Surface Ion-imprinted Polymer Research Articles

Advancing selective copper detection in water: Innovative electrode utilizing surface ion-imprinted polymer

Researchers are still faced, with the challenge of creating a readily fabricated ion-imprinted electrode that can quickly and precisely detect trace metal ions. In this paper, a novel surface ion-imprinted polymer (sur-IIP) based on Au nanoparticle with high conductivity was synthesized and modified on the glassy carbon electrode (GCE). From structural characterization, the functional monomer, thiolated chitosan, was self-assembled on the surface of Au nanoparticle by the ‘Au-S’ bond and formed an imprinted layer in 15 nm thick. During the electrochemical measurement, different detection parameters such as supporting electrolyte, pH, deposition potential, deposition time were optimized under the optimal conditions, the modified electrode exhibited a extensive linear range from (0.05–30 μmol L-1) and lowest limit of detection was 0.0487 μmol L-1. The developed sensor was applied for the detection of traces of Cu (II) ions from tap water as well as from drinking water successfully. Compared with other surface ion-imprinted polymers, the sur-IIP in this paper were more conductive and could be modified tightly on the electrode by dip-dropping. The overall strategy of preparing the ion-imprinted polymer on the surface of Au nanoparticles were accessible and efficient.

A recoverable magnetic surface ion-imprinted polymer based on graphene oxide for fast and selective adsorption of Ni(ii) from aqueous solution: experimental and DFT calculations

A magnetic GO-based imprinted adsorbent exhibited a high adsorption capacity, good removal rate and good reusability for Ni(ii) adsorption.

Preparation of Magnetic Surface Ion-Imprinted Polymer Based on Functionalized Fe3O4 for Fast and Selective Adsorption of Cobalt Ions from Water

A novel cobalt ion-imprinted polymer (Co(II)-MIIP) based on magnetic Fe3O4 nanoparticles was prepared by using Co(II) as the template ion, and bis(2-methacryloxyethyl) phosphate and glycylglycine as dual functional monomers. The fabricated material was analyzed by Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, X-ray diffraction, and vibrating sample magnetometer. The adsorption experiments with Co(II)-MIIP, found that the maximum adsorption capacity could reach 33.4 mg·g−1, while that of the non-imprinted polymer (Co(II)-NIP) was found to reach 15.7 mg·g−1. The adsorption equilibriums of Co(II)-MIIP and Co(II)-NIP was established within 20 min and 30 min, respectively. The adsorption process could be suitably described by the Langmuir isotherm model and the pseudo-second-order kinetics model. In binary mixtures of Co(II)/Fe(II), Co(II)/Cu(II), Co(II)/Mg(II), Co(II)/Zn(II), and Co(II)/Ni(II), the relative selectivity coefficients of Co(II)-MIIP toward Co(II)-NIP were 5.25, 4.05, 6.06, 11.81, and 4.48, respectively. The regeneration experiments indicated that through six adsorption–desorption cycles, the adsorption capacity of Co(II)-MIIP remained nearly 90%.

Fabrication of recoverable magnetic surface ion-imprinted polymer based on graphene oxide for fast and selective removal of lead ions from aqueous solution

In this study, a novel Pb(II) ion-imprinted polymer based on magnetic laminar graphene oxide composite materials (MnFe2O4@SiO2/GO-IIP) was synthesized by surface ion-imprinted technique for the selective removal of lead ions from aqueous solutions. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurement system were used to characterize the structure and property of as-prepared adsorbents. The adsorption experiments exhibited the MnFe2O4@SiO2/GO-IIP possessed a good adsorption performance and the maximum adsorption capacity of Pb (II) ions reached 58.82 mg g-1. The adsorption could be accomplished within 30 min and the adsorbents could be separated quickly by a permanent magnet. The Langmuir adsorption isotherm and pseudo-second-order kinetic models were used to describe the adsorption procedure appropriately and the result proved that the chemisorption was the rate-limiting step. The selectivity coefficient of Pb (II)/Ni(II), Pb (II)/Zn(II), Pb (II)/Cd(II), Pb (II)/Co(II) were 25.37, 19.71, 33.07 and 45.7, respectively. In addition, the regeneration experiments confirmed the high stability and reproducibility of adsorbents. Lastly, X-ray photoelectron spectroscopy (XPS) proved the bonding mechanisms of the material and Pb(II) ions with a coordination N‒Pb bond.

