Poly{tris[4-(2-thienyl)phenyl]amine} and poly[tris(4-carbazoyl- 9-yl phenyl)amine] conjugated microporous polymers as absorbents for highly efficient iodine adsorption

Boron nitride aerogels incorporated with metal nanoparticles: Multifunctional platforms for iodine capture and detection

Radioactive iodine vapors produced by nuclear fission can pose a significant risk to human health and the environment. Effective monitoring of iodine vapor leakage, capture and storage of radioactive iodine vapor are of great importance for the safety of the nuclear industry. Herein, we report a novel structure-function integrated solid iodine vapor adsorbent based on metal-modified boron nitride (BN) aerogel. Metal-modified BN aerogels incorporated with Cu/Ag nanoparticles (named as BN-Cu and BN-Ag, respectively) are successfully prepared by a metal-induced, ultrasonic-assisted, and in-situ transformation method. The metal-modified BN aerogels show improved mechanical properties in both of the maximum stress and residual deformation. Remarkably, due to the greatly enhanced "host-guest" and "guest-guest" effects by the introduction of metal nanoparticles, the BN-Cu and BN-Ag aerogels exhibit record-breaking iodine vapor adsorption capacities among inorganic adsorbents (1739.8 and 2234.13 wt% respectively), which are even higher than that of most organic adsorbents. Furthermore, an integrated iodine adsorption detection device based on metal-modified aerogels is constructed to realize real-time detection of the electrical properties of aerogels during iodine adsorption. This work provides a foundation for the development of BN aerogels as multifunctional platforms for effective iodine capture and detection. It also introduces new ideas for the use of structural-functional integrated materials in the prevention and control of radioactive iodine pollution.

An Azo-Group-Functionalized Porous Aromatic Framework for Achieving Highly Efficient Capture of Iodine

The strong radioactivity of iodine compounds derived from nuclear power plant wastes has motivated the development of highly efficient adsorbents. Porous aromatic frameworks (PAFs) have attracted much attention due to their low density and diverse structure. In this work, an azo group containing PAF solid, denoted as LNU-58, was prepared through Suzuki polymerization of tris-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-amine and 3,5-dibromoazobenzene building monomers. Based on the specific polarity properities of the azo groups, the electron-rich aromatic fragments in the hierarchical architecture efficiently capture iodine molecules with an adsorption capacity of 3533.11 mg g−1 (353 wt%) for gaseous iodine and 903.6 mg g−1 (90 wt%) for dissolved iodine. The iodine uptake per specific surface area up to 8.55 wt% m−2 g−1 achieves the highest level among all porous adsorbents. This work illustrates the successful preparation of a new type of porous adsorbent that is expected to be applied in the field of practical iodine adsorption.

Lignin-based electrospinning nanofibers for reversible iodine capture and potential applications

The capture of radioactive iodine has recently attracted much attention due to the release of radioactive iodine during nuclear waste disposal and disasters. Exploring highly efficient, sustainable, and eco-friendly materials for capturing radioactive iodine has great significance in developing safe nuclear energy. We reported highly efficient, natural, lignin-based, electrospun nanofibers (LNFs) for reversible radioiodine capture. Abundant iodine adsorption sites, such as functional groups and the interaction between the intermolecular forces exist in LNFs. The capacity of the LNFs for the saturated adsorption of iodine was found to be 220 mg·g^-1, which is higher than that of the majority of bio-based adsorbents studied. Moreover, the LNFs exhibited an excellent recycling behavior, and their absorption capacity remained at 84.72% after 10 recycles. Therefore, the results imply that the lignin-based nanofibers can act as a natural, sustainable and eco-friendly packed material for the purification columns in industrial applications. The results demonstrate that the novel, nanostructured, natural biomass, as an ideal candidate has the potential for practical nuclear wastewater purification.

Efficient and simultaneous capture of iodine and methyl iodide achieved by a covalent organic framework

Radioactive molecular iodine (I₂) and organic iodides, mainly methyl iodide (CH₃I), coexist in the off-gas stream of nuclear power plants at low concentrations, whereas few adsorbents can effectively adsorb low-concentration I₂ and CH₃I simultaneously. Here we demonstrate that the I₂ adsorption can occur on various adsorptive sites and be promoted through intermolecular interactions. The CH₃I adsorption capacity is positively correlated with the content of strong binding sites but is unrelated to the textural properties of the adsorbent. These insights allow us to design a covalent organic framework to simultaneously capture I₂ and CH₃I at low concentrations. The developed material, COF-TAPT, combines high crystallinity, a large surface area, and abundant nucleophilic groups and exhibits a record-high static CH₃I adsorption capacity (1.53 g·g⁻¹ at 25 °C). In the dynamic mixed-gas adsorption with 150 ppm of I₂ and 50 ppm of CH₃I, COF-TAPT presents an excellent total iodine capture capacity (1.51 g·g⁻¹), surpassing various benchmark adsorbents. This work deepens the understanding of I₂/CH₃I adsorption mechanisms, providing guidance for the development of novel adsorbents for related applications.

Radioactive molecular iodine (I₂) and methyl iodide (CH₃I) coexist in the off-gas stream of nuclear power plants at low concentrations and only few adsorbents can effectively adsorb low-concentration I₂ and CH₃I simultaneously. Here, the authors demonstrate simultaneous capture of I₂ and CH₃I at low concentrations by exploiting different adsorptive sites in a covalent organic framework.

