Adsorption Behavior Of Iodine Research Articles

Constructing cationic flexible covalent organic frameworks through post-functionalization for enhancing the iodine adsorption capacity

With the incresing development of nuclear power plants, the radioactive iodine produced from nuclear waste and nuclear accidents poses increasing threat to the human health and environment. The iodine adsorption behavior of the neutral flexible covalent organic skeleton has been somewhat studied, but to our knowledge, there are no reports of iodine capture by ionized flexible COFs. Herein, we apply a post-functionalization process to construct two cationic flexible COFs (iCOFs-AB-1 and iCOFs-AB-2) for the first time. The iCOFs-AB-1 and iCOFs-AB-2 exhibit I2 uptake capacities of 3.36 and 4.26 g g−1 at 77 °C, which are improved 1.19 and 1.14 times compared to that of neutral flexible COFs. The promotion of ionic groups on iodine adsorption and the iodine valence states adsorbed at diverse sites have identified by experiments. The adsorption mechanism studies show that the segregative bromide and iodide anions in iCOFs-AB-1 and iCOFs-AB-2 can induce molecular iodine to engender polyiodide anions, and the quaternary ammonium salt cations in iCOFs-AB-1 and iCOFs-AB-2 can come into being the Coulomb interaction force with the aforementioned polyiodide anions. This study demonstrates an efficient method to synthesize cationic flexible COFs and further use them as adsorbents for capturing iodine.

Preparation of Novel Nitrogen-Rich Fluorinated Hyperbranched Poly(amide-imide) and Evaluation of Its Electrochromic Properties and Iodine Adsorption Behavior.

In this study, we successfully synthesized a novel triacid monomer by means of the thermal cyclization reaction. Subsequently, a series of nitrogen-rich (A3+B2)-type fluorinated hyperbranched poly(amide-imide)s (denoted as PAI-1 and -2, respectively) were prepared by means of a one-pot method using this triacid monomer and a diamine monomer with a triphenylamine-carbazole unit as precursors. The degree of support of the prepared hyperbranched PAIs was found to be about 60% via 1H NMR calculations. Through X-ray photoelectron spectroscopy (XPS), it was found that the binding energies of C-N (398.4 eV) and -NH (399.7 eV) became lower under a current, while the binding energy peak of N+ appeared at 402.9 eV. In addition, the PAIs have good solubility and thermal stability (Tgs: 256-261 °C, T10%: 564-608 °C). Cyclic voltammetry (CV) analysis shows that the hyperbranched PAI films have good redox properties, and a range of values for the HOMO (4.83 to 4.85 eV) versus LUMO (1.85 to 1.97 eV) energy levels are calculated. The PAI films have excellent electrochromic properties: PAI-1 on coloration efficiency (CE) and transmittance change (ΔT, 852 nm) are 257 cm2/C and 62%, respectively, and have long-lasting redox properties (100 cycles). In addition, we conduct iodine adsorption tests using the structural features of PAIs with electron-drawing units, and the results show that PAI-1 had a high adsorption capacity for iodine (633 mg/g).

Study on the mechanical strength and iodine adsorption behavior of coal-based activated carbon based on orthogonal experiments

To prepare coal-based activated carbon with high mechanical strength and adsorption performance for the removal of iodine from wastewater, the effects of carbonization temperature, heating rate, activation time and activator on the mechanical strength of activated carbon were studied; the optimal production conditions were determined by comprehensively considering the specific surface area, iodine value, compressive strength and wear resistance based on previous studies. Iodine adsorption kinetics and equilibrium adsorption experiments were carried out on activated carbon prepared under the optimum conditions. The results showed that the increase in mechanical strength was caused by the release of volatile matter and secondary reactions, which formed the carbon skeleton, while the decrease in mechanical strength was due to the intervention of the activator, which destroyed the carbon skeleton. The adsorption kinetics showed that a pseudo-second order kinetic model was more suitable for the adsorption behavior of iodine on activated carbon. The equilibrium adsorption experiment results showed that iodine was evenly adsorbed on the surface of activated carbon, and with increasing temperature, the affinity of the active sites of activated carbon to iodine also increased.

