Assessment and modelling of Ni(II) retention by an ion-imprinted polymer: Application in natural samples

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

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

A mesoporous melamine/chitosan/activated carbon biocomposite: Preparation, characterization and its application for Ni (II) uptake via ion imprinting

A novel imprinted biocomposite and its non-imprinted form were developed by melaminating and crosslinking of chitosan coated onto a bio-based activated carbon and characterized using FTIR, BET, FESEM-EDS and XRD. Nickel, 4-Toluenesulfonyl chloride, and glutaraldehyde were used as a template, converter of hydroxyl and amine groups to good leaving groups, and cross-linker, respectively. The factors affecting adsorptivity and imprinting factor were optimized by using the Taguchi method for the subsequent comparative adsorptivity, kinetics, isotherms, selectivity, and reusability studies of imprinted biocomposite with its non-imprinted one. The pseudo-first-order and Langmuir models were best fitted to the experimental kinetics and equilibrium isotherm data, respectively. The maximum Ni (II)) adsorptivity of 109.86 mg/g, the imprinting factor (I·F) of 5.45 and Ni (II) selectivity coefficients values of 3.13, 4.48, 3.72, 2.51 for Ni (II) toward Zn (II), Cd (II), Cu (II) and Pb (II), respectively, were obtained at optimum conditions. After five consecutive adsorption-desorption cycles, the biocomposites still presented a high adsorptivity (>83%), indicating their excellent reusability.

Selective adsorption behavior of Cd2+ imprinted acrylamide-crosslinked-poly(alginic acid) magnetic polymers: fabrication, characterization, adsorption performance and mechanism

Poly(acrylamide) grafted and glutaraldehyde-crosslinked alginic acid nano-magnetic adsorbent (AAMA) was prepared by selecting Cd²⁺ as a template ion. Scanning electron microscope (SEM), thermo-gravimetric analyzer (TGA), vibrating sample magnetometer (VSM) and infrared spectroscopy (IR) were used to characterize the morphology and structure of AAMA. The adsorption of AAMA for different metal ions was compared and the impact of various factors for adsorption of Cd²⁺ was systematically investigated. These results suggested that the AAMA was the aggregates of Fe₃O₄ nanoparticles with a diameter of about 50-100 nm and had selectivity for Cd²⁺ adsorption. The maximum adsorption capacity for Cd²⁺ is 175 mg/g at pH 5.0 and 303 K. The experimental data were well described by the Langmuir isotherm model and pseudo-second-order model. The parameters of adsorption thermodynamics concluded that the adsorption progress is spontaneous and endothermic in nature. The parameters of adsorption activation energy suggested that there is physical adsorption and chemisorption on the adsorption of metal ions. AAMA could be regenerated by EDTA and still keep 71% adsorption capacity in the fifth consecutive adsorption-regeneration cycle. Therefore, AAMA would be useful as a selective and high adsorption capacity nano-magnetic adsorbent in the removal of Cd²⁺ from wastewater.

Nanopowder synthesis of novel Sn(II)-imprinted poly(dimethyl vinylphosphonate) by ultrasound-assisted technique: Adsorption and pre-concentration of Sn(II) from aqueous media and real samples

