydroxypropyl-β-cyclodextrin (HP-β-CD) in a modified Lewis cell, in which HP-β-CD dissolved in 0.1 mol/l NaH₂PO₄/H₃PO₄ buffer solution was selected as chiral extractant. α-CHMA enantiomers were extracted from an organic phase to an aqueous phase in the extraction module. The theory of extraction accompanied by chemical reactions has been used to obtain the intrinsic kinetics of this extraction module. The different factors affecting the extraction rate, such as agitation speed, interfacial area, initial enantiomers concentration in an organic phase as well as HP-β-CD concentration in an aqueous phase were separately studied. The experimental results demonstrate that the extraction reaction kinetics is fast. The reactions between α-CHMA enantiomers and HP-β-CD in a stirred cell fall in regime 3 and are first order with respect to α-CHMA enantiomers and second order with respect to HP-β-CD with forward rate constants of 6.9×10⁻² m⁶/(mol² s) and 2.5×10⁻² m⁶/(mol² s) for S-α-CHMA and R-α-CHMA, respectively. These data will be useful in the design of the extraction process.     

Selective adsorption of ketoconazole from aqueous solutions using a new molecularly imprinted polyurethane coated magnetic multiwall carbon nanotubes

New magnetic molecularly imprinted polyurethanes based on magnetic multi-walled carbon nanotubes (MMWNTs-MIPUs) were synthesized with specific selectivity toward ketoconazole (KTZ) as an anti-fungal drug. First, novel N-(4-carboxyphenyl) trimellitimide diisocyanate (NTDIS) was prepared from the reaction of trimellitic anhydride and 4-amino benzoic acid in two steps. Then, NTDIS was functionalized by β-cyclodextrin and methacrylic acid (MAA-NTDIS-β-CD). MAA-NTDIS-β-CD was used as a functional monomer, KTZ as a template, ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent and 2,2′-azobisisobutyronitrile (AIBN) as initiator. Structure and properties of the prepared compounds were characterized by FTIR, ¹H NMR, FESEM, XRD, VSM, BET, and EDX. The influence of parameters such as solution pH, contact time, temperature, and initial concentrations in controlled absorption of KTZ using MMWCNTs-MIPU and MMWCNTs-NIPU were evaluated. The kinetic data were measured using the pseudo-first-order and pseudo-second-order equation. The pseudo-second-order equation displayed the best fit for the kinetic studies (R² 0.9958). The adsorption equilibrium of KTZ using MMWCNTs-MIPU could be well-defined with the Langmuir isotherm model, and the maximum adsorption capacity was calculated as 52.35 mg g^–1. The prepared MMWCNTs-MIPU can be simply separated by an external magnetic field and, MMWCNTs-MIPU can be used after six filtration-regeneration cycles.

     

以b-环糊精、2-羟丙基-b-环糊精和4-乙烯吡啶为功能单体制备氟比洛芬分子印迹聚合物及其吸附特征

以b-环糊精(β-CD)、2-羟丙基-β-环糊精(HP-β-CD)和4-乙烯吡啶(4-VP)为功能单体,以氟比洛芬为模板分子,以环氧氯丙烷和乙二醇二甲基丙烯酸酯为交联剂,采用本体聚合法制备分子印迹聚合物(MIPs),对氟比洛芬与功能单体的相互作用和MIPs的结构进行了表征,比较了3种MIPs对氟比洛芬的吸附性能. 结果表明,β-CD, HP-β-CD和4-VP与氟比洛芬之间以较强的相互作用形成复合物,通过交联、聚合形成聚合物,以HP-β-CD作功能单体所得聚合物印迹效果最佳,具有较强的特异性吸附能力,印迹因子和特异性吸附率分别为1.79和38.92%,分子印迹机制是β-CD的锥筒包结作用和羟丙基的亲和作用形成印迹空穴.     

