Adsorption Of Iodide Research Articles

Heterogeneous oxidation and adsorption of iodide by Bi-Fe-Mn ternary oxide: Roles of different metal oxide

Long-term consumption of groundwater with high iodine content can lead to thyroid damage and other endemic diseases. Hence, there is an urgent need to develop an efficient iodine removal technology suitable for the complex water quality conditions of actual groundwater. In light of the small water treatment capacity and low investment in drinking water in remote areas, we combined Fe-Mn binary oxides (FMBO), which have been widely used in engineering, with bismuth oxides to construct a Bi-Fe-Mn ternary metal oxide (BFMTO) heterogeneous interface that can efficiently remove and regulate the species of iodine. Compared to FMBO and Bi-Mn binary oxides, BFMTO is less affected by coexisting ions, organic matter, and pH during the iodine removal process. When the dosage of BFMTO is 1.0 g/L, the iodide (I-) concentration is 120 μg/L, and the reaction time is 60 min, the removal rates of I- and iodate (IO3-) in groundwater reach 53.82 % and 84.74 %, respectively. The reaction process follows the pseudo-second-order kinetic equation, and the maximum adsorption capacities are 1084.0 μg/g and 1143.4 μg/g, respectively. Based on the results of XPS, HPLC-ICP/MS, and DFT, it can be observed that the metal oxides in BFMTO simultaneously play the function of I- removal. Among them, FeOOH and Bi intrinsic oxides (Bi Ntv Ox) play a crucial adsorption role in the removal of I-, and Mn(IV) and Mn(III) play an oxidation role. In addition to being directly adsorbed and removed, some I- in water is oxidized to I2 and IO3-. This study offers technical support for practical projects such as the control and purification of I- in rural groundwater.

Regulating the Spin‐State of Cobalt in Three‐Dimensional Covalent Organic Frameworks for High‐Performance Sodium‐Iodine Rechargeable Batteries

Although the catalytic activity is heavily reliant on the electronic structure of the catalyst, understanding the impact of electron spin regulation on electrocatalytic performance is still rarely investigated. This work presents a novel approach involving the single‐atom coordination of cobalt (Co) within metalloporphyrin‐based three‐dimensional covalent organic frameworks (3D‐COFs) to facilitate the catalytic conversion for sodium‐iodine batteries. The spin state of Co is modulated by altering the oxidation state of the porphyrin‐centered Co, achieving optimal catalysis for iodine reduction. Experimental results demonstrate that CoII and CoIII are incorporated into the 3D‐COFs, exhibiting spin ground states of S = 1/2 and S = 0, respectively. The low spin state of CoIII is favorable to hybridize with the sp 3d orbitals of I3‐, thus facilitating the conversion of I3‐ to I‐. Density‐functional theory (DFT) calculations further reveal that the presence of CoIII enhances iodide adsorption and accelerates the formation of NaI in 3D‐COFs‐CoIII, thereby promoting its rapid kinetic behaviors. Notably, the I2@3D‐COFs‐CoIII cathode achieves a high reversible capacity of 227.7 mAh g‐1 after 200 cycles at 0.5 C and demonstrates exceptional cyclic stability, exceeding 2000 cycles at 10 C with a minor capacity fading rate of less than one 0.01% per cycle.

Regulating the Spin-State of Cobalt in Three-Dimensional Covalent Organic Frameworks for High-Performance Sodium-Iodine Rechargeable Batteries.

Although the catalytic activity is heavily reliant on the electronic structure of the catalyst, understanding the impact of electron spin regulation on electrocatalytic performance is still rarely investigated. This work presents a novel approach involving the single-atom coordination of cobalt (Co) within metalloporphyrin-based three-dimensional covalent organic frameworks (3D-COFs) to facilitate the catalytic conversion for sodium-iodine batteries. The spin state of Co is modulated by altering the oxidation state of the porphyrin-centered Co, achieving optimal catalysis for iodine reduction. Experimental results demonstrate that CoII and CoIII are incorporated into the 3D-COFs, exhibiting spin ground states of S = 1/2 and S = 0, respectively. The low spin state of CoIII is favorable to hybridize with the sp 3d orbitals of I3-, thus facilitating the conversion of I3- to I-. Density-functional theory (DFT) calculations further reveal that the presence of CoIII enhances iodide adsorption and accelerates the formation of NaI in 3D-COFs-CoIII, thereby promoting its rapid kinetic behaviors. Notably, the I2@3D-COFs-CoIII cathode achieves a high reversible capacity of 227.7 mAh g-1 after 200 cycles at 0.5 C and demonstrates exceptional cyclic stability, exceeding 2000 cycles at 10 C with a minor capacity fading rate of less than one 0.01% per cycle.

