I2 Vapor Research Articles

Imaging the Iodine Sorption-Induced Synchronous Skeleton-Pore Interactions of Single Covalent Organic Framework Particles.

Covalent organic frameworks (COFs) are promising iodine adsorbents. For improved performances, it is critical and essential to fundamentally understand the underlying mechanism. Here, using the operando dark-field optical microscopy (DFM) imaging technique, the observation of an extraordinary structure shrinkage of 2D triphenylbenzene (TPB)-dimethoxyterephthaldehyde (DMTP)-COF upon the adsorption of I2 vapor at the single-particle resolution is reported. Combining single-particle DFM imaging with other experimental and theoretical methods, it is revealed that the shrinkage mechanism of the TPB-DMTP-COF is attributed to the I2 sorption-induced synchronous skeleton-pore interactions. The redox reaction of I2 and TPB-DMTP-COF yields some cationic skeletons and I3 - species, which triggers the multi-directional halogen-bonding interactions of I2 and I3 - as well as strong cation-π interactions between neutral and cationic skeletons, accompanying the synchronous in-plane skeleton shrinking in the xy plane and compact out-of-plane layer packing in the z-direction. This understanding of the synchronous action between the skeleton and pore breaks the perspective on the structure robustness of 2D COFs with excellent stability during the I2 uptake, which offers pivotal guidance for the rational design and creation of advanced microporous adsorbents.

Improvement of Electrical Conductivity of In Situ Iodine-Doped Polypyrrole Film Using Atmospheric Pressure Plasma Reactor with Capillary Electrodes.

To improve the electrical conductivity of polypyrrole (PPy) nanostructure film through in situ iodine (I2) doping, this study proposes an atmospheric pressure plasma reactor (APPR) where heated I2 dopant vapor is fed through capillary electrodes that serve as electrodes for discharge ignition. A large amount of the heated I2 vapor introduced into the reactor separately from a monomer gas can be effectively activated by an intense plasma via capillary electrodes. In particular, intensive plasma is obtained by properly adjusting the bluff body position in the APPR. Based on the ICCD and OES results, the I2 vapor injected through the capillary nozzle electrode is observed to form I2 charge species. The formed I2 species could directly participate in growing in situ I2-doped PPy films. Thus, in situ I2-doped PPy nanostructure films grown using the proposed APPR exhibit higher thicknesses of 15.3 μm and good electrical conductivities, compared to the corresponding non-doped films.

Efficient capture of iodine in steam and water media by hydrogen bond-driven charge transfer complexes

Untreated radioactive iodine (129I and 131I) released from nuclear power plants poses a significant threat to humans and the environment, so the development of materials to capture iodine from water media and steam is critical. Here, we report a charge transfer complex (TCNQ-MA CTC) with abundant nitrogen atoms and π-conjugated system for adsorption of I2 vapor and I3- from aqueous solutions. Due to the synergistic binding mechanism of benzene/triazine rings and N-containing groups with iodine, special I-π and charge transfer interaction can be formed between the guest and the host, and thus efficient removal of I2 and I3- can be realized by TCNQ-MA CTC with the adsorption capacity up to 2.42 g/g and 800 mg/g, respectively. TCNQ-MA CTC can capture 92% of I3- within 2.5 min, showing extremely fast kinetics, excellent selectivity and high affinity (Kd = 5.68 × 106 mL/g). Finally, the TCNQ-MA CTC was successfully applied in the removal of iodine from seawater with the efficiency of 93.71%. This work provides new insights in the construction of charge transfer complexes and lays the foundation for its environmental applications.

Molecular and morphological diversity, qualitative chemical profile and antioxidant activity of filamentous fungi of the digestive tract of Phylloicus sp. (Trichoptera: Calamoceratidae).

