Iodine Vapor Research Articles

Influence of a magnetic field on the frequency of a laser stabilized to molecular iodine

We report on the effect of a weak magnetic field applied on an iodine cell used to frequency stabilize a laser. A 1.5 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu $$\\end{document}m laser is frequency tripled in order to excite the molecular transitions at 0.51 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu $$\\end{document}m and frequency locked on a hyperfine line. With this frequency reference, we report short-term stability about 3×10-14τ-1/2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$3 \ imes 10^{-14}~\ au ^{-1/2}$$\\end{document}, with a minimum value of 4×10-15\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$4 \ imes 10^{-15}$$\\end{document} at 200 s. The lower part of 10-15\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10^{-15}$$\\end{document} frequency stability domain is reached, in our case, only by adding an efficient magnetic shield around the sealed quartz iodine cell. In order to quantify the Zeeman effect, we applied magnetic fields of several ×10-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes 10^{-4}$$\\end{document} T on the cell containing the iodine vapour. The Zeeman effect affects the lineshape transition in such a way that we observe a modification of the laser frequency. We have measured this linear Zeeman shift at (1062±6)×104\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(1062\\pm 6) \ imes 10^{4}$$\\end{document} Hz/T for the a1 hyperfine component of the R(34) 44-0 transition, near 514 nm by applying a magnetic field along the cell. Thus, in case of uncontrolled magnetic fields of an order of magnitude of 1×10-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ imes 10^{-4}$$\\end{document} T, the frequency stability is limited in the upper of the 10-14\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10^{-14}$$\\end{document} domain.

Capture of volatile iodine by aromatic amines solutions

Abstract The presence of an excessive amount of iodine, especially radioactive iodine, is dangerous to the environment. Amine solutions are the most common and technically mature class of chemical sorption used for the capture of the pollutants. The iodine vapor diffusion and release capabilities of the aromatic amine solutions have been investigated. The iodine diffusion and release experiments were examined by UV-visible spectroscopy. Many electronic spectrophotometric studies have been reported in the coordination chemistry field on complexes. Generally, these complexes were obtained by using different electron donors with various organic or metallic electron acceptors in polar and non-polar solvents. The absorption spectra of the donor, acceptors, and the resulted complexes were carried out in methanol in the region of 200–600 nm. The correlation between the spectral characteristics of molecular complexes of iodine with various aromatic amines and the ionization potentials of the donor molecules is discussed. The concentrations of the diffused iodine and the formed complex were calculated using mathematical models and calibration curves. The values of the formation constant (k AD), molar extinction coefficient (ε AD), and absorption band energy of complexes were estimated. The ionization potential of the donor I D was calculated from the complex band energies. The kinetic of the above association and reverse reactions was studied, and some kinetic parameters have been estimated.

Fabrication of carbonized derivatives from a novel azo polymer as a precursor for the layered adsorption of iodine and bromine

A nitrogen-rich polymer (AZO-TPA) was synthesized and employed as a precursor for calcined carbonized derivatives. After this polymer was activated with KOH, it was doped separately with melamine and urea, both of which are rich in carbon and nitrogen, and nine distinct carbonized derivatives were obtained through carbonization at various temperatures. Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) characterization revealed that the carbonized structures were rich in nitrogen functional groups, including pyridinic-N, pyrrolic-N, and N+–O- (nitrogen oxides), and possess additional active sites such as –OH and CO groups. The adsorption of bromine, iodine, and the fractional adsorption of bromine/iodine were investigated via the prepared carbonized derivatives. The results indicated that the polymer was successfully doped with urea and yielded carbonized derivatives at 600 °C (AZO-TPAU-600) which exhibited favorable adsorption capacity, particularly after KOH activation and urea doping (iodine vapor: 2782 mg g−1; bromine/iodine: 1854 and 867.55 mg g−1). In addition, the AZO-TPA-600 exhibited high selectivity for bromine adsorption in I2–Br2/cyclohexane solution, and the carbonized derivatives loaded with iodine/bromine could be efficiently desorbed via organic solvents, the adsorption capacity remains above 75 % even after 4 cycles. Finally, the adsorption mechanism was explained in detail.

