Removal Of Iodine Research Articles

Vinyl-functionalized covalent organic frameworks for effective radioactive iodine capture in aqueous solution

131I radioisotopes have been widely employed in diagnostic and therapeutic medicine processes, particularly for thyroid cancer. The radiation hazard of 131I offers a potential threat to environmental safety or human health, so the wastewater generated from the production of 131I drugs must be effluent disposed of on time. In this study, we developed novel vinyl-functionalized covalent organic frameworks (COFs) with large pore volume and internal surface area for highly effective radioactive iodine ions adsorption in water. The as-produced spherical COFs (COF-V) exhibited a rapid adsorption rate (0.318 g g−1 min−1) and exceptionally high adsorption capacity of up to 437.8 mg g−1 for iodine ions in water. Furthermore, it demonstrated more than 90% removal of Na131I in water with radiation doses ranging from 181.3 MBq (4.9 mCi) to 1017.5 MBq (27.5 mCi). Additional characterizations and density functional theory (DFT) calculations revealed that the vinyl groups were linked with a benzene ring and imine to form a large and complete π-π conjugate system with 1D open channels. These channels provided sufficient sites for the effective adsorption of I ions on vinyl groups and benzene rings through hydrogen bonding. The excellent adsorption performance and radiation stability make the developed spherical COF-V a promising candidate for efficient radioactive iodine removal in wastewater.

Photocatalytic unification of iodine species using platinum-loaded titanium dioxide

Removal of iodine from water contaminated by nuclear accidents or releasing radioactive waste is complicated and costly because iodine exists in various forms in the water. We investigated the unification of iodine species by photocatalysis as a pretreatment for removing radioactive iodine species from water. The effect of the TiO2 crystal phase of Pt-TiO2 and solution pH on the photocatalytic redox reactions of iodide (I−), iodate (IO3−), and o-iodobenzoic acid were evaluated. When anatase Pt-TiO2 was used at pH 12 or higher, the mixture of I− and IO3− was converted to IO3−. In contrast, when anatase/rutile mixed-phase Pt-TiO2 was used at pH 9 or 10, the mixture of iodine species in the solution was converted to I−. Regardless of the type of Pt-TiO2, the iodine in o-iodobenzoic acid was mineralized to I− under alkaline conditions. Because the iodine species can be unified into a single species by selecting the photocatalyst and the solution pH, this photocatalytic treatment could be applied to remove iodine species with high efficiency.

New Hg(II) coordination polymers based on a thioimidazole ligand with good performance to detoxify Hg(II) and reversibly capture iodine.

In the current paper, we have successfully synthesized three new mercury coordination polymers with fascinating structures and properties via a flexible sulfur donor ligand, namely, {[Hg(μ2-Cl)(μ2-Ls)]}n[BF4]n(1), {[Hg(μ2-Cl)(μ2-Ls)]}n[ClO4]n(2), and [Hg(SCN)2(μ2-Ls)]n(3) [Ls = 1,1-bis(3-methyl-4-imidazoline-2-thione)methane]. These complexes have been characterized by means of different techniques such as single crystal X-ray crystallography, FT-IR, elemental analysis (CHNS), UV-Vis, PXRD, BET, and TGA. Suitable single crystals of all complexes were obtained using the branch tube method with a very high yield and good stability due to the high affinity of mercury to bind to the thione groups. The cationic moieties of polymers 1 and 2 were isostructural, with a HgCl2S2 coordination core structure. The voids of the quasi-hexagonal packing of the columnar chains were occupied by unbonded tetrahedral BF4- ions in 1 and perchlorate anions in polymer 2. Polymer 3 has a less distorted tetrahedral geometry than 1 and 2, with a HgS4 core structure. By considering the thiophilicity of mercury, a thioamide-based Ls ligand was used to detoxify Hg(II) into insoluble polymers 1-3. The results of an MTT assay for (HepG2) liver cells confirmed the excellent cytoprotective effect of this ligand against mercury. Based on IC50 calculations, their toxicity was in order of polymer 1 > polymer 2 > polymer 3. These polymers were also considered as adsorbents for the reversible removal of iodine from solution and the kinetics of the process has been studied in detail. Interestingly, all of them showed an excellent stability and high capacity, in order of 763.53 mg g-1, 877.10 mg g-1, and 905.31 mg g-1 for polymers 1-3, respectively.

