Iodine Adsorption Research Articles

Synthesis and Characterization of Silver-Modified Nanoporous Silica Materials for Enhanced Iodine Removal.

In aquatic environments, the presence of iodine species, including radioactive isotopes like 129I and I2, poses significant environmental and health concerns. Iodine can enter water resources from various sources, including nuclear accidents, medical procedures, and natural occurrences. To address this issue, the use of natural occurring nanoporous minerals, such as zeolitic materials, for iodine removal will be explored. This study focuses on the adsorption of iodine by silver-modified zeolites (13X-Ag, 5A-Ag, Chabazite-Ag, and Clinoptilolite-Ag) and evaluates their performance under different conditions. All materials were characterized using scanning electron microscopey (SEM), energy-dispersive X-ray spectroscopy (EDS), powdered X-ray diffraction (P-XRD), Fourier-transform infrared spectrometry (FTIR), and nitrogen adsorption studies. The results indicate that Chabazite-Ag exhibited the highest iodine adsorption capacity, with an impressive 769 mg/g, making it a viable option for iodine removal applications. 13X-Ag and 5A-Ag also demonstrated substantial adsorption capacities of 714 mg/g and 556 mg/g, respectively, though their behavior varied according to different models. In contrast, Clinoptilolite-Ag exhibited strong pH-dependent behavior, rendering it less suitable for neutral to slightly acidic conditions. Furthermore, this study explored the impact of ionic strength on iodine adsorption, revealing that Chabazite-Ag is efficient in low-salinity environments with an iodine adsorption capacity of 51.80 mg/g but less effective in saline conditions. 5A-Ag proved to be a versatile option for various water treatments, maintaining its iodine adsorption capacity across different salinity levels. In contrast, Clinoptilolite-Ag exhibited high sensitivity to ionic competition, virtually losing its iodine adsorption ability at a NaCl concentration of 0.1 M. Kinetic studies indicated that the pseudo-second-order model best describes the adsorption process, suggesting chemisorption mechanisms dominate iodine removal. Chabazite-Ag exhibited the highest initial adsorption rate with a k2 value of 0.002 mg g-1 h-1, emphasizing its superior adsorption capabilities. Chabazite and Clinoptilolite, naturally occurring minerals, provide eco-friendly solutions for iodine adsorption. Chabazite superior iodine removal highlights its value in critical applications and its potential for addressing pressing environmental challenges.

Density functional theory analysis of iodine coadsorbed OH-copper phthalocyanine for dopamine sensing

Density functional theory (DFT) was employed to investigate the sensing behaviour of the neurotransmitter dopamine (DA) when interacting with OH-functionalised copper phthalocyanines (CuPcs) and copper phthalocyanines coadsorbed with iodine (CuIPc), both in gaseous and aqueous media. This study revealed that CuIPc demonstrates a superior capacity for detecting dopamine molecules compared to CuPc. Within these complexes, hydrogen bonds and coordination bonds were observed, with hydrogen bonds playing a pivotal role in the dopamine adsorption process. The enhanced electrical conductivity of the CuPc sheets after iodine adsorption, along with the high adsorption energy of the iodine-coadsorbed CuPc/DA complexes, underscores the significance of iodine in this context. Notably, the utilisation of iodine significantly enhances the sensing response for dopamine. In summary, copper phthalocyanine coadsorbed with iodine has emerged as a promising material for dopamine sensors, offering possibilities for further advancements in this field.

Utilizing Date Palm Leaf Biochar for Simultaneous Adsorption of Pb(II) and Iodine from Aqueous Solutions

