Iodine Capture Research Articles

Bicarbazolyl-based covalent organic frameworks for highly efficient capture of iodine and methyl iodide

Bicarbazolyl-based covalent organic frameworks for highly efficient capture of iodine and methyl iodide

Nitrogen-doped hierarchically porous carbon derived from biomass for efficient capture of iodine

Effectively capturing radioactive iodine formed during nuclear energy utilization is crucial for environment protection and human health. Herein, we present a facile and effective strategy to synthesize a nitrogen-doped hierarchically porous carbon from corn stalks for iodine capture in gaseous and liquid environment. The as-prepared carbon material possesses a hierarchically micro/mesopore structure with highly developed mesopores, a large specific surface area (1892.99 m2 g−1), and suitable nitrogen-doping (2.32 at.%). As a result, the carbon material exhibits efficient iodine capture performance, showing a large capture capacity of 3.14 g g−1 at 80 °C for iodine vapor and a fast removal rate of ∼97 % within 5 min for iodine aqueous solution, outperforming most of carbon-based materials for iodine capture reported in literatures. Thermodynamic and kinetic analyses reveal that the adsorption of iodine vapor conforms to the Langmuir model and pseudo-second-order model, respectively. Density functional theory calculation results indicate that the doped-nitrogen heteroatoms strengthen the interaction between iodine molecules and carbon, which can enhance the affinity for iodine molecules by forming a donor–acceptor complex through the donation of lone-pair electrons, thereby facilitating effective capture of iodine. This work develops a biomass-based porous carbon with potential to efficiently capture radioactive iodine.

Influence of Elevated Temperature and Oxygen on the Capture of Radioactive Iodine by Silver Functionalized Silica Aerogel

Reprocessing is considered a competent strategy for spent nuclear fuel management, yet radioiodine (129I) is emitted in reprocessing off-gas as a hazardous byproduct. Silver functionalized silica aerogel (Ag0-aerogel), a promising iodine capture material, experiences a reduction in its capacity after prolonged exposure to off-gas components at elevated temperatures, a phenomenon termed as aging. To fully understand this process, we isolated the contribution of each aging factor, exposing Ag0-aerogel samples to N2 and dry air gas streams, respectively, at 150°C for different time periods. Aged samples were loaded with I2 to examine the capacity change and comprehensively characterized to investigate the evolution of their properties. Results show that temperature alone did not alter Ag0-aerogel’s capacity but triggered Ag0 nanoparticles sintering and generated organic sulfur species. The presence of O2 reduced the capacity by ∼20%, causing (i) formation of silver sulfide (Ag2S) crystals and (ii) oxidation of Ag-thiolate (Ag-S-r) to Ag sulfonate (Ag-SO3-r). Given that Ag2S readily adsorbs I2, the formation of Ag-SO3-r is the major inhibitor for iodine adsorption. This hypothesis was supported by density functional theory (DFT) simulations. These findings unraveled key mechanisms of Ag0-aerogel aging, which are useful in the development of materials that withstand realistic spent-nuclear-fuel-reprocessing off-gas conditions.

Benzonquanmine-based hypercrosslinked polymers for high-efficiency and reversible iodine capture

Benzonquanmine-based hypercrosslinked polymers for high-efficiency and reversible iodine capture

Deposition of Imidazole into Mesoporous Zirconium Metal-Organic Framework for Iodine Capture.

Efficient capture of radioiodine is essential for the protection of the ecological environment and the sustainable development of nuclear energy generation. Metal-organic frameworks (MOFs) and their derivatives provide alternative potential for overcoming the limitations of traditional iodine adsorbents. Herein this work, imidazole (Im) is dispersed into a robust mesoporous zirconium MOF PCN-222 by the heat deposition method, forming a high-uniformity composite Im@PCN-222. The large pore size and marked chemical resistance skeleton of PCN-222 allow the incorporation of Im to reach 43 wt % while surviving the chemical corrosion of activated Im. The nearly saturated loading of Im significantly benefits the sorption capability toward iodine and gives rise to an exceptional adsorption capacity of 10.04 g g-1 and excellent recyclability. This value is higher than that of most of the MOFs and their derivatives. Further, Im was also successfully deposited onto the PCN-222 functionalized porous Al2O3 ceramic filtration membrane, which endowed the hybrid membrane with efficient iodine sorption and separation properties. This work highlights a new strategy for the fabrication of the MOF-based radioiodine adsorption composite as well as MOF composite-based filters.

