Ion Imprinted Polymer Materials Research Articles

Synthesis and Characterization of Adsorbent Materials Magnetite Mercaptosilicate Ion Imprinted Polymer as Cadmium Ion Adsorbent

Cadmium (Cd) is a toxic heavy metal with the active property of reacting with other components so that cadmium residues can quickly enter the food chain and cause cardiovascular, kidney, and cancer diseases. The purpose was to synthesize the magnetite mercaptosilicate ion imprinted polymer adsorbent material by forming Ion-Imprinted Polymer as a template, to analyze the characterization results using XRD and SEM-EDS, and to determine the adsorption test results for Cd metal ions. The results of the characterization of XRD show that there is a broad peak at a diffraction angle of 2θ= 20-220 with an amorphous structure, which is silica, and there is a high peak at a diffraction angle of 2θ= 35.55140 which indicates magnetite. The results of SEM analysis with magnifications of 500x, 1000x, and 5000x showed that the surface morphology of the particles was not uniform. For the EDS results, it can be seen that the components of the magnetite mercaptosilicate ion imprinted polymer material are elements C, O, Si, S, and Fe, with a mass percentage of 25.0%; 41.2%; 29.9%; 3.28% and 0.8%. The results of the adsorption test for the Magnetite-IIP-Mercaptosilika Material were able to adsorb Cd ions with the highest adsorption capacity of 10.536 mg/g at a concentration of 100 mg/L. Then the selectivity coefficient value of the Ion Cd metal ion is 2.32 greater than 1, indicating that the selectivity of the magnetite mercaptosilicate ion imprinted polymer material is much higher for Ion Cd metal ions than for Cu and Cr ions with a selectivity coefficient of 0.1 and 0.26.

Synthesis of a magnetic crown ether ion imprinted polymer material for the selective adsorption of lithium

OS@FeSi@CE-OH has specific recognition ability for Li+and solves the problems of difficult separation and recovery of powder adsorbent.

Synthesis of Ion-imprinted materials with amidoxime groups for enhanced UO22+ adsorption

Ion imprinted polymer (IIP) of mesoporous nature was prepared for uranyl ion (template) in two steps:(i) by formation of ternary (benzamidoxime (BAOX) and 4-vinylpyridine) complex in 2-methoxy ethanol as porogen and (ii) by thermally copolymerizing them with methacrylic acid (MAA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinking monomer using 2,2′-azobisisobutyronitrile as initiator. The imprinted particles were leached by HCl 2 mol L−1 to obtain leached materials which then remove uranyl ions selectively from aqueous solutions. Non-imprinted polymer (NIP) was also similarly prepared under identical experimental conditions exactly as the IIP but in the absence of template ions.The above synthesized IIP (both unleached and leached) and NIP materials were characterized by using SEM, FT-IR, UV–Vis and BET-surface area and pore size analysis. The optimal pH for quantitative removal is 6.0 and the IIP materials offered either higher or comparable retention capacity 125 mg g−1 (C0 = 100 mg L−1) with respect to most of the hitherto prepared uranyl IIP materials. Further, the imprinting and amidoxime groups effect was noticed in the experimental variables and selectivity characteristics.

A novel non-imprinted adsorbent with superior selectivity towards high-performance capture of Ag(I)

Ion imprinted polymer (IIP) technology is traditionally used to selectively recover heavy metal ions from wastewater, but the low adsorption capacity and high cost has restricted its large-scale practical application. Exploring a novel method with high selectivity and low cost to capture heavy metals is necessary but very challenging. Herein, we first report a highly selective and high-performance absorbent via free radical polymerization of thiolactone functionalized acrylamide (named as PAM-TL). The PAM-TL demonstrated much higher capacity (145.2 mg/g) for Ag(I), which is 5.8 times that of corresponding IIP (25.07 mg/g). Moreover, the distribution coefficient of PAM-TL (576.1) was 5.1 times that of the IIP material (113.8). Furthermore, PAM-TL absorbent was also equipped with superior stability and recyclability (outstanding adsorption performance after six cycles). The excellent performance was attributed to the abundant binding site density and the strong interaction between absorbent and Ag(I), which was determined by X-ray photoelectron spectroscopy and elemental analysis. This work provides a novel approach for highly effective and selective capturing heavy metal ions, which is of great significance to actual applications in wastewater treatment.