This study addresses the environmental and health hazards posed by Pb(II) and iodine, two significant contaminants. The objective was to explore the adsorption of these substances from aqueous solutions using biochar derived from the leaf midribs of the date palm through a slow pyrolysis process. The pyrolysis was conducted in two stages within a vacuum furnace: initially at 300 °C for 1 h followed by overnight cooling, and then at 600 °C with a similar cooling process. The resulting biochar was characterized for its microstructural features and functional groups using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. It exhibited a porous structure with large numbers of pores (20 to 50 μm in size) and functional groups including O-H, C-H, and C=C, which are integral to its adsorption capabilities. For the adsorption studies, a 100 ppm Pb(II) ion solution was treated with varying amounts of biochar (20, 40, 60, and 80 mg) for 24 h. In parallel, iodine adsorption was tested, with biochar quantities ranging from 0.1 to 0.4 g/50 mL. Both treatments were followed by filtration and analysis using atomic absorption spectroscopy to determine the remaining concentrations of Pb(II) and iodine. The study also explored the effect of varying incubation periods (up to 30 h) on iodine adsorption. The results were significant; 100% adsorption of Pb(II) was achieved with the addition of 60 mg of biochar per 10 mL of solution. In contrast, for iodine, a maximum adsorption of 39.7% was observed with 30 mg or 40 mg of biochar per 50 mL. These findings demonstrate the potential of date palm-derived biochar as an effective and sustainable material for the removal of Pb(II) and iodine from contaminated water, offering valuable insights for environmental remediation strategies.

Interconnected pyrolysis and activation with in-situ H3PO4 activation of biochar from pear wood chips in a pilot scale dual fluidized bed

Interconnected pyrolysis and activation is a novel technology for combustible gas and biochar production in dual fluidized bed (DFB). The study proposed one-step and two-step methods for pyrolysis and activation of biomass in a pilot scale DFB with capacity of 100 kg/h. Physical and chemical activation occurred simultaneously in DFB system by phosphoric acid (H3PO4) impregnation pretreatment of pear wood chips, and flowing hot flue gas and steam. Stable operating parameters were observed for both methods. The one-step method was superior to the two-step method in terms of the pyrolysis gas quality, biochar pore distribution, micro- and meso-pores structures of biochar, while one-step method reduced the biochar yields. As an activation agent, H3PO4 increased the yields of biochar and pyrolysis gas, promoted formation of micropores and enriched the surface functional groups of biochar with increasing ratio of H3PO4. H3PO4 to biomass ratio of 1:5 reached the maximum biochar yield of 42.3 wt% and highest iodine adsorption value of 648.5 mg/g, increasing by 70.6 % and 90.3 % compared to the biochar without H3PO4 pretreatment, respectively. This DFB system facilitated the diversified use of fluidized beds and the co-production of biochar and product gas with energy saving and CO2 emission reduction.

Preparation of copper-based carbon composites for adsorption of iodine gas

Exploring efficient, cheap and scalable adsorbents to capture the radioactive iodine gas is crucial for the sustainable development of nuclear energy. Herein, novel copper-based carbon (Cu–C) adsorbents were facilely prepared and applied for iodine adsorption. C supports were prepared by a simple sintering method using rice husk as carbon source. Cu–C adsorbents were synthesized by an improved impregnation reduction method. The adsorption behaviors impacted by Cu content and contact time were investigated. The adsorption mechanism was elucidated through XRD, SEM, XPS and TGA analyses. The results demonstrated that the adsorption capacity of 30%Cu–C sample reached up to 1282 mg/g due to the synergistic effect of copper and carbon. In addition, the obtained Cu–C adsorbents and adsorbed iodine exhibited high thermal stability. The dominant mechanism for the adsorption of iodine gas on Cu–C materials were chemical reaction (2Cu + I2 = 2CuI) and C–I interaction. Thanks to the excellent properties, the obtained Cu–C materials could be added into the list of potential iodine gas adsorbents.

A Three-Blade-Paddlewheel Unit-Based Layered Metal–Organic Framework with Synergistic Intermolecular Interactions for Efficient Iodine Adsorption

A Three-Blade-Paddlewheel Unit-Based Layered Metal–Organic Framework with Synergistic Intermolecular Interactions for Efficient Iodine Adsorption

Fabrication of bimetallic-doped materials derived from two polymorphic Ni-Mo-based coordination polymers for enhanced dye removal and gaseous iodine capture

Two polymorphic Ni–Mo-based coordination polymers (CPs) based on the ligand N,N′-bis(4-pyridinecarboxamide)-1,2-cyclohexane (4-bpah) were created using hydrothermal synthesis. Each of these CPs (denoted as Ni–Mo-1 and Ni–Mo-2) has the similar main framework [Ni(4-bpah)2(Mo2O7)], but they each show different crystalline phases with different 2D grid windows. Moreover, the Ni–Mo-based CP-derived carbon-based composites (C–Ni–Mo-X-Y, X = 1 or 2 and Y = 400, 450, or 500) were prepared by thermal cracking and “low-temperature” calcination below 500 °C using two CPs as precursors. The results show that the Ni–Mo-based CP-derived carbon-based composites prepared at different temperatures exhibit irregular morphologies with different micron-sized or nano-sized loose structures and chemical compositions. Furthermore, the dye and gas iodine adsorption properties of the C–Ni–Mo-X-Y composites were investigated in detail.