Selective and rapid removal of Mo(VI) from water using functionalized Fe3O4-based Mo(VI) ion-imprinted polymer.

Fe3O4 nanoparticles-based magnetic Mo(VI) surface ion-imprinted polymer (Mo(VI)-MIIP) was elaborated employing 4-vinyl pyridine as a functional monomer. The adsorbent preparation was confirmed by Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, vibrating sample magnetometer, thermogravimetric analysis, and surface area analysis. Batch adsorption experiments showed that the maximum adsorption capacity of Mo(VI)-MIIP was 296.40 mg g-1 at pH 3, while that of the magnetic non-imprinted polymer (MNIP) was only 147.10 mg g-1. The adsorption isotherm model was well fitted by the Langmuir isotherm model. The adsorption experiments revealed that Mo(VI)-MIIP reached adsorption equilibrium within 30 min, and the kinetics data fitting showed that the pseudo-second-order kinetics model suitably described the adsorption process. Mo(VI)-MIIP exhibited an excellent adsorption selectivity to Mo(VI) in binary mixtures of Mo(VI)/Cr(VI), Mo(VI)/Cu(II), Mo(VI)/H2PO44-, Mo(VI)/Zn(II), and Mo(VI)/I-, with relative selectivity coefficients toward MNIP of 13.71, 30.27, 20.01, 23.53, and 15.89, respectively. After six consecutive adsorption-desorption cycles, the adsorption capacity of Mo(VI)-MIIP decreased by 9.5% (from 228.4 mg g-1 to 206.7 mg g-1 at initial Mo(VI) concentration of 250 mg L-1), demonstrating its reusability.

Preparation, characterization and adsorption characteristics of diatom-based Cd(II) surface ion-imprinted polymer

In order to effectively treat wastewater containing heavy metal ions and form comprehensive utilization of resources, we prepared a novel diatom-based Cd(II) ion-imprinted polymer (Dt-IIP) based on surface imprinting technique by using the diatomite as a matrix material and 3-mercaptopropyltrimethoxysilane (MPS) as a functional monomer. Through SEM, XRD, XPS, TGA, FTIR and Elemental analysis to confirm the structural transformation and composition changes of the materials during the preparation process. The optimal pH, kinetics, adsorption isotherms and thermodynamics of ion-imprinted polymer for Cd(II) adsorption process were investigated. The experimental results showed that the optimal pH value of the adsorption process was 6.0 and the theoretical maximum adsorption capacity was 5.5025 mg g−1. The adsorption reaction conformed to the Langmuir isotherm model and kinetic data was more suitable to be explained by pseudo-second-order model. Furthermore, the thermodynamic adsorption process was spontaneous and endothermic. The analysis of XPS and FTIR revealed that the adsorption of Cd(II) ions was achieved mainly through the interaction of Cd(II) ions with thiol groups. Compared with non-imprinted polymer (Dt-NIP), Dt-IIP possessed a higher adsorption capacity and superior selectivity for target ions. In addition, test of regeneration showed that the Dt-IIP was reusable and stable.

