Ion-imprinted Polymer Research Articles

A novel ion-imprinted polymer based on the principle of ion exchange by bulk polymerization for specific recognition and adsorption of nitrate in polluted groundwater

A novel NO3− ion imprinted polymer (IIP-NO3−) was successfully synthesized based on the principle of “ion exchange” and the method of “bulk polymerization”. The NO3− anions, cationic monomers dimethyldiallylammonium chloride (DMDAAC) and acrylamide (AM) was used as template ions and functional monomers respectively. The material characterization showed that IIP-NO3− has an irregular porous structure. The maximum nitrate adsorption capacity of IIP-NO3− on NO3− was 48.486 mg/g under an optimal preparation condition. The isothermal adsorption (R2 = 0.9947) of IIP-NO3− for NO3− basically conformed to the Langmuir model. The adsorption process followed with the pseudo-secondary order kinetic model (R2 > 0.99), and it can reach equilibrium within 5 min. The IIP-NO3− had an obviously lower adsorption capacity for another common anion NO2−, HCO3−, SO42− ions in groundwater pollution than NO3− ions. The recognition selectivity coefficient of IIP-NO3− for NO3− ions were 2.839, 6.450, 1.773 respectively due to the imprinted effect. And this ion imprinted polymers with high selectivity to nitrate can be combined with the chemical reduction and the electrochemical reduction method, so as to improve the nitrate chemical reduction efficiency and reduce the regeneration cost of the IIP-NO3−.

Nanomaterials-Based Ion-Imprinted Electrochemical Sensors for Heavy Metal Ions Detection: A Review

Heavy metal ions (HMIs) pose a serious threat to the environment and human body because they are toxic and non-biodegradable and widely exist in environmental ecosystems. It is necessary to develop a rapid, sensitive and convenient method for HMIs detection to provide a strong guarantee for ecology and human health. Ion-imprinted electrochemical sensors (IIECSs) based on nanomaterials have been regarded as an excellent technology because of the good selectivity, the advantages of fast detection speed, low cost, and portability. Electrode surfaces modified with nanomaterials can obtain excellent nano-effects, such as size effect, macroscopic quantum tunneling effect and surface effect, which greatly improve its surface area and conductivity, so as to improve the detection sensitivity and reduce the detection limit of the sensor. Hence, the present review focused on the fundamentals and the synthetic strategies of ion-imprinted polymers (IIPs) and IIECSs for HMIs detection, as well as the applications of various nanomaterials as modifiers and sensitizers in the construction of HMIIECSs and the influence on the sensing performance of the fabricated sensors. Finally, the potential challenges and outlook on the future development of the HMIIECSs technology were also highlighted. By means of the points presented in this review, we hope to provide some help in further developing the preparation methods of high-performance HMIIECSs and expanding their potential applications.

Integrated sensor printed on the separator enabling the detection of dissolved manganese ions in battery cell

Conventional monitoring of Li-ion battery cell performance is carried out by combining empirical measurement of the extrinsic parameters with multipart modeling and approximation algorithms. A step forward would be enabling more reliable built-in sensing systems that allow collecting direct information, such as a degree of constituting materials degradation. Transition metal dissolution is one of the most severe degradation processes affecting the performance of the whole battery cell. It can be accelerated through different mechanisms, and its monitoring has been a topic of several studies in recent decades. In this work, we establish an approach for unambiguous detection of dissolved manganese ions via the built-in electrochemical sensor with scavenger moieties. We demonstrate that manganese ion-imprinted polymer (Mn(II)-IIP) deposited between two electrodes printed directly on the separator can be used as a sensing layer. The resistance of this sensing layer changes due to the coordination of the ion-imprinted polymer with dissolved manganese ions and this is then precisely monitored by the electrochemical impedance spectroscopy in the mid-frequency range. Both the electrodes and sensing layer remain stable within the voltage range of battery cycling over a longer application time. The sensor performance was validated in the single-layer pouch cell using Li||LiMn2O4 chemistry. The use of printing technology permits large-scale commercialization; sensors printed on the separator do not significantly alter the current production technology and, most importantly, have a negligible impact on the cell energy density. The approach is universal and can eventually be extended to the detection of other degradation products in the electrolyte.