This study aimed to identify by molecular analysis, morphology, chemistry and antioxidant extracts of filamentous fungi isolated from the digestive tract of Phylloicus sp, an aquatic insect that lives on leaf packages in tropical streams and participates together with fungi of the decomposition of plant substrates in aquatic habitats. Insect larvae of Phylloicus sp. were collected in streams in the state of Tocantins, Brazil. Fungi were isolated from the digestive tract of larvae after disinfection and dissection, then described and purified for identification purposes and testing for antioxidant activity. Molecular identity was performed of ITS1 and ITS4, TUB e TEF sequencing. Fungal extracts were produced in 70% ethanol solution and later lyophilized. For analysis of chemical groups of extracts, thin layer chromatography (TLC) was performed in two mobile phases and different developers. Morphology was performed by optical microscopy stained with Toluidine Blue and measurement performed using the ImageJ program. Antioxidant activity performed in TLC and by quantitative method for DPPH and hydrogen peroxide (H2O2) radicals. Four fungi were identified: Endomelanconiopsis endophytica, Myxospora musae, Neopestalotiopsis cubana and Fusarium pseudocircinatum. The TLC showed several spots with acetone/chloroform mobile phase and UV 254 nm developers and I2 vapor. Fungal extracts demonstrate antioxidant action to reduce the DPPH free radical and especially for H2O2 above 50%, E. endophytica 91.6%, M. musae 87.8%, N. cubana 89.5% and 92.3% for F. pseudocircinatum. This study demonstrated that the molecular technique by PCR was satisfactory for identifying fungi, and extracts with numerous chemical groups and potent reducing agents. Thus future work, should be carried out evaluating these four species for industrial use.

Monolithic Cu/Al2O3-palygorskite composite aerogel for high-efficiency iodine elimination in a multimedia environment

Radioactive iodine has highly radioactive and biological toxicity, and its effective recovery is of primary importance. However, few materials can show good iodine adsorption in different media. Herein, Cu/Al2O3-Pal aerogels with improved mechanical properties and hierarchical pore structures were prepared by constructing the three-dimensional support skeleton of the aerogel with palygorskite fibers. The Cu/Al2O3-Pal aerogel exhibited excellent adsorption properties for I− (aqueous phase, 264–411 mg/g) and I2 (organic phase, 503–744 mg/g), I2 vapor (459–1122 mg/g), and CH3I vapor (559–1032 mg/g). Notably, the aerogel also exhibited ultra-high removal rates for trace iodide in solution (>90 %) and was able to efficiently convert to stable CuI. Importantly, the Cu/Al2O3-Pal aerogel can be prepared directly for use as a monolithic material, allowing for an easy recovery process. Overall, our work demonstrates the great potential of Cu/Al2O3-Palx wt% aerogels for radioactive iodine elimination.

NixSy/NF composites assembled by sulfidation of nickel foam (NF) for highly effective capture of iodine

Under a facile one-step hydrothermal reaction by changing thiourea dosage to regulate sulfidation degree of nickel foam (NF), a variety of nickel sulfide composites of n-NixSy/NF (1-Ni3S2/NF, 3-Ni3S2 and 6-Ni3S2/Ni9S8) were prepared and utilized to capture iodine for the first time. The compositions and structures of the composites and their influence on iodine adsorption performance were elaborated in detail. During adsorption, Ni0 in NF and Ni0/S2− in Ni3S2/Ni9S8 both served as reducing agents to achieve the chemisorption for iodine, where the Ni0 and S2− were oxidized to Ni2+ and elemental S0 (S8), and the I2 molecules were reduced to I− which then reacted with the Ni2+ to form NiI2. The 1-Ni3S2/NF, 3-Ni3S2 and 6-Ni3S2/Ni9S8 exhibited different iodine adsorption capacities (qmI) of 1442, 1109 and 420 mg/g for iodine vapor, and 1191, 869 and 296 mg/g for iodine in solutions, respectively, giving the largest qmI of 1442 (for I2 vapor) and 1191 mg/g (for I2 in solution) by 1-Ni3S2/NF. The capture mechanism for iodine in solution was mainly by chemisorption, while for iodine vapor, profiting from the three-dimensional skeleton of NF, besides the chemisorption, physical sorption also played a role. After γ irradiation, the structures of n-NixSy/NF were well-maintained and iodine adsorption performance did not deteriorate, indicating the good radiation resistance. This work provides an important reference for tailoring new kinds of cost-effective sorbents to trap iodine from radioactive nuclear wastes.