Fe3O4/SiO2/CS surface ion-imprinted polymer modified glassy carbon electrode for highly sensitivity and selectivity detection of toxic metal ions

A surface ion-imprinting polymer (IIP) based on Fe3O4/SiO2/CS was selected to modify the glassy carbon electrode (Fe3O4/SiO2/CS/Nafion/GCE), and the sensor exhibits ultrasensitive and highly selective to monitor trace level of Cu (II). SiO2 was homogeneously coated on the Fe3O4 magnetic core to enhance the resistance in the harsh environment, especially various acids in the real environment. After that, chitosan film, incorporating copper ions as template ions, covered the Fe3O4/SiO2 and cross-linked with glutaraldehyde. The prepared electrode was used as a working electrode to construct an electrochemical sensor for detecting trace Cu (II) and amplifying the electrochemical signal through the formation of the ion imprinted polymer. The Fe3O4/SiO2/CS/Nafion/GCE IIP based sensors were characterized by XRD, FT-IR, SEM, and TGA. During the electrochemical measurement, different experimental parameters were optimized, and the sensors exhibited a wide linear detection range (0.01 to 20 μmol L−1) and low limit of detection (5 nmol L−1). Besides that, the sensors also demonstrated highly selective to Cu ion, comparing with other interfering ions. The Fe3O4/SiO2/CS/Nafion/GCE-IIP based sensor displayed notable reproducibility and the RSD was 3.3%. The sensors based on Fe3O4/SiO2/CS ion imprinted polymer have the potential to monitor other toxic metal ion pollution in harsh environment.

Plasma polymerization mediated construction of surface ion-imprinted polypropylene fibers for the selective adsorption of Cr(VI)

This work reports the preparation of a surface ion-imprinted polymer (IIP) using polypropylene (PP) fibers as substrates for the selective adsorption of Cr(VI). Glycidyl methacrylate was firstly grafted onto PP fibers through a plasma polymerization-induced process, followed by the construction of imprinted sites. The resultant sorbent was characterized using SEM, FT-IR, TGA, XPS, and water contact angle. The results of batch adsorption experiments showed that the maximum Cr(VI) adsorption capacity was 103 mg/g at pH 3 and 25 °C. The Cr(VI) adsorption process followed a pseudo-second-order rate model, and the equilibrium data were best described by a Langmuir isotherm model. Meanwhile, the adsorption process was spontaneous and endothermic. IIP showed a high adsorption selectivity for Cr(VI) in binary systems with Cr3+, Cu2+, and SO42−, respectively, compared with that of non-imprinted fibers. The removal mechanism of Cr(VI) was investigated combining with FT-IR and XPS analysis, and the results suggested that chemical adsorption occurred between the functional groups on IIP and Cr(VI), as did the partial transformation of Cr(VI) to Cr3+. The results demonstrated that the prepared material is a good candidate for selective Cr(VI) adsorption in practical use.

Synthesis of surface ion-imprinted polymer for specific detection of thorium under acidic conditions

A fibrous surface ion-imprinted polymer (IIP) was synthesized for thorium removal through direct electron beam radiation using thorium as a template. Polypropylene coated by polyethylene non-woven fabrics (PE/PP) was used as a substrate. The PE/PP non-woven fabrics were irradiated in the presence of the phosphoric monomer (2-HMPA) composed of 2-hydroxyethyl methacrylic phosphoric acid diester (50%) and monoester (50%) emulsified with the crosslinker. Hence, the formation of the three-dimensional IIP-Th crosslinked network and complexation between thorium (template) and 2-HMPA was investigated. The emulsion stability and particle size distribution of emulsion were determined using dynamic light scattering (DLS). Various factors influencing the synthesis of the thorium ion-imprinted (Th-IIP) non-woven PE/PP such as the absorbed radiation dose, monomer concentration, and type of crosslinker were investigated. The IIP-Th was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy–energy-dispersive X-ray (SEM–EDX), and X-ray photoelectron spectroscopy (XPS) and applied as an adsorbent for the removal of thorium using the batch adsorption method. The IIP-Th achieved a maximum distribution coefficient of 3.293 g/L and selectivity ratio (Th(IV)/U(VI)) of 9.5 after 90 min of contact time under acidic conditions. The adsorption kinetics of IIP-Th followed the pseudo-second-order kinetic model for both Th(IV) adsorption and U(VI) adsorption. The synthesized fibrous surface ion-imprinted polymer is a promising candidate for the selective removal of thorium ions from aqueous solution.

