Ion-imprinted Membrane Research Articles

Efficiently selective adsorption Rb(I) based on ion-imprinted membrane chromatography: Batch adsorption and dynamic filtration

The development of efficient separation and enrichment methods for rare and precious metal rubidium (Rb) has attracted more and more attention the hydrometallurgy. Here, based on the phenolic hydroxyl-rich copolymer poly(styrene-co-4-hydroxylstyrene) (P(S-co-VPh)), the Rb+ imprinting nanofiber membrane (P(S-co-VPh)-(IIP)) was prepared using electrostatic spinning. NMR, FTIR, XPS, FESEM and EDS were used to comprehensively characterize the composition and structure of the copolymer and nanofiber membranes. Batch adsorption results indicated that the optimal adsorption conditions were pH = 9 at room temperature, and the process of Rb+ adsorption was spontaneous exothermic reaction. Ion imprinting technology not only enhanced adsorption capacity and recycling performance of the P(S-co-VPh20)-(IIP) membrane, but more importantly, significantly improved its selectivity, so that the selectivity coefficient (β) of Rb+/Mn+ for the interfering ions Na+, Mg2+, Ca2+, and K+ were 1438.17, 864.38, 434.6, and 307.25, respectively. The adsorption kinetics fitted well to the pseudo-second-order rate expression, and the maximum theoretical adsorption capacity (qm) could reach 140.00 mg/g from the Langmuir model fitting. The dynamic filtration experiment of the stacked membranes chromatography indicated that the breakthrough times were significantly affected by the different operation conditions (Flow rate, initial Rb+ concentration and membrane dosage). Among the four typical models of Thomas, Yoon-Nelson, EXY and BJP, the breakthrough curves can be well described by the EXY model.

A DFT-designed neodymium ion-imprinted membrane with fouling resistance and high flux

The rare earth metal neodymium (Nd) is widely used in advanced industries such as hybrid cars and aerospace. Therefore, recovering neodymium from wastewater presents valuable opportunities for secondary recycling. The recovery of Nd3+ from wastewater using ion imprinting technology (IIT) for efficient selective separation holds significant importance. In this study, hydrophilic Nd(III) ion-imprinted membranes, termed Nd(III)–P/P/TIIM, were synthesized using the IIT technique. Nd(III)–P/P/TIIM exhibited efficient and selective separation capabilities for Nd3+ with a remarkable retention rate of 95.68 % and a high water flux reaching up to 636.94 L·m−2·h−1. Additionally, its relative selectivity coefficients for interfering ions (KLa, KEu, KCu) were 3.9, 29.5, and 37.9, respectively. Various analyses, including DFT calculations, HOMO and LUMO calculations, MEP images, and XPS spectroscopy, confirm that the mechanism of selective retention of Nd3+ by Nd(III)–P/P/TIIM in solution is due to Coulombic adsorption between the –COO− anion and Nd3+ as well as an imprint memory effect. Even after undergoing three water-BSA cycles, the membrane maintained a water flux of 357.96 L·m−2·h−1. The antifouling principle of Nd(III)–P/P/TIIM was investigated by XDLVO theory, attributed to the increase of electron donor tension (γ−) and Lewis acid-base interactions (ΔGAB) at the membrane surface. This work provides an insightful guidance for engineering high-performance membranes and has the potential to provide an alternative method for recycling neodymium.

A acylthiourea based ion-imprinted membrane for selective removal of Ag+ from aqueous solution

The efficient removal of Ag+ ions from wastewater not only preserves the environment but also promotes the reutilization of silver metal. Therefore, in this study, we have developed an advanced ion imprinted membrane (IIM) and employed it as an adsorbent for the efficient removal of Ag+ ions from aqueous solution. The dynamic adsorption results demonstrated that the prepared IIM exhibited superior filtration and separation performance when applied to feed solutions with lower concentrations (12 mg/L) and higher pH levels (pH=6). The presence of co-existing metal ions in the feed solution had negligible impact on the separation efficiency of IIM towards Ag+ ions, highlighting its exceptional recognition ability and selective separation capability. The results from static adsorption experiments indicated that the adsorption of Ag+ ions onto the membrane surface conformed to both Langmuir model and the pseudo-second-order model, indicating that the adsorption process was a monolayer chemisorption. Reusability findings revealed a slight decline in uptake capacity and water flux of IIM after five desorption-adsorption cycles, showcasing its potential application value in Ag+ ions removal. The EDS, FTIR and XPS results substantiated that Ag+ ions were adsorbed onto the IIM surface through the chemical reactions between Ag+ ions and CS and CO groups.