Disulfide‐Bridged Dynamic Covalent Triazine Polymer Thin Films by Interface Polymerization: High Refractive Index with Excellent Optical Transparency

AbstractExploring innovative strategies for molecular structuring of dynamic materials that combine self‐correcting intrinsic reversibility with the robustness of covalent bonds, has been a long‐standing objective from applications perspective in fields ranging from molecular engineering to nanotechnology and interfacial science. To establish dynamic covalent chemistry approaches combined with interfacial polymerization, herein, a distinct synthetic approach is reported to develop disulfide‐bridged 2D polymeric C3N3S3 triazine thin‐films by interfacial thiol‐disulfide dynamic exchange process crosslinking tritopic planar 1,3,5‐triazine‐2,4,6‐trithiol molecular tectons via intermolecular disulfide formation in the presence of I2 vapors at the air/water interface under redox condition. The resulting centimeter‐scale polymeric thin‐films are covalently cross‐linked, dynamic in nature, featuring tunable thickness (6–200 nm) and significant morphological variations are realized under the influence of varying reaction time, concentration and types of reducing agents. Notably, C3N3S3 polymer thin films exhibit a transflectance of around 99.5% in the range from 430 to 1800 nm, show high refractive indices (1.730–1.488) and optical anisotropy with uniaxial negative birefringence. The C3N3S3 free‐standing polymer thin‐films can be easily transferred to different substrates or possibly into application‐relevant forms for device fabrications, making this useful from materials application perspective.

Bifunctional thiophene-based covalent organic frameworks for Hg2+ removal and I2 vapor adsorption

Novel bifunctional thiophene-based COFs were constructed according to Schiff base reaction between tetrakis(4-aminophenyl)-ethane and 2,5-thiophenedicarboxaldehyde/ thieno[3;2-b]thiophene-2,5-dicarboxaldehyde. The loading of N/S heteroatoms in the skeleton not only take the COFs abundant functional groups, but also elevate the stability of the functional groups, and avoid the blocking of the pores from the post-functionlization of functional groups. The thiophene-based COFs all showed good crystalline structure, high Brunauer–Emmett–Teller (BET) surface area (SBET), pore volume (Vtotal), and N/S content, indicative of the COFs good performance in Hg2+ adsorption and I2 vapor capture. Especially, the COF-S1, which showed high SBET of 2133 m2/g and Vtotal of 1.672 cm3/g, exhibited a relative high I2 vapor capacity of 7.74 g/g. Although COF-S2 showed lower SBET (1430 m2/g) and Vtotal (1.186 cm3/g), the higher N/S content make COF-S2 higher Hg2+ adsorption capacity of 834 mg/g. The COFs also showed outstanding adsorption selectivity and good recyclability. This work provides guidance for the design and preparation of multi-functional adsorbents.

Robust Hierarchical-pore covalent triazine framework for efficient iodine capture and ammonia adsorption

Radioactive iodine (I2) in nuclear waste and corrosive ammonia gas (NH3) are harmful to human health and efficient removal of them is a serious task. Herein, two 2D covalent triazine frameworks (CTF) with hierarchical-pore structure were prepared by the nitrile trimerization of 2, 4, 6 trinitrile styryl-s-triazine (TCST) monomer via an ionic thermal strategy. The resulting CTF-TCSTs have high porosity and excellent chemical stability. The obtained CTF-TCST-500 has a richer mesoporous structure than that of CTF-TCST-400 and the introduced mesoporous structure can increase the I2 adsorption of CTF-TCST-500. Specifically, the I2 adsorption capacity of CTF-TCST-500 for I2 vapor and solution are 4.72 g g−1 and 4.02 g g−1, respectively. Surprisingly, CTF-TCST-500 exhibits the record I2 adsorption capacity in hexane solvent. In addition, CTF-TCST-400 with ultramicroporous structure possesses excellent adsorption performance for alkaline NH3 and the adsorption capacity is up to 7.2 mmol g−1. To our knowledge, this is the first report of CTF adsorbent for NH3 adsorption. This work not only provides two robust CTF adsorbents with conjugate structure and high adsorption capacities for I2 and NH3, but also emphasizes the significant contribution of defective mesoporous structure for I2 capture and ultramicroporous structure for NH3 adsorption.

