Carboxymethylated Polyethyleneimine Research Articles

A hyperbranched polymer synthetic strategy for the efficient fixation of metal species within nanoporous structures: Application in automotive catalysis

In the present study, a novel synthetic approach, called assisted impregnation technique, is described for the production of highly active Pd monometallic three-way catalysts supported on SBA-15. The assistance in this method originates from a hyperbranched polymer (carboxy-methylated polyethyleneimine, Trilon-P), able to entrap metal ions and therefore act as a metal binding agent due to its unique chemical and chelating properties. A series of Pd / SBA-15 samples with different Pd loadings, varying from 0.13 to 3 wt%, were produced. All the as-developed materials, evaluated under simulated exhaust conditions at the stoichiometric point, exhibit an excellent CO and HC oxidation performance, providing even very high CH4 conversions at low temperatures. However, material with 3 wt% Pd loading stands out affording complete NO reduction at 300 °C. The positive effect of the employed synthetic procedure is clearly demonstrated by comparing the latter sample with its counterpart derived from conventional dry impregnation technique. As deduced by a combination of techniques, assisted impregnation technique succeeds to deliver very small highly dispersed PdO nanoparticles uniformly distributed within SBA-15 porous network, through metal-polymer complex formation. The derived PdO nanoparticles demonstrate an average size ranging between 2.1 and 2.4 nm with tight distribution and pronounced stability considering the negligible aggregation and particle growth phenomena after the catalytic reaction. On the contrary when dry impregnation is employed the size of PdO nanoparticles undergoes a two-fold increase from approximately 3 to 6 nm upon exposure at automotive exhaust conditions.

Thermal Decomposition Behavior of a Chelating Resin Immobilizing Carboxymethylated Polyethyleneimine: Possibility of Estimation of Carboxymethylation Rate.

Chelating resins immobilizing carboxymethylated polyethyleneimine (CM-PEI) with different carboxymethylation rates were prepared. The thermal decomposition behavior of CM-PEI resins was investigated using thermogravimetry-differential thermal analysis/photo ionization-quadrupole mass spectrometry (TG-DTA/PI-QMS) and ion attachment ionization-quadrupole mass spectrometry equipped with direct inlet probe (DIP/IA-QMS). The obtained results suggested that the carboxymethyl group decomposed at relatively low temperature (150 °C - 300 °C); the peak areas at m/z 45 and 59 in TG-DTA/PI-QMS and m/z 58, 70, and 72 in DIP/IA-QMS significantly increased with increasing carboxymethylation rate. These relationships should be useful for estimating the carboxymethylation rate of CM-PEI resin.

Carboxymethylated polyethylenimine modified magnetic nanoparticles specifically for purification of His-tagged protein.

Employing immobilized metal-ion affinity chromatography and magnetic separation could ideally provide a useful analytical strategy for purifying His-tagged protein. In the current study, a facile route was designed to prepare CMPEI-Ni2+ @SiO2 @Fe3 O4 (CMPEI=carboxymethylated polyethyleneimine) magnetic nanoparticles composed of a strong magnetic core of Fe3 O4 and a Ni2+ -immobilized carboxymethylated polyethyleneimine coated outside shell, which was formed by electrostatic interactions between polyanionic electrolyte of carboxymethylated polyethyleneimine and positively charged surface of 3-(trimethoxysilyl)propylamin modified SiO2 @Fe3 O4 . The resulting CMPEI-Ni2+ @SiO2 @Fe3 O4 composite nanoparticles displayed well-uniform structure and high magnetic responsiveness. Hexa His-tagged peptides and purified His-tagged recombinant retinoid X receptor alpha were chosen as the model samples to evaluate the adsorption, capacity, and reusability of the composite nanoparticles. The results demonstrated the CMPEI-Ni2+ @SiO2 @Fe3 O4 nanoparticles possessed rapid adsorption, large capacity, and good recyclability. The obtained nanoparticles were further used to purify His-tagged protein in practical environment. It was found that the nanoparticles could selectively capture His-tagged recombinant retinoid X receptor protein from complex cell lysate. Owing to its easy synthesis, large binding capacity, and good reusability, the prepared CMPEI-Ni2+ @SiO2 @Fe3 O4 magnetic nanoparticles have great potential for application in biotechnological fields.