Preparation of an electron-rich polyimide-based hypercrosslinked polymer for high-efficiency and reversible iodine capture

Effective and reversible iodine adsorption is among the most important means to solve nuclear pollution. Herein, a novel electron-rich hypercrosslinked polymer (HCP) was obtained via a simple photocycloaddition of the cinnamoyl-containing polyimide precursor. The resulting polymer showed a high specific surface area of 531 m2 g−1 and high thermal stability. Taking advantage of the high porosity, high electron-rich heteroatoms contents and π-electron conjugated backbone, the material exhibits excellent iodine capture performance, including ultrahigh iodine vapor capture (528 wt%) and iodine removal efficiency from aqueous solution. The capture behavior is consistent with the pseudo-second-order model and the spectral results indicate that the captured iodine existed in the form of polyiodide anions. Furthermore, the HCP maintained 90.76% of the uptake capacity after four cycles. This study provides a new proposal for the preparation of functional HCP as an efficient iodine absorbent to solve environmental issues.

Two Facile Aniline-Based Hypercrosslinked Polymer Adsorbents for Highly Efficient Iodine Capture and Removal

Effective capture and safe disposal of radioactive iodine (129I or 131I) during nuclear power generation processes have always been a worldwide environmental concern. Low-cost and high-efficiency iodine removal materials are urgently needed. In this study, we synthesized two aniline-based hypercrosslinked polymers (AHCPs), AHCP-1 and AHCP-2, for iodine capture in both aqueous and gaseous phases. They are obtained by aniline polymerization through Friedel-Crafts alkylation and Scholl coupling reaction, respectively, with high chemical and thermal stability. Notably, AHCP-1 exhibits record-high static iodine adsorption (250 wt%) in aqueous solution. In the iodine vapor adsorption, AHCP-2 presents an excellent total iodine capture (596 wt%), surpassing the most reported amorphous polymer adsorbents. The rich primary amine groups of AHCPs promote the rapid physical capture of iodine from iodine water and iodine vapor. Intrinsic features such as low-cost preparation, good recyclability, as well as excellent performance in iodine capture indicate that the AHCPs can be used as potential candidates for the removal of iodine from radioactive wastewater and gas mixtures.

Sequential combination of pre-chlorination and powdered activated carbon adsorption on iodine removal and I-THMs control in drinking water

Combining pre-oxidation with activated carbon adsorption was explored as an ideal approach for removing iodine from water source to eliminate the formation of Iodinated trihalomethanes (I-THMs). Compared with permanganate and monochloramine, chlorine is more suitable as pre-oxidant to obtain higher active iodine species (HOI/I2). Active iodine species adsorption using both powdered activated carbon (PAC) and granular activated carbon (GAC) can be well fitted the pseudo-second-order kinetic model indicating that chemical adsorption was the dominant mechanism for HOI/I2 adsorption. The average pore size of activated carbons was the most strongly correlated with the adsorption capacity (R2 > 0.98), followed by methylene blue (R2 > 0.76), pore volume (R2 > 0.70) and iodine number (R2 > 0.67). Moreover, three models, including intraparticle diffusion, Byod kinetic, and diffusion-chemisorption were used to illustrate the mechanisms of HOI/I2 adsorption. Chemical adsorption was the dominant mechanism for HOI/I2 adsorption. In summary, at the molar ratio of [NaClO] and [I−] as 1.2, pre-chloriantion time of 5 min, subsequently dosage of 15 mg/L of PAC E with 20 min adsorption can remove 79.8% iodine. In addition, the combined process can eliminate 61%–87.2% of I-THMs in the subsequent chlor(am)ination. The results indicate that pre-chlorination combined with PAC can effectively removed HOI/I2 and attenuate I-THMs formation in the subsequent disinfection process.