Biomass betulin-based porous aromatic frameworks nanomicrospheres as adsorbents for reversible capture of iodine

Betulin with a modifiable hydroxyl group and a rigid backbone is a kind of natural triterpene product that extracted from white barked birch bark with up to 30 % of its dry weight. Herin, we prepared a series of betulin-based porous aromatic frameworks (BEPAFs) nanomicrospheres by [Rh(nbd)Cl]2 polymerization or Sonogashira-Hagihara coupling reaction for iodine vapor capture and adsorption. The resulting BEPAFs nanomicrospheres presented perfect thermal stability and high specific surface areas that up to 324.6 m2 g−1, 506.3 m2 g−1 and 320.5 m2 g−1 for BEPAF-1, BEPAF-2 and BEPAF-3, respectively. Based on the above characteristics, the BEPFAs nanomicrospheres showed an excellent iodine capture performance with the volatile iodine capture ability reached 3.79 g g−1 and iodine adsorption in cyclohexane solution up to 389.9 mg g−1. The iodine capture behavior is consistent with the pseudo-second-order model, indicating that the iodine adsorption process of BEPAFs microspheres belongs to multilayer heterogeneous surface chemical adsorption. Furthermore, the BEPFAs nanomicrospheres could maintained 88.26 % of the absorption capacity after four cycles that endow them a great potential in practical application. This research provides a facile synthesis of biomass porous aromatic framework nanomicrospheres adsorbents based on the natural product.

Nanoscale assembly of MoS2/CoS2/Ni3S2 grown on Ni foam for synergistic capture of iodine

We report a series of MoS2/CoS2/Ni3S2/NF heterogeneous interfaces with multiple types of adsorption sites, which exhibit excellent iodine capture performance. The optimized MoS2/CoS2/Ni3S2/NF-13 obtained at Mo:Co molar ratio of 1:3 shows an extremely large maximum iodine capture of 1804 mg/g. For the including component of Ni3S2/NF, REDOX reaction between Ni0/S2- and I2 offers the main driving force of chemisorption toward iodine (forming NiI2 and S8), while for MoS2, the electrostatic adsorption makes the main contribution to the iodine capture, and for CoS2, interfacial interactions promote the uptake capability of iodine. We perform density functional theory (DFT) calculations to determine the iodine adsorption energies (Ead), which show that in Ni3S2 the Ni and S both serve as iodine sorption sites and Ni site binds more tightly to I2 than S site does, while for MoS2, the S site (rather than Mo) prefers to adsorb the I2. X-ray absorption fine structures (XAFS) indicate that after iodine capture, oxidation states of Mo and Ni are increased more than that of Co, verifying Ni3S2 and MoS2 interact more than CoS2 on I2. Though CoS2 component does not directly adsorb I2, interfacial electron transfers of Co → Ni and Co → Mo significantly promote iodine sorption capability. Synergistic effect of the multiple components/sites in the MoS2/CoS2/Ni3S2/NF assembly offers the wonderful iodine capture. This work provides a novel perspective and theoretical reference for tailoring effective metal sulfides-based sorbents to trap iodine from radioactive wastes.

Solvent-Responsive Nonporous Adaptive Crystals Derived from Pyridinium Hydrochloride and the Application in Iodine Adsorption.

