Adsorption characteristics of Cr(III) ionic imprinting polyamine on silica gel surface

In this paper, a kind of ionic imprinting polyamine (IIP) was prepared through an advanced approach. Firstly, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles, and the PEI/SiO₂ was formed. Secondly, the ionic imprinting process was carried out using Cr³⁺ ion as a template, and epichlorohydrin (ECH) as a crosslinking agent, and Cr³⁺ ionic imprinting polyamine IIP-PEI/SiO₂ was prepared. The adsorption properties of IIP-PEI/SiO₂ for Cr³⁺ ion were studied in details by adopting both static and dynamic methods, and the effects of main imprinting conditions, such as the concentrations of Cr(III) ion and the amount of ECH, on the adsorption property of the imprinted material IIP-PEI/SiO₂ were examined. The experimental results show that the IIP-PEI/SiO₂ has high affinity and excellent selectivity for the template ion. Its adsorption amounts for template ion enhances nearly two times compared to PEI/SiO₂, and its relative selectivity coefficients relative to Zn²⁺ and Pb²⁺ are 24.63 and 59.32 respectively. Besides, the IIP-PEI/SiO₂ has a fine elution property using HCl solution as eluent.     

Effective removal of Fe(II) impurity from rare earth solution using surface imprinted polymer

Rare earth is a very important resource. But, impurities, such as Fe²⁺, have great influence on the properties of rare earth material. In this paper, a novel Fe²⁺-ionic imprinted polyamine functionalized silica gel adsorbent was prepared by a surface imprinting technique for selective adsorption of Fe²⁺ from rare earth solution. Firstly, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles, and the PEI/SiO₂ was formed. Secondly, the ionic imprinting process was carried out using Fe²⁺ ion as a template, and Cr³⁺ ionic imprinting polyamine IIP-PEI/SiO₂ was prepared. The adsorption and recognition properties of IIP-PEI/SiO₂ for Fe²⁺ were studied in detail, and the effects of main imprinting conditions, such as the amount of crosslinking agent and reaction time, on the adsorption property of the imprinted material IIP-PEI/SiO₂ were examined. The experimental results showed that the IIP-PEI/SiO₂ possesses strong adsorption affinity, specific recognition ability, and excellent selectivity for Fe²⁺. The adsorption capacity could reach to 0.334 mmol g⁻¹, and relative selectivity coefficients to Pr³⁺ and Ce³⁺ are 23.25 and 18.42, respectively. Besides, the IIP-PEI/SiO₂ was regenerated easily using diluted hydrochloric acid solution as eluent and IIP-PEI/SiO₂ possesses better reusability.     

Adsorption and recognition properties of ionic imprinted polyamine IIP‐PEI/SiO2 towards Pb2+ ion

In this article, an ionic imprinted polyamine (IIP) grafted on the surface of silica gel was prepared through a new surface imprinting approach. The adsorption and recognition properties of IIP‐PEI/SiO₂ for Pb²⁺ ion were studied in detail using batch rebinding studies. The experimental results showed that the IIP‐PEI/SiO₂ had high affinity, specificity, and selectivity for the template ion. The isothermal adsorption data was fit using the Langmuir equation. The adsorption was typical of chemisorption of a monolayer. The selectivity coefficients relative to Zn²⁺ and Cr³⁺ were 32.43 and 68.36, respectively. pH and temperature were found to have a strong influence on the adsorption properties. The adsorption amount increases with rising of temperature and the value of ΔH is plus. The adsorption of Pb²⁺ by IIP‐PEI/SiO₂ was spontaneous and endothermic. At pH = 7, the adsorption capacity of the polymers was the highest. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Molecular imprinted material prepared by novel surface imprinting technique for selective adsorption of pirimicarb

