Reversible Iodine Capture Research Articles

Functional porous organic polymer with high S and N for reversible iodine capture

Abstract Nuclear waste such as radioactive iodine has been received worldwide attention because of the effects of radiation on biological health. The efficient capture of radioactive iodine is of great importance for the safe utilization of nuclear energy. In this study, a functional porous organic polymer (P-TzTz) with high sulfur and nitrogen contents was synthesized by the catalyst-free hydrothermal process of dithiocarbanate (DTO) and benzo[1,2-b:3,4-b′:5,6-b″]trithiophene-2,5,8-tricarbaldehyde (BTT-THO) in N,N-dimethylformamide under N2 atmosphere. This tailor-made amorphous polymer exhibits high affinity and adsorption capacity for iodine owing to its effective electron-rich sorption sites, π-conjugated structure and hierarchically porous structure. P-TzTz displays an excellent reversible iodine uptake with capacity of 326 wt% for volatile iodine. After five cycles of volatile iodine adsorption, P-TzTz almost retains the same adsorption capacity with the original adsorbent. In addition, P-TzTz also exhibits excellent adsorptive performance for the removal of iodine from iodine/cyclohexane solution with an adsorption capacity of 494.09 mg g−1, suggesting that P-TzTz may be also an effective adsorbent for the removal of iodine from solution.

N- and S-rich covalent organic framework for highly efficient removal of indigo carmine and reversible iodine capture

Abstract Organic dye containing wastewater and nuclear waste have received more worldwide attention because of the significant environmental problems and the effects of radiation on health. Adsorption is considered to be an efficient, low-cost, and environmentally friendly method for pollutant removal. In this paper, we developed a novel covalent organic framework (BTT-TAPT-COF) adsorbent which contains abundant S and N active sites as well as extended π-conjugated structure. This COF shows high crystallinity, large surface area, and thermal stability. Due to the porous feature, existence of electron-rich heteroatoms as well as the large π-conjugated network structure, BTT-TAPT-COF exhibits excellent adsorptive performance for the removal of hazardous dye indigo carmine with an adsorption capacity of 547.33 mg g−1 and rapid reversible volatile iodine uptake with an adsorption capacity of 276 wt%. After five cycles, BTT-TAPT-COF almost retains the same iodine adsorption capacity with the original adsorbent.

Highly efficient, reversible iodine capture and exceptional uptake of amines in viologen-based porous organic polymers.

A viologen-based porous organic polymer, POP-V-VI, was designed and synthesized by a facile nucleophilic substitution between cyanuric chloride and 1,2-bis(4-pyridinium) ethylene. Together with the reported POP-V-BPY with a similar structure, these viologen-based porous organic polymers bear high charge density, phenyl ring and nitrogenous affinity sites, which endow them with excellent iodine vapor uptake capacity (4860 mg g−1 for POP-V-VI and 4200 mg g−1 for POP-V-BPY) and remarkably high adsorption capacity for pyridine (4470 mg g−1 for POP-V-VI and 8880 mg g−1 for POP-V-BPY) and other aliphatic amines. POP-V-VI and POP-V-BPY could be efficiently recycled and reused three times without significant loss of iodine vapor uptake. All these results demonstrate that POP-V-VI and POP-V-BPY are promising adsorbents for practical applications in portable devices such as gas masks.

Triazine-based covalent organic polycalix[4]arenes for highly efficient and reversible iodine capture in water

Novel triazine-based covalent organic polycalix[4]arenes, CalCOPs, were synthesized via the copolymerization of calix[4]arene derivatives and 2,4,6-trichloro-1,3,5-triazine (TCT) or 2,4-dichloro-1,3,5-triazine (DCT). The resulting CalCOPs have permanent pores that can be regulated by the variation of the alkyl chain lengths of the calixarene backbones and the reaction sites. With the alkyl chain length at the low rim in calixarene units increasing from ethyl to butyl during the reaction, the Brunauer–Emmett–Teller surface areas decrease with surface areas of 280, 31.5, 18.4 and 1.6 m2 g−1 obtained for CalCOP1, CalCOP2, CalCOP3 and CalCOP4, respectively. Among these CalCOPs, CalCOP1 shows ultrahigh absorption for iodine capture in a water solution with an uptake of up to 232 wt%. Furthermore, the adsorption and release efficiency of iodine were obtained by using the UV–Vis spectroscopy. In addition, these polymers can be recycled at least five times while maintaining high removal capacity, suggesting that CalCOPs are ideal absorbent materials for reversible iodine capture in the mitigation of environmental issues.