Nonporous adaptive crystals (NACs) are crystalline nonporous materials that can undergo a structural adaptive phase transformation to accommodate specific guest via porous cavity or lattice voids. Most of the NACs are based on pillararenes because of their flexible backbone and intrinsic porous structure. Here a readily prepared organic hydrochloride of 4-(4-(diphenylamino)phenyl)pyridin-1-ium chloride (TPAPyH), exhibiting the solvent dimension-dependent adaptive crystallinity is reported. Wherein it forms a nonporous α crystal in a solvent with larger dimensions, while forming two porous β and γ crystals capable of accommodating solvent molecules in solvent with small size. Furthermore, the thermal-induced single-crystal-to-single-crystal (SCSC) transition from the β to α phase can be initiated. Upon exposure to iodine vapor or immersion in aqueous solution, the nonporous α phase transforms to porous β phase by adsorbing iodine molecules. Owing to the formation of trihalide anion I2Cl- within the crystal cavity, TPAPyH exhibits remarkable performance in iodine storage, with a high uptaking capacity of 1.27 g g-1 and elevated iodine desorption temperature of up to 110 and 82°C following the first and second adsorption stage. The unexpected adaptivity of TPAPyH inspires the design of NACs for selective adsorption and separation of volatile compound from organic small molecules.

Porous Aromatic Frameworks Enabling Polyiodide Confinement toward High Capacity and Long Lifespan Zinc-Iodine Batteries.

Aqueous zinc-iodine batteries (AZIBs) are attracting increasing attention because of their high safety and abundance of resources. However, the performance of AZIBs is compromised by inadequate confinement of soluble polyiodides, the undesired shuttle effect, and slow reaction kinetics. In this study, a porous aromatic framework (PAF) with abundant benzene motifs and a well-organized pore structure is adopted as the iodine host, which exhibits high iodine adsorption capacity and robust polyiodide confinement. Both experimental characterizations and theoretical simulations indicate that the interactions between iodine species and the PAF-1 facilitate the redox reaction by coupling the electronic structures of the active species in the framework. A comparison of PAF-1, PAF-5, and PAF-11 also emphasizes the structural advantages of the high surface area and interconnected three-dimensional channels of PAF-1. Consequently, the I2@PAF-1 cathode can deliver a high capacity of 328 mAh g-1 at 0.5 C, outstanding rate performance, and a stable cycling life of 20000 cycles (86 % retention at 10 C). The robust polyiodide confinement and superb electrochemical performance of Zn-I2@PAF-1 provide insights into the practical application of PAFs as excellent electrode materials for AZIBs.

Study on the microstructure and adsorption mechanism of different silver-based iodine adsorbents

To further clarify the iodine adsorption mechanism of three-dimensional ordered macroporous silver-silica (3DOM-SA) composite aerogel, based on the establishment of the relationship between pore structure and adsorption properties, the kinetic analysis of the adsorption process of gaseous iodine was carried out, and a comprehensive comparison was made with silver nitrate impregnated silica (AgS) which has been applied in engineering. The results show that the adsorption of gaseous iodine by 3DOM-SA and AgS fits well with the pseudo-second-order and pseudo-first-order kinetic model, corresponding to the main roles played by chemical adsorption and physical adsorption. The iodine adsorption capacity of 3DOM-SA (925 ± 46 mg/g) is much larger than that of AgS (64 ± 11 mg/g) due to the 3DOM structure and more dispersed nano-active components.

Fabrication of carbonized derivatives from a novel azo polymer as a precursor for the layered adsorption of iodine and bromine

A nitrogen-rich polymer (AZO-TPA) was synthesized and employed as a precursor for calcined carbonized derivatives. After this polymer was activated with KOH, it was doped separately with melamine and urea, both of which are rich in carbon and nitrogen, and nine distinct carbonized derivatives were obtained through carbonization at various temperatures. Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) characterization revealed that the carbonized structures were rich in nitrogen functional groups, including pyridinic-N, pyrrolic-N, and N+–O- (nitrogen oxides), and possess additional active sites such as –OH and CO groups. The adsorption of bromine, iodine, and the fractional adsorption of bromine/iodine were investigated via the prepared carbonized derivatives. The results indicated that the polymer was successfully doped with urea and yielded carbonized derivatives at 600 °C (AZO-TPAU-600) which exhibited favorable adsorption capacity, particularly after KOH activation and urea doping (iodine vapor: 2782 mg g−1; bromine/iodine: 1854 and 867.55 mg g−1). In addition, the AZO-TPA-600 exhibited high selectivity for bromine adsorption in I2–Br2/cyclohexane solution, and the carbonized derivatives loaded with iodine/bromine could be efficiently desorbed via organic solvents, the adsorption capacity remains above 75 % even after 4 cycles. Finally, the adsorption mechanism was explained in detail.