In this paper, a molecular imprinted material with high performance for recognizing pirimicarb, which is a kind of carbamate pesticide, was prepared by adopting the novel surface molecular imprinting technique put forward by us previously. Firstly, the functional macromolecule poly(methacrylic acid) (PMAA) was grafted on the surface of silica gel particles in the manner of “grafting from” using 3-methacryloxypropyl trimethoxysilane (MPS) as an intermediate, and the grafted particle PMAA/SiO₂ was formed. Afterwards, the molecular imprinting was carried out towards the macromolecule PMAA grafted on the surface of silica gel particles using pirimicarb as template and ethylene glycol diglycidyl ether (EGGE) as crosslinking agent via the intermolecular hydrogen bond and electrostatic interaction, and pirimicarb imprinted material MIP-PMAA/SiO₂ was obtained. The combining characteristic of MIP-PMAA/SiO₂ for pirimicarb was studied profoundly with static method. The experimental results show that the surface-imprinted material MIP-PEI/SiO₂ has excellent combining affinity and recognition selectivity for the template molecules of pirimicarb. Before imprinting, PMAA/SiO₂ has greater adsorption capacities for pirimicarb as well as for the contrast substances, atrazine and propoxur, whose structures are similar to pirimicarb, and the selectivity coefficients of PMAA/SiO₂ for pirimicarb with respect to atrazine and propoxur are only 1.523 and 0.612, respectively. However, after imprinting, the combining capacities of MIP-PMAA/SiO₂ towards atrazine and propoxur decrease remarkably, whereas that of MIP-PMAA/SiO₂ for pirimicarb still remains higher. The coefficients of MIP-PMAA/SiO₂ for pirimicarb with respect to atrazine and propoxur were enhanced greatly, and they are 12.20 and 14.15, respectively. Besides, MIP-PMAA/SiO₂ adsorbing pirimicarb in a saturated state has fine elution and reuse properties.     

Selectively removal of Al(III) from Pr(III) and Nd(III) rare earth solution using surface imprinted polymer

Rare earth is a very important strategic resource. But, impurities, such as Al³⁺, have great influence on the properties of rare earth material. In this paper, an Al³⁺-ionic imprinted polyamine functionalized silica gel sorbent was prepared by a surface imprinting technique for selectively adsorbing Al³⁺ from rare earth solution. The adsorption and recognition properties of IIP-PEI/SiO₂ for Al³⁺ were studied in detail. The experimental results showed that IIP-PEI/SiO₂ possessed strong adsorption affinity, specific recognition ability, and excellent selectivity for Al³⁺. The adsorption isotherm data greatly obey the Langmuir model, and the adsorption was typical monolayer. The adsorption capacity could reach to 1.98 mmol g^?1, and relative selectivity coefficients relative to Pr³⁺ and Nd³⁺ are 23.47 and 22.85, respectively. Besides, IIP-PEI/SiO₂ was regenerated easily using diluted hydrochloric acid solution as eluent and IIP-PEI/SiO₂ possesses better reusability.     

Characterization and adsorption behavior of newly synthesized sodium bis(2-ethylhexyl) sulfosuccinate–cerium (IV) phosphate (AOT–CeP) cation exchanger

A new cationic exchange material, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) with cerium (IV) phosphate (AOT–CeP) has been synthesized. The characterization of the ion exchanger was performed by using infra red spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo gravimetric analysis/differential thermo gravimetric analysis (TGA/DTA/DTG) and elemental analysis. The ion exchange properties like ion exchange capacity, elution and concentration behavior of AOT–CeP were determined by taking the material into a column and elution of H⁺ was done by NaNO₃. The thermal stability of the ion exchanger was studied by determining ion exchange capacity after heating to different temperatures for one hour. The adsorption studies on AOT–CeP demonstrated that the material is selective for Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions. AOT–CeP was found to be effective for the separation of Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions in the presence of alkali metals/alkaline earth metals. This cationic exchanger was also effective for the removal of Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions in the presence of acid and other transition metal ions. Thus, AOT–CeP can be used for the removal of these ions from the waste water during its treatment.     