Rapid and scalable preparation of highly quaternized polymer networks to achieve efficient simultaneous adsorption of iodide and pertechnetate

Rapid and scalable preparation of highly quaternized polymer networks to achieve efficient simultaneous adsorption of iodide and pertechnetate

Mesoporous TiO2@nitrogen-doped carbon nanosheets implanted in flexible and robust chitosan membrane with dual-function for efficient adsorption of iodide and methyl orange from aqueous solution

Radioactive iodide (I−) and methyl orange (MO) are two leading pollutants in wastewater, posing significant health risks. Crosslinked chitosan membranes (CCM) combined with TiO2@nitrogen-doped carbon nanosheets (CCM/TiO2@NC) were prepared as efficient I− and MO adsorbents in wastewater. These membranes leverage multiple interactions between I−/MO and functional groups (−NH2, nitrogen-doped carbon, and TiO2) within the membrane. As expected, CCM/TiO2@NC exhibited high I− removal efficiencies of nearly 82 % across a wide pH range (pH 3 − 11) and an exceptional MO removal efficiency of 96.1 % at a neutral condition. The adsorption behaviors followed the Langmuir isotherm and pseudo-second order kinetic model for both species, achieving maximum adsorption capacities of 1.383 mmol/g (175.6 mg/g) for I− and 661.4 mg/g for MO, respectively. Additionally, CCM/TiO2@NC maintained a high absorption efficiency for both I− and MO through five regeneration cycles. The I− adsorption mechanism of CCM/TiO2@NC involves electrostatic attraction, anion-π interaction, and hydrogen bonding, while MO adsorption involves electrostatic attraction, n/π-π interactions, and hydrogen bonding. This study offers feasible guidance on developing chitosan/nanomaterial composites as promising adsorbents for removing I− and MO from wastewater.

Synthesis of bulk foam-like palygorskite based adsorbent for efficient and convenient recyclable removal of radioactive iodine and iodide

Radioactive iodine is the inevitable product of nuclear fission, and the types and valence states of iodine are relatively rich and easy to convert to each other. Therefore, the synthesis of a material that can be easily recovered and efficiently remove polyvalent radioactive iodine has great strategic significance for the safe use of nuclear power. Bulk foam-like palygorskite based adsorbents (PDMA-PAL) with the macroscopic pore size of 40 to 150 μm were synthesized by the emulsion template method using dimethylaminoethyl methacrylate (DMAEMA) as the functional monomer and cheap palygorskite (PAL) as the matrix material. The excessive addition of DMAEMA and PAL will lead to the collapse of the porous structure. Optimized PDMA2-PAL shows excellent adsorption capacity (2.14 g/g) for iodine in cyclohexane solution with the equilibrium time of 5 h. PDMA2-PAL also exhibits an excellent adsorption capacity for gaseous iodine (308 wt%), and the I2 adsorption mechanism is the strong affinity and charge transfer of electron-rich N heteroatoms for electron-deficient iodine. PDMA2-PAL also achieves an outstanding iodide adsorption capacity (2.1mmol/g) within 5 min, and the I− adsorption mechanism is the electrostatic interaction between I− and the derivatization of tertiary amine under acidic conditions. Moreover, the deprotonation in alkaline solution can desorb iodide efficiently, which makes PDMA-PAL exhibit excellent recyclability. Importantly, PDMA-PAL also shows excellent simultaneous adsorption ability of iodide and iodine, and also exhibits stable adsorption activity in actual water. This study provides promising results for the removal of polyvalent radioactive iodine by bulk foam-like palygorskite based adsorbent in environmental remediation.

A new look at metal–carbon hybrids: Molecular-scale study of covalently grafted gold

The reliable integration of new nanocarbons in future molecular and hybrid electronics requires mastery of chemical binding between dissimilar materials down to the individual bond. Here, we present a detailed study of covalent grafting of aryl radicals on single crystal Au(111), and investigate their electrochemical stability and oxidative desorption. Copper underpotential deposition and Gaussian deconvolution of its current–potential trace are used to map the thermodynamic and kinetic landscape of the modified Au surface. Scanning tunnelling microscopy in a high-boiling organic solvent suggests that grafting is accompanied by vacancy island formation on the Au surface, while iodide adsorption heals these vacancies and allows high-contrast imaging of individual covalent grafts.