Magnetic ion-imprinted polyacrylonitrile-chitosan electro-spun nanofibrous membrane as recyclable adsorbent with selective heavy metal removal and antibacterial fouling in water treatment

Water pollution has become one of the most concerned environmental issues on the worldwide scale. Due to the harmfulness of the heavy metal ions and microorganisms in wastewater, novel filtration membranes for water treatment are expected to simultaneously clear these pollutants. Herein, the electro-spun polyacrylonitrile (PAN) based magnetic ion-imprinted membrane (MIIM) were fabricated to achieve both selective removal of Pb(II) ions and excellent antibacterial efficiency. The competitive removal experiments showed that the MIIM displayed efficiently selective removal of Pb(II) (45.4 mg·g−1). Pseudo-second-order mode and Langmuir isotherm equation is well matched with the equilibrium adsorption. The MIIM showed sustained removal performance (~79.0 %) against Pb(II) ions after 7 adsorption-desorption cycles with negligible Fe ions loss of 7.3 %. Moreover, the MIIM exhibited excellent antibacterial properties that >90 % of E. coli and S. aureus were killed by the MIIM. In conclusion, the MIIM provides a novel technological platform for integration of multi-function with selective metal ions removal, excellent cycling reusability, and enhanced antibacterial fouling property, which can be potentially utilized as a promising adsorbent in actual treatment of polluted water.

Highly efficient separation and enrichment of hafnium from zirconium oxychloride solutions by advanced ion-imprinted membrane separation technology

Hafnium (Hf) is an important strategic material for the semiconductor, aerospace and nuclear industries. In this paper, an advanced ion-imprinted membranes (IIMs) separation system was prepared for the first time to achieve efficient separation and enrichment of Hf ions from zirconium oxychloride solutions. IIMs were constructed by a keyhole complex imprinting method with N, N-di-2-ethylhexyl diglycolamic acid (D2EHDGAA) as the carrier molecule, cellulose triacetate (CTA) as the base polymer and Hf ions as the template ion. In addition, amide acid driven IIMs were coupled with aspartic acid in the feed phase, which changes from preferential extraction of Zr to preferential extraction of Hf. To characterize it, we used Fourier transform infrared (FT-IR) spectroscopy and scanning election microscopy (SEM). The results showed that IIMs can increase CHf/CZr from 2.33:100 to 33.33:100 within 1 h compared with polymer inclusion membranes (PIMs) and ionic liquid supported liquid membranes (SLMs), which increased by 3.33 and 3.67 times. The selectivity and enrichment performance for the enrichment of Hf ions from Zr solution were significantly improved due to the high recognition selectivity of ion imprinting. Therefore, IIMs, as an advanced membrane separation system, may have good potential for industrial application in the field of efficient separation and enrichment of Hf ions.

A novel lithium ion-imprinted membrane with robust adsorption capacity and anti-fouling property based on the uniform multilayered interlayer

Effective modification strategies contribute to high adsorption capacity, separation efficiency and anti-fouling properties of ion-imprinted membranes. The design of a homogeneous and hydrophilic interlayer between the substrate membrane and ion-imprinted layer is crucial factor for the excellent performance of ion-imprinted membranes. In this study, a novel multilayered interlayer (SiO2@SP-PDA) was developed and uniformly coated on the substrate surface (PVDF membrane). The polydopamine (PDA) prepared via oxidation of sodium periodate (SP-PDA) increases the uniformity of SiO2@SP-PDA modification, which reduces the agglomeration of the ion-imprinted layer, and thereby boosts the adsorption capacity to 231.77 mg·g−1. The prepared ion-imprinted membrane (SiO2@SP-PDA-IIM) exhibits a favorable anti-fouling property due to the incremental hydrophilicity and the presence of SiO2 nano interlayer. Based on the XDLVO theory, it can be deduced that the SiO2 modification increases the membrane surface electron donor tension (γ−), which plays an essential role in enhancing the anti-fouling property of SiO2@SP-PDA-IIM. In this paper, the design of multilayered structure is of great significance to make the ion-imprinted membrane be a potential candidate for Li+ efficient separation in natural water.

