Template Ion Research Articles

A Novel Ion-imprinted Polymer Based on Multi-walled Carbon Nanotubes for Solid Phase Extraction of Pd(II)

A novel Pd(II) ion-imprinted polymer (Pd(II)[email protected]) was constructed by using 2-(N-allyl)aminopyridine (AAP), vinyl functionalized multi-walled carbon nanotubes (VMWCNTs), ethylene glycol dimethacrylate (EGDMA) and Na2PdCl4 as functional monomer, carrier, cross-linker and template ions, respectively. The structure, morphology, adsorption property and applicability as adsorbent in solid phase extraction were characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), binding experiment and solid phase extraction (SPE) experiment, respectively. The equilibrium adsorption capacity and imprinting factor of Pd(II)[email protected] for Pd(II) were found to be 9.053 mg/g and 3.46, respectively. The SPE column packed with Pd(II)[email protected] displayed good adsorption selectivity to Pd(II). The adsorption rate and extraction rate of this column to Pd(II) were more than 90% and 74%, but below 40% and 15% to the other coexisting ions under the optimized SPE conditions. The obtained Pd(II)-AAP- [email protected] SPE method could be combined with inductively coupled plasma optical emission spectroscopy (ICP-OES) for determination of Pd(II) in environmental water. The recoveries were in the range of 87.2%–91.6% with the relative standard deviations of 2.5%–6.8%.

Graphene oxide modified H4L‐ion imprinting electrochemical sensor for the detection of uranyl ions

AbstractThe rapid development of the nuclear industry has gradually aroused people′s attention to the problem of nuclear pollution. Due to the biological toxicity of uranium and its aqueous solution, simple and rapid detection of uranium in the water environment is quite important. An ion imprinted carbon nanomaterial (graphene oxide) electrochemical sensor for the detection of trace uranyl ions was prepared by using the synthesized bipolar tetradentate macrocyclic uranyl ligand cyclo‐bis‐phenylenediamine‐bis‐(phenylmethyl‐diphyrrolecarbaldehyde) (H4L) as functional monomer. The sol‐gel polymer was prepared by hydrolysis and polymerization of H4L ligand, 3‐aminopropyltrimethoxysilane and tetraethoxysilane. H4L‐ion imprinted polymer (U‐IIP) was prepared by adding 1 mM uranyl ion as template ions. Then the polymer was bonded to graphene oxide modified carbon paste electrode, and the template ions were eluted to obtain H4L‐ion imprinted‐graphene oxide modified carbon paste electrode (U‐IIP/GO/CPE). Differential pulse voltammetry was used to detect trace uranyl ions. The results showed that the U‐IIP/GO/CPE sensor system can detect uranyl ions with high sensitivity and specificity, and the peak current appeared around −0.26v. In the range of 0.01 μM∼3.0 μM, the detection current had a good linear relationship with the molar concentration of uranyl ions, and the method detection limit was 1.32 nM (S/N=3). Through the detection of actual samples, it had a good acceptable recovery rate (95.45 %∼106.25 %), and the relative standard deviation was less than 3.25 %.

Copper(I) Alkynyl Clusters with Crystallization-Induced Emission Enhancement.

Four copper(I) alkynyl complexes incorporating phosphate ligands, namely, [Cu16(tBuC≡C)12(PhOPO3)2]n (1; PhOPO3 = phenyl phosphate), [Cu16(tBuC≡C)12(1-NaphOPO3)2]n (2; 1-NaphOPO3 = 1-naphthyl phosphate), [VO4@Cu25(tBuC≡C)19(1-NaphOPO3)](PF6)0.5(F)0.5 (3), and [PO4@Cu25(tBuC≡C)19(1-NaphOPO3)](PF6)0.5(F)0.5 (4), were solvothermally synthesized and well-characterized by IR spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. Single-crystal X-ray analysis revealed that the Cu16 cluster-based coordination chain polymers 1 and 2 are formed by assembly during crystallization, while 3 and 4 contain high-nuclearity copper(I) composite clusters enclosing orthovanadate and phosphate template ions, respectively, that are supported by ROPO32- ligands. Complexes 1-4 exhibit crystallization-induced emission enhancement. Their crystalline state shows strong luminescence, in striking contrast to the weak emission of the amorphous state and solution phase. A detailed investigation of the crystal structure suggests that well-arranged C-H···π and π···π interactions between the ligands are the major factors for this enhanced emission. Clusters 3 and 4 also exhibit photocurrent responses upon visible-light illumination.

