Synthesis and characterisation of nano structure lead (II) ion-imprinted polymer as a new sorbent for selective extraction and preconcentration of ultra trace amounts of lead ions from vegetables, rice, and fish 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).

Three-dimensional tree-like branched TiO2 nanorods for the highly selective enrichment and determination of lead

Branched titanium dioxide nanorods (B-TiO₂ NRs) grown on fluorine-doped tin oxide glass (FTO) were developed, which can be used as a solid-phase extractant for preconcentration and determination of trace Pb(II) combined with inductively coupled plasma optical emission spectrometry (ICP-OES). The B-TiO₂ NR-based glass substrate displayed excellent adsorptive selectivity and capacity for Pb(II); the maximum adsorption capacity was found to be 168.4 mg⋅g^-1 PB(II) at pH = 5.0. It proved that the primary extraction mechanism was attributed to soft acid/soft base interactions to form complexes for chemisorption. Investigating the adsorption kinetics and isotherms indicated that the pseudo-second-order and Langmuir models can better describe Pb(II) adsorption on the B-TiO₂ NRs. The proposed method presented good linearity from 0.01 to 5 mg⋅L^-1 with a correlation coefficient (R²) of 0.9989 and a low limit of detection (LOD) of 2.2 μg⋅L^-1 for Pb(II) under optimal conditions. The method was successfully applied to Pb(II) determination in foodstuffs with desirable recoveries from 93.18 to 108.1% and good precision with an RSD of less than 12.2%. This work provides a new strategy for selective extraction and determination of Pb(II) in complicated matrix samples.

The synthesis and characterisation of porous and monodisperse, chemically modified hypercrosslinked poly(acrylonitrile)-based terpolymer as a sorbent for the adsorption of acidic pharmaceuticals

The synthesis and characterization of porous poly(acrylonitrile(AN)-co-divinylbenzene-80 (DVB-80)-co-vinylbenzylchloride (VBC)) polymers with high specific surface areas and weak anion-exchange character have been successfully researched. The hypercrosslinked (HXL) microspheres were chemically modified with 1,2-ethylenediamine (EDA) to enhance the adsorption selectivity of the HXL materials. The zeta potential of EDA-modified HXL poly(AN-co-DVB-80-co-VBC) revealed that the surface of the modified terpolymer was positively charged. The FT-IR spectra of the chemically modified hypercrosslinked poly(AN-co-DVB-80-co-VBC) showed that the nitrile groups derived from the AN unit were utilised by the presence of diamine groups. The BET-specific surface areas of the EDA-modified hypercrosslinked poly(AN-co-DVB-80-co-VBC) was 503 m2 g−1; meanwhile, the specific surface area of the HXL terpolymer was 983 m2 g−1. The adsorption isotherm data were well fitted by both the Langmuir and Freundlich models, whereas the adsorption kinetics followed the pseudo-second-order kinetic model. This study confirms that the EDA-modified hypercrosslinked poly(AN-co-DVB-80-co-VBC) terpolymer is a potential adsorbent for the adsorption of acidic pharmaceuticals.

Preparation of highly efficient ion-imprinted polymers with Fe3O4 nanoparticles as carrier for removal of Cr(VI) from aqueous solution

Fe₃O₄ magnetic nanoparticles were prepared by hydrothermal synthesis and their surface was modified by the sol-gel method. Polymers imprinted with magnetic Cr (VI) were prepared by using Cr₂O₇^2- as template ion, 4-vinyl pyridine (4-VP) as monomer, isopropanol as solvent and Fe₃O₄ as matrix. The effects of solvent type, amount of Cr (VI) addition and volume of crosslinking agent on the adsorption properties of the imprinted polymers were investigated. The polymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The adsorption equilibrium was reached within 50 min, and the maximum adsorption capacity was 201.55 mg·g^-1. The adsorption process conformed to the Langmuir model, and the results of kinetic fitting showed that the pseudo-first-order kinetic model applied. In the Cr₂O₇^2-/AlF₄^- and Cr₂O₇^2-/CrO₄^2- competitive systems, the imprinted polymer showed good selectivity to the template ions, with relative selectivity factors of 6.91 and 5.99, respectively. When the imprinted polymer was reused 6 times, the adsorption capacity decreased by only 8.2%, demonstrating good reusability.

Fabrication and investigation of gold (III) ion-imprinted functionalized silica particles

Au (III) ion-imprinted mesoporous silica particles (Au-Si-Py) was manufactured by the condensation reaction of (3-Aminopropyl)triethoxysilane (AT)and 2-pyridinecarboxaldehyde (Py). The obtained AT-Py Schiff base ligand was then coordinate with the template gold ions and the polymerizable gold-complex was allowed to gel in presence of tetraethoxysilane (TEOS) and then the coordinated gold ions were leached out of the obtained silica matrix using acidified thiourea solution. During the synthetic steps, the obtained materials were investigated utilizing advanced instrumental and spectral methods. Moreover, the morphological structure of both Au (III) ions imprinted Au-Si-Py and non-imprinted NI-Si-Py silica particles were visualized using scanning electron microscope (SEM). Various adsorption experiments had been carried out using both Au-Si-Py and NI-Si-Py to examine their potential for selective extraction of gold ions under different conditions.

