Ion Imprinting Research Articles

Detection of Heavy Metal Ions With Ion Imprinting Microfiber Sensor Arrays

Detection of Heavy Metal Ions With Ion Imprinting Microfiber Sensor Arrays

Fabrication of ion imprinted graphene oxide-chitosan membrane cross linked by self polymerized polydopamine for selective adsorption of La(III)

Recovery of rare earths from secondary sources tallies with environmental remediation and sustainable exploitation of rare earth resources simultaneously. Herein, La(III) imprinted graphene oxide-chitosan membrane cross linked by self polymerized PDA (IIP-GO-CS-PDA) was constructed via using CS as functional monomer, PDA as cross linker and La(III) as template. The as constructed IIP-GO-CS-PDA was elaborately characterized in terms of crystallinity, morphology, chemical structure, porosity and thermal stability. Subsequently, adsorption efficiency and selective recovery performance of IIP-GO-CS-PDA towards La(III) were evaluated via batch adsorption. Result indicates, adsorption of La(III) by IIP-GO-CS-PDA is induced by electrostatic interaction, thereby reaching maximum adsorption efficiency at pH = 5. Functional groups C-O, C-N, −C(=O)–NH, –NH2 in IIP-GO-CS-PDA provides heterogeneous affinity for La(Ⅲ), inducing chemical adsorption. Adsorption proceeds rapidly to reach equilibrium in 30 min, manifesting impressive efficiency. The maximum adsorption capacity determined by Langmuir fitting is 275.48 mg·g−1. By virtue of its ion imprinting sites, IIP-GO-CS-PDA demonstrates selectivity coefficients 3.20, 3.34, 8.68, 9.28, 9.43, 9.58 towards La(Ⅲ) for binary solutions La/Eu, La/Dy, La/Cr, La/Cu, La/Cd, La/Pb, respectively. Owing to its membrane configuration, IIP-GO-CS-PDA can be easily recovered for cyclic adsorption, whereby retaining adsorption quantity 91.72 mg·g−1 for La(Ⅲ) in five consecutive cycles. Compared with other adsorbents, IIP-GO-CS-PDA exhibits rapid equilibrium, superior adsorption capacity and selectivity towards La(Ⅲ). This work provides a novel solution for fabricating bio adsorbent towards selective recovery of La(Ⅲ).

Fabrication of ion imprinted diethylenetriamine pentaacetic acid-polyethylenimine modified magnetic graphene oxide for selective adsorption of Ce(III)

Selective recovery of rare earth elements is essential for both sustainable exploitation of rare earth resources and environmental remediation. Herein, Ce(Ⅲ) imprinted diethylenetriamine pentaacetic acid-polyethylenimine modified magnetic graphene oxide (IIP-DTPA-PEI-MGO) was fabricated for selective adsorption of Ce(Ⅲ). Adsorption efficiency and selectivity performance of IIP-DTPA-PEI-MGO towards Ce(Ⅲ) were evaluated via batch adsorption targeted at single and mixed solution, respectively. Adsorption mechanism was elucidated based on versatile adsorption fittings (isotherms, kinetics, thermodynamics) and spectroscopic tests (XPS, FTIR). Result presents, maximum adsorption efficiency of IIP-DTPA-PEI-MGO for Ce(III) is reached at pH = 5 in 30 min, demonstrating superior efficiency. The maximum mono layer adsorption capacity determined by the Langmuir model is 281.69 mg g−1. After adsorption, 75.65 % of original Ce(Ⅲ) is transferred into Ce(Ⅳ), while 24.35 % remain as Ce(Ⅲ). Furthermore, by virtue of its paramagnetic property, IIP-DTPA-PEI-MGO can be easily recovered for cyclic adsorption, thereby keeping adsorption quantity 90.44 mg g−1 on Ce(Ⅲ) in five consecutive cycles. Owing to ion imprinting sites, IIP-DTPA-PEI-MGO exhibits selectivity coefficient 1.34, 1.69, 2.32, 2.96, 15.24, 10.51 towards Ce(III) for binary solution Ce/La, Ce/Nd, Ce/Eu, Ce/Dy, Ce/Cu, Ce/Cr, respectively. In terms of adsorption mechanism, versatile functional groups O-H, C-N, C-O in IIP-DTPA-PEI-MGO provide heterogeneous affinity for Ce(Ⅲ), inducing chemical adsorption. This work provides a novel approach towards fabricating magnetic bio adsorbent for selective recovery of Ce(Ⅲ).