二苯基甲烷二异氰酸酯改性β-环糊精吸附性能

以二苯基甲烷二异氰酸酯(MDI)为交联剂、对β-环糊精(β-CD)进行修饰改性,制得吸附剂二苯基甲烷二异氰酸酯-β-环糊精(MDI-β-CD),并用于吸附处理苯酚废水.采用红外光谱(IR)及扫描电镜(SEM)对交联产物进行表征,结果发现,所得的交联产物即为目标产物.考察了振荡时间、溶液pH值,吸附温度、聚合物MDI-β...     

Adsorption Behavior of Azo Dye Eriochrome Black T from Aqueous Solution by β-Cyclodextrins/Polyurethane Foam Material

β-cyclodextrin/polyurethane (β-CD/PU) materials were prepared by foaming technique. The adsorption behavior of EBT on β-CD/PU material and the influences on the adsorption efficiency were investigated. Under the optimal experimental conditions, the maximum adsorption efficiency of EBT was 93.14%. The kinetics characteristic and thermodynamic parameters were analyzed. The experimental isotherms data were analyzed using Langmuir and Freundlich isotherm equations and the results indicated that the Langmuir isotherm showed a better fit for EBT adsorption. The experimental results suggest that the β-CD/PU foam materials have potential application for the wastewater treatment containing EBT dye.     

Inclusion complexes of atorvastatin calcium (ATV-Ca) and rosuvastatin calcium (ROV-Ca) drugs with α-CD, β-CD, γ-CD,HP-β-CD,M-β-CD,and maltodextrin along with their characterizations through experimental and computational methods

The aim of this research is a comparison of the efficiency of six commercially available cyclodextrins (CDs) to improve the solubility and oral bioavailability of atorvastatin calcium (ATV-Ca) and rosuvastatin calcium (ROV-Ca) drugs in aqueous media. Inclusion complexes of both drugs with non-toxic α-CD, β-CD, γ-CD, HP-β-CD, M-β-CD, and maltodextrin were prepared in a 1:1 stoichiometry via the kneading method. To reach the best CD, various experimental and computational analyses were performed including phase solubility, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), hydrogen-1 nuclear magnetic resonance (¹HNMR), carbon-13 nuclear magnetic resonance (¹³CNMR), and molecular docking calculations. The M-β-CD turned out to be the best substrate for the micro-encapsulation of both drugs. Also, ATV showed a higher tendency than ROV to form inclusion complexes with CDs. Molecular docking studies showed that HP–β–CD and M-β-CD are the most suitable substrates for the formation of inclusion complexes, respectively. Our research showed that the β-CD is not necessarily the most efficient substrate for increasing solubility based on previous reports in the literature; meanwhile, the other employed substrates in this study can show acceptable performances in this regard. According to our results, M-β-CD is the best substrate for the micro-encapsulation of both drugs, which increases their solubility in water.     

Morphological, structural and rheological properties of beta-cyclodextrin based polypseudorotaxane gels

Supramolecular self-assembled gels of polypseudorotaxane (PPR) were made through sequential inclusion complexations between beta-cyclodextrin (β-CD) and reverse Pluronic^® (RPL, or PPG-PEG-PPG). This study aimed to disclose the differences in morphological, structural and rheological properties of the PPR gels made in citric acid and other conditions. β-CD/RPL mixture in citric acid solution incubated at 25 °C (β-CD/RPL-C-25) had the most homogeneous, fine and continuous structure, the lowest crystallite size, and the highest gel strength and thixotropy. It was hypothesized that the citric acid partially interfered with the crystal growth of PPR, and thus led to high degree of crosslinking which explained its largest gel strength and thixotropy. β-CD/RPL mixtures in water incubated at 65 °C (β-CD/RPL-W-65) underwent PPR rearrangement, resulting in larger crystallites and a more integrate net-like structure, therefore yielding higher gel strength as compared with β-CD/RPL mixture in water incubated at 25 °C.     