Construction of N-loaded conjugated polymer for highly effective removal of iodine in organic solution

Efficient capture of radioiodine is critical during nuclear fuel reprocessing and nuclear accidents. The development of material with excellent adsorption properties of radioiodine has always been a significant challenge. Three kinds of N-loaded conjugated polymers were prepared using the solvothermal method by changing the N-group in pyrrole. The effect of nitrogen type on the structure of conjugated polymers was investigated by SEM, BET, FT-IR, XPS, and EPR. Despite their low specific surface area, their mesoporous structure is conducive to transporting iodine molecules. The results showed that in the conjugated system, the adsorption capacity of alkyl tertiary amines for iodine was better than that of aminoethyl tertiary amines and secondary amines, and the maximum adsorption capacity could reach 737.4 mg/g. The adsorption mechanism of iodine on N-loaded conjugated polymer is mainly the interaction of charge transfer between iodine and N-aromatic in the organic solution.

Biochars and Activated Biocarbons Prepared via Conventional Pyrolysis and Chemical or Physical Activation of Mugwort Herb as Potential Adsorbents and Renewable Fuels

The main objective of this study was to prepare a series of biochars and activated biocarbons via conventional pyrolysis as well as chemical or physical activation of solid residue after solvent extraction of wild growing plant (popular weed)-mugwort. The influence of the variant of the thermochemical treatment of the precursor on such parameters as elemental composition, textural parameters, acidic-basic character of the surface as well as adsorption abilities of the prepared carbonaceous materials was checked. Moreover, the suitability of the biochars prepared as renewable fuels was also investigated. It has been shown that the products obtained from the mugwort stems differ in many respects from the analogous materials obtained from mugwort leaves. The products were micro/mesoporous materials with surface area reaching 974.4 m2/g and total pore volume-1.190 cm3/g. Surface characterization showed that chemical activation with H3PO4 results in the acidic character of the adsorbents surface, whereas products of pyrolysis and especially physical activation show strongly alkaline surface properties. All the adsorbents were used for methylene blue and iodine adsorption from the aquatic environment. To understand the nature of the sorption process, the Langmuir, Freundlich and Temkin isotherm models were employed. The Langmuir model best described the experimental results, and the maximum sorption capacity calculated for this model reached 164.14 mg of methylene blue per gram of adsorbent. In case of iodine removal, the maximum capacity reached 948.00 mg/g. The research carried out for the biochars prepared via conventional pyrolysis showed that the value of their heat of combustion varies in the range from 21.74 to 30.27 MJ/kg, so they can be applied as the renewable fuels.

Two nitrogen-rich conjugated microporous polymers for efficient iodine sequestration and removal

Two nitrogen-rich conjugated microporous polymers for efficient iodine sequestration and removal

Water-stable porous Al24 Archimedean solids for removal of trace iodine

In this paper, we report a unique type of core-shell crystalline material that combines an inorganic zeolitic cage structure with a macrocyclic host arrangement and that can remove trace levels of iodine from water effectively. These unique assemblies are made up of an inorganic Archimedean truncatedhexahedron (tcu) polyhedron in the kernel which possesses six calixarene-like shell cavities. The cages have good adaptability to guests and can be assembled into a series of supramolecular structures in the crystalline state with different lattice pore shapes. Due to the unique core-shell porous structures, the compounds are not only stable in organic solvents but also in water. The characteristics of the cages enable rapid iodine capture from low concentration aqueous I2/KI solutions (down to 4 ppm concentration). We have studied the detailed process and mechanism of iodine capture and aggregation at the molecular level. The facile synthesis, considerable adsorption capacity, recyclability, and β- and γ-radiation resistance of the cages should make these materials suitable for the extraction of iodine from aqueous effluent streams (most obviously, radioactive iodide produced by atomic power generation).

Virtual non-contrast reconstructions improve differentiation between vascular enhancement and calcifications in stereotactic planning CT scans of cystic intracranial tumors