Synthesis of Copper and Lead Ion Imprinted Polymer Submicron Spheres to Remove Cu2+ and Pb2+

In this paper, Methacrylic acid (MAA) and 4-vinyl pyridine (4-VP) as functional monomers, Ethylene glycol two methyl acrylate (EGDMA) as crosslinking agent, isopropyl alcohol as the solvent, prepared the Cu(II)- and Pb(II)- imprinted polymers (IIPs) submicron spheres by precipitation polymerization. The presence/absence of the template ion in the preparation of the imprinted polymer was confirmed by EDX spectroscopy, and the structure of the particles was investigated using IR, SEM and BET analysis. From different components of crosslinker/monomer (C/M) ratio analysis, C/M at 1:3 was the optimal ratio for preparing IIPs. Atomic absorption spectroscopy (AAS) was characterized the imprinted polymers absorption behavior. The results show that the maximum adsorption capacity of Cu2+ and Pb2+ -imprinted polymer were 26.9 mg g−1 and 25.3 mg g−1, respectively. They also have good adsorption capacity and superior selectivity property for Cu2+ and Pb2+ in water, respectively. The selectivity factors (α) for Ni2+, Zn2+, Co2+ and Fe2+ were 16.5 (Cu2+) and 12.1 (Pb2+), 13.8 (Cu2+) and 16.2 (Pb2+), 10.8 (Cu2+) and 10.1 (Pb2+), 20.4 (Cu2+) and 20.7 (Pb2+), respectively. The regeneration experiment result demonstrates an excellent re-utilization property of these two type IIPs, after ten uses, the adsorption capacity can maintain above 60%.

Microstructure of mayenite 12CaO·7Al2O3 and electron emission characteristics

AbstractElectron emission characteristic, electrical conductivity of polycrystalline mayenite (12CaO·7Al2O3) electride, formation of [Ca24Al28O64]4+(e−)4 framework as a function of phase content, and microstructure have been investigated. The mayenite microstructure was investigated using high‐resolution transmission microscopy which revealed the type cage structure of 12CaO·7Al2O3 partially filled by extra‐framework oxygen ions. Incorporation of electrons by means of carbon ion template 12CaO·7Al2O3 produces complex structure, and an incomplete ion template 12CaO·7Al2O3 structure consisting of mixture of a [Ca24Al28O64]4+(e−)4 and [Ca24Al28O64]4+(O2−)2 framework had a direct effect on the electron emission. Surface chemistry and stability of the 12CaO·7Al2O3 electride have been studied using x‐ray photoelectron spectroscopy. The work function of phase pure 12CaO·7Al2O3 electride was determined from direct thermionic emission data and compared to the measurement from ultraviolet photoelectron spectroscopy (UPS). Depending on the extent of ion template of 12CaO·7Al2O3 structure, a work function of 0.9–1.2 eV and 2.1–2.4 eV has been measured and thermionic emission initiating at 600°C.

Microwave-assisted synthesis of magnetic Pb(II)-imprinted-poly(schiff base-co-MAA) for selective recognition and extraction of Pb(II) from industrial wastewater