带β-环糊精侧基水凝胶的制备与性能研究

用顺丁烯二酸酐（MAH）对β-环糊精（β-CD）进行化学改性制备丁烯二酸单酯化β-环糊精单体（MAH-β-CD）。用氧化还原自由基引发单体MAH-β-CD、丙烯酰胺（AM）以及丙烯磺酸钠（SAS）共聚,合成水凝胶,用红外光谱对产物结构表征。溶胀研究结果表明该水凝胶具有良好的温度、pH敏感性。     

Core-shell Fe3O4@SiO2 nanoparticles synthesized with well-dispersed hydrophilic Fe3O4 seeds

Silica coated magnetite (Fe3O4@SiO2) core-shell nanoparticles (NPs) with controlled silica shell thicknesses were prepared by a modified St?ber method using 20 nm hydrophilic Fe3O4 NPs as seeds. The core-shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and UV-Vis adsorption spectra (UV-Vis). The results imply that NPs consist of a crystalline magnetite core and an amorphous silica shell. The silica shell thickness can be controlled from 12.5 nm to 45 nm by varying the experimental parameters. The reaction time, the ratio of TEOS/Fe3O4, and the concentration of hydrophilic Fe3O4 seeds were found to be very influential in the control of silica shell thickness. These well-dispersed core-shell Fe3O4@SiO2 NPs show superparamagnetic properties at room temperature.     

Self-assembled, optically responsive nematic liquid crystal/polymer core-shell fibers: Formation and characterization

We report here the formation and structural characterization of optically responsive, highly birefringent electrospun nematic liquid crystal (LC) microfibers. The LC microfibers are electrospun from a solution of polylactic acid (PLA) and low molecular weight 4-pentyl-4^’-cyanobiphenyl (5CB) in chloroform/acetone solvent. In the electrospinning process, the low molecular weight 5CB phase-separates and self-assembles to form a planarly aligned nematic core within a PLA shell. The solubility limit of 5CB in PLA and the degree of phase separation of LC in the 5CB/PLA core/sheath fibers is determined using the phase transition enthalpies associated with LC and polymer components. Structural analysis revealed that the LC core and dissolved LC in the fibers promote the formation of the α-form of PLA crystals and increase the degree of crystallinity of the PLA shell in 5CB/PLA fibers from 6.6% to 52%. Competition between 5CB droplet formation and PLA fiber formation is observed as a function of spinning solution composition and applied electrospinning voltage. Alignment of the 5CB within the PLA core is confirmed by polarizing optical microscopy.     

Adsorption studies of Cu2+ onto poly (vinyl alcohol)/poly (acrylamide-co-N-isopropylacrylamide) core–shell nanogels synthesized through surfactant-free emulsion polymerization

Poly (vinyl alcohol) (PVA) nanoparticle core and poly (acrylamide-co-N-isopropylacrylamide) P(AAm-co-NIPAm) hydrogel shell were fabricated to produce well-defined PVA/P(AAm-co-NIPAm) core–shell nanogels using Surfactant Free Emulsion Polymerization (SFEP). The nanogel was characterized by the FTIR, TEM TGA thermogram and SEM techniques. The adsorbent was utilized for Cu²⁺ removal from aqueous solution. Batch adsorption process indicated that 0.9 mol% PAAm nanogel exhibited higher adsorption affinity toward Cu²⁺. The kinetics parameters were investigated according to the pseudo-first-order, pseudo-second-order and intraparticle diffusion rate models. The adsorption equilibrium match with Langmuir adsorption isotherm rather than Freundlich isotherm. The Cu²⁺ loaded nanogels were effectively desorbed using 0.1 mol/l from HCl as stripping agent.     

β-环糊精与罗丹明B及番红花红T包合作用的研究

合成了以β-环糊精为主体,罗丹明B及番红花红T为客体的包合物.用红外光谱、荧光光谱、共振瑞利散射光谱和差示扫描量热谱研究了β-环糊精与染料的包合机理.实验结果表明:β-环糊精与客体分子分别形成了1:1的包合物,客体分子进入β-环糊精分子的疏水性空腔内,当β-环糊精加入到一定浓度的客体溶液中时,罗丹明B体系的荧光强度和共振瑞利散射强度减弱,而番红花红T体系的荧光强度和共振瑞利散射强度增强.还通过荧光光谱法及共振瑞利散射光谱法分别测定了15、25和35 ℃ 3个不同温度时染料与β-环糊精包合体系的稳定常数.结果表明:包合物的形成主要取决于β-环糊精与客体分子的分子结构及两者作用力的大小,β-环糊精空腔大小与客体分子或其某些基团的大小越接近,越容易包合,包合物的稳定常数就越大.包合物的表观热力学常数显示,在上述包合体系反应的推动力是疏水作用力.     