Effect of porogen solvent on the properties of nickel ion imprinted polymer materials prepared by inverse suspension polymerization

Ion-imprinted polymers (IIPs) for nickel were synthesized by inverse suspension copolymerization of vinylbenzyl iminodiacetic acid (VbIDA) with ethyleneglycol dimethacrylate (EDMA) in the presence of nickel(II) ions with various porogen solvents to study their impact on the IIPs properties. They were prepared with mixtures of acetonitrile and dimethylsulfoxide (DMSO), 50/50%v/v, for IIP-A/D and 2-methoxyethanol and DMSO, 50/50%v/v, for IIP-M/D. The structure and properties of these polymers were compared with those of IIP-D previously prepared with pure DMSO as porogen solvent. Although IIP-A/D and IIP-M/D were less porous than IIP-D, they presented better nickel adsorption properties and selectivity towards Zn2+, Co2+ and Pb2+. This is assumed to be the result of the stabilization of the ligand-metal complex during the polymerization process. Moreover, the nickel binding capacities of the prepared IIPs in competitive conditions are remarkably high (184μmol/g for IIP-D, 170μmol/g for IIP-A/D and 174μmol/g for IIP-M/D). The impact of the VbIDA chelating monomer was highlighted by comparing the adsorption properties of a copolymer of methyl methacrylate (MMA) and EDMA with NIP-D. It was proved that the methacrylic polymer matrix has low binding properties.

Highly selective solid phase extraction of mercury ion based on novel ion imprinted polymer and its application to water and fish samples

A novel ion imprinted polymer (IIP) material has been synthesized for mercury ion. The IIP material is applied to the solid phase extraction (SPE) of Hg2+ from complex matrixes including water and fish samples. The IIP-SPE method is operated prior to cold vapor atomic absorption spectroscopy (CV-AAS) to determine mercury ion. In the polymer synthesis, mercury ion, 2-vinylpyridine, ethyleneglycol dimethacrylate and 2,2′-azobisisobutyronitrile are used as target, Hg2+ complexing reagent monomer, cross-linker and initiator, respectively. The polymer is characterized on the basis of FT-IR and thermal analysis (thermogravimetric, TGA; differential thermic, DTA; and differential scanning calorimetry, DSC). The obtained polymer block is ground, sieved and Hg2+ ions are removed from polymer particles by leaching with EDTA, which leaves a cavity in the polymer particles. The maximum Hg2+ adsorption capacity of IIP is 24.6 mg/g. Effective parameters on retaining Hg2+ such as pH, flow rate of sample and eluent, nature of the eluent, ionic strength, selectivity coefficient and retention capacity are investigated. The detection limit and the relative standard deviation are 5 × 10−4 ng/mL and 2.4%, respectively. After 20 adsorption cycles, the recovery of Hg2+ on IIP is only decreased by 3.2%. The column selective adsorption experiments of Na+, Cu2+, Pb2+, Cd2+, Ca2+ and Mg2+ ions with respect to mercury are conducted by using imprinted and non-imprinted polymer. These results showed that the IIP is highly selective for Hg2+ over the other metals.

