Immobilization of iodide on copper(I) sulfide minerals

Efficient Iodine Removal by Porous Biochar-Confined Nano-Cu2O/Cu0: Rapid and Selective Adsorption of Iodide and Iodate Ions

Iodine is a nuclide of crucial concern in radioactive waste management. Nanomaterials selectively adsorb iodine from water; however, the efficient application of nanomaterials in engineering still needs to be developed for radioactive wastewater deiodination. Artemia egg shells possess large surface groups and connecting pores, providing a new biomaterial to remove contaminants. Based on the Artemia egg shell-derived biochar (AES biochar) and in situ precipitation and reduction of cuprous, we synthesized a novel nanocomposite, namely porous biochar-confined nano-Cu₂O/Cu⁰ (C-Cu). The characterization of C-Cu confirmed that the nano-Cu₂O/Cu⁰ was dispersed in the pores of AES biochar, serving in the efficient and selective adsorption of iodide and iodate ions from water. The iodide ion removal by C-Cu when equilibrated for 40 min exhibited high removal efficiency over the wide pH range of 4 to 10. Remarkable selectivity towards both iodide and iodate ions of C-Cu was permitted against competing anions (Cl^-/NO₃^-/SO₄^2-) at high concentrations. The applicability of C-Cu was demonstrated by a packed column test with treated effluents of 1279 BV. The rapid and selective removal of iodide and iodate ions from water is attributed to nanoparticles confined on the AES biochar and pore-facilitated mass transfer. Combining the advantages of the porous biochar and nano-Cu₂O/Cu⁰, the use of C-Cu offers a promising method of iodine removal from water in engineering applications.

Fabrication of Multifunctional Electronic Textiles Using Oxidative Restructuring of Copper into a Cu-Based Metal-Organic Framework

This paper describes a novel synthetic approach for the conversion of zero-valent copper metal into a conductive two-dimensional layered metal-organic framework (MOF) based on 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) to form Cu₃(HHTP)₂. This process enables patterning of Cu₃(HHTP)₂ onto a variety of flexible and porous woven (cotton, silk, nylon, nylon/cotton blend, and polyester) and non-woven (weighing paper and filter paper) substrates with microscale spatial resolution. The method produces conductive textiles with sheet resistances of 0.1-10.1 MΩ/cm², depending on the substrate, and uniform conformal coatings of MOFs on textile swatches with strong interfacial contact capable of withstanding chemical and physical stresses, such as detergent washes and abrasion. These conductive textiles enable simultaneous detection and detoxification of nitric oxide and hydrogen sulfide, achieving part per million limits of detection in dry and humid conditions. The Cu₃(HHTP)₂ MOF also demonstrated filtration capabilities of H₂S, with uptake capacity up to 4.6 mol/kg_MOF. X-ray photoelectron spectroscopy and diffuse reflectance infrared spectroscopy show that the detection of NO and H₂S with Cu₃(HHTP)₂ is accompanied by the transformation of these species to less toxic forms, such as nitrite and/or nitrate and copper sulfide and S_x species, respectively. These results pave the way for using conductive MOFs to construct extremely robust electronic textiles with multifunctional performance characteristics.

Effectiveness of enriching lettuce with iodine using 5-iodosalicylic and 3,5-diiodosalicylic acids and the chemical composition of plants depending on the type of soil in a pot experiment

Iodine is a beneficial element for humans, animals and plants. This study was a comparison of the effectiveness of iodosalicylate uptake by lettuce. The experiment included two sub-blocks: organic soil and mineral soil with the addition of the same fertigation of plants (8 times every 7 days) with 10 µM solutions (100 mL/per one plant/one application) of potassium iodate (KIO3), salicylic acid (SA) alone or together with KIO3, 5-iodosalicylic acid (5-ISA) or 3,5-diiodosalicylic acid (3,5-diISA). None of the tested iodine compounds negatively affected the yield of lettuce. When growing plants on mineral soil, plants accumulated more iodine in the leaves than plants grown on peat substrate. The use of 5-ISA allowed for achieving better efficiency of plant biofortification in iodine than the application of KIO3 and 3,5-diISA. The type of soil significantly modified the chemical composition of lettuce.