Magnetic ion imprinting techniques for the separation and analysis of elemental speciation

Metal and metalloid elements have various possible isotopic compositions and oxidation states and often form coordination or covalent compounds with inorganic and organic small molecules or biological macromolecules, resulting in complex elemental speciation. Different species of the same element often have different properties, which dictate their behavior. Thus, elemental speciation analysis is vital for comprehensively and accurately assessing an element's environmental and biological effects and the corresponding risks. Because elemental speciation determines the behavior of an element in different environmental and biological processes, the analysis of elemental species has, in recent years, been important in various subjects, including analytical chemistry, environmental chemistry, geochemistry, ecology, agronomy, and biomedicine. The complexity of environmental and biological sample matrices, as well as the multiformity, low levels, and lability of chemical forms pose severe challenges in elemental speciation analysis. Therefore, the highly selective identification and efficient separation of native species is necessary for conducting the identification, quantification, ecotoxicity evaluation, and physiological function study of elemental speciation. Sample pretreatment by solid-phase extraction is an effective solution to the aforementioned problems, but the existing methods do not meet the requirements of current research. The transition of the target species from pre-processing to the detection device includes both on- and off-line arrangements. Compared with the on-line approach, the off-line approach requires more manual participation, increasing the analysis workload. However, the off-line approach can improve the analysis efficiency through high-throughput pretreatment when large batches of samples are encountered, meaning the off-line approach is still an effective model. Ion imprinting technology has been developed based on existing molecular imprinting technology, with four main steps present in the synthesis of ion imprinted polymers. First, ion imprinting technology uses metal ions as templates. Then, these templates are combined with the functional monomers through coordination, electrostatic or hydrogen bonding. The functional monomers simultaneously surround and fix the templates, after which the cross-linkers and functional monomers polymerize to prepare ion-imprinted polymers with a specific structure and composition. Finally, the imprinted holes are created in the polymers by eluting the template ions. Therefore, the template molecules, functional monomers, and cross-linkers are three precursors necessary for synthesizing ion-imprinted polymers. These polymers can specifically bind to the imprinted metal ions with accuracy, sensitivity, and reliability. In recent years, they have been widely used in separating, enriching, analyzing, and detecting elemental species. During solid-phase extraction, the non-magnetic adsorbent materials dispersed in the sample solution need to be separated by centrifugation or filtration, which is time-consuming and laborious. Because an external magnetic field can be used for rapid magnetic solid-phase extraction, it has become a potential method for separating and enriching elemental species. This review systematically summarizes the latest progress in ion-imprinting technology, including its principle and the preparation methods of ion-imprinted polymers. The challenges faced by ion imprinting technology are analyzed in the context of the development of ion-imprinting magnetic solid-phase extraction in elemental speciation analysis. Finally, the direction of future development and the strategies of ion imprinting technology in elemental speciation analysis are proposed. It is important to exploit novel organic-inorganic hybrid polymerization-based multifunctional ion-imprinted magnetic nanocomposites for the magnetic solid-phase extraction and separation of elemental species. By establishing the pretreatment protocols with high recognition selectivity, strong separation ability, large adsorption capacity, and good speciation stability, we expect to achieve the research objectives of simultaneously separating and enriching the multiple-species of typical metal/metalloid elements in environmental and biological samples.

Histidine-mediated dendritic mesoporous magnetic ion-imprinted polymer toward effective and recoverable cadmium removal

In this study, a magnetic dendritic mesoporous silica nanoparticle material (MDMS@MAH-Cd-IIP) was prepared via surface ion-imprinted technique for selective removal of Cd(Ⅱ) from aqueous solution. The material was based on an ion-imprinted copolymers of 4-vinyl pyridine (4-VP) and N-methacryloyl-L-histidine (MAH), a synthesized ligand monomer to complex with cadmium ions as ion recognition layer. The obtained polymer was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and magnetic measurement system. The adsorption experiments exhibited MDMS@MAH-Cd-IIP showed fast (within 35 min) and selective capture of Cd(Ⅱ) with maximum uptake capacity of 21.04 mg g−1. The adsorption process followed pseudo-second order kinetic and Langmuir adsorption isotherm models, indicating monolayer chemisorption on homogeneous sites was the rate-limiting step. Meanwhile, the MDMS@MAH-Cd-IIP also showed a specificity recognition ability for Cd(Ⅱ) using analogues Co(Ⅱ), Pb(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) as interference. Moreover, the MDMS@MAH-Cd-IIP based magnetic SPE can extract approximately 90.0–102.0% of Cd (Ⅱ) in real water samples with a RSD of 3.34–8.23%, which indicated the polymer had the high stability and reproducibility and presented itself a promising material for the Cd(Ⅱ) adsorption and detection from aqueous solution.