Electronic-rich large conjugated molecules dispersing through ionic liquid solution process for fluorescent detection of iodine gas

Materials containing large conjugated structures have good applications prospects in multiple fields due to their electron-rich properties. Nevertheless, the rigid structures of such materials make them difficult to process, making them difficult to be utilized adequately, which limits further development of their performance potentials. Herein, through ionic liquid solution process (ILSP), the electron-rich and fluorescent properties of pentacene have been successfully liberated to detect iodine vapor. Pentacene can be dissolved in BmimNTf2 to form (Ph)5@BmimNTf2 solution with excellent fluorescence. (Ph)5@BmimNTf2 solution was loaded onto polyamide membranes to prepare composite membrane detectors, which can detect iodine vapors, showing rapid response, portability and low cost. Theoretical calculations indicate a charge-transfer complex is formed between pentacene and iodine. The amount of charge transfer (δQ) between pentacene and iodine monomer molecules can be up to 0.115e. This study provides potential for exploiting the applications of large conjugated materials utilizing ILSP.

Performance investigation of a low-power Hall thruster fed on iodine propellant

The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive, and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost, extensive availability, low vapor pressure, and ionization potential. The performance of a low-power iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor’s mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate. At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are 7.19 and 7.58 mN, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8% and 14.5%, and thrust to power ratios are 35.9 and 37.9 mN/kW under the conditions of 250 V, 0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.

Simple and scalable preparation of lignin based porous carbon coated nano-clay composites and their efficient removal for the diversified iodine

Here, lignin and nano-clay were used to prepare novel composite adsorbents by one-step carbonization without adding activators for radioactive iodine capture. Specially, 1D nano-clay such as halloysite (Hal), palygorskite (Pal) and sepiolite (Sep) were selected as skeleton components, respectively, enzymatic hydrolysis lignin (EHL) as carbon source, lignin based porous carbon/nano-clay composites (ELC-X) were prepared through ultrasonic impregnation, freeze drying, and carbonization. Characterization results indicated lignin based porous carbon (ELC) well coated on the surface of nano-clay, and made its surface areas increase to 252 m2/g. These composites appeared the micro-mesoporous hierarchical structure, considerable N doping and good chemical stability. Results of adsorption experiments showed that the introduction of ELC could well promote iodine vapor uptake of nano-clay, and up to 435.0 mg/g. Meanwhile, the synergistic effect between lignin based carbon and nano-clay was very significant for the adsorption of iodine/n-hexane and iodine ions, their capacity were far exceed those of a single material, respectively. The relevant adsorption kinetic and thermodynamics, and mechanism of ELC-X composites were clarified. This work provided a class of low-cost and environmentally friendly adsorbents for radioactive iodine capture, and opened up ideas for the comprehensive utilization of waste lignin and natural clay minerals.

Modification of boron nitride aerogels with APTES for enhanced iodine capture performance

Development of effective iodine capture materials and techniques is crucial for addressing the diverse applications of iodine and its significance in various contexts, including nuclear pollution control. This study presents the creation of a new 3-Aminopropyltriethoxysilane (APTES)-modified boron nitride (BN) aerogel designed for effective iodine capture. The internal structural units of BN aerogel, specifically the one-dimensional BN fibers, have been successfully functionalized with amine groups, resulting in the formation of an amine-rich SiOx capping layer on the surface of these fibers. The APTES modification not only establishes a stable connection within the internal BN fibers network but also imparts the material with a significant number of iodine capture sites. The resulting aerogel demonstrates an impressive iodine vapor capture capacity of 313.64 wt% at 350 K and atmospheric pressure, and up to 1028.96 mg/g in iodine/n-hexane solution, surpassing the capabilities of pure BN aerogel and most existing iodine capture materials. The excellent iodine capture performance of APTES-modified BN aerogel suggests its promising potential for future applications in iodine capture.