Application of a Novel Hybrid Cation Exchange Material in Metal Ion Separations

A novel hybrid cation exchange material of the class of tetravalent metal acid (TMA) salt, titanium diethylene triamine pentamethylene phosphonate (TiDETPMP) has been synthesized by the sol gel method. The material has been analyzed by spectroscopy and thermal methods. Physico-chemical and ion exchange characteristics have also been studied. The distribution coefficient (K _d ) has been determined in aqueous as well as various electrolyte media/concentrations for Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ (transition metal ions) and Cd²⁺, Hg²⁺, Pb²⁺, Bi³⁺ (heavy metal ions) using TiDETPMP. Based on the differential affinity/selectivity, the breakthrough capacity (BTC) and elution behavior of various metal ions towards TiDETPMP, a few binary and ternary metal ions separations have been carried out.     

Preparation of functionalized ion‐imprinted phenolic polymer for efficient removal of copper ions

In this work, an ion‐imprinted polymeric material based on functionalized phenolic resin was developed for the efficient selective removal of Cu²⁺ ions from aqueous solution. p‐Aminophenol‐isatin Schiff base ligand (HPIS) was first synthesized and combined with Cu²⁺ ions to prepare the corresponding complex [Cu(PIS)₂]. The Schiff base ligand along with its copper complex was fully investigated and characterized before anchoring in a base‐catalyzed condensation copolymerization with formaldehyde and resorcinol. The Cu²⁺ ions were removed from the obtained resin construction and the resulting Cu²⁺ ion‐imprinted material (Cu‐PIS) was employed for the selective extraction of Cu²⁺ ions under different pH values, initial concentrations and contact time conditions. The optimum pH for the removal process was chosen as 6 and the maximum adsorption capacity was 187 ± 1 mg g^–1. Also, the kinetics showed a better fit with the pseudo‐second‐order equations. The selectivity of the prepared Cu‐PIS was also evaluated in a multi‐ionic species containing Ni²⁺, Cd²⁺, Pb²⁺, Co²⁺ besides Cu²⁺ ions and the determined parameters confirmed a superior recognition capability toward the imprinted Cu²⁺ ions. © 2019 Society of Chemical Industry     

Polyethylenimine–polyepichlorohydrin interpolymer for chelating ion-exchange membrane

Polyethylenimine membranes consisting of linear polyethylenimine (PEI) and polyepichlorohydrin (PECH) were prepared by casting and heating an N,N-dimethylformamide solution of the two polymers under nitrogen at 100°C for 60 min. The membrane was also prepared by a heat-press method in a conventional manner. The cast membrane obtained was transparent. The membrane has a crosslinked structure due to the reaction between the secondary amino groups in PEI and the chloromethyl groups in PECH. Although a larger feed ratio of PEI/PECH gave membranes with a larger adsorption capacity for Cu²⁺ ions, the optimum ratio was 40/100 with respect to mechanical properties. A belt conveyor system using the PEI membrane was able to transport Cu²⁺ ions from one bath to another. In a diffusion dialysis against 1N HCl, the PEI membrane crosslinked rather tightly showed a specific ion-selective transfer character. For example, in Cu²⁺–Ca²⁺ system the permeability ratio P_cu/P_ca was about 3.8. The selectivity arises from the difference between affinities (extractabilities) of PEI toward metal ions. The selectivity was changed depending on the pH value.     

Synthesis of novel copper ion-selective material based on hierarchically imprinted cross-linked poly(acrylamide-co-ethylene glycol dimethacrylate)