Chelating resin immobilizing carboxymethylated polyethyleneimine for selective solid-phase extraction of trace elements: Effect of the molecular weight of polyethyleneimine and its carboxymethylation rate

The effect of the molecular weight of polyethyleneimine (PEI), defined as a compound having two or more ethyleneamine units, and of its carboxymethylation rate (CM/N), represented by the ratio of ion-exchange capacity to the amount of N on the resin, on the selective solid-phase extraction ability of the chelating resin immobilizing carboxymethylated (CM) PEI was investigated. The chelating resins (24 types) were prepared by immobilization of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, PEI300 (MW=ca. 300), and PEI600 (MW=ca. 600) on methacrylate resins, followed by carboxymethylation with various amounts of sodium monochloroacetate. When resins with approximately the same CM/N ratio (0.242−0.271) were used, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, Zn, and alkaline earth elements increased with increasing the molecular weight of PEIs under acidic and weakly acidic conditions; however, the extraction behavior of Mo and V was only slightly affected. This was probably due to the increase in N content of the resin, resulting in an increase in carboxylic acid groups; the difference in the molecular weight of PEIs immobilized on the resin exerts an insignificant influence on the selective extraction ability. The CM/N ratio considerably affected the extraction behavior for various elements. Under acidic and neutral conditions, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn increased with increasing CM/N values. However, under these conditions, the recovery of alkaline earth elements was considerably low when a resin with low CM/N ratio was used. This is presumably attributed to the different stability constants of the complexes of these elements with aminocarboxylic acids and amines, and to the electrostatic repulsion between the elements and the protonated amino groups in the CM-PEI. The recovery of Mo and V decreased or varied with increasing CM/N values, suggesting that the extraction of these elements occurred mainly by the anion-exchange reaction. For the separation and preconcentration of trace elements in samples containing large amounts of alkali and alkaline earth elements, the CM-PEI600 resin with CM/N=0.131 (Cu(II) extraction capacity, 0.37mmolg−1) was found to be the most suitable because it scarcely extracts alkali and alkaline earth elements under acidic and neutral conditions. This resin proved to be convenient for separating and preconcentrating Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in the certified reference materials (EnviroMAT EU-L-1 wastewater and ES-L-1 ground water) and commercially available table salt.

Preparation and application of chelating polymer-mesoporous silica composite for Europium-ion adsorption

Ordered mesoporous silica (MCM-48) functionalized with a carboxymethylated polyethyleneimine (CMPEI) was prepared and applied to adsorb Eu(III) ions. The samples were characterized by SEM, TEM, XRD and N2 adsorption-desorption experiments. Adsorption studies of Eu(III) onto the MCM-48 and CMPEI-functionalized mesoporous silica, which are denoted as CMPEI/MCM-48, were performed by batch experiments. The adsorption of Eu(III) on the CMPEI/MCM-48 obeyed the Langmuir isotherm model. The CMPEI/MCM-48 exhibited much higher adsorption capacity at pH 3.0 to 5.0 compared to that of the pristine MCM-48. The Eu(III) adsorption of the CMPEI/MCM-48 increased with the pH. This was attributed mainly to a change in the chemical structure of CMPEI, which is strongly dependent on the solution pH. The XPS depth profiles showed that CMPEI was present on the mesopore walls inside the MCM-48 as well as on the surface of the particle, and further showed that a change in the Eu(III) content with etching time was not severe, indicating that the complexation of Eu(III) with CMPEI/MCM-48 occurred uniformly, even inside the CMPEI/MCM-48. The overall results showed that the mesopore surface of MCM-48 was functionalized successfully with CMPEI and the resulting CMPEI/MCM-48 could be used as a proper adsorbent for the recovery of trivalent actinide species. Open image in new window

Removal of uranium(VI) from aqueous solutions by nanoporous carbon and its chelating polymer composite

High surface area, ordered nanoporous carbon (CMK-3) and its chelating polymer composites were suc- cessfully prepared and utilized for the removal of U(VI) from aqueous solutions. Carboxymethylated polyethyl- eneimine (CMPEI) with a strong chelating property was introduced to the pore surface and inner pores of CMK-3 substrate. CMPEI-modified CMK-3 composite (CMPEI/ CMK-3) was characterized by scanning electron micros- copy and nitrogen sorption. U(VI) sorption capacity was significantly improved by the surface modification of CMK-3 by CMPEI. The CMPEI/CMK-3 showed enor- mously increased sorption capacities, compared with those of previous sorbents (e.g., surface-functionalized silicas). In particular, the CMPEI/CMK-3 showed a significantly high uranium retention property while allowing only about 1% U(VI) to leach out over a 4 month time period, when treated with polyacrylic acid.