An effective lithium ion-imprinted membrane containing 12-crown ether-4 for selective recovery of lithium

The high lithium content in spent lithium ion batteries (LIBs) and a large number of spent LIBs generation shift the target of lithium recovery to solid waste. Adsorption separation is of great application value for lithium recovery. There is still a lack of a lithium adsorption material with excellent properties. Herein, an environmental hydrolytic polymerization to prepare lithium ion-imprinted membranes (LIIMs) with high adsorption capacity and selectivity is presented. The LIIMs can reach adsorption equilibrium in 40 min, showing fast adsorption kinetics. The optimal adsorption capacity of the LIIMs for Li+ was 132.00 mg g−1 after immersing in a 300 mg L−1 LiCl solution based on ample binding sites and a strong affinity force. Langmuir isothermal adsorption results proved that the imprinting sites on LIIMs were homogeneous. The selective separation factors (α) of Li+ to Mg2+, K+, Ca2+, Na+ were 6.80, 17.00, 21.30, and 24.60, respectively, which implies the superior selectivity LIIMs toward Li+. The adsorption capacity of LIIMs remained about 97 % after six cycles. Due to the suitable cavity, abundant rebinding sites, and strong affinity, the LIIMs have a good selective adsorption ability to Li+. Therefore, the LIIMs would have potential applications for separating Li+ from spent LIBs.

A Novel Electrochemical Sensor Modified with a Computer-Simulative Magnetic Ion-Imprinted Membrane for Identification of Uranyl Ion.

In this paper, a novel ion-imprinted electrochemical sensor modified with magnetic nanomaterial Fe3O4@SiO2 was established for the high sensitivity and selectivity determination of UO22+ in the environment. Density functional theory (DFT) was employed to investigate the interaction between templates and binding ligands to screen out suitable functional binding ligand for the reasonable design of the ion imprinted sensors. The MIIP/MCPE (magnetic ion imprinted membrane/magnetic carbon paste electrode) modified with Fe3O4@SiO2 exhibited a strong response current and high sensitivity toward uranyl ion comparison with the bare carbon paste electrodes. Meanwhile, the MCPE was fabricated simultaneously under the action of strong magnetic adsorption, and the ion imprinted membrane can be adsorbed stably on the electrode surface, handling the problem that the imprinted membrane was easy to fall off during the process of experimental determination and elution. Based on the uranyl ion imprinting network, differential pulse voltammetry (DPV) was adopted for the detection technology to realize the electrochemical reduction of uranyl ions, which improved the selectivity of the sensor. Thereafter, uranyl ions were detected in the linear concentration range of 1.0 × 10−9 mol L−1 to 2.0 × 10−7 mol L−1, with the detection and quantification limit of 1.08 × 10−9 and 3.23 × 10−10 mol L−1, respectively. In addition, the sensor was successfully demonstrated for the determination of uranyl ions in uranium tailings soil samples and water samples with a recovery of 95% to 104%.

Efficiently selective removal of Pb(II) by magnetic ion-imprinted membrane based on polyacrylonitrile electro-spun nanofibers

The development of membrane for heavy metal ion removal in water treatment is still impeded by low adsorption efficiency, poor selectivity, and deficient recyclability, which has gained great interests in both laboratorial research and industrial application. Herein, our aim is to fabricate the magnetic ion-imprinted PAN membranes (MII-PMs) based on polyacrylonitrile electro-spun nanofibers with improved adsorption ability, selectivity, and recyclability for efficient and selective removal of Pb(II) from water. The chemical structure and chemo-physical properties of the as prepared MII-PMs were characterized. Remarkably, in competitive adsorption experiment the MII-PMs demonstrated a much higher adsorption capacity towards Pb(II) than other interfering metal ions with the selective order of Pb2+>Cu2+>Mg2+>Co2+>Ni2+>Cd2+>Zn2+>Na+>K+. In investigation of the adsorption mechanism towards Pb(II), the equilibrium adsorption data of MII-PMs fitted better with Freundlich isotherm equation, and the kinetic parameters matched well with pseudo-second-order mode. In regeneration and reusability experiment, the MII-PMs could be regenerated with eluting solution and displayed good adsorption capacity towards Pb(II) during 6 adsorption–desorption cycles. Only small amount of Fe ions was leached out after the regeneration experiments. Generally, the as prepared magnetic ion-imprinted membrane with improved adsorption capability, high selectivity, and excellent reusability towards Pb(II) ions can be utilized as a promising and efficiently potential adsorbent in actual water treatment.