A novel hierarchically imprinted cross-linked poly(acrylamide-co-ethylene glycol dimethacrylate) using a double-imprinting approach for the Cu²⁺ selective separation from aqueous medium was prepared. In the imprinting process, both Cu²⁺ ions and surfactant micelles (cetyltrimethylammonium bromide – CTAB) were employed as templates. The hierarchically imprinted organic polymer named (IIP-CTAB), single-imprinted (IIP-no CTAB) and non-imprinted (NIP-CTAB and NIP-no CTAB) polymers were characterized by SEM, FTIR, TG, elemental analysis and textural data from BET (Brunauer–Emmett–Teller) and BJH (Barrett–Joyner–Halenda). Compared to these materials, IIP-CTAB showed higher selectivity, specific surface area and adsorption capacity toward Cu²⁺ ions. Good selectivity for Cu²⁺ was obtained for the Cu²⁺/Cd²⁺, Cu²⁺/Zn²⁺ and Cu²⁺/Co²⁺ systems when IIP-CTAB was compared to the single-imprinted (IIP-no CTAB) and non double-imprinted polymer (NIP-CTAB), thereby confirming the improvement in the polymer selectivity due to double-imprinting effect. For adsorption kinetic data, the best fit was provided with the pseudo-second-order model for the four materials, thereby indicating the chemical nature of the Cu²⁺ adsorption process. Cu²⁺ adsorption under equilibrium was found to follow dual-site Langmuir–Freundlich model isotherm, thus suggesting the existence of adsorption sites with low and high binding energy on the adsorbent surface. From column experiments 600 adsorption–desorption cycles using 1.8 mol L⁻¹ HNO₃ as eluent confirmed the great recoverability of adsorbent. The synthesis approach here investigated has been found to be very attractive for the designing of organic ion imprinted polymer and can be expanded to the other polymers to improve performance of ion imprinted polymers in the field of solid phase extraction.     

Selective Transport of Copper(I,II), Cadmium(II), and Zinc(II) Ions through a Supported Liquid Membrane Containing Bathocuproine,Neocuproine, or Bathophenanthroline

Abstract

Some selective transport systems for heavy metallic ions through a supported liquid membrane (SLM) containing a 2,2′-dipyridyl derivative ligand, 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine), 2,9-dimethyl-1,10-phenanthro-line (neocuproine), or 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline), were investigated. The transport of copper(I, II), cadmium(II), zinc(II), lead(II), and cobalt(II) ions was accomplished with a halogen ion such as chloride, bromide, or iodide ion as a pairing ion species for any SLM. The ranking of the permeability of the metallic ions was Cu^+,2+, Zn²⁺, Cd²⁺ ? Pb²⁺, Co²⁺. When the oxidation-reduction potential gradient was used as a driving force for metallic ions, the transport of Cu⁺ ion was higher than those of Cd²⁺ and Zn²⁺ ions for any SLM containing bathocuproine, neocuproine, or bathophenanthroline. On the other hand, in the transport system which used the concentration gradient of pairing ion species, the permeability of the Cu²⁺ ion decreased whereas that of the Cd²⁺ ion increased. Moreover, it was found that the different selectivity for the transport of metallic ions is produced by using various pairing ion species.     

Synthesis and Characterization of Site-Selective Ion-Exchange Resins Templated for Lead(II) Ion

Abstract

Ion-exchange resins that exhibit enhanced selectivity for the Pb(II) ion have been synthesized by the copolymerization of styrene with lead(II) vinylbenzoate. Removal of the Pb(II) ion by acid washing left cavities templated for the Pb(II) ion. Sorption characteristics of the template resins have been studied over a large range of template loadings by varying the degrees of crosslinking, and with or without the use of ultrasonification during copolymerization. The capacity of the lead templated resins increases logarithmically with the increase of template complex content for levels of lead template content below 5 mol%. The complexation equilibrium constants of the resins reach a maximum at 3 mol% template complex content. The resins show marked preference for binding the Pb(II) ion. The selectivity,α _pb,cd, has been found to be 174 for the 1 mol% templated polymer. In comparison to untemplated resins, the template process enhances the selectivity by roughly a factor of 3 over Cu²⁺ and 2 over Cd²⁺. The selectivity enhancement is mainly ascribed to “coordination-geometry selectivity.”     