PurposeTo assess the diagnostic value of spectral-detector CT (SDCT) derived virtual non-contrast images (VNC) for differentiation between vascular enhancement and wall calcifications of cystic intracranial tumors in contrast-enhanced stereotactic planning examinations. Method48 patients with cystic intracranial tumors who underwent stereotactic SDCT examinations between 02/2017 and 02/2020 were retrospectively included. In each patient, two separate hyperattenuating structures along the cyst wall were defined as either enhancement or calcification, respectively, using reference MRI examinations. Quantitative analysis was performed ROI-based in conventional images (CI) and VNC. In the subjective analysis, two radiologists diagnosed the predefined peri-cystic structures in binary decisions as either enhancement or calcification using CI and the combination of CI and VNC, and rated diagnostic confidence, image noise and removal of iodine in VNC. Moreover, a potential diagnostic benefit of VNC was indicated. ResultsAttenuation in CI was higher as compared to VNC across all assessed ROI (all p < 0.01). In VNC, CNR between calcification and white matter was significantly higher as compared to CNR between vascular enhancement and white matter (2.6 vs 1.3, p < 0.01), while there was no significant difference in CI. In the qualitative assessment, diagnostic accuracy was significantly higher using both VNC and CI compared to using CI alone. Raters reported less image noise in VNC as compared to CI. An additional diagnostic benefit of VNC was indicated in 84.4 % of all cases. ConclusionsSDCT-derived VNC images facilitate differentiation between peri-cystic contrast enhancement in blood vessels and calcifications in stereotactic planning scans of cystic intracranial tumors.

A Zirconium-Organic Framework Constructed from Saddle-Shaped Tetratopic Carboxylate for High-Rate and -Efficiency Iodine Capture.

Metal-organic frameworks (MOFs) exhibit strong potential for applications in molecular adsorption and separation because of their highly tunable structures and large specific surface areas and have also been used for iodine capture. However, most works on MOF-based iodine capture focus on the adsorption capacity while taking little consideration of the capture rate and efficiency. Herein, we report the design of a saddle-shaped tetratopic carboxylic acid containing four thiophene groups (H4COTTBA) and the synthesis of a 4,8-connected flu-type zirconium MOF (HIAM-4014) using this linker. HIAM-4014 exhibits highly efficient iodine capture. The large cagelike pore structure, OH- groups on the unsaturated Zr6 clusters, electron-rich nature of the thiophene group in the linker, and high surface area are all attributed to the tetrahedral geometry of H4COTTBA, which endows HIAM-4014 with a relatively high iodine adsorption capacity of 2.50 g/g within 2 h and an equilibrium adsorption capacity of 2.68 g/g after 5 h. Coupled with a high elution ratio and great recyclability, HIAM-4014 is a good candidate for the efficient removal of waste iodine.