Effects of cellulose addition on the physicochemical properties, pore structure and iodine adsorption of lignin-based biochar

The effects of different doped cellulose contents (0 ∼ 50 wt%) on the physicochemical properties, surface morphology, pore structure and iodine adsorption behavior of a lignin-based biochar were studied, and carbon nanotubes (CNTs) were successfully prepared during the pyrolysis process. The results showed that after the addition of cellulose, more micropores were formed on the surface of biochar, but cellulose inhibited the pyrolysis of the lignin to a certain extent. In particular, biochar with 40 wt% cellulose added exhibited a higher yield and more surface functional groups; additionally, CNTs were successfully prepared with this biochar sample. The iodine adsorption kinetics showed that the pseudo-second order kinetic model provided the best fit to the iodine adsorption data for this biochar. L6-C4 exhibited a higher saturation adsorption capacity of 467.38 mg·g−1 in the equilibrium adsorption experiment. Finally, combined with the Fourier transform infrared (FTIR) results, it was found that the enhanced iodine adsorption performance of L6-C4 was mainly caused by its surface functional groups.

Characteristics of iodine-bearing silver-impregnated alumina sorbents and their direct solidification via hot isostatic pressing.

Waste management for radioiodine is a key issue for the sustainable nuclear fuel cycle. The iodine adsorption behavior on a bed column of a silver-impregnated alumina sorbent (AgA) under conditions designed to match those of the Rokkasho reprocessing facility dissolver off-gas (DOG) system was investigated using different volatilized iodine concentrations. Cross-sectional observations of iodine-bearing AgA grains revealed that iodine was adsorbed as silver iodide and silver iodate, and gradually distributed from the surface to the inside of the AgA. The iodine distribution throughout the AgA beds allowed us to estimate the length of the mass-transfer zone. This suggests that the iodine load fraction in AgA (adsorbed iodine/total impregnated silver) will be averaged to 50% in the expected facility equipment design. This study also describes the waste form durability after disposal. To reproduce the average iodine loading in the waste form, 100%-loaded AgA grains were mixed with an equal amount of commercially available alumina reagents and consolidated through hot isostatic pressing at 175MPa and 1,325°C for 3h. The resultant 50%-loaded solid was used for the static leaching test over 4.5years, where the leached iodine was less than 0.2% under simple reducing conditions. This suggested that the HIPed solid of AgA from Rokkasho DOG showed preferable water resistance for after disposal safety.

A diamond-like cuprous coordination polymer based on the [Cu8I6]2+ cluster with multistimuli-responsive luminescence and iodine adsorption behavior

A diamond-like cuprous coordination polymer based on the [Cu8I6]2+ cluster has been successfully synthesized. This complex exhibits thermochromic and mechanochromic luminescence properties as well as good performance for the sorption and release of I2.

Structural transformation of copper (II)-based complexes driven by N, S cooperative coordination and iodine adsorption behavior

The controlling synthesis of coordination compounds with diverse structures using functional ligand and metal center is still a challenge. In this work, three copper-containing complexes 1–3 were synthesized using a flexible tripodal ligand L1 (where L1 ​= ​1, 3, 5-trispyridylsulfanylethyl)-2, 4, 6-triethylbenzene, 2-mercaptopyridine) with a N, S cooperative chelation coordination geometry. Upon binding with CuCl2 salt, Cu (II)-based mononuclear complex 1 [(CuCl2) L12) and two-dimensional coordination polymer 2 ([(CuCl2)3L1] n) were constructed via cooperative Cu–N/Cu–S coordination interactions. Interestingly, the free N, S chelation sites in complex 1 can be gradually activated to react with cuprous iodide in solution and lead to the formation of as-prepared complex 2 and tetranuclear complex 3 ([Cu2L14]), respectively. Such structural transformation behaviour can be precisely controlled through the addition of the extra cuprous iodide in solution. All three copper (II) complexes were characterized by PXRD, XPS, FT-IR and NMR spectroscopy. Moreover, complex 1 has an irregular linear channel in the crystal structure and can capture iodine (adsorption capacity 1.1 ​g/g) from hexane solution.