Preparation of a novel ion-imprinted membrane using sodium periodate-oxidized polydopamine as the interface adhesion layer for the direction separation of Li+ from spent lithium-ion battery leaching solution

In this paper, a novel ion-imprinted membrane (SP-IIM) was prepared by combining graft polymerization with chemical modification and from polydopamine (PDA) oxidized by sodium periodate (SP-PDA) as the interface adhesion layer. The PDA was oxidized by sodium periodate at pH 5.0, causing it to undergo extensive cross-linking within the adhesion layer to provide better chemical stability for improving the reusability of the membrane. The flaky microstructure of the SP-PDA provided more surface area for the loading of 12-Crown-4 (12C4). The optimal adsorption capacity of the SP-IIM for Li+ was 42.58 mg·g−1 after incubating the membrane in a 200 mg·L–1 solution of Li+ for 180 min. The kinetics and isotherm data of the adsorption of Li+ onto the SP-IIM were fitted to pseudo-second-order kinetics and Langmuir model, respectively. Through selective adsorption experiments, the optimal selective separation factors of Li+/Mn2+, Li+/Co2+, Li+/Ni2+ were 6.71, 5.84 and 3.03, respectively. Density functional theory (DFT) calculations were performed on the coordination of metal cations (Li+, Mn2+, Co2+, and Ni2+) by 12C4, the results of which showed that the weak binding of Li+ to 12C4, as well as the favorable dehydration of Li+, made it easier for Li+ to be coordinated by 12C4 in a multicomponent solution containing Li+, Mn2+, Co2+, and Ni2+. The oxidation of the PDA by sodium periodate caused significant intermolecular cross-linking within the SP-PDA layer to reduce the possibility of the ion-imprinted layer detaching from the membrane, thereby increasing the reusability of the SP-IIM. After five repeated adsorption–desorption cycles, the adsorption capacity of the SP-IIM only decreased by 4.6%, which indicated that the SP-IIM was highly reusable. This work improved the adsorption capacity and reusability of ion-imprinted membranes by changing the microstructure of the interface adhesion layer, which was of great significance to the further development of ion-imprinted membranes.

Insights into ion imprinted membrane with a delayed permeation mechanism for enhancing Cd2+ selective separation

Ion imprinted polymers exhibit great potential in ion separation from wastewater. However, the difficulty of ion separation by membrane is proverbial, which severely restricts the application of membrane in metal resource recovery from industrial wastewater. Herein, a rational molecular-level design approaches for membrane fabrication was developed to modify a layer of ion imprinted polymer onto the PVDF membrane. Batch rebind and permeation experiments suggest that specific host-guest binding sites had been fabricated along the membrane pore in ion imprinted membranes (IIM). A higher monomer dose leads to a higher rejection of Cd2+, and the more bind sites in IIM. The binding of IIM to Cd2+ was 1.84 times that of non-ion imprinted membranes (NIM). Permselectivity factors (γ) of IIM are larger than 5.39 in mixture ions solutions. Chemical characterization and density functional theory (DFT) calculation reveal that the Cd2+ recognition sites of functional groups are C−S and C˭S. Cd2+ mass transport in IIM suggest that the imprint effects provide a binding force that would delay Cd2+ to permeate through IIM, so as to selectively separate Cd2+ with other ions. The imprint effects may enlighten a novel molecular-level design approaches for membrane fabrication to enhance the selectivity of ion-ion.

Bio-inspired fabrication of Ester-functionalized imprinted composite membrane for rapid and high-efficient recovery of lithium ion from seawater