Construction of hollow CMPs microspheres based on the kinetic quantum sieving effect for highly efficient adsorption of Iodide/Cesium ions

Considering the dangers of radioactive elements to the human body and the environment, the efficient and rapid removal of radioactive ions in water is an urgent matter. In this paper, an efficient adsorption material based on kinetic quantum sieving (KQS) effect through skillfully molecular design with specific space structure conjugated microporous polymer hollow spheres (CMPs-1) for disposal of radioactive iodide/cesium ions is reported. The adsorption properties of iodide/cesium ions at different concentrations at 10℃ were investigated. Moreover, the test results show that the iodide ions adsorption capacity of the CMPs-1 will increase with the increase of iodine ions concentration when the temperature, volume, and other conditions are fixed. The CMPs-1 exhibited up to the highest 16.93 mg g−1 iodide adsorption capacity for the solution containing 0.10 mmol L-1 iodide ions within 6 h under static adsorption experiments at a low temperature of 10℃, and the adsorption rate fitted by the pseudo-second-order kinetic model was 0.11 g mg-1 h−1. Besides, the CMPs-1 maintained an effective adsorption capacity of 16.93, 7.51 and 5.92 mg g-1 at pH = 7, 10 and 13, respectively. Furthermore, unexpectedly, the constructed CMPs-1 showed superior heat resistance with higher adsorption capacity (26.32 mg g-1, 1.6 times) at 30℃ compared to 10℃. The improvement reason is that the expansion of pores (significantly increased at 4–20 nm), and the developed porosity can provide enough space to accelerate the diffusion rate of reactants and intermediates, exposing more active sites. And the π-conjugated system and hollow structure of CMPs materials can effectively solve the problem of low diffusion rate caused by low temperature and microporous structure in the transfer of iodide/cesium ions. Therefore, this work demonstrates the customizable potential of materials in the field of molecular adsorption applications and also provides a new idea for the design of unique hollow structure adsorption materials.

Iodide adsorption from aqueous solutions using zirconium-containing anion exchange resin as an oxidizing resin: batch and column studies

Iodide adsorption from aqueous solutions using zirconium-containing anion exchange resin as an oxidizing resin: batch and column studies

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.

Effects of moisture and aging upon decomposition of methyl iodide by reduced silver mordenite

Reduced silver mordenite has been considered as a sorbent for the capture of organic iodides, especially methyl iodide, from off-gases produced by aqueous used nuclear fuel reprocessing operations. The adsorption capacity of this material has been unpredictable especially when NOx and water are present. Previous work has found that a catalytic decomposition reaction is occurring on the surface but few determinations have been made of the kinetics of this reaction. The work presented tested the adsorption behavior and apparent catalytic reaction rate in humid conditions and compared those to dry conditions testing. Both experiments observed a first order reaction with rate constants of 0.0847 L/g sorbent/s and 0.1202 L/g sorbent/s respectively. Such a reduction in apparent rate constant is possibly due to either water obstructing methyl iodide adsorption or product desorption limitation. Changes in the adsorption profile were also apparent between these two, with the humid conditions experiment reaching saturation sooner than the dry conditions experiment. Additionally, an experiment into the effects of sorbent storage in a controlled laboratory environment was performed. The performance of the sorbent materials that were stored with silver in the zerovalent state was slightly inferior to those materials that were stored in ionic form (Ag+) and reduced to zerovalent silver immediately prior to subjecting them to sorption test. The materials stored with silver in the ionic form (and reduced just prior to application) behaved essentially similarly to the freshly synthesized (and reduced) sorbents in the sorption tests. This suggests that zerovalent silver experiences some oxidation resulting in deactivation of some sites.

Spontaneous Appearance of Triiodide Covering the Topmost Layer of the Iodide Solution Interface Without Photo-Oxidation.

Ions containing iodine atoms at the vapor-aqueous solution interfaces critically affect aerosol growth and atmospheric chemistry due to their complex chemical nature and multivalency. While the surface propensity of iodide ions has been intensely discussed in the context of the Hofmeister series, the stability of various ions containing iodine atoms at the vapor-water interface has been debated. Here, we combine surface-specific sum-frequency generation (SFG) vibrational spectroscopy with ab initio molecular dynamics simulations to examine the extent to which iodide ions cover the aqueous surface. The SFG probe of the free O-D stretch mode of heavy water indicates that the free O-D group density decreases drastically at the interface when the bulk NaI concentration exceeds ∼2 M. The decrease in the free O-D group density is attributed to the spontaneous appearance of triiodide that covers the topmost interface rather than to the surface adsorption of iodide. This finding demonstrates that iodide is not surface-active, yet the highly surface-active triiodide is generated spontaneously at the water-air interface, even under dark and oxygen-free conditions. Our study provides an important first step toward clarifying iodine chemistry and pathways for aerosol formation.