Chelation ion‐exchange properties of copolymer resin derived from 4‐hydroxyacetophenone,oxamide, and formaldehyde

A copolymer (4‐HAOF) prepared by condensation of 4‐hydroxyacetophenone and oxamide with formaldehyde in the presence of an acid catalyst proved to be a selective chelating ion‐exchange copolymer for certain metals. Chelating ion‐exchange properties of this copolymer were studied for Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, and Hg²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal‐ion uptake involving the measurements of the distribution of a given metal ion between the copolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for Fe³⁺ ions than for Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺, Ni²⁺, and Hg²⁺ ions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 787–790, 2003     

The competitive heavy metal removal by hydroxyethyl cellulose-g-poly(acrylic acid) copolymer and its sodium salt: The effect of copper content on the adsorption capacity

Summary Crosslinked hydroxyethyl cellulose-g-poly(acrylic acid) (HEC-g-pAA) graft copolymer was prepared by grafting of acrylic acid (AA) onto hydroxyethyl cellulose (HEC) using [Ce(NH₄)₂(NO₃)₆]/HNO₃ initiator system in the presence of poly(ethyleneglycol diacrylate) (PEGDA) crosslinking agent in 1:1 (v/v) mixture of methanol and water at 30 °C. Carboxyl content of copolymer was determined by neutralization of –COOH groups with NaOH solution and sodium salt of copolymer (HEC-g-pAANa) was swelled in distilled water in order to determine the equilibrium swelling value of copolymer. Both dry HEC-g-pAA and swollen HEC-g-pAANa copolymers were used in the heavy metal ion removal from three different aqueous ion solutions as follows: a binary ion solution with equal molar contents of Pb²⁺and Cd²⁺, a triple ion solution with equal molar contents of Pb²⁺, Cu²⁺ and Cd²⁺, and a triple ion solution with twice Cu²⁺molar contents of Pb²⁺and Cd²⁺. Higher removal values on swollen HEC-g-pAANa were observed in comparison to those on dry polymer. The presence of Cu²⁺decreased the adsorption values for Pb²⁺ and Cd²⁺ ions on both types of HEC copolymer. However, with further increase in Cu²⁺ content both dry and swollen copolymers became apparently selective to Cu²⁺ removal and Cu²⁺ removal values exceeded the sum of adsorption values for Pb²⁺ and Cd²⁺. Maximum metal ion removal capacities were 1.79 and 0.85 mmol Me²⁺/g_polymer on swollen HEC-g-pAANa and dry HEC-g-pAA, respectively.     

Preparation and characterisation of a novel copper‐imprinted polymer based on β‐cyclodextrin copolymers for selective determination of Cu2+ ions

A novel ion‐imprinted polymer (IIP) using (6‐O‐butene diacid ester)‐β‐cyclodextrin (β‐CD‐MAH) as the functional monomer and copper ions as the template was developed for Cu²⁺ sensing. First, reactive β‐cyclodextrin (β‐CD) monomers with vinyl carboxylic acid functional groups were synthesised and were co‐polymerised with styrene via radical polymerisation. Then, the β‐CD copolymers were complexed with Cu²⁺ in order to obtain the IIP. The imprinting effect was realised by removing the template ions from the imprinted polymer. The structure, composition and morphology of the IIP were characterised by Fourier transform IR spectroscopy, energy‐dispersive spectroscopy and field‐emission SEM. The adsorption capacity was investigated by UV–visible spectroscopy in batch operation mode. The maximum adsorption capacity for the Cu²⁺ template ions was 28.91 mg g^?1, and the adsorption selectivity was clearly illustrated from the increased sorption affinity towards Cu²⁺ ions over other competing ions. The adsorption was affected by the pH of the aqueous medium, and enhanced adsorption capacity was observed at pH 5. The prepared IIP could be used 10 times after its regeneration without significant loss of the adsorption capacity. © 2018 Society of Chemical Industry     

A new molecularly imprinted polymer prepared by surface imprinting technique for selective adsorption towards kaempferol