Lithium ion (Li+) is one of the important sustainable resource and it's urgently demanded to develop high-selectivity and high-efficient method to extract of Li+ from seawater. Hence, we propose the ester-functionalized ion-imprinted membrane (IIMs) with high selectivity and stability for the rebinding and separation of Li+ in aqueous medium via ion imprinted technology and membrane separation technology. In this work, the hydrophilic polydimethylsiloxane membranes (PDMS) are synthesized by self-polymerization of dopamine (DA) in aqueous solution, resulting in the fabrication of dense poly-dopamine (PDA) layer on the surface of PDMS (PDMS-PDA). In view of weak bonding forces (such as hydrogen bond, ionic bond and Van der Waals' force) between traditional imprinted polymer and ligand, the ester groups are formed between modified PDMS-PDA and ligand by surface grafting. The obtained Li+ imprinted membranes (Li-IIMs) have a suitable cavity and high adsorption capacity toward Li+ which reveal a high rebinding capacity (50.872 mg g−1) toward Li+ based on ample rebinding sites and strong affinity force. The superior relative selectivity coefficients (αNa/Li, αK/Li and αRb/Li are 1.71, 4.56 and 3.80, respectively) can be also achieved. The selectivity factors of Li-IIMs for Na+, K+ and Rb+ are estimated to be 2.52, 2.8 and 3.03 times larger than Li+ non-imprinted membranes (Li-NIMs), which imply the superior selectivity of Li-IIMs toward Li+. The regeneration ability of Li-IIMs is observed by systematic batch experiments. In summary, it can be concluded that the rebinding capacities of Li-IIMs is slightly decrease after eluting process, owing to the Li-IIMs with outstanding stability performance. Presentation of the method pave a fine prospect for coming true the long-term use of imprinted membrane.

A novel ion-imprinted membrane induced by amphiphilic block copolymer for selective separation of Pt(IV) from aqueous solutions

A novel ion-imprinted blend membrane was fabricated to separate selectively platinum(IV) from aqueous media. An amphiphilic copolymer poly(methyl methacrylate)-b-poly(4-vinylpyridine) (PMMA-b-P4VP) was firstly synthesized via the reversible addition fragmentation chain transfer polymerization, and characterized by 1H NMR, FT-IR and GPC. Subsequently, poly(vinylidene fluoride) (PVDF) blend membranes were prepared using PMMA-b-P4VP as a blending additive. Effects of the following factors on performance of blend membranes were systematically examined: P4VP content of PMMA-b-P4VP, solvent type, and PMMA-b-P4VP/PVDF ratio. Further, platinum(IV) ion-imprinted membrane (Pt(IV)-IIM) was fabricated by blending polymer-Pt(IV) complexes with PVDF. SEM, FTIR-ATR, contact angle, water flux and adsorption capacity were employed to characterize all membranes. Results indicated that the membrane, which was prepared using the copolymer with high P4VP content (polymerization time 10 h) as a functional polymer, N,N-dimethylacetamide as a solvent and PMMA-b-P4VP/PVDF ratio of 30 wt%, exhibited an intriguing morphology and much higher performance. Pt(IV)-IIM showed higher adsorption and selectivity for Pt(IV) (selectivity coefficients of 27.66 ± 1.38 and 77.16 ± 3.86 for Pt(IV)/Cu(II) and Pt(IV)/Ni(II), respectively) compared with a non-imprinted membrane. During membrane filtration, Pt(IV)-IIM was effective and selective for separation of Pt(IV) in the presence of Cu(II) and Ni(II) ions. Also, Pt(IV)-IIM was chemical stable, and had a good regeneration performance.

Electrochemical sensor for detection of europium based on poly-catechol and ion-imprinted sol-gel film modified screen-printed electrode

As a result of the increasing applications in different fields, europium has become a threat to the environment and human health. Thus, it is necessary to develop a simple and rapid method for determination of europium in trace level. In this paper, a sensor for determination of Eu3+ was established by modifying a screen printed electrode (SPE) successively with poly catechol as signal amplifying element and Eu(III) ion-imprinted membrane fabricated by sol-gel method as the recognition material. After the factors influenced the sensitivity of the sensor for Eu3+ was optimized in detail, Eu3+ can be determined by differential pulse adsorptive stripping voltammetry (DPASV) in the concentration range of 3.0 × 10−7–1.0 × 10−3 mol L−1 with the detection limit of 1.0 × 10−7 mol L−1. The fabricated sensor owns outstanding selectivity, perfect stability and good regeneration. 50-fold excess concentration of rare earth ions such as Ce3+, Tb3+, Ho3+, Dy3+, Er3+, Gd3+, Pr3+, Nd3+, Yb3+ and 100-fold excess concentration of other metal ions such as Fe3+, Ni3+, Cu2+, Zn2+ and Co2+ have no influence on the determination of 1.0 × 10−5 mol L−1 Eu3+. The obtained sensor, which can maintain >90% of its original response after used >60 times or stored in the water for 2 months, has been satisfactorily used to detect Eu3+ in water samples with the relative standard deviation (RSD) of <3.6% (n = 5) and recoveries in the range of 97.6%–101.6%.