Study on the compatibility between iodine and common aerospace materials

Iodine has proven to be a promising alternative to xenon as a propellant for Hall and ion thrusters. High atomic mass and favourable ionization characteristics, comparable to xenon in terms of propulsive performance, together with lower cost compared to xenon makes it an attractive option. However, its reactivity and corrosive nature raise concerns. Tests to assess material compatibility and determine whether thruster components are susceptible to corrosion are unavoidable for its safe adoption as a propellant. This paper describes the main results of an experimental campaign aimed at a qualitative assessment of the compatibility with iodine of different materials. The study included more than fifteen materials that find application in electric propulsion devices, such as cathodes, thrusters and feeding systems, including ceramics such as LaB6, polymers, iron and aluminum alloys, and graphite. The specimens were exposed to iodine vapor environments at temperatures reaching approximately 200 °C for extended periods (from three to over 30 h) or were directly exposed to liquid iodine. The experimental setup and results of morphological and elementary analyses are presented and discussed. The research provides some insights into the viability of using iodine as a propellant and the potential challenges associated with its corrosive properties.

High-performance PbS detectors sensitized from one-step sensitization

Two-step sensitization is the key technique for achieving high-performance uncooled lead-salt infrared photoconductive detectors fabricated from vapor physic deposition (VPD) method. However, the commercialization of these devices is inhibited by the intricate sensitization processes, especially the iodination step, which requires precise control over high concentrations of iodine vapor. Herein, a one-step sensitization technique was proposed to improve the reliability of lead sulfide (PbS) detectors manufactured from VPD method. Moreover, the dependence of the detectivity on sensitization parameters involving the oxygen concentration, time, and temperature, was established and interpreted based on extensive studies on the sensitization of lead salt devices. The feasibility of the simplified sensitization was demonstrated by a room-temperature peak detectivity of 2.47 × 1010 cm Hz1/2 W−1 at 2.7 μm attained at 430 °C for 10 min in 50 % oxygen ambient. The evolution of phase, microstructure and electrical properties confirms the enhanced performance results from the improvement in PbS crystal quality as well as the formation of Pb3O2I2 and Pb2(SO4)O from high-temperature recrystallization. Therefore, the one-step sensitization paves a way for accelerating commercialization of lead-salt detectors fabricated by VPD technique.

Humic acid-based polyphenol-functionalized collagen fiber for efficient recognition capture of iodine vapor

Effective capture of radioactive iodine vapor is a crucial part of the spent fuel reprocessing process. In this study, humic acid (HA), which has excellent recognition capture of iodine vapor, is introduced as the active site construction center, functionalizing and modifying alkali-activated collagen fiber (ACF), to prepare the biomass composite functional materials (HA@ACF). The results demonstrate that HA@ACF exhibits exceptional recognition ability and a strong affinity for iodine vapor, with an adsorption capacity of 2811.8 mg/g (ACF is only 1068.6 mg/g). Simultaneously, under relative humidity of 27 % and strong acid conditions, the iodine vapor capture capacity of HA@ACF only decreased by 17.2 %, indicating that the material exhibits excellent iodine capture performance under complex conditions. The excellent adsorption performance is attributed to the synergistic effect of abundant −NHR, C = O, and phenolic hydroxyl active sites in HA@ACF, which recognize and induce iodine vapor, resulting in the capture of iodine molecules as I3-. Meanwhile, DFT calculations reveal the excellent adsorption energy (−0.51 eV) of iodine vapor on the phenolic hydroxyl groups on HA. Therefore, the HA@ACF biomass composite functional material can be an ideal candidate adsorbent for the efficient recognition capture of radioactive iodine vapor in airborne effluent.