Microwave-assisted magnetic Pb(II)-imprinted-poly(schiff base-co-Methacrylic acid) (MA/Fe3O4@Pb(II)-IIP) was prepared by inverse emulsion-suspension polymerization using lead ion as template ion, methacrylic acid and salicylaldehyde schiff base as bifunctional monomers, ethylene glycol dimethacrylate and azodiisobutyronitrile as cross linker and initiator, respectively. The influence of various single factor on the adsorption effect was analyzed. MA/Fe3O4@Pb(II)-IIP had the best adsorption capacity at 60 mg·L−1, pH 6, 303 K and 60 min, and the maximum value was 107.75 mg·g−1. The adsorption mechanism of MA/Fe3O4@Pb(II)-IIP was evaluated by kinetic model and adsorption isotherm. The experimental process could be better fitted by pseudo-second-order kinetics, intra-particle diffusion model and Langmuir adsorption isotherm. Under the optimum SPE conditions of pH 6, 10 ug·L−1 Pb(II) solution and 5 mL, 0.5 M eluent, the extraction rates of MA/Fe3O4@Pb(II)-IIP for Pb2+, Cu2+, Cd2+ and Zn2+ were 92.32%, 41.86%, 31.39% and 30.57%, respectively, indicating that it had good reusability and specific recognition. The regeneration and reuse studies revealed that the MA/Fe3O4@Pb(II)-IIP showed no significant decrease in 5 cycles. All these adsorption performance suggested that the proposed polymer had specific recognition ability, high selectivity and high stability. It can be a promising candidate for selective recognition of lead(II) in industrial wastewater.

Synthesis, characterization and analytical applications of Ni(II) ion-imprinted polymer prepared by N-(2-hydroxyphenyl)acrylamide

In the present study, a novel Ni(II) ion-imprinted polymer (Ni(II)-IIP) was successfully synthesized by copolymerization of N-(2-hydroxyphenyl)acrylamide as a functional monomer, 2,2′-Azobis(2-methylpropionitrile) (AIBN) as an initiator and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in the attendance of nickel nitrate as a template ion. The nickel ions in the Ni(II)-IIP were eliminated by ethylenediaminetetraacetic acid (EDTA) leaching. The functional monomer, complex and the obtained polymer particles were characterized by 1H NMR, FT-IR, CHNS, FESEM and the concentration of Ni(II) ions in the solution were determined by flame atomic absorption spectrophotometer (FAAS). The effects of pH, flow rate, temperature, sample concentration, sorbent particle size, desorption eluent conditions, selectivity and reusability on the extraction of Ni(II) ions were surveyed. The results of the study revealed that most favorable pH value for quantitative enrichment was 7 and maximum adsorption capacities of Ni(II) ions on the IIP was 38 mg/g. In addition, the relative standard deviation (RSD) for six separately experiments with a nickel concentration of 20.0 μg/L was 2.72% and limit of detection was found to be 0.7 μg/L.

Effect of ethylene diamine tetra‐acetic acid and functional monomers on the structure and adsorption properties of copper (II) ion‐imprinted polymers

Novel copper (II) ion‐imprinted polymers (Cu‐IIPs) were synthesized by bulk polymerization using 1 mmol of copper (II) sulfate pentahydrate as the template ion, 1 mmol of ethylenediaminetetraacetic acid (EDTA) as the ligand, and 4 mmol of 4‐vinyl pyridine (4‐VP) or methacrylic acid (MAA) as the functional monomer dissolved in a porogen of 20 mL of methanol. Polymerization was performed with 20 mmol of pentaerythritol triacrylate (PETA) as the crosslinker and 1 mmol of benzoyl peroxide as the initiator. The effect of pH, time, initial concentration of Cu2+, and selectivity tests on the adsorption capacity were investigated using flame atomic absorption spectroscopy (FAAS). The prepared polymers were characterized by Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM) and X‐ray diffraction (XRD). Adsorption capacity of Cu‐IIPs prepared with MAA increased from 0.794 to 2.163 mg g−1 at pH 6 within 24 hours, while Cu‐IIPs from MAA had high recognition ability with better recognition of Cu2+ than other ions. Thus, these Cu‐IIPs demonstrated potential application as an adsorbent for efficient removal of Cu2+ from aqueous solutions.

СИНТЕЗ МОЛЕКУЛЯРНО-ИМПРИНТИРОВАННЫХ ПОЛИМЕРОВКОМПЛЕМЕНТАРНЫХ К ИОНАМ ЛАНТАНА И СКАНДИЯ

The effect of the solvent/monomer (S/M) ratio on the structure and adsorption properties of microporous polymer particles imprinted with lanthanum and scandium ions is studied. Microporous particles imprinted with lanthanum and scandium ions were obtained from two functional monomers-methacrylic acid (MAC) and vinylpyridine (4-VP) - by forming a complex with the template ion of lanthanum and scandium by ion interactions. The selfassembled lanthanum/monomer complex was polymerized in the presence of an ethylene glycol dimethacrylate (EGDMA) crosslayer by suspension polymerization. The chemical structure, morphology, and adsorption capacity of microporous particles imprinted with lanthanum and scandium ions were analyzed by infrared spectroscopy. Molecular polymers showed high selectivity with respect to lanthanum and scandium ions.