Ionic Functionalization of Multivariate Covalent Organic Frameworks to Achieve an Exceptionally High Iodine-Capture Capacity

Adsorption-based iodine (I₂ ) capture has great potential for the treatment of radioactive nuclear waste. In this study, we apply a "multivariate" synthetic strategy to construct ionic covalent organic frameworks (iCOFs) with a large surface area, high pore volume, and abundant binding sites for I₂ capture. The optimized material iCOF-AB-50 exhibits a static I₂ uptake capacity of 10.21 g g^-1 at 75 °C and a dynamic uptake capacity of 2.79 g g^-1 at ≈400 ppm I₂ and 25 °C, far exceeding the performances of previously reported adsorbents under similar conditions. iCOF-AB-50 also exhibits fast adsorption kinetics, good moisture tolerance, and full reusability. The promoting effect of ionic groups on I₂ adsorption has been elucidated by experimentally identifying the iodine species adsorbed at different sites and calculating their binding energies. This work demonstrates the essential role of balancing the textural properties and binding sites of the adsorbent in achieving a high I₂ capture performance.

A Carbazole-Functionalized Porous Aromatic Framework for Enhancing Volatile Iodine Capture via Lewis Electron Pairing

Nitrogen-rich porous networks with additional polarity and basicity may serve as effective adsorbents for the Lewis electron pairing of iodine molecules. Herein a carbazole-functionalized porous aromatic framework (PAF) was synthesized through a Sonogashira-Hagihara cross-coupling polymerization of 1,3,5-triethynylbenzene and 2,7-dibromocarbazole building monomers. The resulting solid with a high nitrogen content incorporated the Lewis electron pairing effect into a π-conjugated nano-cavity, leading to an ultrahigh binding capability for iodine molecules. The iodine uptake per specific surface area was ~8 mg m-2 which achieved the highest level among all reported I2 adsorbents, surpassing that of the pure biphenyl-based PAF sample by ca. 30 times. Our study illustrated a new possibility for introducing electron-rich building units into the design and synthesis of porous adsorbents for effective capture and removal of volatile iodine from nuclear waste and leakage.

Rationally designed conjugated microporous polymers for contaminants adsorption

Adsorption technology has been widely developed and employed for water and air pollution control. Conjugated microporous polymers (CMPs) emerge as the appropriate adsorbents candidate. To fulfill high capacity and good selectivity for the adsorption, strategies of flexible micropores design and functional group modification that facilitate the physical and chemical effect are considered desirable. The review firstly summarizes the advancements in structural studies of CMPs and the applications for contaminants adsorption from water and air. Further, the mechanisms involved in the remarkable capacity and selectivity of CMPs adsorbents are addressed. Finally, upcoming research efforts on materials design, adsorption principle, and resource recovery to overcome current practical bottlenecks are proposed.

A series of thiophene- and nitrogen-rich conjugated microporous polymers for efficient iodine and carbon dioxide capture

A series of thiophene- and nitrogen-rich conjugated microporous polymers can be used for high iodine and carbon dioxide capture.

Capture of iodine in solution and vapor phases by newly synthesized and characterized encapsulated Cu2O nanoparticles into the TMU-17-NH2 MOF

The efficient capture and storage of radioactive iodine (¹²⁹I or ¹³¹I) formed during the extensive use of nuclear energy is of paramount importance. Therefore, it is a great deal to design new adsorbents for effectively disposing of iodine from nuclear waste. In this work, a new Cu₂O/TMU-17-NH₂ composite has been prepared by a simple encapsulation of Cu₂O nanoparticles (NPs) into the metal organic framework (MOF) TMU-17-NH₂ for the first time. The as-synthesized Cu₂O/TMU-17-NH₂ was fully characterized in details and the iodine sorption/release capability of the Cu₂O/TMU-17-NH₂ composite has been investigated both in solution and in the vapor phase. According to the FE-SEM images, the Cu₂O/TMU-17-NH₂ was obtained with same morphology to that of the pristine TMU-17-NH₂. The I₂ sorption/release experiments were examined by UV-vis spectroscopy. The optimal iodine sorption was obtained by almost complete removal of iodine with a sorption capacity of about 567 mg/g. Detailed experimental evidence demonstrating that the iodine was captured by chemisorption process. Furthermore, photoluminescence (PL) properties of Cu₂O/TMU-17-NH₂ have also been investigated in which indicate that the Cu₂O/TMU-17-NH₂ composite exhibits stronger emission than the pristine TMU-17-NH₂.

Fluorescent conjugated microporous polymers containing pyrazine moieties for adsorbing and fluorescent sensing of iodine

Two kinds of fluorescent conjugated microporous polymers containing pyrazine moieties were prepared by the polymerization reaction of 2,5-di-triphenylamine-yl-pyrazine (DTPAPz) and N,N,N',N'-tetrapheny-2,5-(diazyl) pyrazine (TDPz) with 2,4,6-trichloro-1,3,5-triazine (TCT) through Friedel-Crafts reaction using the methanesulfonic acid as a catalysts. Both CMPs have high thermal stability and decomposition temperature reaches above 596 and 248 °C under nitrogen atmosphere, respectively. By right of porous morphology and electron-donating nitrogen, as well as electron-rich π-conjugated structures, the adsorption performance for iodine vapor on the CMPs is very excellent, which can reach 441% and 312%. In addition, fluorescence studies showed that the two CMPs exhibited high fluorescence sensitivity to electron-deficient iodine, o-nitrophenol (o-NP), and picric acid (PA) via fluorescence quenching.

Polytriazine porous networks for effective iodine capture

Herein we present a rational strategy for the development of nitrogen-enriched conjugated microporous polymers (CMPs) (TBTT-CMP@1, 2 and 3) via a BH coupling reaction under mild conditions, for the super absorption of iodine. TBTT-CMP@1 exhibited iodine capture amount up to 442 wt%.