Conformal Coating Testing in Various Test Environments

Conformal coatings have traditionally been tested by determining the mean time to failure of conformally coated hardware exposed to corrosive test environments. This test approach has serious shortcomings: The test temperatures are most often too high. At these high temperatures, the conformal coating properties may be quite different from those at the application temperatures. In addition, the times to failure are unacceptably long extending into many months. Overcoming these shortcomings is an iNEMI championed test that involves exposing conformally coated thin films of copper and silver to sulfur vapors at 40-50 oC in flowers of sulfur (FoS) chamber and using the corrosion rates of the coated metal thin films as a measure of the corrosion protection capabilities of the conformal coatings. The test temperatures are similar to the application temperatures, the test durations are no more than a week and can be conducted under various temperature and humidity conditions. The purpose of this paper was to determine if testing in the industry-standard mixed-flowing gas corrosion chamber would give similar results as those using the FoS chamber. Acrylic, fluorinated acrylate, and atomic layer deposition conformal coatings were tested in three environments: (a) flowers of sulfur (FoS), (b) mixed-flowing gas (MFG), and (c) iodine vapor. The performance of the coatings tested in the FoS and the MFG corrosion chambers were quantitatively similar. The iodine vapor test results were in qualitative agreement with the FoS and MFG test results. In addition, we present early results pointing to the utility of terahertz-frequency imaging as a technique for measuring conformal-coating thickness nondestructively.

Biomass derived porous carbon for efficient iodine adsorption from vapor and solution

The efficient adsorption and storage of radioactive iodine from uranium fission reactions is essential for safe nuclear energy. Bio-based adsorption materials have gained significant attention in the field of radioactive contaminants removal. This is primarily due to their numerous advantages, including a wide range of raw material sources, low cost, ease of preparation, low toxicity, high removal efficiency and stable storage. In this study, rape pollen was chosen as sources of biomass porous carbon, which possesses a micron-sized ellipsoidal shape, homogeneous size, porous structure with sparsely linked network inside, and high carbon content. A biomass derived porous carbon (K-RPC) was synthesized by pretreatment, heat treatment, and advanced treatment techniques. The results indicate that the K-RPC exhibited a hierarchical porous structure with homogeneous and wormhole-like micro- or nanopores, and high specific surface area. The K-RPC demonstrates exceptional iodine capture performance, the capacity surpasses that of most bio-based adsorbents. Remarkably, the maximum adsorption capacity of iodine vapor is approximately fifteen times higher than that of commercial silver exchanged zeolite. The adsorption mechanism, primarily characterized by chemisorption. This study is the first attempt to apply pollen in the field of iodine capture, and the biomass porous carbon extracted from rape pollen has the potential to be a cost-effective iodine adsorption material.

Experimental and kinetic evaluation on cobalt Salen conjugated organic polymers for CO2 cycloaddition reactions and iodine vapor adsorption

The fixing reactions of carbon dioxide with epoxides will not only help to ameliorate the problem of global warming, but also facilitate the synthesis of cyclic carbonates that have a multitude of applications. Herein, a new sequence of Salen cobalt complexes adjusted with different counterions and interconnected with pyrene group were synthesized through Friedel–Crafts alkylation, which were served as conjugated organic polymers (SP-COPs) for taking advantage of catalytic CO2 fixation reactions and iodine adsorption. Further characterizations were carried out through FT-IR, UV, TGA, and SEM to comprehend the intact structure, thermal stability, morphology and other physical and chemical properties. All materials exhibited effective catalytic performance, and in particular, SP-COP-1 with co-catalyst of TBAI achieved 96.2% conversion under ultra-mild conditions. The Ea was obtained to be 46.4 kJ·mol−1 by performing kinetic experiments at different temperatures by fitting the experimental data. The performance of iodine vapor adsorbed by these materials at ambient pressure of 75°C reached 2.8 g·g−1, 2.2 g·g−1 and 2.6 g·g−1 respectively, and the adsorption process is describable in terms of pseudo-first-order and pseudo-second-order adsorption kinetics.