Study on the Preparation and Application of Chitosan/Silica Cu(II) Imprinted Microspheres

Molecularly imprinted polymers are functional polymers for selective recognition of imprinted molecules, which may have a wide range of applications in separation and purification, environmental monitoring, etc. Chitosan has excellent chelation for metal ions, being widely used in food, environmental protection, etc. In this paper, chitosan/silica Cu(II) imprinted microspheres were prepared by using natural product chitosan as functional monomer, silane-doped, Cu(II) as template ion and glutaraldehyde as crosslinking agent. The adsorption properties of the chitosan/silica Cu(II) imprinted microspheres for Cu( II) were studied by flame atomic absorption spectrometry. The experimental results showed that the adsorbability of Cu(II) on the chitosan/silica Cu(II) imprinted microspheres was better than that of chitosan/silica non imprinted microspheres. The results of orthogonal test showed that the order of influence on the adsorption capacity of the chitosan/silica Cu(II) imprinted microspheres was chitosan, glutaraldehyde, Cu(II) and silane. Under the optimum conditions, the adsorption capacity of the chitosan/silica Cu(II) imprinted microspheres for Cu(II) could reach 33.38mg/g. Scanning electron microscopy showed that the diameter of the chitosan/silica Cu(II) imprinted microspheres was lower than 3 urn. Chitosan/silica Cu(II) imprinted microspheres were obviously harder than chitosan Cu(II) imprinted microspheres.

Preparation of Porous Mo(VI)-Imprinted Algae for Recognizing Molybdenum(VI)

ABSTRACT In this article, a novel Mo(VI)-imprinted adsorbent based on brown algae (Mo-PVA-SA-I) was synthesized through an ion-imprinting technique in combination with surface imprinting and polymer crosslinking. As the template ion, H3Mo7O24 3 – also acts as the cross-linker to effectively decrease the space and distance between the molecular chains and make the algae form a uniform size of porous structure, it can be used to construct Mo(VI)-matching specific “cavities” after being eluted. Results indicated that the Mo(VI)-imprinted algae have a poor adsorption capacity for its coexisting ions, such as rhenium, copper, iron, zinc, and manganese metal ions at pH 3, while it exhibits apparently higher selective recognition ability for Mo(VI) than the non-imprinted absorbent (Mo-PVA-SA-N). In addition, the prepared Mo(VI)-imprinting algae was equipped with a high adsorption capacity of 114.40 mg·g–1 for Mo(VI). The excellent adsorption performance of this novel Mo-PVA-SA-I adsorbent has been proven to be due to electrostatic attraction between the C = N+–H imine groups and H3Mo7O24 3 – in the “cavities” by both FT-IR and XPS analysis. As a result, this novel and environment-friendly Mo(VI)-imprinted algae will be a promising candidate for recovering Mo(VI) from industrial wastewater.

Synthesis and optimization selective ion-imprinted polymer for the elimination of Ca II ions using Taguchi design