Facile preparation of novel layer-by-layer surface ion-imprinted composite membrane for separation of Cu2+ from aqueous solution

A novel surface ion-imprinted composite membrane was fabricated using layer-by-layer technology for selective adsorption separation of copper ion. The ion-imprinted multilayer was introduced on modified polyethersulfone substrates by electrostatic interaction. Photocrosslinking was initiated by adding 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt and template ions were eluted by HAc solution. Effects of preparation and adsorption conditions, such as cationic polyelectrolyte species, crosslinking agent concentration, assembly layer number, pH and initial Cu(II) concentration, on adsorption behaviors were investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscope and X-ray photoelectric spectroscopy were used for the characterization of the copper ion-imprinted membrane (Cu-IIM). Batch adsorption experiments for studies of adsorption kinetics, adsorption selectivity and stability were conducted. The maximum adsorption capacity reached up to 48.0 mg·g−1 when 3.5 bilayers were deposited on the surface of membrane under specific experimental conditions (C0 = 200 mg·L−1, pH 6.0, 400 mL, 25 °C). The Cu-IIM exhibited a higher selectivity for copper ions when competitive ions were present. In addition, the Cu-IIM showed good stability. Moreover, according to the observation of the surface color change of the Cu-IIM during the adsorption process, the membrane could be used for qualitative concentration detection of copper ions in aqueous solution.

Stripping voltammetric determination of europium via ultraviolet-trigger synthesis of ion imprinted membrane

To solve the problem that the ion-imprinted membrane modified on glassy carbon electrode (GCE) usually easily falls off, a screen printed electrode (SPE) which has a relative rough surface than GCE, was selected as the base electrode for preparation of an ion-imprinted sensor for determination of Eu(III). The sensor was obtained by modifying SPE successively with carboxylic multiwalled carbon nanotubes (MWCNs-COOH) as signal amplifying element and Eu(III) ion-imprinted membrane (Eu(III)-IIM) as specific recognition material. To avoid damaging SPE by thermal initiation, the Eu(III)-IIM was prepared via radical photopolymerization at 380 nm using azobisisobutyronitrile (AIBN) as initiator. Differential pulse adsorptive stripping voltammetry (DPASV) was used for determination of Eu3+ by the obtained sensor. After the detection condition was optimized in detail, the sensor showed a linear response to Eu3+ in the concentration range of 1.0 × 10−7–1.0 × 10−3 mol L−1 with the detection limit of 4.0 × 10−8 mol L−1. The obtained sensor possesses of good regeneration, stability and practicability, it can maintain more than 95% of its original response after used more than 30 times or stored in the water for two months. The satisfactory results with the relative standard deviation (RSD) of less than 3.5% (n = 5) were obtained for the determination of europium in water samples by the novel sensor.

Preparation and characterization of ion selective membrane and its application for Cu2+ removal

Membranes are used in industrial wastewater treatment for the removal and recovery of heavy metals. A persistent challenge in heavy metals removal using membranes is the lack of selectivity for specific target ions, such as the removal and recovery of copper from other metal ions in industrial wastewater. This work reports the preparation of a new Cu(II)-selective ion-imprinted polymeric membrane. Membrane synthesis was conducted by applying an advanced immobilization method which comprises the preparation of polymerizable chelating monomer divinylbenzyl triethylenetetramine (diVB-TETA), the formation of the copper complex Cu-divinylbenzyl triethylenetetramine monomer (diVB-TETA-Cu), the polymerization/cross-linking of diVB-TETA-Cu within the Polyvinylidene fluoride (PVDF) pores to produce a copper-loaded membrane and finally the leaching of the copper (imprinting) from the membrane to produce ion-imprinted PVDF/diVB-TETA-Cu membrane. The chemical, elemental morphological properties of the synthesized ion-imprinted membrane were characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope coupled with Energy dispersive X-ray spectroscopy (SEM-EDS), Proton nuclear magnetic resonance (1H NMR) and Carbon-13 nuclear magnetic resonance (13C NMR). To assess selective separation of Cu2+ from the mixture of Cu2+ and Ni2+, adsorption at different pH settings and diffusion permeation experiments were carried out. The results show that diVB-TETA-Cu was successfully synthesized and its immobilization through polymerization/cross-linking almost filled all PVDF pores. The PVDF/diVB-TETA-Cu membrane permeation flux ratio of Cu2+:Ni2+ is 3.78. The prepared membrane is suitable for Cu2+ ion selective separation processes.