Simple and efficient ion imprinted polymer for recovery of uranium from environmental samples

Ion imprinted polymer material (IIP) was prepared by forming ternary complexes of uranyl imprint ion with 1-(prop-2-en-1-yl)-4-(pyridin-2-ylmethyl)piperazine and methacrylic acid followed by thermal copolymerization with ethylene glycol dimethacrylate as the cross-linking monomer in the presence of 1,1'-azobis(cyclohexanecarbonitrile) initiator and 2-methoxy ethanol porogenic solvent. HCl solution (5 mol/L) was used to leach out the uranyl template ion from the IIP particles. Similarly, the control polymer (CP) material was also prepared exactly under the same conditions as the IIP but without the uranyl ion template. Various parameters such as solution pH, initial concentration, aqueous phase volume, sorbent dosage, contact time and leaching solution volumes were investigated. SEM, IR and BET-surface area and pore size analysis were used for the characterization of IIP and CP materials. The extraction efficiency of the IIP and CP was compared using a batch and SPE mode of extraction. The optimal pH for quantitative removal is 4.0-8.0, sorbent amount is 20 mg, contact time is 20 min and the retention capacity is 120 mg of uranyl ion per g of IIP. The IIP prepared demonstrated superior selectivity towards coexisting cations and therefore it can be used for selective removal of uranium from complex matrices.

Synthesis, Characterization and Selective Recognition of Lead Using a New Ion Imprinted Polymer Material

A new ion-imprinted polymer (IIP) material was synthesized by copolymerization of 4-vinylpyridine(VP) as monomer, ethylene glycol dimethacrylate(EGDMA) as crosslinking agent and 2,2΄-azobisisobutyronitrile(AIBN) as initiator in the presence of Pb–1,5-diphenylcarbazone(Pb-DHCB) complex. Blank non-imprinted polymer (NIP) were prepared under identical conditions without the use of lead imprint ion. The synthesized polymers were characterized by IR spectroscopy and elemental analyzer techniques. Of the several polymers synthesized, only the imprinted polymer formed with binary complex of Pb2+–DHCB showed quantitative enrichment of lead ion from aqueous solution. The relative standard deviation of the five replicate determinations of Pb (II) was3.26%. The detection limit for 150 mL of sample was 1.6 µg L-1 using flame atomic absorption spectrometry. The developed method was successfully applied to the determination of trace lead in environmental samples with satisfactory results.

Synthesis of a New Ion Imprinted Polymer Material for Separation and Preconcentration of Traces of Neodymium Ions

Neodymium ion imprinted polymers (IIP) were synthesized by formation of ternary complexes of neodymium ion with Vanillin Benzidine(VLB) and 4-vinylpyridine (VP) as chelating agent following copolymerizing with styrene as func­tional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linking monomer using 2,2´-azobisisobutyronitrile as initiator. Control polymers（CPs） were prepared under identical conditions without the use of neodymium imprint ion. The synthesized polymers were characterized by IR spectroscopy and elemental analyzer techniques. Of the several polymers synthesized, only the imprinted polymer formed with ternary complex of Nd3+–VLB–VP(1:1:2 IIP) showed quantitative enrichment of neodymium ion from aqueous solution.

Synthesis and characterization of new ion-imprinted polymer for separation and preconcentration of uranyl (UO22+) ions

UO(2)(2+) ion-imprinted polymer materials used for solid-phase extraction were prepared by copolymerization of a ternary complex of uranyl ions with styrene and divinyl benzene in the presence of 2,2'-azobisisobutyronitrile. The imprinted particles were leached by HCl 6M. Various parameters in polymerization steps such as DVB/STY ratio, time of polymerization and temperature of polymerization were varied to achieve the most efficient uranyl-imprinted polymer. X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA), UV-vis and nitrogen sorption were used to characterize the polymer particles. The XRD results showed that uranyl ions were completely removed from the polymer after leaching process. IR Analysis indicated that the N,N'-ethylenebis(pyridoxylideneiminato) remained intact in the polymer even after leaching. Some parameters such as pH, weight of the polymer, elution time, eluent volume and aqueous phase volume which affects the efficiency of the polymer were studied.