Imaging Solvent‐Triggered Gaseous Iodine Uptake on Single Covalent Organic Frameworks

AbstractCovalent organic frameworks (COFs) are promising solid absorbents for the treatment of gaseous iodine. However, extensive efforts are still focused on empirical optimizations of specific binding sites and pore structures in COFs, and the chemical control of gaseous iodine uptake on COFs remains challenging. In this study, the chemically triggered sorption properties of COF‐300 for I2 vapors at the single‐particle level with the dark‐field microscope (DFM) are explored. The present operando single‐particle DFM imaging method enables the direct visualization of an adsorption activity transformation from inactive COF‐300 to active solvated COF‐300 toward gaseous I2 vapors. Exploiting the useful reaction information from time‐lapsed DFM images, the tunable adsorption performance of solvated COF‐300 is quantitatively compared by various solvents. The results illustrate that the isopropanol (IPA)‐solvated COF‐300 achieves the optimum adsorption capacity for I2 among the absorbents. The reaction mechanism is elucidated to be the channel size enlargement and modification of internal surface chemistry in the IPA‐solvated COF‐300, producing a stable I2/IPA‐solvated COF‐300 complex after the sorption reaction. The present chemical control of the sorption behavior of COF‐300 revealed by DFM opens up a new fundamental paradigm for rationally developing high‐performance COF‐based absorbents for removing I2 vapors.

Visualized electrochemiluminescence iodine sensor based on polymer dots with Co-reactive group for real-time monitoring system

Trace iodine (I2) radioisotopes are commonly regarded as an indicator in nuclear security early warnings. Herein, we develop a visualized I2 real-time monitoring system using electrochemiluminescence (ECL) imaging technology for the first time. In detail, the polymers based on poly [(9,9-dioctylfluorene-alkenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1’,3}-thiadiazole)] are synthesized for iodine detection. An ultra-low limit of detection (0.01 ppt) to iodine can be achieved by adding the modification ratio of tertiary amine onto PFBT as a co-reactive group, which is the lowest detection limit in known iodine vapor sensors. This result can be attributed to the co-reactive group poisoning response mechanism. Considering to the strong ECL behavior of this polymer dots, P-3 Pdots with ultra-low detection limit for iodine is combined with ECL imaging technology to realize the visualized rapid I2 vapor response with high selectivity. ECL imaging component based on ITO electrode can make iodine monitoring system more convenient and suitable for real-time detection in early warning of nuclear emergency. The detection result cannot be affected by vapor of organic compounds, humidity and temperature, indicating a good selectivity to iodine. This work provides a strategy for nuclear emergency early warning, showing its significance in environmental and nuclear security fields.

Encapsulating covalent organic frameworks (COFs) in cellulose aerogels for efficient iodine uptake

Efficient capture and storage of radioiodine are of great importance for developing nuclear energy and tackling nuclear waste, which however remain challenging due to the scarcity of powerful materials. In this work, we rationally design and fabricate a hybrid material by encapsulating covalent organic frameworks (COFs) into ultralight cellulose aerogels for efficient iodine (I2) capture. Two kinds of functionalized cellulose precursors that can be covalently cross-linked are synthesized. Solvothermally synthesized COF particles with a uniform diameter of ∼ 500 nm are then introduced into the precursors followed by freeze drying to produce hybrid aerogels. With the presence of rich and ordered micropores afforded by COFs, these highly porous aerogels exhibit excellent organic solvent absorption performances and high uptake capacities toward solvent-dissolved and vaporized I2. More importantly, in view of the processable and robust structure, we realize the shaping of hybrid aerogels into aerogel columns to effectively capture I2 vapor and I2 solute in continuous operations. Therefore, this work not only provides a new way to shape COF materials but also could inspire the design of viable platforms for high-performance I2 capture.