Recent Advances in Synthesising and Applying Magnetic Ion-Imprinted Polymers to Detect, Pre-Concentrate, and Remove Heavy Metals in Various Matrices

Magnetic ion-imprinted polymers (MIIPs) are an innovative material that combines the selectivity of ion imprinting with the ease of separation provided by magnetic properties. Recent advancements in MIIPs have shown that they have higher selectivity coefficients compared to non-imprinted materials. The synthesis of MIIPs involves creating specific recognition sites for target ions in magnetic nanomaterials. Various nanomaterials, such as graphene oxide, carbon nanotubes, and silica, have been incorporated into the IIPs to improve their analytical performance for different environmental applications, including metal extraction, monitoring, detection, and quantification. This review stresses the need to develop new monomers with a high affinity for the target analyte and to find supporting materials with groups that facilitate the effective removal of the target analyte. It also explores the influence of experimental parameters on metal determination.

Synthesis of an ion-imprinted starch phosphate porous carbonaceous material removing U(VI) from wastewater: Kinetics and mechanism

Uranium enrichment and separation are important for the sustainable development of nuclear energy. In this study, reverse-phase emulsion crosslinking polymerization was used to synthesize spherical hollow porous carbon materials (II-CLSPC) with a “red blood cell” morphology after roasting. The soft template method was used to modify II-CLSPC to obtain an open pore structure, which increased its contact area. Based on this, ion imprinting was conducted to improve the selective adsorption of U(VI). A spatial site matching the size of U(VI) was formed after ion template removal, which played a crucial role in this process. Multifaceted and multilevel improvements of II-CLSPC facilitated rapid adsorption, reaching equilibrium at 40 min and a removal rate of 94.6 % (pH 5, 298 K). The pseudo-second-order kinetic model and Langmuir isothermal model indicated that the adsorption process of uranyl ions by II-CLSPC involved via monolayer chemisorption with a theoretical saturation adsorption capacity of 653.6 mg g−1. In addition, II-CLSPC exhibited excellent selectivity (KdU = 3.7 × 104 mL g−1), cyclic stability, and salt tolerance, making it a promising candidate for uranium removal from wastewater.

Efficiently selective adsorption Rb(I) based on ion-imprinted membrane chromatography: Batch adsorption and dynamic filtration

The development of efficient separation and enrichment methods for rare and precious metal rubidium (Rb) has attracted more and more attention the hydrometallurgy. Here, based on the phenolic hydroxyl-rich copolymer poly(styrene-co-4-hydroxylstyrene) (P(S-co-VPh)), the Rb+ imprinting nanofiber membrane (P(S-co-VPh)-(IIP)) was prepared using electrostatic spinning. NMR, FTIR, XPS, FESEM and EDS were used to comprehensively characterize the composition and structure of the copolymer and nanofiber membranes. Batch adsorption results indicated that the optimal adsorption conditions were pH = 9 at room temperature, and the process of Rb+ adsorption was spontaneous exothermic reaction. Ion imprinting technology not only enhanced adsorption capacity and recycling performance of the P(S-co-VPh20)-(IIP) membrane, but more importantly, significantly improved its selectivity, so that the selectivity coefficient (β) of Rb+/Mn+ for the interfering ions Na+, Mg2+, Ca2+, and K+ were 1438.17, 864.38, 434.6, and 307.25, respectively. The adsorption kinetics fitted well to the pseudo-second-order rate expression, and the maximum theoretical adsorption capacity (qm) could reach 140.00 mg/g from the Langmuir model fitting. The dynamic filtration experiment of the stacked membranes chromatography indicated that the breakthrough times were significantly affected by the different operation conditions (Flow rate, initial Rb+ concentration and membrane dosage). Among the four typical models of Thomas, Yoon-Nelson, EXY and BJP, the breakthrough curves can be well described by the EXY model.