Removal of uranium from mining industry feed simulant solutions using trapped amidoxime functionality within a mesoporous imprinted polymer material

Ion imprinted polymer (IIP) material of mesoporous nature was prepared in two steps: (i) by forming binary/ternary complexes of uranyl imprint ion with a suitable non-vinylated uranophile, formamidoxime and/or vinylated ligand, 4-vinyl pyridine (VP) and (ii) by thermally copolymerizing them with 2-hydroxy ethyl methacrylate (HEMA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linking monomer in presence of 2,2′-azobisisobutyronitrile as initiator and 2-methoxy ethanol as porogen. The IIP material formed was subsequently leached with 50% (v/v) HCl to obtain leached materials which then rebind uranyl ions selectively from aqueous solutions. Corresponding non-imprinted polymer (NIP) materials were also prepared under the same conditions exactly as the IIP but in the absence of the uranyl ion template. Extensive characterization of IIP (both unleached and leached) and NIP materials were done using SEM, XPS, EDS, IR and BET-surface area and pore size analysis. The optimal pH for quantitative removal is 8.0–9.0 and the IIP materials offered either higher or comparable retention capacity 80.0 μmol of uranyl ion per g of polymer with respect to most of the hitherto prepared uranyl IIP materials. In addition, the imprinting effect was noticed in all the experimental variables and selectivity characteristics. The applicability of IIP material for the removal of emerging toxic pollutant uranium from uranium mining industry feed simulant solution is successfully demonstrated.

Design of two-dimensional biomimetic uranyl optrode and its application to the analysis of natural waters

A two-dimensional biomimetic optrode for the detection and quantification of uranium in natural waters was fabricated. The sensing element was designed by the inclusion of uranyl ion imprinted polymer particles into polymethyl methacrylate followed by casting a thin film on a glass slide without any plasticizer. The ion imprinted polymer material was prepared via covalent immobilization of the newly synthesised ligand 4-vinyl phenylazo-2-naphthol by thermal polymerization. Operational parameters such as pH, response time and the amount of sensing material were optimized. The response characteristics of the imprinted and the corresponding non-imprinted polymer inclusion optrodes of uranium were compared under optimum conditions. The imprinted polymer inclusion optrode responds linearly to uranium in the concentration range 0–1.0 μg mL −1 with a detection limit of 0.18 μg mL −1, which is much better than the solution studies using 4-vinyl phenylazo-2-naphthol (1.5 μg mL −1). Triplicate determinations of 100 μg of uranium(VI) present in 250 mL of solution gave a mean absorbance of 0.018 with a relative standard deviation of 8.33%. The superior sensitivity of imprinted polymer inclusion optrode is exemplified by lower detection limits and broader dynamic range over non-imprinted polymer inclusion optrode. The developed imprinted polymer inclusion optrode was found to give stable and precise response for 3 months and can be used without any loss in sensitivity. The applicability for analysing ground, lake and tap-water samples collected in the vicinity of uranium deposits was successfully demonstrated.

Synthesis of Zn(II) ion-imprinted solid-phase extraction material and its analytical application

Zn(II) ion-imprinted polymer materials used for solid-phase extraction (SPE) column were prepared by the copolymerization of 8-acryloyloxyquinoline (8-AOQ) monomer and a crosslinker ethylene glycol dimethacrylate (EGDMA) in the presence of 2,2′-azobisisobutyronitrile (AIBN) as an initiator. After removing Zn(II) ion from the polymer, molecularly imprinted polymers (MIPs) capable of selectively rebinding Zn(II) ion were obtained. The maximum adsorption capacity of Zn(II) on MIPs beads was about 3.9 mg g −1. The effect of pH and flow rate for quantitative enrichment was also investigated. The Zn(II)-imprinted microbeads have a greater affinity for Zn(II) with respect to Cu(II), Co(II) and Ni(II) ions. A detection limit of 0.65 μg L −1(3 σ) and a relative standard deviation (R.S.D., n = 7) of 2.9% were obtained. The MIPs–SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.65 to 130 μg L −1. Zn(II) ion-imprinted beads enabled the selective extraction of zinc ions from a complex matrix, and after 20 times of adsorption and desorption cycle, the recovery of adsorption capacity of Zn(II) on MIPs beads was only decreased 3.2%. The results suggested that these MIPs can be used several times without considerable loss of adsorption capacity.