Highly Selective and Sensitive Detection of Pb2+ in Aqueous Solution Using Tetra(4-pyridyl)porphyrin-Functionalized Thermosensitive Ionic Microgels

Tetra(4-pyridyl)porphyrin (TPyP)-functionalized thermosensitive ionic microgels (TPyP5-MGs) were synthesized by a two-step quaternization method. The obtained TPyP5-MGs have a hydrodynamic radius of about 189 nm with uniform size distribution and exhibit thermosensitive character. The TPyP5-MG microgel suspensions can optically respond to trace Pb²⁺ ions in aqueous solution with high sensitivity and selectivity over the interference of other 19 species of metal ions (Yb³⁺, Gd³⁺, Ce³⁺, La³⁺, Bi³⁺, Ba²⁺, Zn²⁺, Ni²⁺, Co²⁺, Mn²⁺, Cr³⁺, K⁺, Na⁺, Li⁺, Al³⁺, Cu²⁺, Ag⁺, Cd²⁺, and Fe³⁺) by using UV-visible spectroscopy. The sensitivity of TPyP5-MGs toward Pb²⁺ can be further improved by increasing the solution temperature. The limit of detection for TPyP5-MG microgel suspensions in the detection of Pb²⁺ in aqueous solution at 50 °C is about 25.2 nM, which can be further improved to be 5.9 nM by using the method of higher order derivative spectrophotometry and is much lower than the U. S. EPA standard for the safety limit of Pb²⁺ ions in drinking water. It is further demonstrated that the TPyP5-MG microgel suspensions have a potential application in the detection of Pb²⁺ in real world samples, which give consistent results with those obtained by elemental analysis.

Facile preparation of a nano-imprinted polymer on magnetite nanoparticles for the rapid separation of lead ions from aqueous solution

A novel nanostructured magnetic ion-imprinted polymer (IIP) was synthesized for the selective adsorption of Pb(ii) from aqueous solution. The IIP was prepared on functional Fe3O4@SiO2 core/shell nanoparticles as a support. Monomer units in the polymer featured the typical bidentate ligand itaconic acid. We used ethylene glycol dimethacrylate and 2,2-azoisobisbutyronitrile as a cross-linker and an initiator, respectively. Monomers with different acid-base properties and different proportions of cross-linker were investigated to obtain high-performance adsorbents. Our results showed that the IIP prepared from itaconic acid had a high adsorption capacity owing to the strong binding between the monomer and Pb(ii) template ion. The IIPs were characterized using Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, thermogravimetric analysis, and transmission electron microscopy. We confirmed the formation of a nano-imprinted shell layer on the surface of Fe3O4@SiO2. The adsorption rate was fast, conforming to a pseudo-second-order kinetic and Langmuir adsorption model; the adsorption mechanism was deemed to be chemisorption as a single molecular layer. The maximum adsorption capacity of the IIP (51.2 mg g-1) was approximately three times as large as that of the non-imprinted polymer (17.9 mg g-1). The selectivity factors for Pb(ii) in mixed solutions of Pb(ii)/Co(ii), Pb(ii)/Cu(ii), and Pb(ii)/Zn(ii) were 45.6, 6.45, and 8.3, respectively. Pb-IIP exhibited a high selectivity towards Pb(ii), which enabled the enrichment of Pb(ii) in aqueous solution.

Synthesis and application of a novel core-shell-shell magnetic ion imprinted polymer as a selective adsorbent of trace amounts of silver ions

Ion-imprinted polymer (IIP) technology has received considerable attention for its greatest potential application. In this work, a novel magnetic nano ion-imprinted polymer (MIIP) for the selective and sensitive pre-concentration of silver (I) ions were used. It was obtained using Fe3O4@SiO2@TiO2 nanoparticles as a magnetic support of adsorbent, Ag(I)-2,4-diamino-6-phenyl-1,3,5-triazine (DPT) complex as the template molecule and methacrylic acid (MAA), 2,2′-azobisisobutyronitrile (AIBN), ethylene glycol dimethacrylate (EGDMA), as the functional monomer, the radical initiator and crosslinker, respectively. The synthesized polymer nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Brunauer-Emmett-Teller (BET). Silver ions were separate from the polymer and measured by flame atomic absorption spectrometry (FAAS). The maximum adsorption capacity of the novel imprinted adsorbent for Ag(I) was calculated to be 62.5 mg g−1. The developed method was applied to the preconcentration of the analyte in the water, radiology film and food samples, and satisfactory results were obtained.