In this research, a novel Sn(II)-imprinted poly(dimethyl vinylphosphonate) nanopowder (Sn(II)-IPDMVPN) was prepared using Sn²⁺, dimethyl vinylphosphonate, azobis isobutyronitril and ethylene glycol dimethacrylate as the template, ligand, initiator and cross linker, respectively. The non-imprinted poly(dimethyl vinylphosphonate) nanopowder (NIPDMVPN) was also synthesized utilizing the same procedure without using SnCl₂·2H₂O in order to compare the results with the Sn(II)-IPDMVPN. The structure, morphology and composition of the products were characterized by XRD, SEM, EDX, XRF, BET, FT-IR and NMR techniques. Some experimental conditions including pH, eluent concentration and sample volume were optimized to maximize Sn(II) adsorption by the Sn(II)-IPDMVPN. It was found that the optimum conditions are pH = 5, 1.00 M of HNO₃ as eluent and sample volume up to 50 mL. The results obtained by ICP-MS indicated that the Sn(II)-IPDMVPN had much higher adsorption capacity for Sn(II) ions (about threefold) than the NIPDMVPN. The applicability of the Sn(II)-IPDMVPN was also investigated in three different real samples. Under the best experimental conditions, the calibration graphs were linear in the range of 0.19-90 μg L^-1 with a coefficient of determination (R²) of 0.990. The detection limit was calculated to be 0.06 μg L^-1. The relative standard deviation (RSD) for six replicate measurements of Sn(II) at 1.00 ng mL^-1 was determined to be 1.8%. The results showed that the Sn(II)-IPDMVPN-ICP-MS is a very simple, rapid, sensitive and efficient method for the determination of Sn(II) ions in water samples.

Preparation and adsorption characteristics of an ion-imprinted polymer for fast removal of Ni(II) ions from aqueous solution

A novel Ni(II) ion-imprinted polymer (IIP) was synthesized by bulk polymerization for fast removal of Ni(II) ions from aqueous solution. Effects of preparation conditions on adsorption performance were investigated. Diphenylcarbazide (DPC) and N,N-azobisisobutyronitrile (AIBN) were used as ligand and initiator, respectively. Various monomers, solvents, cross-linking agents and molar ratios of template, monomer and cross-linking agent for polymerization were studied to obtain the largest adsorption capacity. The prepared Ni(II)-IIPs were characterized using Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA). The elution process has no influence on the three-dimension network structure observed on the surfaces of Ni(II)-IIPs. Ni(II) ions could be eluted from IIPs successfully with HCl solution. Effects of operating time, pH and initial concentration of Ni(II) in aqueous solution on adsorption performance were investigated too. The adsorption equilibrium was reached within 30min. The maximum adsorption capacity of Ni(II)-IIPs was 86.3mgg^-1 at pH 7.0 with initial Ni(II) concentration of 500mgL^-1. The adsorption by Ni(II)-IIPs followed a pseudo-second-order kinetic and Freundlich isotherm models. The selectivity coefficients for all Ni(II)/interfering ions are larger than one because of the imprinting effect. The Ni(II)-IIPs also showed high reusability and stability.

Selective adsorption behavior of Cd(II) ion imprinted polymers synthesized by microwave-assisted inverse emulsion polymerization: Adsorption performance and mechanism

Microwave-assisted inverse emulsion polymerization method was used to prepare Cd(II) imprinted polymer (IIP) by using β-cyclodextrin (β-CD) and acrylamide (AM) as functional monomer, epichlorohydrin (ECH) as crossing-linking agent, ammonium persulfate as initiator. The Cd(II) imprinted polymer was characterized by SEM, FTIR and TGA. The influences of initial concentration of Cd(II), pH values, temperature, time and competitive ions on adsorption capacity and recognition properties are investigated. Under the optimal conditions, the adsorption capacity could reach 107mg/g. Furthermore, pseudo first order kinetic model, pseudo second order kinetic model and intra-particular diffusion model were used to describe the adsorption kinetic behavior. Results showed that the pseudo-second-order model (R² 0.9928-0.9961) had the best agreement with the experimental data. Langmuir adsorption isotherm model described the experimental data well, which indicated that adsorption was mainly monolayer absorption. Moreover, the study of adsorption thermodynamics (ΔG⁰<0, ΔH⁰>0, ΔS⁰>0) suggested that the adsorption process was a spontaneous and endothermic process. Competitive selectivity experiment revealed that imprinted polymer could selectively recognize Cd(II). It provides a new idea for removing Cd(II) from aqueous solution.

Preparation and application of Ni(ii) ion-imprinted silica gel polymer for selective separation of Ni(ii) from aqueous solution

A novel Ni(ii) ion-imprinted sulfonate functionalized silica gel polymer was prepared with the surface imprinting technique for selective seperation of Ni(ii) from aqueous solution.