One of the most important problems associated with calcium measurement is the possibility of underdiagnosed due to a false prediction of hypercalcemia results. Ion imprinting has become one of the fast growing technologies that have gained a lot of attention recently especially in the area of materials science. The present work proposes the synthesis and characterization of ion-imprinted polymer (IIP) in the form of porous film for the removal of Ca (II) from aqueous solution and human blood serum. Ca (II)-IIP films are prepared from mixing of two naturally formed biopolymers cellulose and sodium alginate, CaCl2, ECH, EDTA are used as the source of template ions, cross-linker and extraction agent, respectively. Taguchi method is used to optimize the synthesis and adsorption parameters of the new developed IIP. The optimum IIP films are characterized using FTIR, TGA, FESEM and XRD for determining the performance of the imprinting process achieved. PH dosage, initial concentration, reusability, selectivity, isotherm and kinetic study are investigated for the optimized IIP in Ca (II) aqueous solution. The resulted optimum conditions are pH 5.9, initial concentration (50 mg/l), dosage (300 mg) and 90 min contact time. It was clear from the adsorption data that the Ca (II) sorption by Ca (II)-IIP was fitted with the Langmuir isotherm model. The Langmuir adsorption constants for the adsorption of Ca (II) at room temperature are calculated to be (0.017 L/mg) and the R is 0.9469. The rate of removal of Ca (II) by Ca (II)-IIP is sustained between 98.99 and 86.12% for five periods. Furthermore, findings show that the Ca (II)-IIP is can successfully applied for the removal of free Ca (II) ions in human blood serum.

Construction of a novel ion imprinted film to remove low concentration Cu2+ from aqueous solution

To develop a green approach to ion capturing and separation, an electrochemically assisted imprinting and elution strategy was proposed. Novel ion imprinted film (Cu2+-IIF) was synthesized by combining ion imprinting technology with electrochemically switched ion exchange technology for removal of low concentration Cu2+ from aqueous solution. Cu2+-IIF was prepared by using Cu2+ as template ion, potassium ferrocyanide as doping agent, pyrrole as cross-linker and conductor. To enhance the ability to remove Cu2+ at low concentration, adsorption and reduction were integrated. The morphologies and microstructures of samples were characterized by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transformation infrared spectrometry and X-ray photoelectron spectroscopy. The removal ability and selectivity of Cu2+ were tested. The results show that more than 90% of Cu2+ at the concentration of 5 ppm was removed, thus meeting the requirement for direct emission. The adsorption capacity reaches 7.57 mg g−1 at initial Cu2+ concentration of 5 ppm. The selectivity factor of Cu2+ with respect to Cd2+, Zn2+ and Ni2+ was 49.27, 26.52 and 30.16, respectively. The removal capacity of Cu2+-IIF remained 95.13% after five cycles.

Self-assembly of a layered two-dimensional molecularly woven fabric.

Fabrics-materials consisting of layers of woven fibres-are some of the most important materials in everyday life1. Previous nanoscale weaves2-16 include isotropic crystalline covalent organic frameworks12-14 that feature rigid helical strands interlaced in all three dimensions, rather than the two-dimensional17,18 layers of flexible woven strands that give conventional textiles their characteristic flexibility, thinness, anisotropic strength and porosity. A supramolecular two-dimensional kagome weave15 and a single-layer, surface-supported, interwoven two-dimensional polymer16 have also been reported. The direct, bottom-up assembly of molecular building blocks into linear organic polymer chains woven in two dimensions has been proposed on a number of occasions19-23, but has not previously been achieved. Here we demonstrate that by using an anion and metal ion template, woven molecular 'tiles' can be tessellated into a material consisting of alternating aliphatic and aromatic segmented polymer strands, interwoven within discrete layers. Connections between slowly precipitating pre-woven grids, followed by the removal of the ion template, result in a wholly organic molecular material that forms as stacks and clusters of thin sheets-each sheet up to hundreds of micrometres long and wide but only about four nanometres thick-in which warp and weft single-chain polymer strands remain associated through periodic mechanical entanglements within each sheet. Atomic force microscopy and scanning electron microscopy show clusters and, occasionally, isolated individual sheets that, following demetallation, have slid apart from others with which they were stacked during the tessellation and polymerization process. The layered two-dimensional molecularly woven material has long-range order, is birefringent, is twice as stiff as the constituent linear polymer, and delaminates and tears along well-defined lines in the manner of a macroscopic textile. When incorporated into a polymer-supported membrane, it acts as a net, slowing the passage of large ions while letting smaller ions through.

Selective adsorption behavior of Cd2+ imprinted acrylamide-crosslinked-poly(alginic acid) magnetic polymers: fabrication, characterization, adsorption performance and mechanism.