A novel ion-imprinted polymer based on pyrrole as functional monomer for the voltammetric determination of Hg(II) in water samples

A novel selective ion-imprinted polymer (IIP) was synthesized, characterized, and used as part of a carbon paste electrode (CPE) for the electrochemical analysis of Hg(II) in real water samples by differential pulse anodic stripping voltammetric (DPASV). Hg-IIP (mercury-ion imprinted polymer) was synthesized using pyrrole for the first time as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker agent, and sodium persulfate as initiator. The CPE was modified with IIP (CPE-IIP) with a composite mixture of Hg-IIP (10%), graphite (90%), and 0.08 g of paraffin oil. A notable difference in the Hg(II) Iap (anodic peak current) between a CPE, CPE-IIP and CPE-NIP (non-imprinted polymer) was observed when optimizing the differential pulse anodic stripping voltammetry (DPASV) parameters by a Box-Behnken design. When analyzing a 50 µmol l−1 Hg(II) solution, the optimal conditions (step potential: 0.11 V, amplitude: 0.15 s, modulation time: 0.005 s, and interval time: 0.15 s) allowed an Iap of 144 µA with a %RSD < 10% for the CPE-IIP response, in comparison to the Iap of 1.47 µA obtained with the CPE-NIP, Iap confirming the existence and performance of the recognition cavities in the IIP. The proposed methodology presents a limit of detection (LOD) of 0.02 mg l−1 within a linear range of 0.09 mg l−1 to 20.05 mg l−1. The inter-day and intra-day precision were measured in two concentration levels (1 mg l−1 and 10 mg l−1) with %RSD < 10%. The developed methodology was successfully applied to determine Hg(II) in three spiked samples (10 mg l−1) of natural water sources without acid digestion, obtaining percentage recoveries close to 99.74%, which demonstrates that digestion treatment is not required for this kind of samples.

Influence of Synthesis Parameters and Polymerization Methods on the Selective and Adsorptive Performance of Bio-Inspired Ion Imprinted Polymers

Ion-imprinted polymers (IIPs) have been widely used in different fields of Analytical Sciences due to their intrinsic selective properties. However, the success of chemical imprinting in terms of selectivity, as well as the stability, specific surface area, and absence of swelling effect depends on fully understanding the preparation process. Therefore, the proposal of this review is to describe the influence of relevant parameters on the production processes of ion-imprinted polymers, including the nature (organic, inorganic, or hybrid materials), structure, properties of the salt (source of the metal ion), ligand, crosslinking agent, porogenic solvent, and initiator. Additionally, different polymerization methods are discussed, the classification of IIPs as well as the applications of these adsorbent materials in the last years (2017–2022).

Ultrasensitive and highly reusable electrochemical sensor with ion imprinted nanobiochar

A novel electrochemical sensor for the ultrasensitive monitoring of Pb2+ and Cd2+ was developed by fabrication of highly conductive and target selective electrode using ball milling biochar (BBC) featured with high conductivity and rich oxygenic functional groups as the conductive material, and cavities of ion-imprinted polymer as specific binding moieties. The nanosized BBC was synthesized with process of high temperature pyrolysis and rigorous ball milling. The ion imprinted BBC electrode was constructed by in situ electropolymerization of L-Cysteine and template metal ions on the BBC that was modified on glassy carbon, and subsequent removal of templates. The BBC presented great electron transfer ability, and contained increased oxygenic compounds than the mild ball milling prepared one, which attributed to formation of stable and cavity-rich imprinting polymer layer and enhancement of sensing signal. With the anodic dissolved differential pulse voltammetry, the electrode could detect extremely low levels of Pb2+ and Cd2+ with lowest detection limits of 5.86 fM and 0.883 aM, and the linear ranges were 25 fM ~ 1 µM and 0.1 fM ~ 1 µM, respectively. The electrode also presented anti-interference to other irrelevant ions and organic compounds, and could reuse at least seven times without decrease of sensing signal.