Synthesis of a new ion imprinted polymer material for separation and preconcentration of traces of uranyl ions

Uranyl ion imprinted polymers (IIPs) were synthesized by formation of ternary or binary complexes of uranyl ion ( UO 2 2 + ) with Piroxicam (Pir) and 4-vinylpyridine (VP) as chelating agent following copolymerizing with styrene as functional monomer and divinylbenzene (DVB) or ethyleneglycoldimethyl methacrylate (EGDMA) as cross-linking monomer using 2,2′-azobisisobutyronitrile as initiator. Control polymers (CPs) were prepared under identical conditions without the use of uranyl imprint ion. The synthesized polymers were characterized by IR spectroscopy, X-ray diffraction and thermal analysis techniques. Of the several polymers synthesized, the imprinted polymer formed with ternary complex of UO 2 2 + -Pir – VP (1:2:2;IIP1) showed quantitative enrichment of uranyl ion from aqueous solution. Then various parameters that affect the preconcentration were optimized in both batch and column methods. The percent enrichment and retention capacity of IIP1 for UO 2 2 + was found to be 98% and 38.58 mg g −1, respectively. The proposed IIP1 was tested for preconcentration of uranyl ion from ground water and sea water samples.

Removal of Toxic Uranium from Synthetic Nuclear Power Reactor Effluents Using Uranyl Ion Imprinted Polymer Particles

Major quantities of uranium find use as nuclear fuel in nuclear power reactors. In view of the extreme toxicity of uranium and consequent stringent limits fixed by WHO and various national governments, it is essential to remove uranium from nuclear power reactor effluents before discharge into environment. Ion imprinted polymer (IIP) materials have traditionally been used for the recovery of uranium from dilute aqueous solutions prior to detection or from seawater. We now describe the use of IIP materials for selective removal of uranium from a typical synthetic nuclear power reactor effluent. The IIP materials were prepared for uranyl ion (imprint ion) by forming binary salicylaldoxime (SALO) or 4-vinylpyridine (VP) or ternary SALO-VP complexes in 2-methoxyethanol (porogen) and copolymerizing in the presence of styrene (monomer), divinylbenzene (cross-linking monomer), and 2,2'-azobisisobutyronitrile (initiator). The resulting materials were then ground and sieved to obtain unleached polymer particles. Leached IIP particles were obtained by leaching the imprint ions with 6.0 M HCl. Control polymer particles were also prepared analogously without the imprint ion. The IIP particles obtained with ternary complex alone gave quantitative removal of uranyl ion in the pH range 3.5-5.0 with as low as 0.08 g. The retention capacity of uranyl IIP particles was found to be 98.50 mg/g of polymer. The present study successfully demonstrates the feasibility of removing uranyl ions selectively in the range 5 microg - 300 mg present in 500 mL of synthetic nuclear power reactor effluent containing a host of other inorganic species.

Investigation of different polymerization methods on the analytical performance of palladium(II) ion imprinted polymer materials

Palladium(II) ion imprinted polymer (IIP) materials were prepared via bulk, precipitation and suspension polymerization methods using similar compositions. In these polymerization methods, the polymerization mixture consists of a ternary complex of palladium(II) imprint ion with 8-aminoquinoline (AQ), 4-vinyl pyridine (VP, monomer), 2-hydroxyethyl methacrylate (HEMA, functional monomer), ethylene glycoldimethacrylate (EGDMA, cross-linking monomer), 2,2′-azobisisobutyronitrile (AIBN, initiator) and 2-methoxy ethanol (Porogen). Various polymerization methods were carried out by thermal means and IIP materials thus obtained were leached with 50% (v/v) HCl to obtain leached IIP particles. Control polymer (CP) particles were similarly prepared by all the three polymerization methods. The above synthesized polymer particles were characterized physically and morphologically by using FTIR, TGA, CHN, X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques. Furthermore, their capacity to rebind palladium(II) was investigated from dilute aqueous solutions and in presence of selected precious and transition elements (which are known to coexist with palladium in its mineral deposits). The rebinding studies of IIP particles obtained via bulk, precipitation and suspension methods reveal that (i) percent enrichment is quantitative with bulk and precipitation, and ∼72% only in case of suspension; (ii) retention capacities are 28.82, 20.16 and 18.76 mg palladium(II)/g materials, respectively; (iii) selectivity for palladium(II) over other noble and transition elements lies in the order bulk ∼ precipitation > emulsion. Moreover, the IIP particles obtained by all three polymerization methods exhibit imprinting effect when compared with respective CP particles.