Amino functionalization of porous aromatic frameworks for efficient and stable iodine adsorption

In view of the excellent stability, ultra-high specific surface area, and structural versatility, porous aromatic frameworks (PAFs) have shown promising potential in gaseous iodine adsorption. Herein, PAF-1 and PAF-5 were synthesized with high specific surface areas. Amino groups as effective binding sites were introduced to these frameworks through post-modification, which facilitated a shift from simple physical adsorption of iodine vapor to a more robust chemical adsorption process. Meanwhile, PAF-6 was synthesized from nitrogen-rich monomers to demonstrate the role of N-binding site in iodine adsorption. PAF-6 exhibited the highest iodine adsorption capacity, verifying the critical role of N-adsorption active sites. The in situ synthesis of nitrogen-rich porous material show advantages over post-modification in creating effective iodine adsorbents. This work highlights the potential of PAFs as a promising material for the adsorption and fixation of radioactive iodine.

Fabrication of Polysulfone Beads Containing Covalent Organic Polymer as a Versatile Platform for Efficient Iodine Capture.

Radioactive iodine poses a significant risk to human health, particularly with regard to reproductive and metabolic functions. Designing and developing highly efficient adsorbent materials for radioactive substances remain a significant challenge. This study aimed to address this issue by the fabricating polymeric beads containing covalent organic polymer (COP) as an effective method for removing iodine vapor. To achieve this, a COP was first synthesized via the Friedel-Crafts reaction catalyzed by anhydrous aluminum chloride. Then, COP-loaded polysulfone (PSf) (COP@PSf) and PSf beads were prepared using a phase separation method. The beads produced in this research have exhibited remarkable proficiency in adsorbing iodine vapor, showing an adsorption capacity of up to 216 wt % within just 420 min, which is higher than that of most other similar beads reported in the literature.

Process for Producing Lithium Iodide Cleanly through Electrodialysis Metathesis.

Lithium iodide is commonly used in the production of batteries and drugs. Currently, the neutralization method is the primary means of producing lithium iodide. This method involves using hydriodic acid as a raw material, adding lithium carbonate or lithium hydroxide, and obtaining lithium iodide through evaporation and concentration. However, hydriodic acid is chemically unstable. Its preparation can lead to explosive accidents and encountering high temperatures generates toxic iodine vapors. These limitations restrict its industrial production. The study evaluates the impact of membrane stack configuration, operating voltage, and initial concentrations and volume ratios of reactants on the production process. Electrodialysis metathesis, characterized by a simpler process flow, lower energy consumption, and environmental benefits, emerges as an effective technique for electrically driven membrane separation in lithium salt production and purification. Under the specific conditions of a C-C-A-C-A-C membrane stack configuration, operating voltage at 25 V, initial potassium iodide concentration at 0.4 mol/L, initial lithium sulfate concentration at 0.2 mol/L, and a 1:1 volume ratio of product liquid to raw material liquid, the method achieves a lithium iodide purity of 98.9% with a production cost of approximately 0.502 $/kg LiI.

Stilbene-Cross-Linked Pillar[5]arene-Based Polymer for Efficient Iodine Vapor Capture and Adsorption from Water

Stilbene-Cross-Linked Pillar[5]arene-Based Polymer for Efficient Iodine Vapor Capture and Adsorption from Water

Multi-components reactions on construction carboxylic-rich conjugated polymeric crown ethers as sustainable materials for CO2-fixation and iodine vapor adsorption: Experimental and kinetics

Carbon dioxide, as an industrial waste gas, has a severe impact on the climate. Thus, efficient catalytic conversion of CO2 has attracted considerable attention worldwide. In this study, a series of crown ether-conjugated microporous polymer materials containing carboxylic groups (CCMPs) were synthesized through multi-components reactions in one pot. This synthesis involved the reaction of dialdehydebenzo-18-crown-6 with different monomers of amino and pyruvate in the presence of DDQ. Fourier transform infrared spectroscopy, carbon-13 cross-polarization magic angle spinning nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were used to characterize the CCMPs. Then, CCMPs were used in CO2 fixation and iodine vapor adsorption. The co-catalyst KI and CCMP-4 exhibited excellent activity in mild conditions, resulting in a 94% yield. The catalytic activity of the CCMP-4 was maintained after the five cycles. The kinetics of CCMP-4 was studied, and a potential reaction mechanism was proposed. The iodine adsorption experiments were conducted on CCMPs. The results showed that CCMPs exhibited excellent adsorption effects at 75 °C. The adsorption capacities of CCMP-1, CCMP-2, CCMP-3 and CCMP-4 were 3.02, 2.68, 2.72 and 3.21 g·g−1, respectively. The experimental results showed that CCMPs effectively absorbed iodine vapor and exhibited an excellent catalytic effect on CO2 cycloaddition under mild conditions, which is proved by density functional theory calculations further.