Application of Ordered Nanoporous Silica for Removal of Uranium Ions from Aqueous Solutions

Ordered nanoporous silica (MSU-H) with high surface area has been utilized as a solid substrate of a surface-modified hybrid sorbent for the application to the removal of U(VI). Carboxymethylated polyethyleneimine (CMPEI) with a strong complexing property has been introduced to the pore surface of MSU-H substrate. CMPEI-modified MSU-H (CMPEI/MSU-H) has been characterized by scanning electron microscopy and nitrogen sorption. In a kinetic experiment for 12.5 ppm U(VI) solution at pH 4.0, 99% U(VI) was removed from solution by the hybrid sorbent within less than 10 min, indicating that the sorption of U(VI) on the CMPEI/MSU-H proceeds very rapidly. It was evident that a U(VI) sorption capacity increased with pH in the range of 2.0 to 4.0. The CMPEI/MSU-H showed a high sorption capacity of 153 mg/g-sorbent at pH 4.0. In particular, the CMPEI/MSU-H showed a significantly high uranium loading stability. Only about 1% U(VI) was released out of CMPEI/MSU-H during 4 months, when the CMPEI/MSU-H was treated with polyacrylic acid.

Preparation of polypyrrole-incorporated mesoporous carbon-based composites for confinement of Eu(iii) within mesopores

Mesoporous polymer-carbon composite (CMPEI/CMK-3) materials were successfully prepared by incorporation of a chelating polymer, carboxymethylated polyethyleneimine (CMPEI), into a mesoporous carbon (CMK-3) and for immobilization of Eu(III) ions, commonly used surrogates for radioactive Am(III) ions. After Eu(III) ions were loaded onto the CMPEI/CMK-3 composite, they were subsequently confined by incorporation of polypyrrole (ppy) into the mesopores of the composites. Ppy was prepared as soluble short-chain polymers using NO+ ions as oxidizing agents in a mildly acidic solution. These polymer chains were easily adsorbed on the walls of Eu-CMPEI/CMK-3 composites, efficiently immobilizing the Eu(III) ions. The use of a metal-free oxidizing agent, NO+, in mildly acidic conditions (pH 6) ensured the minimal loss of Eu(III) ions from the composites during polymerization. The resulting ppy/Eu-CMPEI/CMK-3 composites were characterized by electron microscopy, X-ray diffraction and N2 sorption analysis. The results from these characterizations commonly supported the conclusion that ppy was incorporated into the mesopores of the composites, altering the mesoporous features and reducing the pore volumes of the CMK-3 supports. Eu(III)-leaching tests showed that the presence of ppy layers in the composites could significantly improve the retention of Eu(III) ions. This study demonstrated that chelating polymer-based composites can be used for removal and long-term confinement of radioactive actinide species by properly optimizing polymer incorporation processes.

Preparation and application of chelating polymer–mesoporous carbon composite for copper-ion adsorption

A mesoporous carbon material, CMK-1 was successfully functionalized with carboxymethylated polyethyleneimine (CMPEI) by a simple adsorption method. The physicochemical properties of the polymer–carbon composite (denoted as CMPEI/CMK-1) were investigated by X-ray diffraction, N 2 adsorption–desorption and X-ray photoelectron spectroscopy (XPS). The adsorption behaviors of Cu(II) ion on the CMK-1 and CMPEI/CMK-1 materials were examined under the batch-type experimental conditions. The CMPEI/CMK-1 material showed a typical Langmuir isotherm with a 10-fold increase in adsorption capacity, compared to that of CMK-1. In the case of 0.02 mM Cu(II) solution, the copper ions were completely removed by utilizing the CMPEI/CMK-1 material both at pH values of 3 and 5. The CMPEI/CMK-1 material also exhibited a remarkably high distribution coefficient value ( K d = 2.75 × 10 5). The results from XPS depth profiles before and after the copper-ion adsorption indicated that the CMPEI and the adsorbed Cu(II) ions were uniformly distributed within the CMK-1 particles.

Adsorption Characteristics of Uranyl Ions on Carboxymethylated Polyethyleneimine (CM-PEI) / Activated Carbon Composites

We present the adsorption characteristics of uranyl ions on a new and innovative composite which was composed of a carboxymethylated polyethyleneimine (CM-PEI) and an activated carbon (F400) with a nanopore less than 2 nm in diameter. In this study, we examined the adsorption phenomena of uranyl ions on the CM-PEI/F400 composite and evaluated the adsorption data using various isotherm models. It was found that the adsorption of uranyl ions on the CM-PEI/F400 composite obeys the Langmuir isotherm model. In addition, it was observed that pH of solutions had great influence on the adsorption capacity of uranyl ions on the CM-PEI/F400 composite. Specially, the adsorption capacity of uranyl ions was linearly increased with an increase of pH at pH > 3.0.