Screening of synthesis conditions for the development of a radium ion-imprinted polymer using the dummy template imprinting approach

In this study, a selective and specific sorbent for radium extraction was developed for the first time using ion-imprinted polymer technology. A novel and original approach was used in order to screen the best synthesis conditions. After identifying the best monomer candidates, porogen, and complexation time from electrospray ionization mass spectrometry experiments, solubility tests, and conductimetry experiments, five ion-imprinted polymers (IIPs) were synthesized by bulk polymerization using Ba2+ as a dummy template ion. Non-imprinted polymers (NIPs) were similarly prepared but without template ions. Polymers were packed in solid phase extraction (SPE) cartridges for their characterization. Composition of the percolation and washing solutions (e.g. buffer concentration, nature and pH, and ethanol proportion) was varied to achieve the highest retention for the template ion while minimizing that of interfering ions. The retention, selectivity (retention on IIP versus on NIP), and specificity (targeted ions versus interfering ions) properties of the different polymers were compared by measuring the recovery yields in the SPE collected fractions by inductively coupled plasma mass spectrometry (ICP-MS). The IIP synthesized in acetonitrile/dimethylsulfoxyde (1/1, v/v) using Ba2+ as template ion, vinylphosphonic acid as complexing monomer, and styrene and divinylbenzene as co-monomer and cross-linker showed both selectivity and specificity. It retained strongly Ra2+ while having the potential to isolate it from alkali metals, metalloids and some transition metals.

Iron Ionic Imprinted Polymers IIps for Separation and Preconcentration of Iron from Crude and Fuel Oil

A novel Iron ion-imprinted polymers (IIPs) was synthesized by bulk polymerization using different types of monomers such as 1-vinyl imidazole and Styrene, respectively. Molar ratios of monomer, template and cross-linking agent for polymerization, various monomers and solvents were studied to obtain the largest adsorption capacity for Iron. The prepared Iron-IIPs were characterized using energy dispersive X-ray spectroscopy (EDX), Fourier - transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The three-dimensional network structure surfaces of Iron-IIPs are unaffected by the elution procedure. Iron ions were successfully eluted from IIPs using a mixed solution from ethanol and acetic acid. The maximum adsorption capacity of Iron-IIPs was is (514.5)µmol/g for Iron-IIP1(using styrene as a monomer) and (429.1) µmol/g for Iron-IIP2(using 1-vinyl imidazole as a monomer). The adsorption by Iron-IIPs followed a Langmuir isotherm models. Solid-phase extraction (SPE) syringe packed with ionic imprinted polymers (IIPs) were used to selective separation for Iron ion from Crude or fuel oil and digest the polymer to determination the Iron by flame atomic absorption spectroscopy (FAAS) Abbreviation IIP-SPE-FAAS.

Selective recovery of lithium resources in salt lakes by polyacrylonitrile/ion-imprinted polymer: Synthesis, testing, and computation

Lithium as a strategic metal exhibits extensive applications in the 21st century. The high-efficiency extraction of lithium resources is of economic significance as the market demand for electric vehicles powered by lithium-ion batteries increases rapidly. A novel silica gel (SG)/graphene oxide (GO) composite nanofiber was prepared by combining surface imprinting technology with electrospinning technology to capture Li(I) from salt lakes in an oriented manner. The batch adsorption experiments and fixed-bed adsorption experiments were conducted to evaluate the adsorption performance of the composites. The SG/GO composite exhibited a maximum adsorption capacity of 1.1 mg/g for Li(I). The adsorption kinetics tallied with the pseudo-second-order model, and the isothermal adsorption was similar to the Langmuir model. The adsorption process of the SG/GO composite is one of monolayer chemical adsorption, and the adsorbates did not interact. The adsorption mechanism was revealed by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM), combined with density functional theory (DFT) computation. The mechanism analysis indicated that the charge transfer occurred between the surface functional groups and metal ions in the adsorption process. The electrons mainly transferred from the P and O atoms of the functional groups to the 3p orbit of Li(I) to form coordinate bonds, which finally achieved the goal of oriented capture of Li(I). The polyacrylonitrile (PAN)/ion-imprinted polymer (IIP) composite nanofiber is a novel, high-efficiency adsorbing material for recovering Li(I) from salt-lake brine.