Construction of poly-iodine aromatic carboxylate Mn/Co frameworks and iodine adsorption behavior

Construction of poly-iodine aromatic carboxylate Mn/Co frameworks and iodine adsorption behavior

Rapid synthesis of polyimidazole functionalized MXene via microwave-irradiation assisted multi-component reaction and its iodine adsorption performance

The adsorption applications of MXene-based adsorbents have intensively investigated recently. However, the performance of MXene-based adsorbents has been largely limited owing to their lack of functional groups and adsorptive sites. Therefore, surface functionalization of MXene is an important route to achieve better performance for environmental adsorption. Herein, polyionic liquid functionalized MXene (named as MXene-PIL) was prepared through a multi-component reaction and adsorptive removal of iodine by MXene-PIL was also evaluated. The successful generation of PIL on MXene was confirmed by a series of characterization measurements. Furthermore, the effects of contact time, iodine concentration, environmental temperature and other factors on the adsorption performance of MXene-PIL were investigated. Adsorption kinetic analysis including pseudo-first-order dynamic model, pseudo-second-order dynamic model and Weber-Morris model, adsorption thermodynamic analysis such as Langmuir and Freundlich models and Van’t Hoff equation were used for further analysis the adsorption behavior of iodine by MXene-PIL. We demonstrated that the adsorption capacity could be as high as about 170 mg/g, which is obviously larger than the unmodified MXene and most of other reported adsorbents. Taken together, a simple strategy has been developed for in-situ generation of PIL on MXene and the resultant composites show potential application for adsorptive removal of iodine.

Mesoporous Assembly of Aluminum Molecular Rings for Iodine Capture.

The effective capture and storage of radioiodine are of worldwide interest for sustainable nuclear energy. However, the direct observation of ambiguous binding sites that accommodate iodine is extremely rare. We presented herein a crystallographic visualization of the binding of iodine within mesoporous cages assembled from aluminum molecular rings. These nanocages are formed through π-π interactions between adjacent aluminum molecular rings. Compared with the general nanotubes arrangement, the supramolecular nanocage isomer exhibits better iodine adsorption behavior. The robust molecular nanocages demonstrate a high iodine vapor saturation uptake capacity of 50.3 wt % at 80 °C. Furthermore, the resulting adsorbent can be recycled. Single-crystal X-ray diffraction reveals binding sites of molecular I2 within the pores of the phenyl-based linkers stabilized by the strong I···π interactions. These compounds represent an excellent model to deduce the trapping mechanism of guest molecules interacting with the host. In addition, this work develops a promising cluster-based aluminum material as iodine adsorbents.

A water-stable photochromic MOF with controllable iodine sorption and efficient removal of dichromate

A photochromic cationic MOF with one-dimensional channels was prepared based on a π-conjugated electron-deficient viologen, which exhibits high uptake capacity for Cr2O72− through ion-exchange and controllable iodine adsorption behavior.

Thermochromatographic behavior of iodine in fused silica columns when evaporated from lead\u2013bismuth eutectic

As a step toward licensing a lead–bismuth eutectic (LBE) based reactor design, the adsorption behavior of iodine evaporated from LBE on fused silica was examined. Using inert and reducing carrier gases, depositions with an adsorption enthalpy of − 95 to − 113 kJ mol−1 were observed. These depositions are compatible with a single species, tentatively identified as bismuth monoiodide, BiI. When introducing oxidizing conditions, multiple iodine species with higher volatility form, with adsorption enthalpies ranging from − 67 to − 86 kJ mol−1. Based on an empirical correlation one of these species was identified as monatomic iodine. This work provides fundamental understanding of the LBE/iodine gaseous chemistry and related adsorption deposition behavior.