A new strategy to synthesis of porous polymers from plastic waste for highly efficient adsorption of rhodamine B, malachite green and I2 vapor

Plastic waste has been becoming a severe environmental issue. Developing low-cost and facile strategy to converse them into the high value-added materials for remediation of ecosystem is a big challenge. In this manuscript, Polystyrene foam waste (PSF) was employed as starting material to react with the different mass ratio of cyanuric chloride (CC) to synthesize a series of hyper-cross-linked polymers (HPPCs). HPPCs were porous polymers and mainly composed of micro-pores and meso-pores. Their apparent surface areas (SBET) and pore volumes were in range of 622.9 ± 11 and 719.2 ± 15 m2 g−1, 0.87 and 1.01 cm3 g−1, respectively. The SBET and pore volume could be tuned by the mass ratio of PSF and CC. Adsorption experiments revealed that HPPC-3 showed high adsorption quantities of rhodamine B (RhB) and malachite green (MG) with the maximum adsorption capacities of 2354.0 ± 60.8 and 1331.9 ± 30.6 mg g−1, respectively. The adsorption isotherm and kinetics data suggested that the adsorption behaviors of RhB and MG on HPPC-3 followed the Langmuir models and pseudo-second-order models. Additionally, HPPC-3 displayed high adsorption capacity of iodine vapor up to 188 ± 3.2 wt%. Therefore, this work suggested a new approach for converting plastic waste into the promising adsorbent for removal of dyes and radioactive iodine vapor from contaminated ecosystem.

Superior Iodine Uptake Capacity Enabled by an Open Metal-Sulfide Framework Composed of Three Types of Active Sites

Superior Iodine Uptake Capacity Enabled by an Open Metal-Sulfide Framework Composed of Three Types of Active Sites

Chemically Stable Guanidinium Covalent Organic Framework for the Efficient Capture of Low-Concentration Iodine at High Temperatures

The capture of radioactive I2 vapor from nuclear waste under industrial operating conditions remains a challenging task, as the practical industrial conditions of high temperature (≥150 °C) and low I2 concentration (∼150 ppmv) are unfavorable for I2 adsorption. We report a novel guanidinium-based covalent organic framework (COF), termed TGDM, which can efficiently capture I2 under industrial operating conditions. At 150 °C and 150 ppmv I2, TGDM exhibits an I2 uptake of ∼30 wt %, which is significantly higher than that of the industrial silver-based adsorbents such as Ag@MOR (17 wt %) currently used in the nuclear fuel reprocessing industry. Characterization and theoretical calculations indicate that among the multiple types of adsorption sites in TGDM, only ionic sites can bond to I2 through strong Coulomb interactions under harsh conditions. The abundant ionic groups of TGDM account for its superior I2 capture performance compared to various benchmark adsorbents. In addition, TGDM exhibits exceptionally high chemical and thermal stabilities that fully meet the requirements of practical radioactive I2 capture (high-temperature, humid, and acidic environment) and differentiate it from other ionic COFs. Furthermore, TGDM has excellent recyclability and low cost, which are unavailable for the current industrial silver-based adsorbents. These advantages make TGDM a promising candidate for capturing I2 vapor during nuclear fuel reprocessing. This strategy of incorporating chemically stable ionic guanidine moieties in COF would stimulate the development of new adsorbents for I2 capture and related applications.

Covalently connected core–shell NH2-UiO-66@Br-COFs hybrid materials for CO2 capture and I2 vapor adsorption

Metal organic frameworks (MOFs)@covalent organic frameworks (COFs) (MOFs@COFs) hybrid materials not only combine the advantages of MOFs and COFs, but the possible synergistic effect at the MOFs-COFs interface can improve the performance of the hybrid materials greatly. Herein, the Br-COFs shell was in-situ grown on the surface of the NH2-UiO-66 core by Schiff-based reaction and a kind of novel covalently connected core–shell NH2-UiO-66@Br-COFs hybrid materials were prepared accordingly. Unique structure was generated at the core–shell interface which could be effectively adjusted by the coating amount of Br-COFs. In particular, abundant ultramicropores were generated at the interfacial layers as compared with NH2-UiO-66 and Br-COFs, and the maximum ultramicropore volume (Vultra) was up to 0.157 cm3·g−1. These produced ultramicropores at the core–shell interface made a great positive contribution to the CO2 capacity and the maximum CO2 capacity of the hybrid materials was measured to be 169.5 mg·g−1 at 273 K and 1.0 bar, outperformed the corresponding single MOF and COF. Additionally, the highest I2 vapor uptake of the hybrid materials was determined to be 3.73 g·g−1 and it increased with the increase of the coating amount of Br-COFs. This work presents the successful regulation of the adsorption performance by the rational fabrication of novel hybrid MOFs@COFs interface.