Selective capture of Pd(II) from aqueous media by ion-imprinted dendritic mesoporous silica nanoparticles and re-utilization of the spent adsorbent for Suzuki reaction in water

The development of highly efficient adsorptive material for the selective capture of Pd(II), and re-utilization of spent Pd(II)-loaded adsorbent as an efficient catalyst for organic synthesis are of great significance, but challenging. Particularly, the heterogeneous palladium-catalyzed Suzuki reaction in aqueous media is much more challenging than that of homogeneous. Herein, several novel Pd(II) ion-imprinted polymers (PIIPs) based on dendritic fibrous silica particles are constructed by surface ion imprinting technology (SIIT), using Schiff base and pyridine groups functionalized organosilicon as functional monomer. The PIIP-3 prepared by 3 g of functional monomer exhibits the best adsorption performance, and shows ultrafast (10 min) and selective capture of Pd(II) with high uptake capacity (382.5 mg/g). Moreover, the waste Pd(II) loaded PIIP-3 (PIIP-3-Pd) can serve as a catalyst towards the Suzuki reaction in water, affording 94.2 % yield of the desired product. Interestingly, the PIIP-3-Pd can be reused 12 times without an appreciable decrease in catalytic activity, which is probably due to the imprinted cavity and specific recognition site of PIIP-3 can match and recapture Pd active species in a complex catalytic environment. Thus, this work demonstrates huge potentials of SIIT to enhance the selectivity of adsorption process and increase the lifetime of catalysts.

Development of a novel tailored ion-imprinted polymer for recovery of lithium and strontium from reverse osmosis concentrated brine

This study aims to prepare ion-imprinted polymer (IIP) with the benefit of a metal-based sorbent, which is fabricated to selectively adsorb lithium (Li+) from aqueous solutions, and in an attempt to remove strontium (Sr2+). The adsorption processes were carried out at different pH values, initial concentrations, and temperatures, to optimize the experimental conditions, with the use of response surface methodology (RSM). The seawater reverse osmosis (SWRO) brine was physically and chemically characterized, and the physicochemical characterization of the prepared IIP before and after adsorption was also performed using different spectroscopic methods. The adsorption capacity for Li+ and Sr2+ from SWRO brine was evaluated, and the reusability of IIP was investigated using adsorption–desorption cycles. The results showed that the IIP was efficient to remove Li+ but not Sr2+, and it follows Freundlich adsorption isotherms models. The analysis revealed a significant concentration of minerals in the brine sample It also revealed a low concentration of trace metals, like Ba (0.16 mg/L), Zn (0.845 mg/L), Fe (1.31 mg/L), Cu (1.165 mg/L), Pb (1.505 mg/L), and V (3.88 mg/L), except Li and Sr which shows a higher concentration of 43.32 mg/L and 16.93 mg/L respectively. pH 10 was selected to be the optimum pH for the adsorption isotherm experiments, as it was the highest efficient pH to adsorb Li+ and Sr2+. The thermodynamics study revealed that the adsorption of Li+ on the IIP favored exothermic conditions. It was noticed that the maximum adsorption capacity (Qm) was increased as the temperature rise from 714.3 mg/g at 25 °C to 2500 mg/g at 45 °C. The Li+ desorption results show that 94.03% − 94.71% of the ions were recovered, while the Sr2+ desorption results show that 96.35% − 96.56% of the ions were recovered. The efficiency of IIP to adsorb lithium and strontium from brine shows that the adsorption removal% of Li+ was between 84.21% and 84.68%, while the adsorption removal% of Sr2+ was between 3.83% and 10%. The cost analysis for IIP preparation was 2 USD/g.

Copper Ion Imprinted Hydrogel Photonic Crystal Sensor Film

An ion-imprinted photonic crystal (IIPC) sensor for visual detection of copper ions was prepared by the combination of ion-imprinting polymer and colloidal photonic crystal (CPC) structure. Monodisperse polystyrene (PS) colloidal nanospheres synthesized by the boiling soap-free emulsion polymerization method were used to prepare the CPC template by the solvent evaporation method. An ion-imprinted polymer based on poly(vinyl alcohol) and chitosan (PVA/CS) is infiltrated therein. The IIPC sensor film was then prepared by solvent-assisted freeze–thaw method while the CPC template was strengthened as the air pores of the template were replaced by PVA/CS hydrogel. The shift of the diffraction wavelength can be directly observed by the naked eye through the color change of the IIPCS according to the concentration change of copper ion. Such sensor film showed good selectivity and sensitivity with a lower detection limit of 10–4 M.