Efficient removal of methyl orange by nanocomposite aerogel of polyethyleneimine and β-cyclodextrin grafted cellulose nanocrystals

Owing to the high specific surface area and lightweight, aerogels exhibit excellent adsorption capacity that can be tailored for the fabrication of high-performance environmental purification materials. Cellulose nanocrystal (CNC) is an abundant, bio-based, low-density one dimensional (1D) nanomaterials with high-respect ratio. In this work, CNC is first chemically grafted with polyethylenimine (PEI) and further by β-cyclodextrin (β-CD), which is subsequently crosslinked by polyacrylamide (PAM) to prepare the composted aerogel (CNC-PEI-CD/PAM), and being endowed high-adsorption capacity for methyl orange (MO) (155.93 mg g⁻¹) and removal rate (97.46%). Our unique strategy overcomes the low graft efficiency of β-CD directly onto CNC by connecting PEI. Besides, CNC-PEI-CD/PAM not only shows superior adsorption performance to methyl orange, attributing to the unique “selective” cavity structure of β-CD and dense surface charge of PEI, but also displays the desired reusability. This material shows the huge potential in water purification.     

Self-assembly of telechelic polymers bearing adamantane groups via host-guest inclusion complexes with cyclodextrin polymer

Self-assembly and supramolecular inclusion complexations between telechelic polymers bearing one or double adamantane groups and linear poly(β-cyclodextrin) (P(β-CD)) were investigated in water. An adamantane (Ada) attached to poly (acrylic acid) (PAA) was prepared by reversible addition-fragmentation chain transfer polymerization using s-1-dodecyl-s″ -(α,α′-dimethyl-α″-acetic acid) trithio-carbonate functionalized Ada with tert-butyl acrylate, followed by functional modification. Additionally, two Ada groups capped triblock copolymer F127 were obtained via an esterification reaction. The dynamic light scattering, transmission electron microscope and ¹H 2D NOSEY NMR spectroscopy were conducted to characterize the self-assembly behaviors. With the inclusion complexation of Ada/CD in 1:1 M ratio in water, the spherical micelles were enlarged at 25°C than that of the adamantyl polymer precursors. Due to the PPO segment of Ada-F127-Ada, the micelles aggregation showed temperature dependence from 4 to 37°C for precursor and corresponding inclusion complexation; while in Ada-PAA/P(β-CD) system, the hydrodynamic diameters decreased with pH decreasing.     

浓乳液共聚合法制备β-环糊精多孔分离材料的研究

利用氢氧化钠（NaOH）为催化剂,烯丙基溴（C3H5Br）为修饰剂与β-环糊精（β-CD）反应制备了十四(2,6O烯丙基)β环糊精（Ally-β-CD）,研究了催化剂与修饰剂用量、反应时间、反应温度对合成产物产率的影响。以苯乙烯（St）、Ally-β-CD和二乙烯基苯（DVB）为连续相,过硫酸钾（K2S2O8）、硫酸钾（K2SO4）溶于水中组成分散相,通过反相浓乳液模板法制备了Ally-β-CD与St共聚多孔材料,并研究了β-CD对多孔材料亲水性能与苯酚（PhOH）吸附性能的影响。结果表明,制备Ally-β-CD的最佳反应工艺为n(β-CD)∶n(C3H5Br)= 1∶76.0,n(NaOH)∶n(C3H5Br)=1.34∶1,反应温度为5 ℃,反应时间为48 h;β-CD的引入可以明显提高多孔材料的亲水性能与PhOH吸附性能。