Michael addition-elimination reaction derived covalent organic polyrotaxane xerogels for ultra-high-efficiency capture of iodine pollutants

Herein, covalent organic polyrotaxane xerogels (COPRs), were developed as comprehensive and recyclable “three birds with one stone” platform effectively handling organic/radioactive iodine pollutants challenges. COPRs were synthesized rapidly from β-ketoenamine and aromatic amines β-cyclodextrin (β-CD) inclusion via Michael addition-elimination reaction in water at room temperature and pressure, avoiding the usage of any organic solvents. The formation of β-CD inclusion significantly increases the solubility and reactivity of monomers in water. The threading of β-CD endows multiple absorption sites within the porous skeleton, improving its iodine capture capacity. The integration of β-CD ring throughout the carbon skeleton not only provides a green and ultra-low-cost approach for preparing COPRs with brand-new structure, but also offers direct and effective methods realizing the carbon neutrality from the source of production. This work could be used as a general method for the specifically modifying COPs, providing opportunities to meet the growing needs of society.

Synthesis of a Novel Zwitterionic Hypercrosslinked Polymer for Highly Efficient Iodine Capture from Water.

Cationic porous organic polymers have a unique advantage in removing radioactive iodine from the aqueous phase because iodine molecules exist mainly in the form of iodine-containing anions. However, halogen anions will inevitably be released into water during the ion-exchange process. Herein, we reported a novel and easy-to-construct zwitterionic hypercrosslinked polymer (7AIn-PiP)-containing cationic pyridinium-type group, uncharged pyridine-type group, pyrrole-type group, and even an electron-rich phenyl group, which in synergy effectively removed 94.2% (456 nm) of I2 from saturated I2 aqueous solution within 30 min, surpassing many reported iodine adsorbents. Moreover, an I2 adsorption efficiency of ~95% can still be achieved after three cyclic evaluations, indicating a good recycling performance. More importantly, a unique dual 1,3-dipole was obtained and characterized by 1H/13C NMR, HRMS, and FTIR, correlating with the structure of 7AIn-PiP. In addition, the analysis of adsorption kinetics and the characterization of I2@7AIn-PiP indicate that the multiple binding sites simultaneously contribute to the high affinity towards iodine species by both physisorption and chemisorption. Furthermore, an interesting phenomenon of inducing the formation of HIO2 in unsaturated I2 aqueous solution was discovered and explained. Overall, this work is of great significance for both material and radiation protection science.

A nitrogen-rich halogen-bonded organic framework (XOF) for efficient iodine capture and security printing

A nitrogen-rich halogen-bonded organic framework (XOF) for efficient iodine capture and security printing

Photo‐Assisted Zn‐Iodine Battery via Bifunctional Cathode with Iodine Host and Solar Response Boost

AbstractThe aqueous photo‐assisted battery is considered an efficient means of converting and storing solar energy in one device. However, identifying a suitable photocathode with excellent iodine capture capabilities for photo‐assisted Zn‐iodine batteries still remains challenging. In this work, bifunctional BiOI is prepared as sole cathode material for a photo‐assisted Zn‐iodine battery while simultaneously realizing an iodine host and solar responsiveness. The as‐presented BiOI with abundant vacancies offers highly reversible photo‐assisted iodine redox reactions. Meanwhile, the dual reaction routes involving vacancy iodine storage and reversible two‐steps iodine redox are confirmed by in/ex situ characterization techniques during the energy storage process. Consequently, the assembled battery exhibits areal capacity of 0.24 mAh cm−2 at 1 mA cm−2 with coulombic efficiency exceeding 96.5%. More impressively, benefiting from the wide visible light absorption of the BiOI cathode, the battery demonstrates a much enhanced specific areal capacity of 0.4 mAh cm−2 at 1 mA cm−2 under sun illumination, representing a remarkable increment of 60% compared to that in the dark environment. This work expands the utility of cathode materials for a photo‐assisted Zn‐iodine battery.