Pyrrolidone-based polymers capable of reversible iodine capture for reuse in antibacterial applications

Numerous emerging and re-emerging advanced materials have been successful in capturing iodine pollutants that pose an unprecedented global challenge to public health. However, little attention has been paid to the reutilization of the captured iodine. Herein, we report on a pyrrolidone-based polymer capable of reversible iodine capture for reutilization in antibacterial applications. The pyrrolidone-based polymer poly(N-vinyl-2-pyrrolidone-co-vinyl acetate), denoted as P(VAc-NVP), was synthesized facilely via a one-step radical copolymerization strategy, and the synthesis was regulated by step-by-step optimization, specifically by tuning the feed ratio of NVP to VAc. The as-synthesized P(VAc-NVP) copolymer functioned as an adsorbent for iodine in various solutions, including water/ethanol, cyclohexane, and petroleum ether, in addition to having the special capability of releasing iodine in the presence of starch or bacteria. This opens up a new horizon for its functional practical use as a flexible adsorbent to capture iodine for safe disposal. Interestingly, the P(VAc-NVP) copolymer, after adsorbing iodine, showed antibacterial ability against pathogenic bacteria, including Staphylococcus aureus and Escherichia coli, when a series of simulated and practical antibacterial assays were conducted. It is believed that this proposed strategy based on the synergism of iodine capture and antibacterial use should have great potential for environmental remediation and public healthcare.

The spirobifluorene-based fluorescent conjugated microporous polymers for reversible adsorbing iodine, fluorescent sensing iodine and nitroaromatic compounds

Two new spirobifluorene-based conjugated microporous polymers, TS-TAD and TS-TADP, were constructed via Friedel-Crafts coupling reactions. TS-TAD and TS-TADP possess high BET surface area of 828 and 783 m2 g−1, large pore volume of 1.51 and 0.54 cm3 g−1, good stability, and display excellent guest uptake of 4.15 and 3.65 g g−1 in iodine vapour as well as reversible adsorption of iodine in solution. The specific surface areas of CMPs were increased by the introduction of bispirofluorene rings compared with the corresponding parent polymers. TS-TAD has a similar structure to TS-TADP, but possesses larger specific surface area and pore values than TS-TADP, hence, TS-TAD has a higher adsorption capacity for iodine than TS-TADP. Moreover, the adsorption rate of TS-TAD is slower than that of TS-TADP in I2 vapor, while it is faster than that of TS-TADP in cyclohexane solution. We also highlight that the both resulting CMPs exhibit outstanding performance for fluorescent sensing to iodine and nitroaromatic compounds, thus making the resulting CMPs ideal absorbent materials for reversible iodine capture, sensing iodine and nitroaromatic compounds to address environmental issues.

Guest Controlled Pillar[5]arene and Polyoxometalate Based Two-Dimensional Nanostructures toward Reversible Iodine Capture.

The two-dimensional (2D) nanostructures comprised of polyoxometalate based building blocks are of great value in nanoarchitectures, which have unique properties and widespread potential applications, but it is still challenging in mature preparation. Herein a new strategy to build Cr(III) centered Anderson type polyoxometalate 2D nanostructures based on the modulation of host-guest interaction between cationic pillar[5]arenes and sodium dodecyl sulfonate (SDS) in aqueous media was exploited in this work. Through regulating stoichiometry of SDS, the morphology of assemblies vary from nanobones to 2D nanosheets. The fine assembled structure was discovered by combined 1H NMR, SAXS, and element analyses. The nanomaterials can be used as adsorbents for I2 in various solutions, including n-hexane, cyclohexane, water, and chloroform, where the polyoxometalates play a key role in the effective adsorption of iodine since they can expand the interspace between pillar[5]arenes in the as-prepared nanostructure. Furthermore, such adsorbents are easily regenerated and reused as iodine can be released spontaneously from nanobones@I2 and nanosheets@I2 solids when being immersed in dimethyl sulfoxide.

Highly Porous Covalent Triazine Frameworks for Reversible Iodine Capture and Efficient Removal of Dye

Porous organic frameworks may be a kind of promising material to address environmental issues such as removing the radioactive vapor wastes in fission as well as coping with organic pollutants of wastewater, due to their excellent porous character and remarkable stability. In this report, a covalent triazine-based framework (CTF-CTTD) with hierarchically porous structure and large pore volume was synthesized via the nitrile trimerization. The CTF-CTTD shows an outstanding adsorption ability for iodine with the uptake value of 387% due to their abundant porosity, triazine units, as well as π–π conjugated structures, which is one of the highest values reported so far for iodine uptake values of solid porous adsorbents. Furthermore, iodine captured in CTF-CTTD can be also released easily from the pore of materials because of the highly porous structure. In addition, CTF-CTTD also presents an excellent adsorptive performance for removing Rhodamine B (RhB) with adsorption capacity of 684.9 mg g–1. These result...

Porous Silsesquioxane-Imine Frameworks as Highly Efficient Adsorbents for Cooperative Iodine Capture.