Silver Modified Nanoporous Materials for Iodine Removal

Radioactive elements such as iodine (e.g., 129I or 131I isotopes), which is discharged into the environment as a result of nuclear detonations and reactor accidents, has a negative impact on human health and the ecosystem [1-3]. Radioactive iodine can be discharged as a direct aqueous pollutant when nuclear fission reactors are cooled with water. Both the Chernobyl and Fukushima nuclear disasters resulted in huge amounts of radioactive iodine being released into the atmosphere (the majority of which was subsequently deposited on the soil, where it leached into water), as well as directly into water bodies [1-3]. Medical is a secondary source of radioactive iodine, as radioactive isotopes are commonly employed for diagnostic and therapeutic purposes. Also, seawater is a natural source of iodine, due to that, the iodine can move into drinking water aquifers, causing increased iodine levels. The removal of radioactive elements such as iodine have been the target of numerus studies using different adsorption methods. However, most of the research to far has concentrated on the adsorption of iodine gas or iodine from organic solvents. There have been few cases of iodine removal from water at room temperature [1-3].Nanotechnology have been widely used in many research projects related to environmental issues such as suitable energy and remediations [4-21].The major goal of this research is to synthesize and investigate different nanoporous silicates with different pore size based on synthetic and naturally occurring materials such as zeolites modified with silver to remove iodine from water with high selectivity. The resultant materials are thoroughly investigated, via numerous characterization techniques such as XRD, XRF, SEM/EDX, TEM, and BET surface area measurements. The adsorption study shows a great promises for the resultant composites. For example, iodine was removed from aqueous solutions using synthetic zeolite-13X-Ag (Ag-13X) nanocomposites. The Ag-13X composites results revealed a high removal efficiency (up to 84% removal of iodine from aqueous media) compared to 13X that remove only 22% of iodine under the same adsorption conditions. References Steinhauser, A. Brandl , T.E. Johnson, 470–47, 800-817 (2014)Zhao, X., Han, X., Li, Z., Huang, H., Liu, D., Zhong, C., Appl. Surf. Sci. 351, 760–764 (2015).Tauanov, V.J. Inglezakis, Science of The Total Environment, 682, 259-270 (2019.).W.Chapman, P.J Chupas., T.M Nenoff. J. Am. Chem. Soc., 132, 8897–8899 (2010).ME Mahmoud, SS Haggag, MA Rafea, TM Abdel-Fattah, Polyhedron 28 (16), 3407-3414 (2009)C Huff, JM Long, A Aboulatta, A Heyman, TM Abdel-Fattah, ECS Journal of Solid State Science and Technology 6 (10), M115 (2017)A Wixtrom, J Buhler, T Abdel-Fattah, Journal of Chemical Education 91 (8), 1232-1235 (2014)ME Mahmoud, SS Haggag, TM Abdel-Fattah, Polyhedron 26 (14), 3956-3962 (2007)C Huff, T Dushatinski, A Barzanji, N Abdel-Fattah, K Barzanji, ECS Journal of Solid State Science and Technology 6 (5), M69 (2017)TM Abdel-Fattah, B Bishop, Journal of Environmental Science and Health, Part A 39 (11-12), 2855-2866 (2014)TM Abdel-Fattah, ME Mahmoud, MM Osmam, SB Ahmed, Journal of Environmental Science and health, part A 49 (9), 1064-1076 (2014)ME Mahmoud, TM Abdel-Fattah, MM Osman, SB Ahmed, Journal of Environmental Science and Health, Part A 47 (1), 130-141 (2012)C Huff, E Biehler, Q Quach, JM Long, TM Abdel-Fattah, Colloids and Surfaces A: Physicochemical and Engineering Aspects 610 (5), 125734 (2021)M Abdel-Fattah, A Wixtrom, K Zhang, W Cao, H Baumgart, ECS Journal of Solid State Science and Technology 3 (10), M61 (2014)M. Abdel-Fattah, M.E Mahmoud, M. M. Osmam, S.B. Ahmed, Journal of Environmental Science and health part A, 49, 1064-1076 (2014)C Huff, T Dushatinski, TM Abdel-Fattah, International Journal of Hydrogen Energy 42 (30), 18985-18990 (2017)C Huff, JM Long, A Heyman, TM Abdel-Fattah, ACS Applied Energy Materials 1 (9), 4635-4640 (2018)A Mahapatro, TD Matos Negrón, C Bonner, TM Abdel-Fattah, Journal of Biomaterials and Tissue Engineering 3 (2), 196-204 (2013)T Dushatinski, C Huff, TM Abdel-Fattah, Applied Surface Science 385, 282-288 (2016)ME Mahmoud, MM Osman, SB Ahmed, TM Abdel-Fattah, Chemical engineering journal 175, 84-94 (2011)TM Abdel-Fattah, ME Mahmoud, Chemical engineering journal 172 (1), 177-183 (2011)R Bhure, TM Abdel-Fattah, C Bonner, JC Hall, A Mahapatro, Journal of biomedical nanotechnology 6 (2), 117-128 (2010)TM Abdel-Fattah, D Loftis, A Mahapatro, Journal of biomedical nanotechnology 7 (6), 794-800 (2011)OH Elsayed-Ali, T Abdel-Fattah, HE Elsayed-Ali, Journal of hazardous materials 185 (2-3), 1550-1557 (2011)R Bhure, A Mahapatro, C Bonner, TM Abdel-Fattah, Materials Science and Engineering: C 33 (4), 2050-2058 (2013)BE Bishop, BA Savitzky, T Abdel-Fattah, Ecotoxicology and Environmental Safety 73 (4), 565-571 (2010)

Construction of imide-functionalized aromatic conjugation tetracarboxylate frameworks and adsorption behavior for iodine and selective cationic dyes

Metal-organic frameworks (MOFs) show great potential in environmental contaminants removal owing to their outstanding pore properties and tunable chemical performance. Two new imide-functionalized aromatic conjugation tetracarboxylate frameworks: [Cd4(BDCPPI)2(DMF)2(H2O)3]·2DMF·8H2O (1) and [Zn4(BDCPPI)2(DMF)6]·3DMF·4H2O (2) were designed and synthesized under solvothermal conditions. Due to the micropore size and aromatic conjugation properties with the 3D network structures, complexes 1 and 2 have abundant active sites, resulting in strong iodine capture and dye adsorption capacity. The excellent iodine capture ability on complexes 1 and 2 might due to the interaction of iodine with the carbonyl oxygen atom (I⋯O) and the benzene ring (I···π). The materials were charge and size selective for the adsorption of dyes, and the presence of abundant imide-functionalized groups in the channels can form hydrogen-bonding interactions with dye molecules to promote their adsorption properties. In addition, the high I2 adsorption and release capacity of complexes 1 and 2 indicate their wide application prospects in nuclear waste management. Therefore, the as-synthesized MOFs can be used as potential multifunctional adsorbents for further removal of organic dyes and iodine from wastewater.