Fabrication of an efficient surface ion-imprinted polymer based on sandwich-like graphene oxide composite materials for fast and selective removal of lead ions

An efficient surface Pb(Ⅱ) ion-imprinted polymer based on sandwich-like graphene oxide composite materials (GO-IIP) was synthesized and characterized for studying the morphology and adsorption properties. Effects of preparation and adsorption conditions including solvent type, molar ratio of functional monomer to crosslinking agent, initiator dosage, pH, adsorbent dosage, contact time, ions concentration on the Pb(Ⅱ) removal were studied. Adsorption equilibrium was reached within 30 min and the adsorption process followed pseudo-second-order kinetic and Langmuir adsorption isotherm models, indicating chemisorption was the rate-limiting step. The maximum adsorption capacity of Pb(Ⅱ) ion-imprinted polymer was as high as 40.02 mg g−1 at 25 ℃, which was much higher than that of the non-imprinted polymer (20.45 mg g−1). The selectivity coefficient of Pb / Zn, Pb / Cd, Pb / Co, Pb / Ni and Pb / Ca were 20.12, 14.26, 31.67, 25.65 and 81.29, respectively, further confirming the satisfactory selectivity of GO-IIP. In addition, the prepared adsorbent could be reused 5 times without significant reduction of the adsorption capacity. Furthermore, an XPS spectra analysis was successfully applied to exploring the possible adsorption mechanism between Pb(Ⅱ) and GO-IIP, indicating that nitrogen atom in the amide bond of the functional monomer was the main coordination atom.

Selective Ce(III) ion-imprinted polymer grafted on Fe3O4 nanoparticles supported by SBA-15 mesopores microreactor via surface-initiated RAFT polymerization

Ce(III) ion-imprinted polymer (Ce(III)-IIP) grafted on Fe3O4 nanoparticles supported by SBA-15 mesopores microreactor was successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization for selective removal of Ce(III) from aqueous solution. The characterization results suggest that the surface ion-imprinted polymer (IIP) synthesized by RAFT is a thin layer. Adsorption isotherm experiments indicated that Redlich-Peterson isotherm model best fitted the experimental data and the adsorption capacity of IIP was obviously higher than that of non-imprinted polymers (NIP) at the same conditions. The kinetics of adsorption followed the Thomas model. Moreover, competitive adsorption studies illustrated that Ce(III)-IIP offers the advantages of selectivity towards Ce(III) compared with NIP even in the presence of other metal ions. All above results indicated the potential application of Ce(III)-IIP for selective removal of Ce(III) from aqueous solution.

Selective adsorption of Zn2+ on surface ion-imprinted polymer

A new type of Zn2+ ion-imprinted polymer (Zn2+-IIP) was synthesized on the surface of attapulgite, displaying high affinity and selectivity to Zn2+. Fourier transform infrared spectra (FTIR) revealed Zn2+-IIP to be an organic–inorganic hybrid polymer, with Zn2+ imprinted cavities formed by CTS groups and connected to the surface of the attapulgite by A-187 cross-linked network. The adsorption kinetic investigation showed that the adsorption of Zn2+on Zn2+-IIP was a pseudo-second-order process. The maximum adsorption capacities of Zn2+ were 0.536, 0.665, 0.715, and 0.722 meq/g at 288, 298, 308, and 318 K, respectively, where the activation energy, Ea, was evaluated as 23.8 kJ/mol. By thermodynamic study, ΔH° and ΔS° of the adsorption were determined as 30.862 kJ/mol and 108.664 J/mol K, respectively, while the negative ΔG° decreased with rising temperatures, indicating that the adsorption process was feasible and spontaneous. The adsorption selectivity of the Zn2+-IIP was also investigated via competitive adsorption of Zn2+, Cd2+, Cs+, Co2+, Ba2+, Sr2+, and Pb2+ from a mixture, demonstrating that Zn2+-IIP had the capability of recognizing Zn2+ with high affinity and selectivity. The study of multi adsorption–desorption cycles showed that the Zn2+-IIP can be reused many times without a significant decrease in the adsorption capacity.