Cu/Cu2O-immobilized cellulosic filter for enhanced iodide removal from water

We developed a Cu/Cu₂O-immobilized filter-type adsorbent for efficient iodide anion removal. A cellulose filter (CF) was used as a support, and its surface was modified using acrylic acid to enhance copper immobilization. The modified filter (CF-AA) exhibited 10x higher copper adsorption than the unmodified filter. Cu/Cu₂O was prepared on CF-AA by using a simple hydrothermal method to obtain CF-AA-Cu, and the prepared Cu/Cu₂O was characterized with scanning electron microscopy/energy-dispersive spectroscopy, x-ray photoelectron spectroscopy, and thermogravimetric analysis. While CF and Cu₂O themselves exhibited limited iodide adsorption performance, CF-AA-Cu exhibited fast adsorption kinetics with a half-life of 60 min as well as a high adsorption capacity of 10.32 mg/g, as obtained using the Langmuir adsorption isotherm model. Moreover, it exhibited high selectivity for iodide when high concentrations of other anions were present. The adsorption mechanism was proved by means of material characterization before and after adsorption. The coexistence of Cu⁰, Cu⁺, and Cu²⁺ in CF-AA-Cu make it effective in broader pH conditions via the redox reaction between Cu⁰ and Cu²⁺. Overall, iodide adsorbents in the form of filters with high adsorption capacity, selectivity, and ability over a wide pH range are potentially useful for removing iodide from water.

New Aspects of Uptake and Metabolism of Non-organic and Organic Iodine Compounds-The Role of Vanadium and Plant-Derived Thyroid Hormone Analogs in Lettuce

The process of uptake and translocation of non-organic iodine (I) ions, I^- and IO₃ ^-, has been relatively well-described in literature. The situation is different for low-molecular-weight organic aromatic I compounds, as data on their uptake or metabolic pathway is only fragmentary. The aim of this study was to determine the process of uptake, transport, and metabolism of I applied to lettuce plants by fertigation as KIO₃, KIO₃ + salicylic acid (KIO₃+SA), and iodosalicylates, 5-iodosalicylic acid (5-ISA) and 3,5-diiodosalicylic acid (3,5-diISA), depending on whether additional fertilization with vanadium (V) was used. Each I compound was applied at a dose of 10 μM, SA at a dose of 10 μM, and V at a dose of 0.1 μM. Three independent 2-year-long experiments were carried out with lettuce; two with pot systems using a peat substrate and mineral soil and one with hydroponic lettuce. The effectiveness of I uptake and translocation from the roots to leaves was as follows: 5-ISA > 3,5-diISA > KIO₃. Iodosalicylates, 5-ISA and 3,5-diISA, were naturally synthesized in plants, similarly to other organic iodine metabolites, i.e., iodotyrosine, as well as plant-derived thyroid hormone analogs (PDTHA), triiodothyronine (T3) and thyroxine (T4). T3 and T4 were synthesized in roots with the participation of endogenous and exogenous 5-ISA and 3,5-diISA and then transported to leaves. The level of plant enrichment in I was safe for consumers. Several genes were shown to perform physiological functions, i.e., per64-like, samdmt, msams5, and cipk6.

Use of silver–bentonite in sorption of chloride and iodide ions

Ag–bentonite was prepared by ion exchange process to sorb iodide and chloride ions in batch experiments. The modified bentonite was examined with XRF and XRD. 75% of the cation exchange capacity was exchanged by silver ions. It was found that the sorption of chloride ions is an exothermic precipitation process because the solubility decreases with increasing temperature. In the case of iodide sorption, the dissolution of AgI was observed under high concentration of non-radioactive iodide ions, which is well known in analytical chemistry. The phenomenon occurs not only in the bulk aqueous phase but also in the interlayer space of montmorillonite.