A DFT-designed neodymium ion-imprinted membrane with fouling resistance and high flux

The rare earth metal neodymium (Nd) is widely used in advanced industries such as hybrid cars and aerospace. Therefore, recovering neodymium from wastewater presents valuable opportunities for secondary recycling. The recovery of Nd3+ from wastewater using ion imprinting technology (IIT) for efficient selective separation holds significant importance. In this study, hydrophilic Nd(III) ion-imprinted membranes, termed Nd(III)–P/P/TIIM, were synthesized using the IIT technique. Nd(III)–P/P/TIIM exhibited efficient and selective separation capabilities for Nd3+ with a remarkable retention rate of 95.68 % and a high water flux reaching up to 636.94 L·m−2·h−1. Additionally, its relative selectivity coefficients for interfering ions (KLa, KEu, KCu) were 3.9, 29.5, and 37.9, respectively. Various analyses, including DFT calculations, HOMO and LUMO calculations, MEP images, and XPS spectroscopy, confirm that the mechanism of selective retention of Nd3+ by Nd(III)–P/P/TIIM in solution is due to Coulombic adsorption between the –COO− anion and Nd3+ as well as an imprint memory effect. Even after undergoing three water-BSA cycles, the membrane maintained a water flux of 357.96 L·m−2·h−1. The antifouling principle of Nd(III)–P/P/TIIM was investigated by XDLVO theory, attributed to the increase of electron donor tension (γ−) and Lewis acid-base interactions (ΔGAB) at the membrane surface. This work provides an insightful guidance for engineering high-performance membranes and has the potential to provide an alternative method for recycling neodymium.

A new electrochemical sensor based on a screen-printed electrode modified with an ion-imprinted PEDOT for the detection and the quantification of Cd(II)

In this study, an electrochemical sensor was developed using an ion imprinting technique to create a film, facilitating rapid, sensitive, cost-effective and multiplexed determination of cadmium ions in nature. Indeed, pollution by this substance is of great concern due to its toxic health risks and its cumulative and persistent nature in living organisms. The sensor was functionalized with cyclic voltammetry by directly electropolymerizing ethylenedioxythiophene (EDOT) in the presence of Cd(II) as a template on screen-printed platinum electrodes. After electropolymerization, the structure and the morphology of the sensor ion imprinted polyethylendioxythiophene (IIP-PEDOT/SPPtE) were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and scanning electron microscopy (SEM/EDX). The electrochemical properties of the sensor were studied by cyclic voltammetry and electrochemical impedance spectroscopy. All experimental parameters were optimized by square wave voltammetry. IIP-PEDOT/SPPtE exhibited a linear concentration range of 0.5 to 75 µg/L, a detection limit of 0.07 µg/L and a quantification limit of 0.21 µg/L. Furthermore, the proposed sensor revealed good reproducibility, high stability and high selectivity for cadmium over several potential interferents. The developed device was successfully applied to the Cd(II) detection in industrial water samples via the standard addition method. The results were compared to analyzes of the same samples by ICP-MS. A high recovery rate of around 90–102.2 % and an RSD equal to 5.8 % and 2.5 % were observed.

Nitrogen-doped substrate material ion imprinting-capacitive deionization selective recovery of lithium ions from acidic solutions.

With the continuous development of global industry and the increasing demand for lithium resources, recycling valuable lithium from industrial solid waste is necessary for sustainable development and environmental friendliness. Herein, we employed ion imprinting and capacitive deionization to prepare a new electrode material for lithium-ion selective recovery. The material morphology and structure were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and other characterization methods, and the adsorption mechanism and water clusters were correlated using the density functional theory. The electrode material exhibited a maximum adsorption capacity of 36.94mg/g at a Li+ concentration of 600mg/L. The selective separation factors for Na+, K+, Mg2+, and Al3+ in complex solution environments were 2.07, 9.82, 1.80, and 8.45, respectively. After undergoing five regeneration cycles, the material retained 91.81% of the initial Li+ adsorption capacity. Meanwhile, the electrochemical adsorption capacity for Li+ was more than twice the corresponding conventional physical adsorption capacity because electrochemical adsorption provides the energy needed for deprotonation, enabling exposure of the cavities of the crown ether molecules to enrich the active sites. The proposed environment-friendly separation approach offers excellent selectivity for Li+ recovery and addresses the growing demand for Li+ resources.