Sulfur vacancy-rich bismuth sulfide nanowire derived from CAU-17 for radioactive iodine capture in complex environments: Performance and intrinsic mechanisms

Effective capture and immobilization of volatile radioiodine from the off-gas of post-treatment plants is crucial for nuclear safety and public health, considering its long half-life, high toxicity, and environmental mobility. Herein, sulfur vacancy-rich Vs-Bi2S3@C nanocomposites were systematically synthesized via a one-step solvothermal vulcanization of CAU-17 precursor. Batch adsorption experiments demonstrated that the as-synthesized materials exhibited superior iodine adsorption capacity (1505.8 mg g−1 at 200 °C), fast equilibrium time (60 min), and high chemisorption ratio (91.7%), which might benefit from the nanowire structure and abundant sulfur vacancies of Bi2S3. Furthermore, Vs-Bi2S3@C composites exhibited excellent iodine capture performance in complex environments (high temperatures, high humidity and radiation exposure). Mechanistic investigations revealed that the I2 capture by fabricated materials primarily involved the chemical adsorption between Bi2S3 and I2 to form BiI3, and the interaction of I2 with electrons provided by sulfur vacancies to form polyiodide anions (I3-). The post-adsorbed iodine samples were successfully immobilized into commercial glass fractions in a stable form (BixOyI), exhibiting a normalized iodine leaching rate of 3.81 × 10−5 g m−2 d−1. Overall, our work offers a novel strategy for the design of adsorbent materials tailed for efficient capture and immobilization of volatile radioiodine.

Highly Efficient Capture of Volatile Iodine by Conjugated Microporous Polymers Constructed Using Planar 3- and 4-Connected Organic Monomers.

The effective capture and recovery of radioiodine species associated with nuclear fuel reprocessing is of significant importance in nuclear power plants. Porous materials have been proven to be one of the most effective adsorbents for the capture of radioiodine. In this work, we design and synthesize a series of conjugated microporous polymers (CMPs), namely, TPDA-TFPB CMP, TPDA-TATBA CMP, and TPDA-TECHO CMP, which are constructed based on a planar rectangular 4-connected organic monomer and three triangular 3-connected organic monomers, respectively. The resultant CMPs are characterized using various characterization techniques and used as effective adsorbents for iodine capture. Our experiments indicated that the CMPs exhibit excellent iodine adsorption capacities as high as 6.48, 6.25, and 6.37 g g-1 at 348 K and ambient pressure. The adsorption mechanism was further investigated and the strong chemical adsorption between the iodine and the imine/tertiary ammonia of the CMPs, 3D network structure with accessible hierarchical pores, uniform micromorphology, wide π-conjugated structure, and high-density Lewis-base sites synergistically contribute to their excellent iodine adsorption performance. Moreover, the CMPs demonstrated good recyclability. This work provides guidance for the construction of novel iodine adsorbent materials with high efficiency in the nuclear power field.

Effective Iodine Adsorption and Storage of Volatile Iodine by Nitrogen-Rich Porous Organic Polymers from Flexible Building Blocks

Effective Iodine Adsorption and Storage of Volatile Iodine by Nitrogen-Rich Porous Organic Polymers from Flexible Building Blocks

Preparation of porous materials by ultrasound-intensified acid leaching of high-carbon component in coal gasification fine slag