A new molecularly imprinted polymer (KAE-MPS/SiO₂) with high performance for recognizing kaempferol (KAE) was prepared by adopting the surface molecular imprinting technique with silica nanoparticles modified with 3-methacryloxypropyltrimethoxysilane (MPS) as a carrier material, 2-vinylpridine as the functional monomer and ethylene glycol dimethacrylate as the crosslinker. The static adsorption experiments indicated that KAE-MPS/SiO₂ had significantly higher adsorption capacity for KAE than its non-imprinted polymers. Scatchard analysis revealed that two classes of binding sites were formed in KAE-MPS/SiO₂ with dissociation constants of 0.26 and 2.34 μmol/mL, and the maximum apparent binding capacity was 3.33 and 16.16 μmol/g, respectively. The selectivity coefficients of KAE-MPS/SiO₂ for KAE in relation to competition species myricetin and chlorogenic acid were 2.51 and 4.24, respectively, which suggested that KAE-MPS/SiO₂ had high recognition selectivity and binding affinity for the template KAE. Dynamic binding study showed that the KAE-MPS/SiO₂ had good site accessibility and mass transport for KAE. The KAE-MPS/SiO₂ can be reused many times without decreasing their adsorption capacities significantly.     

Synthesis,characterization, metal sorption,and biological activity of poly(N‐heterocylic acrylamide)

N‐heterocyclic acrylamide monomers were prepared and then transferred to the corresponding polymers to be used as an efficient chelating agent. Polymers reacted with metal nitrate salts (Cu²⁺, Pb²⁺_, Mg²⁺, Cd²⁺, Ni²⁺, Co²⁺_, Fe²⁺) at 150°C to give metal‐polymer complexes. The selectivity of the metal ions using prepared polymers from an aqueous mixture containing different metal ion sreflected that the polymer having thiazolyl moiety more selective than that containing imidazolyl or pyridinyl moieties. Ion selectivity of poly[N‐(benzo[d]thiazol‐2‐yl)acrylamide] showed higher selectivity to many ions e.g. Fe³⁺, Pb²⁺, Cd²⁺, Ni²⁺, and Cu²⁺. While, that of poly[N‐(pyridin‐4‐yl)acrylamide] is found to be high selective to Fe³⁺ and Cu²⁺ only. Energy dispersive spectroscopy measurements, morphology of the polymers and their metallopolymer complexes, thermal analysis and antimicrobial activity were studied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42712.     

Concentration Effects on Separation Selectivity in Foam Fractionation

Abstract

Removal of cadmium, copper, and nickel ions from aqueous solution by foam fractionation has been studied using a chelating surfactant, 4-dodecyl-diethylenetriamine. The rate of removal is a function of concentration of both metallic ions and surfactant. In the low concentration range for the metallic ions compared to that of the surfactant, the order of removal was found to be Cd²⁺ > Ni²⁺ > Cu²⁺. However, at higher concentrations of ions, the order becomes inverse, Cu²⁺ > Ni²⁺ > Cd²⁺. A selectivity coefficient for the separation of a specified ion from one or more ions using a chelating surfactant is shown to be dependent on the surface tension of the complex and the chelation constants. The relationship between separation selectivity of the removal of the metallic ions and concentration of both surfactant and metallic ions is discussed     

Selectivity of heavy metal ions at acidic supramolecular surfaces

Langmuir monolayers containing surface carboxylic acid head groups were examined in order to characterize their selectivity to metal ion adsorption. Experimental data of ion adsorption obtained by surface isotherms and FTIR spectroscopy were analyzed using a thermodynamic-and-electrochemical model. Among bivalent ions examined (Cr²⁺, Pb²⁺, Cu²⁺, Cd²⁺, Zn²⁺, Ca²⁺, Ni²⁺, and Ba²⁺), Langmuir monolayers showed the highest selectivity to chromium ions. In addition, it was found that adsorption constants of the surface ions are quite different from binding constants of the bulk ions. The results show important implications to sensing and separating metal ions by the use of acidic supramolecular materials.