Progress and Prospect of Ion Imprinting Technology in Targeted Extraction of Lithium.

Ion Imprinting Technology (IIT) is an innovative technique that produces Ion-Imprinted polymers (IIPs) capable of selectively extracting ions. IIPs exhibit strong specificity, excellent stability, and high practicality. Due to their superior characteristics, the application of IIPs for lithium resource extraction has garnered significant attention. This paper discusses the following aspects based on existing conventional processes for lithium extraction and the latest research progress in lithium IIPs: (1) a detailed exposition of existing lithium extraction processes, including comparisons and summaries; (2) classification, comparison, and summarization of the latest lithium IIPs based on different material types and methods; (3) summarization of the applications of various lithium IIPs, along with a brief description of future directions in the development of lithium IIP applications. Finally, the prospects for targeted recovery of lithium resources using lithium IIPs are presented.

Selectivity of lanthanum and ytterbium in binary and multi-component system by modified sericin/alginate/poly (vinyl alcohol) adsorbent beads

Rare earths are essential for important industrial applications and for producing high-tech materials. Its recovery from secondary sources is fundamental from an environmental and economic perspective. Biosorption is a promising method that can be used to remove and recover rare earth at low concentrations in an aqueous medium due to its low cost, simplicity, and efficiency. Recently, natural biomaterials based on sericin/alginate began to be investigated as a biosorbent for rare-earths uptake. Sericin is a natural protein of silkworm cocoons, usually discarded along with silk industry effluents, and alginate is a natural carbohydrate extracted from abundant sources of brown algae. The particles produced by the sericin/alginate blend were crosslinked with poly (vinyl alcohol) (PVA), which promotes better properties to this biomaterial. In this study, modified beads of a sericin/alginate/PVA blend were produced by ionic imprinting (Ca(NO3)2, Ca(NO3)2/La(NO3)3, or La(NO3)3) and leaching with HNO3 (0.1 mol/L). The developed particles were applied to remove ytterbium and lanthanum from aqueous solutions through adsorptive affinity and selectivity tests. The results indicated that the modified particles showed superior removal efficiency for lanthanum. For ytterbium, the highest removals were obtained for sericin/alginate/PVA-La(NO3)3 (94.33 ± 0.05%), sericin/alginate/PVA-Ca(NO3)2/La(NO3)3 (94.05 ± 3.12%), and sericin/alginate/PVA-Ca(NO3)2 (92.06 ± 2.01%). For lanthanum, higher removal values were obtained for sericin/alginate/PVA-La(NO3)3 (100.71 ± 0.77%), sericin/alginate/PVA-Ca(NO3)2/La(NO3)3 (99.21 ± 0.28%), and sericin/alginate/PVA-Ca(NO3)2 (98.45 ± 2.98%). In the binary system of rare earths, selectivity between the metals was not observed, however the modified beads showed great selectivity performance for lanthanum and ytterbium in multi-metal solution. Additionally, the modified beads with ionic imprinting were characterized by SEM, EDS, FTIR, XPS, and TGA/DTG. Thus, the results indicated that modified sericin/alginate/poly(vinyl alcohol) beads could be used as an alternative and promising biosorbent to remove and recover rare earths.

Effective removal of Cu(II) ions using graphene Oxide-Based surface imprinted polymeric Beads: Implications for water purification