Poly(acrylamide) grafted and glutaraldehyde-crosslinked alginic acid nano-magnetic adsorbent (AAMA) was prepared by selecting Cd2+ as a template ion. Scanning electron microscope (SEM), thermo-gravimetric analyzer (TGA), vibrating sample magnetometer (VSM) and infrared spectroscopy (IR) were used to characterize the morphology and structure of AAMA. The adsorption of AAMA for different metal ions was compared and the impact of various factors for adsorption of Cd2+ was systematically investigated. These results suggested that the AAMA was the aggregates of Fe3O4 nanoparticles with a diameter of about 50-100 nm and had selectivity for Cd2+ adsorption. The maximum adsorption capacity for Cd2+ is 175 mg/g at pH 5.0 and 303 K. The experimental data were well described by the Langmuir isotherm model and pseudo-second-order model. The parameters of adsorption thermodynamics concluded that the adsorption progress is spontaneous and endothermic in nature. The parameters of adsorption activation energy suggested that there is physical adsorption and chemisorption on the adsorption of metal ions. AAMA could be regenerated by EDTA and still keep 71% adsorption capacity in the fifth consecutive adsorption-regeneration cycle. Therefore, AAMA would be useful as a selective and high adsorption capacity nano-magnetic adsorbent in the removal of Cd2+ from wastewater.

Chitosan-based ion-imprinted polymer for selective extraction of Zn(II) in aqueous samples

ABSTRACT In this study, a new strategy for novel chitosan-based ion-imprinted polymer (IIP) preparation was adopted for selective separation and recovery of Zn(II) ions from aqueous environmental samples using batch extraction experiments. The Zn(II) ion-imprinted polymer was prepared by precipitation copolymerisation of methacrylamide and 2,2- azobisisobutyronitrile along with Zn(II) ions and toluene as a functional complexing monomer, initiator, template ion, and porogenic solvent, respectively, in the presence of chitosan. The ethylene glycol dimethacrylate and tetraethyl orthosilicate were used as cross-linking agents. The prepared Zn(II) ion-imprinted polymer was characterised by Fourier transform infrared spectroscopy, field emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and inductively coupled plasma-optical emission spectroscopy to determine the structural and functional IIP variations before and after Zn(II) adsorption. Characterisation results suggested the formation of Zn(II) ion-imprinted polymer with excellent thermal stability and also have the potential for selective Zn(II) extraction. Further, the Zn(II) sorption using IIP sorbent was also evaluated as a function of pH, IIP sorbent dosages, Zn(II) ion concentration, sorption time, and IIP sorbent reusability. The Zn(II) sorption equilibrium was studied using various isotherm and kinetic models, and the result suggested that the Langmuir and pseudo-second-order model as the best to explain the sorption process. Sorption capacity was calculated using Langmuir isotherm linear equation and its value was found to be 3.06 mg/g. The method detection limit (MDL) and limit of quantification (LOQ) of sorbent were calculated as 0.1 and 0.3 mg/L, respectively. Finally, the developed sorbent Zn(II) IIP was found to be effective in the selective extraction of Zn(II) from the tap and river water samples.

Novel electrochemical sensing platform based on ion imprinted polymer with nanoporous gold for ultrasensitive and selective determination of As3+

An electrochemical sensor has beendeveloped based on ion imprinted polymer (IIP) and nanoporous gold (NPG) modified gold electrode (IIP/NPG/GE) for determination of arsenic ion (As3+) in different kinds ofwater. NPG with high conductivity, large specific surface area, and high biocompatibility was prepared by a green electrodeposition method. Then a layer of IIP was synthesized in situ on NPG surface by electropolymerization, in which As3+ was used as template ion and o-phenylenediamine as functional monomer. We used potassium ferricyanide and potassium ferrocyanide chelates as electrochemical probes to generate signals. The electrochemical behavior of IIP/NPG/GE (vs. Ag/AgCl) was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The linear range forAs3+ was 2.0 × 10-11 to 9.0 × 10-9M, and the lower detection limit was 7.1 × 10-12M (S/N = 3). This newly developed sensor has good stability and selectivity, and has been successfully applied to the As3+ determinationof four kinds of water quality.

Study on Synthesis and Adsorption Properties of ReO4 - Ion-Imprinted Polymer.