Iodine immobilization by materials through sorption and redox-driven processes: A literature review

Radioiodine-129 (¹²⁹I) in the subsurface is mobile and limited information is available on treatment technologies. Scientific literature was reviewed to compile information on materials that could potentially be used to immobilize ¹²⁹I through sorption and redox-driven processes, with an emphasis on ex-situ processes. Candidate materials to immobilize ¹²⁹I include iron minerals, sulfur-based materials, silver-based materials, bismuth-based materials, ion exchange resins, activated carbon, modified clays, and tailored materials (metal organic frameworks (MOFS), layered double hydroxides (LDHs) and aerogels). Where available, compiled information includes material performance in terms of (i) capacity for ¹²⁹I uptake; (ii) long-term performance (i.e., solubility of a precipitated phase); (iii) technology maturity; (iv) cost; (v) available quantity; (vi) environmental impact; (vii) ability to emplace the technology for in situ use at the field-scale; and (viii) ex situ treatment (for media extracted from the subsurface or secondary waste streams). Because it can be difficult to compare materials due to differences in experimental conditions applied in the literature, materials will be selected for subsequent standardized batch loading tests.

Enhanced removal of I- on hierarchically structured layered double hydroxides by in suit growth of Cu/Cu2O

To further improve the removal ability of layered double hydroxide (LDH) for iodide (I^-) anions from wastewater, we prepared hierarchically porous Cu₅Mg₁₀Al₅-LDH and used as a matrix for in suit growth of Cu/Cu₂O on its surface, forming Cu/Cu₂O-LDH, which was characterized and applied as an adsorbent. Results displayed high I^- saturation uptake capability (137.8 mg/g) of Cu/Cu₂O-LDH compared with Cu₅Mg₁₀Al₅-LDH (26.4 mg/g) even thermal activated LDH (76.1 mg/g). Thermodynamic analysis showed that the reaction between I^- anions and Cu/Cu₂O-LDH is a spontaneous and exothermic. Uptake kinetics analysis exhibited that adsorption equilibrium can be reached after 265 min. Additionally, the adsorbent showed satisfactory selectivity in the presence of competitive anions (e.g., SO₄^2-), and could achieve good adsorption performance in a wide pH range of 3-8. A cooperative adsorption mechanism was proposed on the basis of the following two aspects: (1) ion exchange between iodide and interlayer anions; (2) the adsorption performance of Cu, Cu(II) and Cu₂O for I^-. Meanwhile, the difference between the adsorption mechanism of Cu/Cu₂O-LDH, Cu₅Mg₁₀Al₅-LDH and Cu₅Mg₁₀Al₅-CLDH adsorbents was also elaborated and verified.

Removal of iodide from water using silver nanoparticles-impregnated synthetic zeolites

Synthetic zeolite-based Ag-nanocomposites were synthesized, characterized and used to remove iodide from aqueous solutions. The results showed high removal efficiency (up to 94.85%) and the formation silver iodide which is stable into the material. The maximum achieved adsorption capacity of the nanocomposites was between 19.54 and 20.44mg/g. The removal mechanism was meticulously studied by taking into account both water chemistry and surface interactions backed by multiple characterization techniques, such as XRD, XRF, SEM/EDX, TEM and BET. The qualitative and quantitative examination of pre- and post-adsorption of nanocomposite samples proved that the anchored silver iodide was formed via oxidation of initial silver nanoparticles followed by reaction with iodide to form a stable crystalline precipitate on the surface of the materials. A diffusion-based adsorption model indicated that the controlling mechanism is a slow intraparticle surface diffusion with diffusion coefficients in the range of 0.37-1.72×10^-13cm²/s. The investigation of competing and co-existing anions (Cl^-, Br^-, CO₃^2-, and CrO₄^2-) on the removal efficiency of iodide demonstrated a negligible effect showing a kinetically favorable precipitation reaction of iodide over other anions.