Quantitative Analysis of Pb(II) Based on Differential Pulse Anodic Stripping Voltammetry and IIP-Carbon Paste Electrodes

It is well known that Pb(II) is considered a highly toxic metal. The slight difference between toxic and permissible levels in drinking water is a matter of concern; therefore, highly sensitive and selective techniques have been proposed for quantification, such as the electrochemical ones. In this work, an easy, simple, low-cost, and high selective sensor based on carbon paste electrodes (CPE) and ion-imprinted polymers (IIP) is proposed for Pb(II) analysis in real water samples. Recognition cavities, selective to Pb(II), were synthesized based on a cross-linked polymer using vinyl pyridine. A modified CPE was constructed by a mixture of graphite powder, IIP, and paraffin oil. By voltammetry studies, a notable difference was observed in the electrochemical response of the electrodes modified with IIP and those with non-imprinted polymer (NIP), confirming the existence of the recognition cavities in the IIP. The construction and analysis parameters related to the analytical response of Pb(II) (anodic current intensity of stripping voltammetry), were optimized; the selectivity was also studied considering potential interference ions. A linear concentration range from 3.3 mg l−1 to 33 mg l−1 and a limit of detection of 0.99 mg l−1 were achieved. Pb(II) was successfully quantified in real complex samples without previous treatment.

Ultra-preconcentration technique for the determination of thallium (I) in water samples by a combination of thallium (I)-imprinted polymer and vortex-assisted liquid–liquid microextraction

In this research study, thallium(I)-imprinted polymer and vortex-assisted liquid–liquid microextraction methods were used for ultra-preconcentration and extraction of thallium (I) ions for consecution in ultra-trace level in aqueous solution. In the first extraction step, ion-imprinted polymer particles were applied as a selective technique. Next, the eluted solution is used for extraction with the vortex-assisted liquid–liquid microextraction technique. There are several factors that have an effect on the two processes. They were studied to improve the separation performance. The advantages of the method are good linear range (0.015–0.8 ngmL−1), low detection limit (2.1 pgmL−1), and ultra-trace level determination thallium (I) ions. The new procedure has a high-preconcentration factor (PF = 2000) for determining of thallium (I) ions in water samples. The relative standard deviation for five replicate analyses of 0.1 ng mL−1 of thallium(I) was 4.8%. The recovery percentage of thallium was calculated from the electrothermal atomic absorption spectrometry results. The thallium(I)-imprinted polymer and vortex-assisted liquid–liquid microextraction method was successfully employed to determine thallium (I) ions in industrial wastewater, well water, and urban sewage samples with a satisfactory recovery in the range of 90 to 98%.

Chemical Imprinting Technology Applied to Analytical Chemistry: Current Status and Future Outlook in Brazil

Chemical imprinting technologies based on molecularly imprinted polymers (MIPs) and ion imprinted polymers (IIPs) have been widely applied in different fields of analytical chemistry since their discoveries in 19721 and 19762, respectively. MIPs and IIPs are considered biomimetic materials with tailor-made synthetic receptors and are, essentially, obtained by co-polymerization of functional and cross-linking monomers in the presence of a target analyte (a molecule for MIPs and an ion for IIPs). The great advantages of these materials over biological recognition systems include their relatively low cost, quick preparation, and, most importantly, their stability in different media. To date, these biomimetic materials have experienced a rapid development with wide applications in electrochemical sensors, luminescence sensors, separation science, sample preparation, and more specific sensor applications such as surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) sensors. In addition, they have been applied for analysis of samples of environmental, food, and forensic interests, as well as for disease diagnostics.3-8 Figure 1 depicts the increasing number of published papers per year over the past 20 years on the topic of MIPs and IIPs; as expected, most of these papers are devoted to the chemical imprinting of molecules.