The optoelectronic properties improvement of double perovskites Cs2SnI6 by anionic doping (F\u2212)

Tin-based perovskite material is the best choice to replace heavy metal element lead during the last several years. Cs2SnI6 with Sn4+ is a fascinating optoelectronic material, which is a more air-stable composite cesium tin halide peroxide variant from CsSnI3. However, the optoelectronic performance between N and P type of Cs2SnI6 varies considerably. Herein, we synthesized uniform Cs2SnI6 by modified two-step method, which thermal evaporated CsI firstly, and followed annealing in the SnI4 and I2 vapor at 150 °C resulted in uniform Cs2SnI6 films. SnF4 is used as a dopant source to improve the optoelectronic properties of Cs2SnI6 films. Results indicate that good crystallinity was obtained for all films and the doped films underwent a crystalline plane meritocracy transition. The doped films had a flat, non-porous morphology with large grains. The high transmittance of the doped films in the infrared region led to the avoidance of self-generated thermal decomposition. With the help of F−, the films became more conductive and had higher carrier mobility. DFT calculations showed that doping with F reduced the surface energy of (004), resulted in a preferred orientation transition in the crystal of Cs2SnI6. Fluorine doped double layer perovskite materials would have a broader application prospect.

Silver coated and filled carbon nanotubes: Synthesis, electrical and thermal properties, and iodine vapor sensing

Here we present a simple method to fill multiwalled carbon nanotubes (MWCNT) with silver. This method involves stirring of MWCTs in AgNO3 solution at room temperature in open air followed by heating in H2 atmosphere at 250 °C for two hours. Process also leads to small coating of Ag on the surface. We confirmed the presence of crystalline silver in both coating and filling in hybrid MWCNTs by high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction. After silver coating and filling, bulk thermal diffusivity and thermal conductivity of Ag hybrid MWCNTs were increased by 242% and 255%, respectively. Furthermore, current-voltage measurements using tuna probe in atomic force microscopy showed higher number of charge carriers in the Ag hybrid nanotubes compared to pristine MWCNTs which resulted in up to 173% increase in their electrical conductivity. The Ag hybrid MWCNT based sensor also showed rapid and reversible sensing for I2 vapors: bulk sensor film demonstrated sensing response of 45% in just ~60 s at room temperature. However, the sensor recovery was slower: after removal of I2 vapors source, the recovery took 400 s and required heating at 100 °C in air. Response and recovery of sensor film was maintained after repeated cycles of exposure. Finally, the Ag hybrid MWCNTs film displayed high stability and selectivity for I2 vapors.

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

High iodine adsorption by lignin-based hierarchically porous flower-like carbon nanosheets

Developing an efficient adsorbent for adsorbing and capture radioactive iodine as a fission product in air and aqueous solution during the nuclear disposal process and in the event of a nuclear accident is of great importance. In this work, lignin-based porous flower-like carbon nanosheets have been developed by using lignin as a carbon precursor, MgO as a template coupled with KOH-activation (LFC-K), and KOH/NaOH eutectic activation (LFC-KN), which were tested for the adsorption of iodine molecules in iodine vapor and in solution. The combination of nanosheets structure and abundant pores makes LFC-K, and LFC-KN excellent absorbability for iodine. The LFC-K with both micropores and mesopores had a higher adsorption capacity for I2 vapor (4060 mg g−1); in comparison, LFC-KN with both micropores, mesopores and macropores had a higher adsorption capacity for I2 in water (1295 mg g−1). After several iodine adsorption and release cycles, the two adsorbents still exhibit excellent reusability.