Pillar[5]arene-based cross-linked polymer for the rapid adsorption of iodine from water and vapor phases

Pillar[5]arene-based cross-linked microporous polymer ( P[5]A-MPP ) was synthesized via Friedel-crafts polymerization reaction. P[5]A-MPP exhibited high iodine vapor capture capability (3.84 g g −1 ) at 80 °C. Detailed UV–vis spectroscopic analysis revealed the rapid removal of iodine from water. This work highlights the efficient iodine adsorption efficiency in vapor phase, as well as rapid removal of iodine from aqueous solution and the recyclability of pillar[5]arene-based 3D cross-linked microporous polymer. Pillar[5]arene macrocycle-based cross-linked polymer was synthesized and used for iodine adsorption to capture iodine both in vapour phase as well as aqueous solution. The pillar[5]arene based polymer adsorbent showed remarkable recyclability at least five times without losing the efficiency. • Pillar[5]arene-based polymer ( P[5]A-MPP ) is a potential material for the removal of iodine from water. • P[5]A-MPP capture iodine in vapor phase with an iodine uptake capacity of 3.84 g/g. • P[5]A-MPP displayed excellent iodine adsorption capability per unit SBET of 13.6 wt/(m 2 /g). • P[5]A-MPP can remove >83% of iodine during the initial 15 min upon shaking. • P[5]A-MPP showed remarkable recyclability at least five times without losing efficiency.

Cover Feature: Hydroxy‐Functionalized Hypercrosslinked Polymers (HCPs) as Dual Phase Radioactive Iodine Scavengers: Synergy of Porosity and Functionality (ChemPlusChem 11/2022)

The cover feature image illustrates a family of hydroxy-functionalized hypercrosslinked polymers (HCPs) toward efficient capture of radioactive iodine from both vapour and water phase. The polymeric scavengers were also utilized to establish the first case of functionality and porosity synergy in this kind of material for radioactive iodine removal; a key advancement from the energy-economy standpoint of real-time radioactive contaminant sequestration. More information can be found in the Research Article by Sujit K. Ghosh and co-workers.

Study of hydrodynamics and iodine removal by self-priming venturi scrubber

Filtered containment system is a passive safety system that controls the over-pressurization of containment in case of a design-based accidents by venting high pressure gaseous mixture, consisting of air, steam and radioactive particulate and gases like iodine, via a scrubbing system. An indigenous lab scale facility was developed for research on iodine removal by venturi scrubber by simulating the accidental scenario. A mixture of 0.2 % sodium thiosulphate and 0.5 % sodium hydroxide, was used in scrubbing column. A modified mathematical model was presented for iodine removal in venturi scrubber. Improvement in model was made by addition of important parameters like jet penetration length, bubble rise velocity and gas holdup which were not considered previously. Experiments were performed by varying hydrodynamic parameters like liquid level height and gas flow rates to see their effect on removal efficiency of iodine. Gas holdup was also measured for various liquid level heights and gas flowrates. Removal efficiency increased with increase in liquid level height and gas flowrate up to an optimum point beyond that efficiency was decreased. Experimental results of removal efficiency were compared with the predicted results, and they were found to be in good agreement. Maximum removal efficiency of 99.8% was obtained.

Hydroxy-Functionalized Hypercrosslinked Polymers (HCPs) as Dual Phase Radioactive Iodine Scavengers: Synergy of Porosity and Functionality.