Stripping voltammetric determination of cerium in food using an electropolymerized poly-catechol and ion-imprinted membrane modified electrode

For the aim to detect Ce(III) in food with selectivity, sensitivity and speediness, a electrochemical sensor (Ce(III)-IIM/PC/GCE) was constructed by electropolymerization of a poly-catechol (PC) film on glassy carbon electrode (GCE) followed by modifying a Ce(III) ion-imprinted membrane (IIM) formed with electropolymerization using o-phenylenediamine as monomer. After that, a differential pulse adsorptive stripping voltammetry (DPASV) was developed for determination of Ce(III) by the obtained sensor. Under the optimal conditions, the sensor possesses good reproducibility and storage stability. Furthermore, it can be used directly for determination of Ce(III) in the concentration range of 3.0×10−12–1.0×10−4molL−1 with the limit of detection of 1.0×10−12molL−1. Since over 50-fold excess concentration of Fe3+, Cu2+ and Ni2+ will produce some interferences in the direct determination of Ce(III), an extraction method was adopted when it be used in food. After extraction of the samples with 1-phenyl-3-methyl-4-benzoyl-5-benzopyrazolone (PMBP), Ce(III) can be determined by Ce(III)-IIM/PC/GCE in the presence of >500-fold excess concentration of Fe3+, Cu2+ and Ni2+ with the limit of detection of 4.7×10−9molL−1. The sensor was successfully applied to determine cerium in food after extracted by PMBP with a relative standard deviation (RSD) of <3.3% (n=4) and recoveries in the range of 94.9–102.2%.

A New Ion-Imprinted Chitosan-Based Membrane with an Azo-Derivative Ligand for the Efficient Removal of Pd(II).

Herein, we described the synthesis of a novel ion-imprinted membrane for the detection of palladium(II) prepared through the glutaraldehyde crosslinking of chitosan with a 4-[(4-Hydroxy)phenylazo]benzenesulfonic acid ligand trapped into the membrane. The imprinting technology was used to improve adsorption capacity and adsorption selectivity, and was combined with some advantages of the developed membrane, such as low cost and ease of preparation, water-friendly synthesis, and high biocompatible chitosan material. The membranes were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectrometry (EDS). The results obtained showed a high swelling ratio with a maximum value of 16.4 (1640%) at pH 4 with a strong pH dependence. Batch rebinding experiments gave a maximum adsorption capacity of 101.6 mg of Pd(II) per gram of imprinted membrane. The Pd(II) adsorption behavior was well-described by a Langmuir model with a theoretical maximum adsorption capacity of 93.48 mg g−1, similar to the experimental one. Finally, a selectivity study versus Ag(I), Pb(II), and Fe(III) ions demonstrated a good selectivity of chitosan-imprinted membrane towards Pd(II).

An ion imprinted macroporous chitosan membrane for efficiently selective adsorption of dysprosium

Abstract A novel Dy 3+ ion-imprinted membrane material (II-MAC) with interconnected 3D macroporous structure was firstly prepared by a simple immersion-precipitation-evaporation method for the selective solid-liquid extraction of Dy 3+ . The morphology and chemical structure of II-MAC were characterized using multiple physicochemical techniques, such as SEM, nitrogen adsorption/desorption, FTIR, and element analysis. Adsorption experiments shown that the maximum adsorption capacity of II-MAC to Dy 3+ was 23.3 mg g −1 in the optimal pH (7.0) at 25 °C, and the value of imprint factor at pH = 7.0 was the highest. The distribution coefficient for Dy 3+ in the presence of the competitive rare earth metal ions was 494.88 mL g −1 , which was remarkably higher than that of other ions. Moreover, II-MAC could be easily retrieved due to the membrane structure, which could tactfully avoid the complex centrifugation and greatly decrease the operation time. The reusability tests demonstrated that II-MAC could be repeatedly used without significant loss even after the fifth runs. This work not only provides a more straightforward and high-efficiency means in selective extraction of Dy 3+ , but also promotes the development of green and sustainable material.