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.

Solid-phase extraction of ultra-trace levels of lead using tannic acid-coated graphene oxide as an efficient adsorbent followed by electrothermal atomic absorption spectrometry; response surface methodology – central composite design

Tannic acid-coated graphene oxide as a novel and powerful adsorbent for the removal of lead.

A simple lateral flow biosensor for rapid detection of lead(ii) ions based on G-quadruplex structure-switching

A novel strip biosensor equipped with a colorimetric card shows great promise for in-field Pb²⁺ detection.

Imprinted silica nanofiber formation via sol–gel-electrospinning for selective micro solid phase extraction

Molecular imprinted silica nanofibers were implemented for atrazine recognition via an on-line micro-SPE-HPLC set up.

A multi-walled carbon nanotube-based magnetic molecularly imprinted polymer as a highly selective sorbent for ultrasonic-assisted dispersive solid-phase microextraction of sotalol in biological fluids

A modified multiwalled carbon nanotube-based magnetic molecularly imprinted polymer (MWCNT-MMIP) was synthesized and applied for selective extraction and preconcentration of sotalol (SOT) in biological fluid samples by using ultrasonic-assisted dispersive solid-phase microextraction (UA-DSPME).

Highly efficient and selective removal of trace lead from aqueous solutions by hollow mesoporous silica loaded with molecularly imprinted polymers

A novel type of adsorbent for the selective recognition and adsorption of trace Pb²⁺ from aqueous solutions has been successfully constructed simply by grafting molecularly imprinted polymers (MIPs) onto hollow mesoporous silica (HMS). Attractively, the HMS loaded with MIPs (H-MIPs) exhibits a fast adsorption kinetics, marked adsorption capacity of 40.52mg/g and extremely high selectivity toward Pb²⁺ over Cu²⁺, Zn²⁺, Co²⁺, Mn²⁺ and Ni²⁺, and the selectivity coefficients have been determined to be as high as 50. Moreover, such high adsorptive capability and selectivity were retained for at least 6 runs, indicating the stability and reusability of H-MIPs. Lead ion contaminants in real water samples were successfully concentrated and approximately 100% recovered using H-MIPs. Theoretical analysis shows that the adsorption process of H-MIPs follows the pseudo-second-order kinetic and Langmuir isotherm models. These demonstrate that H-MIPs are greatly potential for the rapid and highly efficient removal of trace Pb²⁺ ions in complicated matrices.

Novel imprinted polyethyleneimine nano-fluorescent probes with controllable selectivity for recognizing and adsorbing metal ions

Novel ion imprinted nano-fluorescent probes based on polyethyleneimine (PEI) were obtained via simple imprinting and grafting with fluorescein, and used for high recognition, detection and adsorption of Cu²⁺, Zn²⁺ and Cr³⁺ in aqueous solution.

Synthesis of Pb(ii)-imprinted poly(methacrylic acid) polymeric particles loaded with 1-(2-pyridylazo)-2-naphthol (PAN) for micro-solid phase preconcentration of Pb2+ on-line coupled to flame atomic absorption spectrometry

A new ion-selective imprinted polymer based on poly(methacrylic acid) loaded with 1-(2-pyridylazo)-2-naphthol (PAN) (IIP/PAN) has been synthesized, characterized and evaluated for the preconcentration of Pb²⁺ with on-line determination by flame atomic absorption spectrometry.

Selective trace determination of lead ions in different agricultural products using a novel core–shell magnetic ion-imprinted polymer with the aid of experimental design methodology

One of the most toxic and hazardous elements affecting human health is lead, which is known to be a carcinogenic factor, causing harmful effects on human metabolism.

Chromium Speciation in Wastewater and Sewage by Solid-Phase Extraction Using a New Diphenylcarbazone-Incorporated Resin

A new procedure for the determination of chromium species in polluted environmental samples by flame atomic absorption spectrometry was developed in this work. A new material containing 1,5-diphenylcarbazone included in a polymeric matrix was prepared and employed as a solid-phase extraction material for selective separation of Cr(III) ions under dynamic conditions. Chromium(III) ions were retained on this sorbent with high efficiency and repeatability (95 %, RSD = 1 %) from solutions with pH 9.0. The quantitative recovery of analyte was obtained with 0.1 mol L-1 EDTA. The concentration of Cr(VI) ions was calculated from the difference between the concentration of total chromium and Cr(III) ions. The prepared sorbent exhibits good chemical and mechanical stability, sorption capacity and selectivity towards Cr(III) ions in the presence of Cu(II), Ni(II), Mn(II) and Ca(II) ions. The accuracy of the separation method was proved by analysis of reference material of wastewater RES 10.2. The developed procedure was applied for chromium speciation analysis in municipal sewage samples.