Core–shell Ag@polypyrrole for synchronous pre-enrichment and immobilization of iodine (I−, IO3−) from liquid radioactive wastes

A core–shell silver-encapsulated polypyrrole, Ag@PPy, was prepared via in situ synthesis for simultaneous efficient adsorption and immobilization of iodide and iodate.

Highly efficient iodide adsorption from medical radioactive wastewater by strong alkaline anion exchange fiber

The conventional decay cell technology faces challenges in addressing the growing demand for medical isotopes and the increasing volume of radioactive wastewater. To overcome this, a kind of strongly alkaline anion-exchange fiber (N-AF) was employed in this study for the treatment of radioactive wastewater containing iodine, specifically from nuclear medicine applications in hospitals. A series of adsorption experiments were conducted to assess the potential of N-AF as an adsorbent for removing iodide ions. The static and dynamic adsorption capacities of N-AF for iodide ions were determined to be 347.0 and 288.4 mg g−1, respectively. Characterization techniques such as SEM/EDS, FT-IR, and XPS confirmed the successful capture of iodide ions by N-AF. Furthermore, N-AF demonstrated effective purification of radioactive wastewater containing iodine from actual nuclear medical treatment, reducing the gross-activity from 563.50 to 0.29 Bq L−1. This achievement enables the total activity of radioactive wastewater to comply with the water pollutant discharge standard for medical institutions (GB18466–2005). This outcome holds significant importance in mitigating the risk of radioactive contamination and enhancing treatment rate.

Study on iodine adsorption capacity and adsorption mechanism of AgY

ABSTRACT To systematically study the methyl iodide (CH3I) adsorption performance and adsorption mechanism of Ag ion exchange NaY zeolite (AgY), AgY adsorbents with different Ag content were selected. 16.6% AgY was capable of storing 150 mg/g and 275 mg/g of CH3I when the penetrated CH3I reached 1‰ and 100% inlet concentration. TEM and EDS results presented a high relationship between Ag dispersion and CH3I adsorption capability. The formation of a stable AgI complex rationalized the CH3I adsorption mechanism on AgY. Compared to AgX, AgY was verified to possess a strong acid resistance by FT-IR, SEM and XRD. The effect of three key parameters (temperature, humidity and gas velocity) on CH3I adsorption was carefully investigated by orthogonal experiment design. The experimental results showed that AgY had better iodine removal performance at a high temperature, low humidity, and low flow rate. This work provides technical reference for further engineering applications of 16.6%AgY in spent fuel reprocessing plants.

Adsorption of toxic methyl iodide over Beta, ZSM-5 and SSZ-13 supported silver adsorbents

The efficient capture of radioactive isotopes of iodine uranium fission reactions is a major issue for safe nuclear energy. To investigate the toxic methyl iodide (CH3I) retention performance of Ag/Beta, Ag/ZSM-5 and Ag/SSZ-13, these Ag zeolites with identical Ag loadings and close Si/Al were prepared. The limited pore volume of ZSM-5 makes a larger size of Ag particles (∼7 nm) than Ag/Beta and Ag/SSZ-13. Silver, in the form of Ag+ ions, enters the cages of the zeolites as Lewis acid sites. In terms of the CH3I retention performance, Ag/Beta rivals the currently reported Ag zeolites applied to capture of radioactive iodine compounds. The CH3I storage capacity of Ag/Beta reaches 1.76 g/gAg. The strong CH3I affinity on Ag/Beta is confirmed by DFT method. The CH3I adsorption energy reaches 121.24 kJ/mol. Kinetics analysis shows that CH3I adsorption on three Ag zeolites observes pseudo-second order model. Good fitting of intra-particle diffusion model on Ag/SSZ-13 also demonstrates that intragranular diffusion is the rate-determining step of CH3I adsorption. The mechanism of CH3I retention is CH3I diffusion within the zeolites and then the formation of AgI species. This work expands the research field of Ag zeolite and contributes to its promising application in the capture of radioactive iodine.