This study utilizes graphene oxide (GO) as a versatile support material, employing surface ion imprinting to create mesoporous polymeric beads with a substantial specific surface area of around 434 m2/g and a bead size of approximately 0.6 mm. The graphene-based Cu(II) ion-imprinted polymeric (IIP) beads were developed to fulfil the requirements of selective Cu(II) adsorption from aqueous solutions. Suspension polymerization was employed to synthesize acrylamide precursor-based polymeric beads, with the in-situ addition of GO during the polymerization reaction before the curing step. The resulting Cu(II) imprinted polymeric beads exhibited effective adsorption of Cu(II) ions, achieving a maximum adsorption capacity of 192 mg/g, fitting well with the Langmuir isotherm (R2 = 0.9997). In the presence of the competitive ions Ni(II), Zn(II), Cd(II) and Co(II) the GO-IIP beads displayed high selectivity for Cu(II), with selectivity coefficients for the Cu(II)/Ni(II), Cu(II)/Zn(II), Cu(II)(II)/Cd(II) and Cu(II)/Co(II) in binary systems determined to be 39, 27, 60 and 53, respectively. These GO-IIP beads were successfully employed in five adsorption/regeneration cycles, showcasing their remarkable selectivity, high adsorption capacity, and regenerability. This approach can be applied to create comparable GO-IIPs for water purification, presenting promising solutions for addressing environmental challenges through the selective removal of specific ions from contaminated waters.

Bifunctional magnetic nanoparticles with ion imprinting for improving the flow through determination of ultratraces of Cd(II) using magnetic preconcentration.

A novel bifunctional magnetic sorbent with mercapto and amino groups and ion imprinting (MBII) was synthesized using a one-step aqueous sol-gel process for preconcentration and determination of Cd(II) ions. MBII was employed as a microcolumn (MC) filler in a flow-through system coupled to GFAAS. The magnetic properties of the solid allowed microcolumn magnetic solid-phase extraction (MCMSPE) to be performed by simply including a single circular magnet around the MC. This assembly enabled complete attachment of the solid to the MC wall leaving a central void to facilitate higher sample flow rates without blockage or material loss. For comparison, a bifunctional magnetic solid without imprinting (MBNI) was also synthesized and evaluated. Both MBII and MBNI were characterized by FTIR, SEM, EDX, BET and magnetization measurements. The results showed the preservation of the magnetic core, its superparamagnetism and the functional groups in the solid. Batch studies revealed a maximum adsorption capacity for both materials at pH around 6 with equilibrium reached within 5 minutes. The advantages were reflected in the maximum adsorption capacity of MBII, which was found to be 2.5 times greater than that of MBNI. Both adsorbents were compared as MC fillers for dynamic preconcentration in MCMSPE systems. Under optimized conditions, MBNI showed a PCF of 125 and MBII of 250. The higher selectivity of MBII was corroborated by interfering ion studies. The analytical performance parameters for the proposed method using MBII as an adsorbent showed a detection limit of 0.05 ng L-1, a linear range of 2.0-80 ng L-1, an RSD% of 2.2 (n = 7; 20 ng L-1) and a lifetime of more than 300 preconcentration-elution cycles without loss of sensitivity or need for refilling. The method was successfully applied to the determination of trace Cd(II) in osmosis, lake and tap water with recoveries ranging from 98 to 105%. Comparison of these results with those of similar reported methods showed a considerable improvement primarily attributed to the combined effect of MBII's higher retention capacity and its magnetic properties that allowed higher sample flow rates and, thus, enhanced figures of merit.

Biomass chitosan/sodium alginate colorimetric imprinting hydrogels with integrated capture and visualization detection for cadmium(II)

Due to Cd(II) with highly toxic, persistent and bioaccumulative, the discharge of it into the environment brings serious pollution. Developing strategies that are efficient, low-cost, pollution-free and specific to removing Cd(II) from wastewater is therefore of great urgency and prime importance. A novel chitosan/sodium alginate ionic imprinting(IICA) hydrogels with specific adsorption capacity for Cd(II) was prepared through freeze-thaw and ion imprinting, and finally the colorimetric sensor (IICAS) was prepared via introducing Rhodamine B(RhB) and Victoria blue(VBB) by immersion to achieve visual detection of Cd(II). The IICA hydrogels with imprinted hole structure had higher adsorption capacity and better specific selectivity for Cd(II). As well as internal diffusion, coordination, ion exchange, and hydrogen bonding influenced the adsorption rate. Moreover, the IICAS exhibited good selective detection ability and linearity for Cd(II) with the fitted correlation coefficient (R2) = 0.98, limit of detection (LOD) = 35 nmol/L. Combined with the smartphone platform, portable and quantitative detection of Cd(II) can be achieved, Within the 0–100 mg/L range, R2 remained 0.94, and LOD was 75 nmol/L. This strategy of preparing a novel whole biomass IICAS integrating capture and visual detection provides a new insight into the construction of a promising candidate sensor for the removal and detection of Cd(II).