Application of hydrotalcite in soil immobilization of iodate (IO3 -)

Radioactive iodine is quite mobile in soil and poses threats to human health and the ecosystem. Many materials, including layered double hydroxides (LDH), have been synthesized to successfully capture iodine from aqueous environments. However, limited information is available on the application of LDH in soil to immobilize iodine species. In the present study, the feasibility of using Mg-Al-NO3 LDH for retention of soil iodate (IO3 -) in both batch and column systems was analyzed. The 2 : 1 Mg-Al-NO3 LDH exhibited the greatest removal efficiency of IO3 - from aqueous solution, compared with 3 : 1 and 4 : 1 Mg-Al-NO3 LDH. The Mg2-Al-NO3 LDH demonstrated a strong affinity for IO3 -, with a high sorption capacity of 149 528 mg kg-1 and a Freundlich affinity constant K F of 21 380 L kg-1. The addition of Mg2-Al-NO3 LDH in soil resulted in significant retention of IO3 - in both the batch and column experiments. The affinity parameter K F of soil with the addition of 1.33% Mg2-Al-NO3 LDH was 136 L kg-1, which was 28.6 times higher than soil without LDH added. Moreover, the eluted iodate percentage was only 12.9% in the soil column with the 1.33% Mg2-Al-NO3 LDH addition, whereas almost 43.5% iodate was washed out in the soil column without LDH addition. The results suggested that Mg2-Al-NO3 LDH could effectively immobilize iodate in soil without obvious interference.

Enhanced Uptake of Iodide from Solutions by Hollow Cu-Based Adsorbents

Cu₂O exhibits excellent adsorption performance for the removal of I⁻ anions from solutions by doping of metallic Ag or Cu. However, the adsorption process only appears on the surface of adsorbents. To further improve the utilization efficiencies of Cu content of adsorbents in the uptake process of I⁻ anions, hollow spheres of metallic Cu, Cu/Cu₂O composite and pure Cu₂O were prepared by a facile solvothermal method. Samples were characterized and employed for the uptake of I⁻ anions under various experimental conditions. The results show that Cu content can be tuned by adjusting reaction time. After the core was hollowed out, the uptake capacity of the samples increased sharply, and was proportional to the Cu content. Moreover, the optimal uptake was reached within only few hours. Furthermore, the uptake mechanism is proposed by characterization and analysis of the composites after uptake. Cu-based adsorbents have higher uptake performance when solutions are exposed to air, which further verified the proposed uptake mechanism. Finally, hollow Cu-based adsorbents exhibit excellent selectivity for I⁻ anions in the presence of large concentrations of competitive anions, such as Cl⁻, SO₄²⁻ and NO₃⁻, and function well in an acidic or neutral environment. Therefore, this study is expected to promote the development of Cu-based adsorbents into a highly efficient adsorbent for the removal of iodide from solutions.

Synergistic and simultaneous biosorption of phenanthrene and iodine from aqueous solutions by soil indigenous bacterial biomass as a low-cost biosorbent