In this work, an ion imprinted polymer (ReO4–-IIP) of the perrhenate ion based on acrylamide (AM) and acrylic acid (AA) was prepared by solution polymerization using ReO4– as a template ion, N,N-methylenebisacrylamide (NMBA) as cross-linkers, hydrogen peroxide-vitamin C (H2O2-Vc) as an initiator, and a mixed solution of water (H2O) and methanol (CH3OH) with volume ratio v(H2O)/v(CH3OH) = 3:7 as a solvent. During the process of synthesis condition investigation and optimization, the adsorption capacity (Q) and the separation degree (R) in the equimolar concentration mixture solutions of NH4ReO4 and KMnO4 were adopted as indexes, and the obtained optimal conditions were as follows: the molar ratios of NMBA, NH4ReO4, AA, H2O2, and Vc to AM were 5.73, 0.052, 1.29, 0.02, and 0.003, and the temperature and time of polymerization were 40 °C and 28 h, respectively. Under optimal conditions, the sample with indexes, Q and R of 0.064 mmol/g and 3.20, were harvested. What is more, a further reusability study found that good adsorption selectivity was maintained after repeating the experiment 9 times. Taking the non-IP prepared under the same conditions as a control, Fourier transform infrared spectroscopy, transmission electron microscopy, and Brunauer Emmett Teller were used to characterize the structure of the ReO4–-IIP prepared under the optimal conditions. Finally, the kinetic study results showed that the zero-order kinetic model could better describe the adsorption process. The thermodynamic study results showed that the Langmuir model was more suitable for describing the isotherm adsorption process of the IIP.

Extraction of lithium ions from acidic solution using electrochemically imprinted membrane

A novel lithium ion imprinted membrane (Li+-IIM) was synthesized by unipolar pulsed electropolymerization, using lithium ion as template ion, 2-hydroxymethyl-12-crown-4 ether as capture agent, pyrrole as conductive agent and crosslinking agent. The morphology and structure of the products were characterized by using field emission scanning electron microscopy and Fourier transformation infrared spectroscopy. The adsorption behaviors were detected by inductively coupled plasma-optical emission spectrometry. At pH = 1.0, the maximum adsorption capacity of Li+-IIM towards lithium ion reached 16.40 mg g−1 in 40 mg L−1 Li+ solution, within 80 min. The resulting Li+-IIM exhibited excellent selectivity for Li+ because the selectivity coefficients of Li+ with respect to Na+, K+, Mg2+, Al3+ and Fe3+ are 4.20, 4.11, 4.13, 4.30 and 4.28, respectively. After five adsorption-desorption cycles, the adsorption capacity of Li+-IIM still maintained 95.88%, indicating that the obtained imprinted membrane has excellent regeneration ability.

Propene production at low temperature by bimetallic Ni-Mo and Ni-Re catalysts on mesoporous MCM-41 prepared using template ion exchange

In this work the direct conversion of ethene to propene was carried out using bimetallic Ni-Mo and Ni-Re over MCM-41 and aluminized MCM-41. It was intended to improve typical Ni based catalysts by including a metathesis active metal. All catalysts were characterized by powder-XRD, N2-physisorption, H2-TPR and TEM. Ni-Mo catalysts revealed the formation of bulk mixed molybdenum-nickel-aluminosilicates on the MCM-41 materials. The contrary case was revealed for the Ni-Re catalysts where a weak interaction between Ni, Re and MCM-41 was observed. All materials were catalytically tested in the gas phase reaction of directly converting ethene into propene using a fixed bed reactor. These results revealed no improvement of the catalytic activity when using Ni-Mo catalyst compared to well known Ni on MCM-41 catalysts. This suggests that Mo is not offering active metathesis sites. In contrast, Ni-Re based catalysts revealed a high selectivity of propene at lower temperatures than the Ni-catalysts. However, the conversion of ethene decreased significantly. Nevertheless, the reduced temperature might avoid the trend of catalyst deactivation observed at high temperature. Still, a deeper characterization of the Ni-Re catalyst is required to understand the role of Re in the direct conversion of ethene to propene.