Fiber optic cadmium ion sensors based on functionalization of a magnetic ion-imprinted polymer.

Cadmium poisoning is a chronic accumulation process, and long-term drinking of even low cadmium content water will cause kidney damage, so an ultra-low detection limit is particularly important. However, at the present stage, the traditional detection method cannot reach a sufficiently low detection limit, the response time is too long, and the cost of detection is very high, so that real-time measurement cannot be realized. Therefore, the traditional cadmium ion detection method has a slow response and an insufficient detection limit. This paper presents a fiber optic cadmium ion sensor functionalized based on an Fe3O4@SiO2@CS magnetic ion imprinting polymer (M-IIP). The sensor is based on the coupling characteristics of the optical microfiber coupler (OMC) cone region to achieve a highly sensitive response to the change in the cadmium ion concentration. M-IIP materials were prepared by surface imprinting polymerization to achieve low cross-sensitivity and thus improve the detection limit of the sensor. The results show that the developed fiber sensor has high specificity and a rapid response to cadmium ions. The experimental limit of detection (LOD) reached 0.051 nM within 0-1 μM with a response time of less than 50 s. Moreover, the proposed fiber cadmium ion sensor exhibits excellent performance in terms of sensitivity, stability, repeatability and biocompatibility.

Cross-linking copolymerization on magnetic microspheres surface induced neodymium ion imprinting for high capacity and high selectivity removal of Nd3+ from aqueous solution

The development of reliable ways to recover rare earth metals can avoid the loss of valuable resources in tailings, industrial wastewater and process residues. In this study, 2-acetamidoacrylic acid, which has a strong coordination ability for Nd3+, was selected as the functional monomer through theoretical simulation (DFT calculation) and experimental study (fluorescence burst method). Meanwhile, Nd3+ was used as template ion, N-isopropylacrylamide as an ionic cross-linker, ethylene glycol dimethacrylate was used as cross-linking agent, Fe3O4@SiO2 was used as carrier, and ion imprinted polymer containing Nd3+ vacancy (Nd(III)-V/MIIP) was synthesized by surface imprinting technique. The Nd(III)-V/MIIP prepared by this method can selectively adsorb Nd3+ in various metal ion solutions, and the adsorption capacity was increased by about 40 % compared with that of the MNIP adsorbent without Nd3+ vacancies, with a distribution system of 624.93 mL/g. The Nd(III)-V/MIIP can effectively solve the problem of the difficult separation of the rare earth ions from each other. Based on the results of XPS, DFT, HOMO and LUMO, it can be inferred that −COO− coordination on AAA, where the −COO− is coordinated to Nd3+ with a binding energy of -26.58 eV, which allows selective adsorption of Nd3+ ions in the complex water system.

Supramolecular cellulose-based heavy metal adsorbent for efficient and accurate removal of cobalt (II) for water treatment

Heavy metal ions' high toxicity, carcinogenicity, and non-degradability have been identified as the most severe environmental concerns. Therefore, in this study, a new type of cellulose-based ionic imprinting adsorbent (p-CMs@EPI@PEI@Cys-IIP) with a three-dimensional pore structure was developed to selectively adsorb cobalt (II) using a simple ion-cross-linking technique. In this experiment, p-CMs@EPI@PEI@Cys-IIP were prepared by modifying cellulose microspheres (p-CMs) with epichlorohydrin (EPI), polyethyleneimine (PEI) and L-cysteine (L-Cys).The p-CMs@EPI@PEI@Cys-IIP was found to be able to selectively adsorb Co (II), and it was well characterized with FT-IR, SEM, TGA, and XRD. The system adsorption experiment proved that the maximum adsorption capacity reached 158.93 mg g-1, below the pH 7. After five cycles, the adsorption capacity of p-CMs@EPI@PEI@Cys-IIP still remained above 90%. The results of selectivity experiments indicated that p-CMs@EPI@PEI@Cys-IIP has preferential selectivity for Co (II). The adsorption isotherm and kinetic experiment of Co (II) conformed to the Langmuir model and pseudo-second-order kinetic, respectively. The adsorption process of Co (II) on p-CMs@EPI@PEI@Cys-IIP was also affected by the intra-particle diffusion model. Due to its simple preparation method and good adsorption performance, p-CMs@EPI@PEI@Cys-IIP would have a good application prospect in the selective removal of Co (II) for water treatment.