The removal of phenanthrene and iodine from aqueous solutions in single and binary systems by inactivated soil indigenous bacterial biomass (SIBB), as well as affecting factors, were evaluated. Sorption kinetic and isotherm studies were carried out to investigate the synergistic effects of phenanthrene and iodine. Optimal parameters for the biosorption process included a solution pH of 6.0 and biosorbent dosage of 0.75 g L⁻¹. The ionic strength significantly decreased the biosorption of both phenanthrene and iodine in single conditions, while no obvious influences were found in the binary conditions. A pseudo-second-order model was well fitted to the kinetic biosorption data for both phenanthrene and iodine. The results showed that the presence of co-solute accelerated the biosorption processes and the pseudo-second-order biosorption rates (k₂) for phenanthrene and iodine increased from 0.005441 to 0.009825 g mg⁻¹ min⁻¹ and from 0.000114 to 0.000223 g mg⁻¹ min⁻¹, respectively. The SIBB showed strong affinity with both phenanthrene and iodine, with a partition coefficient K_d (Linear model) of 6892.4 L kg⁻¹ for phenanthrene and affinity parameter K_L (Langmuir model) of 232 500 L kg⁻¹ for iodine. The presence of co-solute illustrated a synergistic effect on the biosorption of phenanthrene and iodine due to intermolecular forces between phenanthrene and iodine, enhancing the K_d of 34.7% for phenanthrene and K_L of 107.0% for iodine, respectively. The results suggested that SIBB was an effective material for the simultaneous biosorption of phenanthrene and iodine from aqueous solutions.

Co-solute significantly enhanced the sorption affinity of phenanthrene and iodine by bacterial biomass.

131I-Labeled Copper Sulfide-Loaded Microspheres to Treat Hepatic Tumors via Hepatic Artery Embolization

Purpose: Transcatheter hepatic artery embolization therapy is a minimally invasive alternative for treating inoperable liver cancer but recurrence is frequent. Multifunctional agents, however, offer an opportunity for tumor eradication. In this study, we were aim to synthesized poly (lactic-co-glycolic acid) (PLGA) microspheres encapsulating hollow CuS nanoparticles (HCuSNPs) and paclitaxel (PTX) that were then labeled with radioiodine-131 (¹³¹I) to produce ¹³¹I-HCuSNPs-MS-PTX. This compound combines the multi-theranostic properties of chemotherapy, radiotherapy and photothermal therapy. In addition, it can also be imaged with single photon emission computed tomography (SPECT) imaging and photoacoustic imaging. Methods: We investigated the value of therapeutic and imaging of ¹³¹I-HCuSNPs-MS-PTX in rats bearing Walker-256 tumor transplanted in the liver. After the intra-arterial (IA) injection of ¹³¹I-HCuSNPs-MS-PTX, ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) micro-positron emission tomography/computed tomography (micro-PET/CT) imaging was used to monitor the therapeutic effect. PET/CT findings were verified by immunohistochemical analysis. SPECT/CT and photoacoustic imaging were performed to demonstrate the distribution of ¹³¹I-HCuSNPs-MS-PTX in vivo. Results: We found that embolization therapy in combination with chemotherapy, radiotherapy and photothermal therapy offered by ¹³¹I-HCuSNPs-MS-PTX completely ablated the transplanted hepatic tumors at a relatively low dose. In comparison, embolization monotherapy or combination with one or two other therapies had less effective anti-tumor efficacy. The combination of SPECT/CT and photoacoustic imaging effectively confirmed microsphere delivery to the targeted tumors in vivo and guided the near-infrared laser irradiation. Conclusion: Our study suggests that there is a clinical theranostic potential for imaging-guided arterial embolization with ¹³¹I-HCuSNPs-MS-PTX for the treatment of liver tumors.

Bimetallic AgCu/Cu2O hybrid for the synergetic adsorption of iodide from solution

To further improve the capacity of Cu₂O to absorb I^- anions from solution, and to understand the difference between the adsorption mechanisms of Ag/Cu₂O and Cu/Cu₂O adsorbents, bimetallic AgCu was doped into Cu₂O through a facile solvothermal route. Samples were characterized and employed to adsorb I^- anions under different experimental conditions. The results show that the Cu content can be tuned by adding different volumes of Ag sols. After doping bimetallic AgCu, the adsorption capacity of the samples can be increased from 0.02 mmol g^-1 to 0.52 mmol g^-1. Moreover, the optimal adsorption is reached within only 240 min. Meanwhile, the difference between the adsorption mechanisms of Ag/Cu₂O and Cu/Cu₂O adsorbents was verified, and the cooperative adsorption mechanism of the AgCu/Cu₂O hybrid was proposed and verified. In addition, the AgCu/Cu₂O hybrid showed excellent selectivity, e.g., its adsorption efficiencies are 85.1%, 81.9%, 85.9% and 85.7% in the presence of the Cl^-, CO₃^2-, SO₄^2- and NO₃^- competitive anions, respectively. Furthermore, the AgCu/Cu₂O hybrid can worked well in other harsh environments (e.g., acidic, alkaline and seawater environments). Therefore, this study is expected to promote the development of Cu₂O into a highly efficient adsorbent for the removal of iodide from solution.