Pt(IV) Adsorption Characteristics of Nanoporous Carbons Modified with Carboxymethylated Polyethyleneimine

In this study, we modified the surface of nanoporous carbons with carboxymethylated polyethyleneimine (CM-PEI) of a high charge density in order to increase the Pt loading on the nanoporous carbons in an aqueous solution. We carried out equilibrium adsorption tests of Pt(IV) on the pure nanoporous carbon and the CM-PEI-coated carbons and evaluated the adsorption isotherm on the CM-PEI-coated carbon using various isotherm models. It was found that the adsorption of Pt(IV) onto the CM-PEI-coated carbons obeys the Langmuir isotherm model.

Preparation of functionalized nanoporous carbons for uranium loading

Ordered nanoporous carbons (CMK-3) with submicron-scale particle size were functionalized with carboxymethylated polyethyleneimine (CMPEI) as a new uranium loading material to increase uranium adsorption capacity, and characterized by Fourier transform-infrared spectroscopy (FT-IR) and powder X-ray diffraction (XRD). The adsorption isotherm of uranyl ions on the functionalized carbons was examined and evaluated using the Langmuir adsorption isotherm model. It was found that the adsorption of uranyl ions on the functionalized carbons follows the Langmuir isotherm model. The maximum uranium adsorption capacity of the adsorbent by the Langmuir model was calculated to be 151.5mgU/g adsorbent. The loading stability of uranium on the adsorbent was examined at pH 4. It was observed that about 30% of uranium was released from CMPEI/CMK-3 within a day, however, uranium contents almost linearly decreased with a low desorption rate from 1 to 20 days.

Application of polymer-modified nanoporous silica to adsorbents of uranyl ions

The surface modification of nanoporous silicas (MSU-H) of submicron-scale particle size with polyethyleneimine (PEI), polyacrylic acid (PAA), and carboxymethylated polyethyleneimine (CMPEI) was carried out for the extraction of uranyl ions. Adsorption behaviors of uranyl ions onto the polymer-modified silicas, denoted as PEI/MSU-H, PAA/MSU-H and CMPEI/MSU-H, were examined in batch experiments. In 0.05mM UO22+ solution, it was found that the nearly complete removal of uranyl ions can be achieved by the CMPEI-modified MSU-H (CMPEI/MSU-H). Especially, the CMPEI/MSU-H exhibited significantly high distribution coefficient value (Kd=2.30×106). In concentrated UO22+ solution (ca. 1mM), uranium-uptake capacities onto the three polymer-modified nanoporous silicas were in the following order: CMPEI/MSU-H>PAA/MSU-H>PEI/MSU-H. It is noteworthy that CMPEI/MSU-H showed excellent uranium-uptake capacity (124mg-U/g-adsorbent), based on the total weight of polymer and silica. In addition, the loading stability of uranium on the adsorbent was examined with time. It was observed that about 15% of uranium was discharged from CMPEI/MSU-H in a day and additional 5% uranium was released with a relatively slow desorption rate in 12 days.

Adsorption of Carboxymethylated Polyethyleneimine (CM-PEI) on a Microporous Activated Carbon

We applied a polymer-based surface modification technique to the surface treatment of a microporous activated carbon. We used a new chelating polymer, carboxymethylated polyethyleneimine (CM-PEI), as a functional polymer to modify the carbon surface. In this study, we examined the adsorption phenomena of the CM-PEI on an activated carbon with a nanopore less than 2 nm in diameter and evaluated the adsorption mechanism using three kinds of models; Langmuir, Freundlich, and Redlich-Peterson isotherm. It was found that the adsorption of CM-PEI on the F400 follows the Freundlich isotherm model. Furthermore, desorption experiments of the CM-PEI were carried out to examine the stability of the CM-PEI adsorption on the F400 and to estimate the applicability of the CM-PEI-coated F400 to the adsorbents. It was observed that most of the CM-PEI remains on the F400 for 7 days in the pH range of 3 to 7. Especially, the adsorption amount of CM-PEI on the F400 did not change after 3 days at the pH range of 5 to 7, indicating that the CM-PEI strongly adheres to the F400.

Preparation and Cu(II) Complexation Characteristics of Carboxymethylated Polyethyleneimine (CM-PEI) / Microporous Activated Carbon Composite

We present the preparation and Cu(II) adsorption characteristics of a new and innovative composite which was composed of a carboxymethylated polyethyleneimine (CM-PEI) and an activated carbon with a nanopore less than 2 nm in diameter. In this study, we examined the adsorption phenomena of Cu(II) on the CM-PEI/F400 composite and evaluated the adsorption data using three kinds of isotherm models (Langmuir, Freundlich, and Temkin isotherms). It was found that the adsorption of Cu(II) on the CM-PEI/F400 composite obeys the Langmuir isotherm model. Furthermore, The Cu element mapping results showed that Cu was well distributed throughout all the surface of the composite particle, suggesting that the surface of the F400 particle was uniformly covered with CM-PEI.