Machine learning approach for ion imprinted (IIP) and non-imprinted (NIP) polymer discrimination based on pyrolysis kinetic data

The improper disposal of effluents containing toxic elements, such as nickel and mercury, can result in the gradual deterioration of surface water quality, impacting aquatic ecosystems and human health. Ionically imprinted polymers (IIPs) are promising candidates for remediating toxic areas due to their high removal rates and selectivity. In this study, multifunctional IIPs were developed using Ni2+ and Hg2+ as template ions and dithizone, methacrylic acid, and ethylene glycol dimethacrylate as complexing agent, monomer, and cross-linking agent, respectively, to remove Ni (II) and Hg (II) from effluents. The thermal decomposition behavior and degradation mechanism of ion imprinted polymers were investigated to address the issue of limited lifespan. The kinetic study revealed that the samples showed significant thermal stability, and the IIP-Duo sample exhibited higher activation energy compared to the non-imprinted polymer (NIP) and the mono-imprinted polymer (IIP), indicating that double impression alters the structure of the polymer and consequently its thermal degradation. Three machine learning models were applied to classify the samples according to imprinting, successfully predicting 95% or more of the classes correctly without overfitting or overmodelling. The master plot method showed that imprinting did not affect the thermal decomposition pathway, with the IIP, IIP-Duo, and NIP samples presenting the same mechanism geometrical contraction model (R3) at a conversion rate between 0.4 and 0.9. These findings suggest that multifunctional IIPs are promising materials for remediating areas impacted by toxic elements.

Carboxymethyl Cellulose/Polyacrylamide/Fe3O4 Magnetic Ion Imprinting Biosorbent for Removal and Recovery of La3.

To use resources rationally, the recovery and recycling of rare earth (RE) from industrial sewage have attracted a lot of attention. Herein, a polymer adsorbent CMC/PAM/Fe3O4 (CPF) was synthesized from renewable carboxymethyl cellulose (CMC), polyacrylamide (PAM), and Fe3O4 by the template of La3+ using ion imprinting technology. The CPF was characterized with X-ray diffraction (XRD), IR, X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM), and results show that PAM and CMC can crosslink with each other and form copolymers with Fe3O4 particles dispersing in it. The adsorption properties for the template ions La3+ were fully studied. It is found that CPF exhibited good adsorption performance with an adsorption capacity of 34.6 mg·g-1. Cycling experiments show that CPF still has high efficiency even after 5 cycles. Meanwhile, the desorption rate can reach more than 98%. The low wastage and high adsorption/desorption efficiency would enable CPF to be a good candidate adsorbent for removal/recovery of La3+ from industrial sewage.

Ionically Imprinting-Based Copper (II) Label-Free Detection for Preventing Hearing Loss

Copper is a microelement with important physiological functions in the body. However, the excess copper ion (Cu2+) may cause severe health problems, such as hair cell apoptosis and the resultant hearing loss. Therefore, the assay of Cu2+ is important. We integrate ionic imprinting technology (IIT) and structurally colored hydrogel beads to prepare chitosan-based ionically imprinted hydrogel beads (IIHBs) as a low-cost and high-specificity platform for Cu2+ detection. The IIHBs have a macroporous microstructure, uniform size, vivid structural color, and magnetic responsiveness. When incubated in solution, IIHBs recognize Cu2+ and exhibit a reflective peak change, thereby achieving label-free detection. In addition, benefiting from the IIT, the IIHBs display good specificity and selectivity and have an imprinting factor of 19.14 at 100 μmol·L−1. These features indicated that the developed IIHBs are promising candidates for Cu2+ detection, particularly for the prevention of hearing loss.