Large-scale nuclear power plant production of iodine radionuclides (129 I, 131 I) pose huge threat in the events of nuclear disaster. Effective removal of radioiodine from nuclear waste is one of the most critical challenge because of the drawbacks of state-of-the-art adsorbents such as high cost, low uptake capacity and non-recyclability. Herein, two hydroxy-functionalized (-OH) hypercrosslinked polymers (HCPs), namely HCP-91 and HCP-92, have been synthesized and employed towards capture of iodine. High chemical stability along with synergistic harmony of high porosity and functionality of these materials makes them suitable candidates for capture of iodine from both vapor phase and water medium. Moreover, both the HCPs showed superior iodine removal performance from water in terms of fast kinetics and high removal efficiency (2.9 g g-1 and 2.49 g g-1 for HCP-91 and HCP-92 respectively). The role of functionality (-OH groups) and porosity has been established with the help of HCP-91, HCP-92 and non-functionalized biphenyl HCP for the efficient capture of I3 - ions from water. In addition, both HCPs exhibited excellent selectivity and recyclability towards triiodide ions, rendering the potential of these materials towards real-time applications. Lastly, Density functional theoretical studies revealed key insights and corroborate well with the experimental findings.

Fabrication of Protonated Two-Dimensional Metal-Organic Framework Nanosheets for Highly Efficient Iodine Capture from Water.

Radioactive iodine (129I and 131I), produced or released from nuclear-related activities, posed severe effects on both human health and environment. The efficient removal of radioiodine from aqueous medium and vapor phase is of paramount importance for the sustainable development of nuclear energy. Herein, a metal-organic framework (MOF) nanosheet with a positive charge was constructed for the capture of iodine for the first time. The as-synthesized ultrathin nanosheets, with a thickness of 4.4 ± 0.1 nm, showed a record-high iodine adsorption capacity (3704.08 mg g-1) from aqueous solution, which is even higher than that from the vapor phase (3510.05 mg g-1). It can be ascribed to the fully interactions between the extensive accessible active sites on the largely exposed surface of 2D MOF nanosheets and the target pollutants, which also gave rise to fast adsorption kinetics with relative high removal efficiencies in the low concentrations, even in seawater. Moreover, a facile recyclability with fast desorption kinetics can also be achieved for the MOF nanosheets. The excellent iodine removal performance in aqueous solution demonstrated that the electrostatic attraction between MOF nanosheets with a positive charge and the negatively charged triiodide (I3-, the dominant form of iodine in aqueous solution) is the driving force in adsorption, which endows the adsorbents with the characteristics of fast adsorption and desorption kinetics. The adsorption mechanism was systematically verified by the studies of ζ potential, Fourier transform infrared, X-ray photoelectron spectroscopy, and Raman spectra.

Species transformation and removal mechanism of various iodine species at the Bi2O3@MnO2 interface

Long-term exposure to excessive iodine via drinking water significantly increases the risk of thyroid diseases. Further, the mechanisms and feasible technologies for iodine removal are far from being well elucidated. In this study, we constructed a heterogeneous Bi2O3@MnO2 interface with oxidation and adsorption efficiency toward iodide (I−), and investigated the performance and mechanisms involved in iodine removal. Bi2O3@MnO2 at the optimized Bi/Mn ratio of 0.05:1 had a maximum adsorption capacity of 1.19, 1.21, and 1.06 mg/g toward I−, iodine elemental (I2), and iodate (IO3−), respectively. According to the density functional theory (DFT) calculation, Bi2O3@MnO2 had an adsorption energy of -2.34, -2.11, and -3.89 eV for I−, I2, and IO3−, and exhibited a better band structure and state density character for iodine removal. Based on the results of XPS, HPLC, and LC-ICP-MS characterization, Bi2O3 plays an important role in adsorbing and capturing I− whereas MnO2 dominates the moderate oxidation of I− and the adsorption of I− and I2. The adsorbed I− and I2 concentrations on the Bi2O3@MnO2 surfaces were 146.3 μg/L and 18.3 μg/L. Notably, IO3− was not detected owing to its moderate oxidation effect. The coexisting ions of chloride (Cl−) and bromide (Br−) tended to occupy the Bi2O3 lattice and form insoluble BiOCl and BiOBr. Further, reductive species, such as sulphite (SO32−), may reduce MnO2 to Mn(III) and Mn(II). The synergistic effect between moderate oxidation and adsorption led to Bi2O3@MnO2 with high iodine removal capability. Overall, this study proposes a strategy for designing suitable interfaces and adsorbents for iodine removal; however, further studies are necessary to advance its application in practice.