Thorium-Organic Framework Constructed with a Semirigid Triazine Hexacarboxylic Acid Ligand: Unique Structure with Thorium Oxide Wheel Clusters and Iodine Adsorption Behavior.

We successfully prepared and characterized a distinctive thorium-based MOF (metal-organic framework) Th-TTHA with thorium oxide wheel clusters under the conditions of solvothermal synthesis by utilizing thorium nitrate and semirigid triazine hexacarboxylic acid linker H6TTHA (H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid). To the best of our knowledge, Th-TTHA is the first thorium-based MOF assembled by semirigid triazine hexapod ligand H6TTHA. It is worth mentioning that Th-TTHA exhibits a novel and distinctive arrangement of structure and topology. Th-TTHA has abundant adsorption sites such as the triazine ring that is rich in nitrogen atoms, N of NH-, and carboxyl oxygen atoms without coordination with a central metal, which drove us to explore its iodine adsorption capacity. The experimental results show that Th-TTHA shows excellent adsorption capacity for iodine, and the adsorption amount in a saturated iodine cyclohexane solution can reach 528 mg/g within 24 h. This work is greatly significant for the development of new structures of thorium-based MOFs and the expansion of its functional characteristics, which is very essential for our in-depth understanding of thorium chemistry and in the management and disposal of radionuclides and application of the nuclear fuel cycle.

High efficient adsorption and storage of iodine on S, N co-doped graphene aerogel.

High efficient adsorption of radioiodine in nuclear waste has attracted extensive attentions all over the world. In this work, we fabricated sulfur and nitrogen co-doped graphene aerogels (SN-GA) through one-step hydrothermal method, and investigated its iodine adsorption behavior including adsorption kinetics and isotherms in water. Our results reveal that SN-GA exhibits a 3D porous architecture with thiophene-S, oxidized-S, pyridine-N, pyrrole-N and graphite-N co-doped into the sp2 carbon frameworks. The adsorption experiment showed SN-GA has a maximum iodine adsorption capacity of 999 mg g-1 determined by Langmuir isotherm, and the adsorption process could be better described by the pseudo-second-order model.

Adsorption Behavior of Iodine by Novel Covalent Organic Polymers Constructed Through Heterostructural Mixed Linkers

The efficient capture and storage radioactive iodine (129I or 131I) formed during the extensive use of nuclear energy is of paramount importance. In this work, we presented a novel covalent organic polymer (JLUE-COP-3) constructed through heterostructural mixed linkers with perforated porousness, plenty of π-conjugated phenyl rings and functional –CO–NH– and –SO3H groups to iodine adsorption process. After fully characterizing the morphology and structure, the adsorption behavior of iodine by the resultant polymers were explored in detail. The external adsorption behavior was determined to obey the pseudo-second order kinetic model according to the kinetic analysis. The maximum liquid adsorption capacity was obtained to reach 153.85 mg/g at 298 K, which was evaluated by the Langmuir isotherm model. In addition, the negative attributes of ΔGo as well as the positive attributes of ΔHo and ΔSo at three temperatures, indicated the nature of the iodine adsorption over JLUE-COP-3 was spontaneous and endothermic.

Capture and adsorption behavior of iodine by edible γ-CD-MOFs

Capture and adsorption behavior of iodine by edible γ-CD-MOFs

Heterometallic Organic Frameworks Built from Trinuclear Indium and Cuprous Halide Clusters: Ligand-Oriented Assemblies and Iodine Adsorption Behavior.