Synthesis of ion-imprinted polymers based on chitosan for high selectivity of La(III), Ce(III) and Sm(III) via solid phase extraction

Lanthanide metal ions are extremely important to the development of economy and technology; however they are difficult to separate because of their chemical similarities. Polymers imprinted with ions have become a promising platform to explore possible solutions to this problem in recent years. The purpose of this work is to develop a new specifically designed IIPs material for separating lanthanide ions (La(III), Ce(III), and Sm(III)) based on chitosan (CS) and polyvinylpyrrolidone (PVP). Tartaric acid, 0.25 M, was used to leach the lanthanide template ion from the Ln(III)IP-CS/PVP particles with the capability of selective extraction. As a model, properties of La(III)IP-CS/PVP (both un-leached and leached) were investigated by using FT-IR, XRD, EDX, SEM, TEM, surface area and TG-DTA measurements. A batch-type experiment has been used to investigate the effect on separation of a variety of parameters such as pH of the solution, time of contact, and ion concentration. Various Ln(III)IP-CS/PVP were found to have adsorption capacities of 39.34, 38.24, and 40.51 mg/g for La(III), Ce(III), and Sm(III). In regard to La(III)IP-CS/PVP, adsorption was analyzed using kinetic and isotherm models. In the presence of interfering ions, such as La3+, Ce3+, Sm3+, Nd3+, Dy3+, Ho3+, Er3+, Eu3+, Pr3+, Cs+, Zr4+, Ni2+, Co2+ and Cd2+, the selectivity behavior of La(III), Ce(III) and Sm(III)IP-CS/PVP was investigated. The target lanthanide ion was selected exceptionally well. A study of the regeneration and reusability of the materials found no significant decrease in the adsorption efficiency after five cycles (>80%). For La(III) ions, a breakthrough curve was constructed using La(III)IP-CS/PVP. An evaluation of the applicability of Ln(III)IP-CS/PV for the separation of La(III), Ce(III) and Sm(III) from Abu-Tartur phosphate rock was conducted.

Novel MOFs-based ion-imprinted polymer for selective separation of cobalt ions from waste battery leaching solution

A novel metal–organic framework (MOF)-based cobalt ion-imprinted polymer (MOF-IIP) was prepared by grafting 2-pyridinecarboxaldehyde (PCA) onto UiO-66-(OH)2 for the selective separation of Co(II) from waste battery leaching solution. The structure and property of MOF-IIP were characterised by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analyses. The adsorption mechanism was explored by X-ray photoelectron spectroscopy (XPS). The adsorption performance was investigated based on batch adsorption experiments, and the results indicated that the adsorption conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, and that it was a homogeneous monolayer exothermic process. Under the optimal parameters, the maximum adsorption capacity of MOF-IIP for Co(II) was 132.8 mg/g, which is higher than the values reported for most imprinted materials. In addition, the selectivity coefficients of MOF-IIP for Co(II)/Ni(II), Co(II)/Ca(II), Co(II)/Li(I), and Co(II)/K(I) were 1.20, 4.61, 78.40, and 3.71, respectively, which were significantly better than those of MOFs-based non-imprinted polymer (MOF-NIP; 0.35, 3.54, 24.9, and 3.00, respectively). In this study, MOFs were used as the matrix to prepare an imprinted adsorbent for the selective separation of cobalt ions. The outstanding adsorption capacity and excellent selectivity obtained in the experiments showed that MOFs-based imprinted materials have great potential for highly selective separation and recovery of metal ions.

Electrochemical Determination of Pb(II) Using Carbon Paste Electrodes Modified with Ion Imprinted Polymers (IIPs)

An easy, low-cost, and highly selective carbon paste electrode based on an ion-imprinted polymer (IIP) to determine Pb(II) in real samples was developed. The recognition cavities based on a cross-linked polymer selective to Pb(II) were created using vinyl pyridine. The modified CPE was constructed by a composite mixture with the synthesized IIP. A notable difference was observed in the electrochemical response of the electrodes modified with the IIP and a non-imprinted polymer, demonstrating the unique properties of the IIP recognition sites. The parameters related to the current intensity were optimized; the selectivity was also studied considering potential interference ions. The proposed modified electrode demonstrated to be as (or more) selective to Pb(II) compared to others previously reported in the literature. A linear concentration range from 3.3 mg/L to 33 mg/L with a limit detection of 1 mg/L was obtained. The Pb(II) preconcentrated on the electrode surface was successfully quantified in real potable water samples without previous treatment.