Coal gasification fine slag is one of the by-products from clean and efficient utilization of coal, and its resource utilization is extremely urgent. In this work, a high carbon fraction with a fixed carbon content higher than 60% was obtained by simple sieving of gasification fine slag, from which a porous material was prepared by ultrasonic acid leaching method. The adsorption performance of porous materials, being used as treatment of radioactive iodine in nuclear wastewater, is characterized by iodine adsorption value. The effects of ultrasound time, ultrasound power, acid concentration, and temperature on the iodine adsorption performance and compositional structure of the porous materials were systematically investigated by combining the results of SEM, BET, XRD, and FT-IR. The mechanisms of ultrasound-enhanced acid leaching on compositional structure of residual carbon and migration and transformation laws of the ash constituents were explored and summarized. The results show that the porous material prepared under conditions of acid concentration of 4 mol/L, acid immersion temperature of 50 °C, ultrasonic power of 210 W, and ultrasonic time of 1.5 h has the best iodine adsorption performance of 468.53 mg/g, with a specific surface area of 474.97 m2/g, and possesses a rich pore structure with predominant mesopores. The order of each factor on the iodine adsorption performance is: sonication time > acid concentration > sonication power > acid immersion temperature. The mechanism of ultrasonic enhanced acid leaching is that ultrasonic cavitation and mechanical wave action firstly enhance dissociation of carbon-ash adherent particles, thus making desorption of ash particles blocked in pore channels of the gasification slag to increase its connectivity; secondly, lead to generation of cracks on surface of the carbon and ash particles to enhance accessibility of inorganic components inside the carbon particles; and thirdly, enhance the acid leaching process by increasing mass transfer rate to strengthen leaching effect of inorganic components in the gasification slag.

Layered rare-earth stabilized Bi2O3: Organic amines intercalation under ambient conditions and their role as a solid adsorbent for iodine

Intercalation chemistry is pivotal in discovering the dimension-dependent properties of 2D materials and expanding their applications. Layered bismuth oxide with composition Bi0.775Ln0.225O1.5 (Ln = La, Pr, Nd, Sm, and Eu) has been demonstrated to intercalate both aliphatic and aromatic amines, resulting in the unit cell expansion along the c-axis. Aliphatic amines were present in a vertical orientation, whereas aromatic amines preferred a horizontal orientation. The intercalated amine concentrations ranged from 0.15 to 0.54 mole per mole of the host. Among the chosen amines, ethylenediamine intercalation enhanced the c-axis of Bi0.775Pr0.225O1.5 by 20 Å, justified by the high amounts of intercalant and intermolecular hydrogen bonding between them, resulting in a bilayer arrangement. The lamellar-plate-like morphology filled with intercalants and twinning collapse was noticed in the FESEM and SAED patterns after the intercalation process. The ethylenediamine intercalated Bi0.775Pr0.225O1.5 was further evaluated for iodine adsorption from non-aqueous solutions through chemisorption following pseudo-second-order kinetics. The X-ray diffraction peaks after adsorption suggested bilayer to monolayer transformation aided by chemical alterations within the host's van der Waals gaps. The N–I vibration mode, observed in the FTIR spectrum of the iodine-adsorbed sample, further augmented the interaction between the two during adsorption.

Hydrophobic nanosheet silicalite-1 zeolite for iodine and methyl iodide capture

Effective capture of radioactive iodine from nuclear fuel reprocessing is of great importance for public safety as well as the secure utility of nuclear energy. In this work, a hydrophobic nanosheet silicalite-1 (NSL-1) zeolite with an adjustable size was developed for efficient iodine (I2) and methyl iodide (CH3I) adsorption. The optimized all-silica zeolite NSL-1 exhibits an excellent I2 uptake capacity of 553 mg/g within 45 min and a CH3I uptake capacity of 262 mg/g within 1 h. Benefiting from the reduced thickness and enhanced porosity, microporous NSL-1 possesses enhanced iodine adsorption capacity and fast adsorption kinetics, which is a considerable high value among inorganic materials. Unexpectedly, the remarkable characters of high hydrophobicity, acid-resistance and anti-oxidation endow it a higher iodine uptake capacity than traditional aluminosilicate zeolites. More importantly, the high uptake selectivity toward I2 possessed by NSL-1 owing to its hydrophobic skeleton under simulated dynamic conditions. The low cost, facile and scalable synthesis of NSL-1 further highlights great prospects for applications in the nuclear industry. This work provides useful insights for designing efficient adsorbents for iodine capture.

Synthesis of Triazole-Linked Porous Cage Polymers: Modulating Cage Size for Tailored Iodine Adsorption

Synthesis of Triazole-Linked Porous Cage Polymers: Modulating Cage Size for Tailored Iodine Adsorption