Two novel heterometallic organic frameworks built from trinuclear indium and cuprous halide clusters, [(In3O)2(Cu2I2)3(ina)12(H2O)6](NO3)2·7DMA·10H2O (1) and [NH2(CH3)2][In3(OH)2(H2O)2(ina)8(Cu4I4)2]·5DMA·8H2O (2), where Hina = isonicotinic acid, have been successfully constructed with the orientation of the ina ligand. 1 shows a fascinating highly porous honeycomb-like 3D cationic framework with a trigonal-bipyramid-type cage based on a planar [In3O(CO2)6]+ trimer and a rhombohedral Cu2I2 cluster. Comparably, 2 displays a 3D negative network with irregular hexagonal channels constructed from a [In3(OH)2(CO2)8]- trimer and a cubane-like Cu4I4 cluster. Especially, 1 displays a reversible I2 adsorption/release performance with high adsorption capacity, whose mechanism has been disclosed by theoretical simulation. Also, the green/red emission of 2 stems from iodocuprate centers with quenched indium-centered emission.

Capture of Iodine Species in MIL-53(Al), MIL-120(Al), and HKUST-1(Cu) Periodic DFT and Ab-Initio Molecular Dynamics Studies

The potential use of three metal–organic frameworks (MIL-53(Al), MIL-120(Al) and HKUST-1(Cu)) to adsorb iodine species (I2 and ICH3), which can be released during a severe nuclear accident, is investigated using periodic dispersion density functional theory for the first time. Competitive adsorption of iodine in the presence of water molecules is also characterized for the hydrophilic HKUST-1(Cu). In the first step, we have found that the absolute values of interaction energies of I2 and ICH3 are higher in the hydrated form of HKUST-1(Cu) than in the dehydrated one, which is of very high interest for iodine trapping. In a second stage, iodine species are strongly adsorbed in MIL-53(Al) than in MIL-120(Al) and HKUST-1(Cu) MOFs and therefore this material could potentially trap iodine compounds. Moreover, we study the influence of the functionalization of the MIL-53(Al) organic linkers on the adsorption behavior of iodine and it turns out that the substitutions does not present a significant effect for this...

Hierarchically porous bismuth oxide/layered double hydroxide composites: Preparation, characterization and iodine adsorption

The discharge of iodine-containing wastewater into environment will lead to the water pollution due to the toxicity and radioactivity of iodine and iodine isotopes. A versatile adsorbent which can effectively adsorb the iodine is in high demanded for this issue. In this work, the hierarchically porous bismuth oxide/layered double hydroxide (Bi2O3/LDHs) composites were prepared based on biological template techniques, and the as-prepared composites show enhanced iodine adsorption capacity compared with LDHs fibers. The MgAl LDHs fibers with hierarchical architectures are synthesized by directly growth of nanoscaled LDHs platelets on Al2O3 fiber surfaces. The Bi2O3/LDHs composites with sponge-like structures are prepared by desorption of Bi2O3 on the surfaces of LDHs fibers. The iodine adsorption behavior on Bi2O3/LDHs composites was examined in sodium iodine aqueous solutions. The appropriate iodine adsorption was obtained at a neutral pH with maximum adsorption capacity of 101.9 mg/g. The Langmuir model successfully describes the iodine adsorption isotherms, while the pseudo-second-order kinetic model is better at describing the iodine adsorption kinetics onto the Bi2O3/LDHs composites. Since the Bi2O3/LDHs composites show near complete removal of iodine ions, the as-prepared Bi2O3/LDHs composites are expected to have practical applications as iodine adsorbent in wastewater treatment.

Simultaneous removal of various iodine species in aqueous solutions of high salt concentrations using novel functional adsorbents

Novel tannic acid-type resin combined with benzimidazole-type anion-exchange resins embedded in high-porous silica beads, named improved tannic acid (ITA)-type resin was synthesized successfully and the adsorption behavior of iodine and iodide species on the synthesized resin have been studied in several types of seawater at a temperature range of 278–318 K, compared with those of some typical resins. We have confirmed that ITA can strongly adsorb iodine and iodide species. From these results, we have proposed that the synthesized ITA is suitable for selective removal of radioactive iodine and iodide species in contaminated seawater containing radioactive nuclides.