The efficient capture and storage of radioactive iodine (129I or 131I), which can be formed during nuclear energy generation or nuclear waste storage, is of paramount importance. Herein, we present highly efficient aerogels for reversible iodine capture, namely, porous silsesquioxane-imine frameworks (PSIFs), constructed by condensation of octa(3-aminopropyl)silsesquioxane cage compound and selected multitopic aldehydes. The resulting PSIFs are permanently porous (Brunauer-Emmet-Teller surface areas up to 574 m2/g), thermally stable, and present a combination of micro-, meso-, and macropores in their structures. The presence of a large number of imine functional groups in combination with silsesquioxane cores results in extremely high I2 affinity with uptake capacities up to 485 wt %, which is the highest reported to date. Porous properties can be controlled by the strut length and rigidity of linkers. In addition, PSIF-1a could be recycled at least four times while maintaining 94% I2 uptake capacity. Kinetic studies of I2 desorption show two strong binding sites with apparent activation energies of 77.0 and 89.0 kJ/mol. These energies are considerably higher than the enthalpy of sublimation of bulk I2.

A benzoquinone-derived porous hydrophenazine framework for efficient and reversible iodine capture.

A type of benzoquinone-derived porous organic polymer with hydrophenazine linkages, porous hydrophenazine frameworks, has been developed. Their application in iodine capture from both air and solution was investigated.

Reversible Iodine Capture by Nonporous Pillar[6]arene Crystals.

Here we report that easily obtained per-ethylated pillar[6]arene (EtP6) is a new adsorbent for iodine capture with high chemical and thermal stability. Nonporous EtP6 solids are shown to capture not only volatile iodine in the air but also iodine dissolved in an organic solvent and aqueous solution. Uptake of iodine leads to a structural transformation of EtP6 in the solid state. In the single crystal structure of iodine-doped EtP6 (I2@EtP6), each adsorbed iodine molecule is located between two adjacent EtP6 molecules to form a linear supramolecular polymer. Iodine is released spontaneously from I2@EtP6 solids when they are immersed in cyclohexane. These EtP6 solids can be reused many times without losing iodine capture capacity.

Highly Efficient and Reversible Iodine Capture in Hexaphenylbenzene-Based Conjugated Microporous Polymers

The effective and safe capture and storage of radioactive iodine (129I or 131I) is of significant importance during nuclear waste storage and nuclear energy generation. Here we present detailed evidence of highly efficient and reversible iodine capture in hexaphenylbenzene-based conjugated microporous polymers (HCMPs), synthesized via Buchwald–Hartwig (BH) cross-coupling of a hexakis(4-bromophenyl)benzene (HBB) core and aryl diamine linkers. The HCMPs present moderate surface areas up to 430 m2 g–1, with narrow pore size distribution and uniform ultramicropore sizes of less than 1 nm. Porous properties are controlled by the strut lengths and rigidities of linkers, while porosity and uptake properties can be tuned by changing the oxidation state of the HCMPs. The presence of a high number of amine functional groups combined with microporosity provides the HCMPs with extremely high iodine affinity with uptake capacities up to 336 wt %, which is to the best of our knowledge the highest reported to date. Two ...

Novel thiophene-bearing conjugated microporous polymer honeycomb-like porous spheres with ultrahigh iodine uptake.

Two conjugated microporous polymers containing thiophene-moieties (SCMPs) were obtained by the polymerization of 3,3',5,5'-tetrabromo-2,2'-bithiophene and ethynylbenzene monomers through the palladium-catalyzed Sonogashira-Hagihara crosscoupling reaction. The resulting SCMPs show high thermal stability with a decomposition temperature above 300 °C. Scanning electron microscopy images show that the resulting SCMPs formed as an aggregation composed of micrometer-sized SCMP spheres, in which honeycomb-like porous spheres with penetrated pores on the surface were observed. Taking advantage of such a unique honeycomb-like porous morphology as well as π-conjugated structures, the SCMPs show ultrahigh absorption performance for iodine vapour with an uptake of up to 345 wt% obtained, which is the highest value reported to date for CMPs, thus making the resulting SCMPs ideal absorbent materials for reversible iodine capture to address environmental issues.

Highly efficient and reversible iodine capture using a metalloporphyrin-based conjugated microporous polymer.

A new metalloporphyrin-based conjugated microporous polymer, NiP-CMP, was constructed via a homo-coupling polymerization reaction. NiP-CMP possesses a high BET surface area of over 2600 m(2) g(-1), a large pore volume of 2.288 cm(3) g(-1), good stability, and displays excellent guest uptake of 202 wt% in iodine vapour. We also highlight that the polymer exhibits outstanding performance for the reversible adsorption of iodine in solution.