Iodine Adsorption-Desorption-Induced Structural Transformation and Improved Ag+ Turn-On Luminescent Sensing Performance of a Nonporous Eu(III) Metal-Organic Framework.

Posttreatment of pristine metal-organic frameworks (MOFs) with suitable vapor may be an effective way to regulate their structures and properties but has been less explored. Herein, we report an interesting example in which a crystalline nonporous Eu(III)-MOF was transferred to a porous amorphous MOF (aMOF) via iodine vapor adsorption-desorption posttreatment, and the resulting aMOF showed improved turn-on sensing properties with respect to Ag+ ions. The crystalline Eu-MOF, namely, Eu-IPDA, was assembled from Eu(III) and 4,4'-{4-[4-(1H-imidazol-1-yl)phenyl]pyridine-2,6-diyl}dibenzoic acid (H2IPDA) and exhibited a two-dimensional (2D) coordination network based on one-dimensional secondary building blocks. The close packing of the 2D networks gives rise to a three-dimensional supramolecular framework without any significant pores. Interestingly, the nonporous Eu-IPDA could absorb iodine molecules when Eu-IPDA crystals were placed in iodine vapor at 85 °C, and the adsorption capacity was 1.90 g/g, which is comparable to those of many MOFs with large BET surfaces. The adsorption of iodine is attributed to the strong interactions among the iodine molecule, the carboxy group, and the N-containing group and leads to the amorphization of the framework. After immersion of the iodine-loaded Eu-IPDA in EtOH, approximately 89.7% of the iodine was removed, resulting in a porous amorphous MOF, denoted as a-Eu-IPDA. In addition, the remaining iodine in the a-Eu-IPDA framework causes strong luminescent quenching in the fluorescence emission region of the Eu(III) center when compared with that in Eu-IPDA. The luminescence intensity of a-Eu-IPDA in water suspensions was significantly enhanced when Ag+ ions were added, with a detection limit of 4.76 × 10-6 M, which is 1000 times that of pristine Eu-IPDA. It also showed strong anti-interference ability over many common competitive metal ions and has the potential to sense Ag+ in natural water bodies and traditional Chinese medicine preparations. A mechanistic study showed that the interactions between Ag+ and the absorbed iodine, the carboxylate group, and the N atoms all contribute to the sensing performance of a-Eu-IPDA.

Green conversion of waste alkaline battery material to zeolitic imidazolate framework-8 and its iodine capture mechanism

Zeolitic imidazolate framework-8 (ZIF-8) exhibits excellent performance in capturing iodine. However, the solvent-based procedures and raw materials for ZIF-8 synthesis often lead to secondary pollution. We developed a solvent-minimizing method for preparing ZIF-8 via ball milling of raw material obtained from spent alkaline batteries, and studied its iodine-capture performance and structural changes. Exposure of the ZIF-8 to iodine vapor for 60 min demonstrated that it exhibited industrially competitive iodine-capture performance (the adsorbed amount reaches to 1123 mg g−1 within 60 min). Spectroscopic studies showed that ZIF-8 underwent a structural transformation upon iodine loading. Iodine molecules were adsorbed onto the surface of ZIF-8 and also formed C–I bond with the methyl groups on the imidazole rings, reducing iodine release. This work represents a comprehensive revelation of long-range order and short-range order evolution of ZIF-8 during iodine vapor adsorption over time. Moreover, this green synthesis of ZIF-8 is of lower cost and generates fewer harmful by-products than existing methods, and the produced ZIF-8 effectively entraps toxic iodine vapor. Thus, this synthesis enables a sustainable and circular material flow for beneficial utilization of waste materials.