Preparation and characterization of surface imprinted polymer for selective sorption of uranium(VI)

A new surface ion-imprinted polymer for the selective sorption of U(VI) from aqueous solution was prepared by copolymerization of a binary complex of U(VI) with methacrylic acid. The adsorption behavior of U(VI) onto the imprinted polymer was investigated by batch experiments and the results demonstrated that the maximum adsorption capacity of U(VI)-imprinted and non-imprinted polymers was found to be 35.92 and 22.58 mg g(-1), respectively. The selectivity study revealed that the U(VI)imprinted polymer exhibited excellent selectivity and affinity toward U(VI) in the presence of competitive metal ions.

Synthesis of hydrophilic surface ion-imprinted polymer based on graphene oxide for removal of strontium from aqueous solution

Scheme depicting the ion-imprinting process on GO surface by RAFT polymerization.

Synthesis and characterization of surface ion-imprinted polymer based on SiO2-coated graphene oxide for selective adsorption of uranium(vi)

A novel surface ion-imprinted polymer based on graphene oxide was synthesized for the selective adsorption of U(vi).

Synthesis and properties of cadmium(ii)-imprinted polymer supported by magnetic multi-walled carbon nanotubes

A novel magnetic surface ion-imprinted polymer was developed by copolymerization of magnetic multi-walled carbon nanotubes as the core, 3-aminopropyltriethoxysilane (APTES) as the functional monomer and tetraethoxysilane (TEOS) as the cross-linker with chelating complexes of Cd(II). The Cd(II)-imprinted polymer was characterized by FT-IR spectroscopy, scanning electron microscopy (SEM) and a batch procedure. Under the optimized conditions, the maximum adsorption of Cd(II) was 27.90 mg g−1 and the adsorption time was 70 min. The imprinted polymer showed higher selectivity for Cd(II) in comparison of the competitive adsorptions of Cd(II), Zn(II) and Cu(II) to the non-imprinted polymer. Relative selectivity factor (k′) values of Cd(II)/Zn(II) and Cd(II)/Cu(II) were 15.44 and 14.32, respectively. The new Cd(II)-imprinted polymer has been tested and applied for the separation and concentration of Cd(II) in tap water, with high recoveries ranging from 103.8% to 108.8%.

Synthesis and characterization of whisker surface imprinted polymer and selective solid-phase extraction of trace Sr(II) from environment aqueous solution

A novel surface ion-imprinted polymer (S-IIP) has been synthesized by surface ion-imprinting concept in the presence of sodium trititanate whisker, Sr(II), chitosan and γ-glycidoxypropyl trimethoxysilane (KH-560) for selective solid-phase extraction of trace Sr(II) from environment aqueous solution. Characterizations of S-IIP were achieved by infrared spectra and surface area measurement. S-IIP was used in the sorption–desorption process; the effect of solution pH, sorbent amount, and flow rate on the extraction of Sr(II) ions from aqueous solutions was investigated. The adsorption kinetics and isotherm were also obtained in detail. The dynamical study showed it was well followed the pseudo-second-order kinetic equation in the adsorption process. Meanwhile, the equilibrium adsorption studies showed that it very good fit the Langmuir isotherm equation for the monolayer adsorption process, and the maximum adsorption capacity was 32.60 mg/g. Selectivity experiments showed that S-IIP had a higher selectivity than non-imprinted polymer. The thermodynamic parameters (positive values ΔG°, ΔH°, and ΔS°) confirmed the non-spontaneous, endothermic, and entropy gained nature within the temperature range evaluated. The precision relative standard deviation and detection limit of this method were 0.93% and 0.30 μg/L, respectively, and it was successfully applied to the determination of trace Sr(II) in different wastewater samples with satisfactory results using inductively coupled plasma atomic emission spectrometry.