Nanoporous N-Rich Covalent Organic Frameworks with High Specific Surface Area for Efficient Adsorption of Iodine and Methyl Iodide

Nanoporous N-Rich Covalent Organic Frameworks with High Specific Surface Area for Efficient Adsorption of Iodine and Methyl Iodide

Adsorption of Iodide (I<sup>-</sup>) from aqueous solution onto biochar derived from pomelo fruit peel

Removing iodide from aqueous solution using biomaterials synthesized from pomelo fruit peel-derived biochar with low costs is a new approach in environmental science and application. The material was characterized by various analytic methods such as XRD, SEM, BET, and FTIR. Additionally, Leuco crystal violet method was used to ascertain the quantity of iodide (I-) adsorbed and UV-Vis spectroscopy was used to quantify it. The effects of pH (2–11) and interaction duration (3–42 h) on the iodide adsorption were carefully examined. To examine the isotherm and dynamic characteristics of the substance, the Langmuir, Freundlich, pseudo-first-order, pseudo-second-order, and in-diffusion models were applied. The results showed that the maximum adsorption took place at pH 2 for 2520 min and the adsorption followed the intra-diffusion kinetic model as well as the maximum capacity (qm) derived from the Langmuir equation was 7,06 mg/g at 303 K, this number is higher than the maximum uptake capacity based on experiment findings (qe = 1,46 mg/g).

Tungsten Oxide-Based Z-Scheme for Visible Light-Driven Hydrogen Production from Water Splitting.

The stoichiometric water splitting using a solar-driven Z-scheme approach is an emerging field of interest to address the increasing renewable energy demand and environmental concerns. So far, the reported Z-scheme must comprise two populations of photocatalysts. In the present work, only tungsten oxides are used to construct a robust Z-scheme system for complete visible-driven water splitting in both neutral and alkaline solutions, where sodium tungsten oxide bronze (Na0.56WO3-x) is used as a H2 evolution photocatalyst and two-dimensional (2D) tungsten trioxide (WO3) nanosheets as an O2 evolution photocatalyst. This system efficiently produces H2 (14 μmol h-1) and O2 (6.9 μmol h-1) at an ideal molar ratio of 2:1 in an aqueous solution driven by light, resulting in a remarkably high apparent quantum yield of 6.06% at 420 nm under neutral conditions. This exceptional selective H2 and O2 production is due to the preferential adsorption of iodide (I-) on Na0.56WO3-x and iodate (IO3-) on WO3, which is evidenced by both experiments and density functional theory calculation. The present liquid Z-scheme in the presence of efficient shuttle molecules promises a separated H2 and O2 evolution by applying a dual-bed particle suspension system, thus a safe photochemical process.

Silver ions immobilized on thiourea/formaldehyde resin for solid phase extraction of iodide ions from aqueous solution

Iodine has been found to have considerable effects on tropospheric photochemistry, which in turn affects climate by lowering ozone's radiative forcing and air quality by lowering extreme O3 concentrations in polluted areas. The majority of the iodine that naturally occurs in the water is in the form of aqueous iodide and iodate. To extract iodide from the aqueous solution, thiourea-formaldehyde resin (TF) was prepared by condensation polymerization and then loaded with Ag(I) ions (Ag-TF). TF resin was characterized by a specific surface area close to 111.3 m2 g−1, and nitrogen and sulphur content of 20.57 and 10.01 mmol g−1, respectively. After calculation of the adsorbed amount of Ag(I) ions, the prepared Ag-TF adsorbent was introduced for the solid phase extraction of iodide anions under various operational parameters of pH (e.g., 1.6 – 10.7), adsorbent dose (e.g., 0.5 – 5.0 g L−1), primary iodide concentrations (e.g., 0.075 – 3.96 mmol L−1), and residence time (e.g., 5 – 400 min), and sonication time (e.g., 5–45 min). The findings revealed that the adsorption of iodide onto as-produced TF adsorbent was matched with the Langmuir model with a prominent loading capacity of 1.26 mmol g−1, under an optimized pH value of 2.7. The study of uptake kinetics investigates the influence of the mode of agitation; comparing more specifically the performance of mechanical agitation with those obtained with ultrasonication (at frequencies of 37 and 80 kHz). The ultra-sonication treatment decreased interestingly the adsorption equilibrium time from 400 min to only 45 min. Overall, the present study illustrates the susceptibility of Ag-TF adsorbent as a promising material for the efficient elimination of I− anions from an aqueous medium.