Effect of Porogen Type on the Synthesis of Uranium Ion Imprinted Polymer Materials for the Preconcentration/Separation of Traces of Uranium

Ion Imprinted Polymer (IIP) materials were prepared from different porogens by copolymerization of UO22+-5,7,dichloroquinoline-8-ol-4-vinylpyridine ternary complex in the presence of styrene as monomer, divinyl benzene as crosslinking agent and 2,2′-azobisisobutyronitrile as initiator. The uranyl ion was removed on leaching with 50% (v/v) HCl, which leaves cavities in the polymer particles. Of the various porogens tested, 2-methoxy ethanol gave a higher retention/adsorption capacity for uranium and better selectivity for uranium over thorium. The optimum pH value for quantitative enrichment is 5.0–7.0, and desorption can be achieved with 5 mL of 1 M HCl. The retention capacity of the uranyl ion imprinted polymer particles was found to be 34.0 mg g−1 for uranium, which is much higher than blank or ion recognition polymer. More significantly, the selectivity coefficient (SU/Th) is much higher (∼99.0) with 2-methoxy ethanol as porogen. The polymer particles obtained from this porogen have been characterized by IR, TGA, DTA, XRD, SEM and EDS analysis. Five replicate determinations of 40 µg of uranyl ion present in 1000 mL of aqueous solution with Arsenazo III spectrophotometric method gave a mean absorbance of 0.185 with a relative standard deviation of 2.46%. The detection limit corresponding to 3 times the standard deviation of the blank was found to be 2 ng mL−1.

Influence of binary/ternary complex of imprint ion on the preconcentration of uranium(VI) using ion imprinted polymer materials

Ion imprinted polymer (IIP) materials were prepared for uranyl ion (imprint ion) by forming binary (5,7-dichloroquinoline-8-ol (DCQ) or 4-vinylpyridine (VP)) or ternary (5,7-dichloroquinoline-8-ol and 4-vinylpyridine) complexes in 2-methoxy ethanol (porogen) and copolymerizing in the presence of styrene and divinyl benzene as functional and crosslinking monomers, respectively and 2,2′-azobisisobutyronitrile as initiator. IIP particles were obtained by leaching the imprint ion in these polymer materials with 50% (v/v) hydrochloric acid, filtering, drying in an oven at 50 °C and grinding. Control polymer particles were also prepared under identical conditions. The above synthesized polymer particles were characterized by IR, CHN, X-ray diffraction, and pore size analyses. These leached polymer particles can now pick up uranyl ions from dilute aqueous solutions. The IIP particles obtained with ternary complex of uranyl ion alone gave quantitative enrichment of traces of uranyl ions from dilute aqueous solutions. The optimal pH for quantitative enrichment is 4.5–7.5 and eluted completely with 10 ml of 1.0 M HCl. The retention capacity of uranyl IIP particles was found to be 34.05 mg of uranyl ion per gram of polymer. Further, the percent extraction, distribution ratio, and selectivity coefficients of uranium and other selected inorganic ions were also evaluated. Five replicate determinations of 25 μg of uranium present in 1.0 l of aqueous solution gave a mean absorbance of 0.036 with a relative standard deviation of 2.50%. The detection limit corresponding to three times the standard deviation of the blank was found to be 5 μg l −1.