Constructing of thiophene-based covalent organic frameworks with electron rich system for enhanced iodine capture

To address the significant energy pollution created by nuclear waste and the environmental catastrophe resulting from rapid industrial expansion, electronic-rich materials are widely developed and applied. However, the stability and reproducibility of the material limit its practical application. Therefore, the development of highly stable electron-rich adsorbents remains a great challenge. Herein, we report two highly stable thiophene-based COFs (JLNU-308 and JLNU-309) for iodine capture. Thiophene groups enhance electron-rich interactions with iodine, boosting adsorption capacity. Both COFs exhibit strong iodine adsorption and stability. Notably, JLNU-309 achieves rapid adsorption within 50 h, reaching 3.840 g g-1 capacity. In addition, theoretical calculations unequivocally demonstrate that in addition to the influence of thiophene groups, the superior adsorption capability of JLNU-309 can be attributed to the robust interaction between the adsorbed iodine and the many triazine nitrogen-rich adsorption sites that are evenly dispersed throughout the pore. Therefore, this study offers a method for designing and developing electron-rich COFs with high stability.

Designing highly porous three-dimensional triazine-bearing covalent organic polymers as prominent adsorbents of carbon dioxide and iodine

A new class of triazine-containing covalent organic porous polymers TCOP1-3 were made using a versatile one-pot [3 + 2] cyclocondensation reaction revealing remarkable robustness as proven by their thermal stability which disclosed a 10 % weight loss temperature ≥400 °C. Investigation of the intrinsic microporosity properties of TCOP1-3 using nitrogen adsorption experiments disclosed salient Brunauer–Emmett–Teller (BET) surface areas ranging from 725 to 932 m2 g−1 with average pore volumes in the range of 0.52–0.65 cm3 g−1. TCOP1-3 exhibited high CO2 uptakes attaining 120 mg g−1 at 273K and low pressure whereas iodine capture tests demonstrated significant results achieving a maximum adsorption of 4.02 g g−1. Recycling experiments confirmed the potential for these polymers to be restored even after a multitude of concurrent iodine adsorption-desorption cycles.

Construction of heterogeneous MOF-on-MOF for highly efficient gaseous iodine sequestration under static conditions

Considering the unexpected nuclear power waste emission and potential nuclear leakage, the exploration of robust materials for the effective capture and storage of radioactive iodine is of great importance but still remains a challenge. In this work, we report the rational synthesis of functionalized NH2-UiO-66-on-ZIF-67 architecture to enhance the static adsorption and retention of volatile iodine. Such MOF-on-MOF heterostructures was fabricated through seeding ZIF-67 core on the surface of NH2-UiO-66 satellite via a facile polyvinylpyrrolidone (PVP) regulated internal extended growth strategies. NH2-UiO-66-on-ZIF-67 exhibited unique core-satellite structure, which significantly promotes the binding interactions with iodine through synergizing of the N-rich imidazole moieties and surface functionalized amino groups within the porosity channels. As a result, the as fabricated NH2-UiO-66-on-ZIF-67 achieves enhanced mass diffusion and high capture capacity of 3600 mg/g for iodine vapor under static sorption conditions. Moreover, water vapor in humid conditions (relative humidity of 18 %) has almost no effect on the static iodine adsorption performance of the material. This study sheds light on a reliable MOF-on-MOF hybrid strategy for effective radioiodine treatment to ensure the safety nuclear waste management.

Capture of Iodine in Vapor and Solution Phases by a Th-Based Metal-Organic Framework.

The efficient capture of radioactive iodine is of paramount importance due to its harmfulness. In this work, a new Th-based metal-organic framework (ECUT-Th-11) for iodine capture was reported. ECUT-Th-11 exhibited a relatively high capacity of capturing vapor iodine (2.03 g/g). Besides, the maximal adsorption capacity of iodine in a cyclohexane solution reaches 258.03 mg/g. All of the results demonstrated that ECUT-Th-11 could be a candidate material for the effective removal of waste iodine.