Preparation of a core–shell magnetic ion-imprinted polymer via a sol–gel process for selective extraction of Cu(ii) from herbal medicines

A novel magnetic surface ion-imprinted polymer (c-MMWCNTs-SiO2-IIP) was synthesized for the first time using magnetic CNTs/Fe3O4 composites (c-MMWCNTs) as the core, 3-ammonium propyltriethoxysilane (APTES) as the functional monomer, tetraethylorthosilicate (TEOS) as the cross-linker and Cu(II) as the template. c-MMWCNTs-SiO2-IIP was evaluated for selective extraction of Cu(II) from herbal medicines via a magnetic solid phase extraction (M-SPE) procedure. One factor affecting the separation and preconcentration of the target heavy metal was pH. Under the optimized experimental conditions, the adsorption kinetics and adsorption capacity of c-MMWCNTs-SiO2-IIP toward Cu(II) were estimated. The results indicated that the adsorption mechanism corresponds to a pseudo-second order adsorption process, with a correlation coefficient (R(2)) of 0.985 and a maximum adsorption capacity of 42.2 mg g(-1). The relative selectivity factor (β) values of Cu(II)/Zn(II) and Cu(II)/Pb(II) were 38.5 and 34.5, respectively. c-MMWCNTs-SiO2-IIP, combined with flame atomic absorption spectrometry, was successfully applied in the extraction and detection of Cu(II) in herbal medicine, with high recoveries ranging from 95.6% to 108.4%.

Solid Phase Extraction of Trace Cobalt(II) from Aqueous Solutions through Physicochemical Adsorption by Surface Ion-Imprinted Polymer

A novel surface ion-imprinted polymer (S-IIP) has been synthesized by surface ion-imprinting concept in the presence of sodium trititanate whisker, Sr(II), chitosan and γ-Glycidoxypropyl trimethoxysilane (KH-560) for selective solid-phase extraction (SPE) of trace Co(II) from aqueous solutions. Characterizations of S-IIP were achieved by FT-IR spectra, SEM and surface area measurement. Results showed that the adsorption of cobalt(II) onto S-IIP follows pseudo-second order kinetics and could be fitted by the Langmuir isotherm with the maximum adsorption capacity Q being 8.27 mg×g-1 at 25°C. Thermodynamic parameters including DHº, DGº andDSº were calculated and it is indicated that Co(II) adsorption on S-IIP is exothermic, spontaneous and physical adsorption reaction. Moreover, according to the dimensionless separation factor RL (RL<1) it indicates that it’s a highly favourable adsorption. Finally, the detection limit (3s) of 5.6 ng·mL-1with the relative standard deviation (RSD) for 1.0 μg×mL-1 cobalt(II) of 1.86% (n=10) were obtained.

Selective Adsorption of Co(II) Ions by Whisker Surface Ion‐Imprinted Polymer: Equilibrium and Kinetics Modeling

AbstractBased on sodium trititanate whisker as support particles, the surface ion‐imprinted polymer (S‐IIP) was synthesized for the selective adsorption of Co(II) ions from aqueous solution. Characterization of S‐IIP was achieved by FTIR spectra and SEM micrographs. Kinetic properties were successfully investigated by the pseudo‐first‐order model and pseudo‐second‐order model, and a chemisorption process as the essential adsorption step was also proposed. Equilibrium data were fitted with the Langmuir, Dubinin‐Radushkevich and Freundlich isotherm equations, and the maximum adsorption amount of monolayer saturation for S‐IIP was 33.75 mg/g at 298 K. Moreover, dimensionless separation factor RL (RL<1.0) indicated a highly favourable adsorption system between Co(II) ions and S‐IIP. Selectivity experiments showed that selective adsorption of Co(II) ions for S‐IIP was significantly higher than that of non‐imprinted polymer (NIP).