Porous Organic Cage as an Efficient Platform for Industrial Radioactive Iodine Capture

AbstractHerein, we firstly develop porous organic cage (POC) as an efficient platform for highly effective radioactive iodine capture under industrial operating conditions (typically ≥150 °C), ≤150 ppmv of I2). Due to the highly dispersed and readily accessible binding sites as well as sufficient accommodating space, the constructed NKPOC‐DT‐(I−) (NKPOC=Nankai porous organic cage) demonstrates a record‐high I2 uptake capacity of 48.35 wt % and extraordinary adsorption capacity of unit ionic site (~1.62) at 150 °C and 150 ppmv of I2. The I2 capacity is 3.5, 1.6, and 1.3 times higher than industrial silver‐based adsorbents Ag@MOR and benchmark materials of TGDM and 4F‐iCOF‐TpBpy‐I− under the same conditions. Furthermore, NKPOC‐DT‐(I−)Me exhibits remarkable adsorption kinetics (k1=0.013 min−1), which is 1.2 and 1.6 times higher than TGDM and 4F‐iCOF‐TpBpy‐I− under the identical conditions. NKPOC‐DT‐(I−)Me thus sets a new benchmark for industrial radioactive I2 adsorbents. This work not only provides a new insight for effectively enhancing the adsorption capacity of unit functional sites, but also advances POC as an efficient platform for radioiodine capture in industry.

Tunable sulfur vacancies in amorphous-crystalline AC-Bi2S3-x@C derived from CAU-17 for efficient capture of radioiodine: Comparison of sulfur vacancies in amorphous and crystalline structures

Solid-phase adsorption has been recognized as an effective method for the control of volatile radioactive iodine in spent fuel reprocessing plant off-gases. However, it is still a challenge to develop efficient and stable iodine capture adsorbents. In this work, sulfur-vacancy-rich amorphous-crystalline AC-Bi2S3-x@C was prepared by solvothermal vulcanization using CAU-17 as a precursor. Based on the synergistic effect of the amorphous structure and sulfur vacancy defects, AC-Bi2S3-x@C exhibited fast adsorption equilibrium time (15 min), distinguished iodine adsorption capacity (1763.9 mg g−1), high percentage of chemical adsorption (93.4 %) as well as favorable thermal and irradiation stability. Adsorption experiments and theoretical calculations verified that the amorphous structure not only enhance the charge transfer between sulfur vacancy defects and iodine molecules, but also offers rapid diffusion channels for iodine molecules to the interior of the adsorbent and sufficient internal binding sites to promote iodine molecule adsorption in its interior. The used adsorbent showed high iodine retention (92.3 %) and excellent chemical durability (normalized iodine leaching rate of 4.63 × 10-5 g m−2 d-1) in glass solidification. In general, this work presented a new concept in the design and synthesis of efficient radioactive iodine capture materials.

Construction of nitrogen-rich groups @ zirconium-based metal-organic frameworks for efficient iodine capture

Efficient capture of radioactive iodine serves as an inevitable demand for secure utilization of nuclear energy, environmental conservation, and human health. In this contribution, a series of iodine adsorbent materials Im@UiO-66 were fabricated by encapsulating imidazole (Im) molecules into the pore of a classical zirconium-based metal–organic frameworks UiO-66, employing a simple and feasible vapor-diffusion strategy. Compared with original UiO-66, the resulting composites achieved a significant enhancement in iodine capture performance. Particularly, Im@UiO-66-3 demonstrated outstanding iodine adsorption performance with capacities of 4.66 g g−1 for vapor and 915 mg g−1 for solution, which were 3.5 and 9.2 times of the original UiO-66, respectively. Moreover, the introduction of nitrogen through ligand encapsulation provided additional sites for iodine immobilization. The primary mechanism underlying this remarkable performance was identified as charge transfer between iodine and imidazole (Im) molecules. The research offers valuable insights for the design of high-efficiency iodine adsorbents.

Engineering SuFEx-derived macrocyclic polysulfates for superior dynamic iodine capture at high temperatures

Efficient dynamic capture of radioiodine vapor from reprocessing of spent nuclear fuel under industrial conditions (∼423.15 K) is critically required due to its detrimental environmental and health impacts. However, conventional adsorbents often suffer from reduced binding affinity and structural degradation at elevated temperatures. To address these challenges, we have engineered a series of advanced polysulfate networks using sulfur (VI) fluoride exchange (SuFEx) click chemistry. These innovative networks integrate supramolecular macrocycle calix[4]pyrrole (C[4]P) and nitrogen-rich co-monomers as building blocks, and utilize polar sulfate bonds as important linkers, which provide availability of adsorptive sites and enhance the structural stability, thereby affording unexpected iodine capture performance at high temperatures. Among these SuFEx-derived materials, C[4]P-Azo exhibits exceptional iodine affinity through cooperative interactions involving multiple binding motifs, achieving an impressive iodine uptake capacity of 0.45 g g−1 at 423.15 K under dynamic adsorption conditions, setting a new benchmark in this field. Comprehensive characterizations and DFT calculations elucidate that advanced linker sulfate bonds enabling the marriage of C[4]P and N-rich monomers, play pivotal roles in facilitating iodine adsorption and maintaining structural integrity. These findings may pave the way for designing robust macrocyclic polysulfate-based adsorbents for dynamic radioiodine capture under industrial conditions.

Calix[4]resorcinarenes as Stable, Metal-Free Unexplored and Unfathomed Material for Iodine Capture: Experimental and Theoretical Insights

Calix[4]resorcinarenes as Stable, Metal-Free Unexplored and Unfathomed Material for Iodine Capture: Experimental and Theoretical Insights

Constructing covalent organic frameworks with dense thiophene S sites for effective iodine capture

Developing versatile sorption materials for radionuclide capture (e.g. iodine) is critical for nuclear energy and environmental science. Covalent organic frameworks (COFs) have recently become a new platform for developing sorption materials because of their high surface area and functionalised skeleton structure. Herein, two types of COF materials containing thiophene were designed as iodine sorbents and synthesised via a Schiff base reaction of benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene-2,5,8-tricarbaldehyde, benzidine (DADP) and p-phenylenediamine (DAB): DADP-COF and DAB-COF. DAB-COF exhibits a unique granular-rod-like morphology and has a higher surface area (1775 m2/g) than DADP-COF (1140 m2/g), which is clearly beneficial for the physical adsorption of iodine. Meanwhile, the COF backbone is rich in N and S sites, which are advantageous for the chemical adsorption of iodine. These two features make the two prepared COFs ideal iodine sorption materials. DAB-COF demonstrates an excellent gaseous iodine adsorption capacity of 4.2 g/g, ranking it as one of the most effective iodine sorption materials, while DADP-COF exhibits a good adsorption capacity of over 235 mg/g for iodine in cyclohexane solutions. Density functional theory calculations prove that imine N and thiophene S serve as active sites during the iodine adsorption. DAB-COF exposes more active sites because of its higher surface area, leading to a higher iodine adsorption capacity than DADP-COF. The results of this study indicate that introducing thiophene to COFs improves sorption efficacy for sorption applications in general and particularly paves the way for developing stable and effective COF sorbents for iodine capture from various environments.

Preparation and characterization of novel polyols-based DESs and their use in efficient sequestration of radioactive iodine

The utilization of Novel DESs can be greener alternative to traditional organic solvents. In present study, four polyols-based DESs are synthesized and characterized by several techniques. The prepared DESs are used for the efficient capture of hazardous iodine. In present study by simple combination of two readily accessible, economical, and biodegradable components four polyols-based DESs have been prepared. For the creation of these DESs, a hydrogen bond donors (HBDs) (polyols) and hydrogen bond acceptors (HBAs) (BTEAC) are used, which havemelting points far lower than their respective melting points. The developed DESs were investigated for their physicochemical properties such as density, dynamic viscosity. Our results revealed distinct trends in these properties across different DES compositions, highlighting unique molecular interactions and solvation capabilities. The FTIR and NMR characterization study indicated considerable intermolecular interaction between the various component of the DES system. Further, Kamlet-Taft solvatochromic parameters were determined using Nile red dye, and other solvatochromic dyes. For synthesized DESs, the solvatochromic parameters ENT, normalized polarity parameter, π*, polarity / polarizability; β, hydrogen-bond acceptor basicity and α, hydrogen-bond donor acidity, have been determined. The ENT parameters demonstrate that both non-specific and specific interactions play a significant role in solute–solvent interactions. The synthesized DESs have been utilized for the efficient capture of the iodine. The removal efficiency of DES depends upon the mass of the DESs taken and time duration. These findings deepen our understanding of DES behavior and underscore their versatility in diverse industrial and scientific applications.