Facile Fabrication of Nanofibrillated Chitin/Ag2O Heterostructured Aerogels with High Iodine Capture Efficiency

Nanofibrillated chitin/Ag₂O aerogels were fabricated for radioiodine removal. Chitin was first fabricated into nanofibers with abundant acetyl amino groups (–NHCOCH₃) on the surface. Then, highly porous chitin nanofiber (ChNF) aerogels were obtained via freeze-drying. The ChNF aerogels exhibited a low bulk density of 2.19 mg/cm³ and a high specific surface area of 179.71 m²/g. Ag₂O nanoparticles were evenly anchored on the surfaces of ChNF scaffolds via strong interactions with –NHCOCH₃ groups, subsequently yielding Ag₂O@ChNF heterostructured aerogels. The composites were used as efficient absorbents to remove radioiodine anions from water and capture a high amount of I₂ vapor in the forms of AgI and iodine molecules. The adsorption capacity of the composite monoliths can reach up to 2.81 mmol/g of I⁻ anions. The high adsorbability of the composite monolithic aerogel signifies its potential applications in radioactive waste disposal.

Synthesis of Cu/Cu2O hydrides for enhanced removal of iodide from water

In order to improve the removal capacity of Cu₂O for I^- anions from water, Cu/Cu₂O hybrids have been synthesized through a facile hydrothermal route, characterized by using SEM, XRD, XPS, and applied to remove I^- anions under different experimental environments. The results demonstrate that the Cu content and morphology of samples can be tuned by the adding amount of ammonia. Meanwhile, the possible crystalline mechanism, Cu₂O formed firstly and then metallic Cu generated, was presented. With the increasing of Cu doped amount, the removal capacity of Cu/Cu₂O hybrids increased significantly from 0.02mmolg^-1 to 0.18mmolg^-1. Furthermore, a reaction mechanism of I^- anions and Cu₂O, which generated from the disproportionation reaction of metallic Cu and CuO, has been proposed according to the characterization analyses of the composites before and after adsorption, explaining the highly efficient removal of I^- anions. In addition, Cu/Cu₂O hybrids showed excellent selectivity for I^- anions in the presence of large concentrations of competitive anions such as SO₄^2- and NO₃^- and could work in an acidic and neutral environment. This study is hopefully to prompt Cu₂O to grow up to be a new and highly efficient adsorbent for the removal of iodide from solutions.

Efficient bioremediation of radioactive iodine using biogenic gold nanomaterial-containing radiation-resistant bacterium, Deinococcus radiodurans R1

A new bioremediation method is developed by using a gold nanomaterial-containing radiation-resistant bacterium.

Enhanced uptake of iodide on Ag@Cu2O nanoparticles

In order to improve the uptake capacity of Cu₂O for I^- anions from water, Ag loaded Cu₂O composites have been synthesized through a facile method, characterized using SEM, XRD, XPS and applied to remove I^- anions under different experimental environments. The results show that the uptake capacity of Ag@Cu₂O increased with the increasing Ag doped amount. Meanwhile, the uptake capacity (0.20 mmol g^-1) of 1.0%-Ag@Cu₂O for the removal of I^- anions is ten times higher than that of pure Cu₂O (0.02 mmol g^-1). Furthermore, a mechanism explaining the highly efficient removal of I^- anions has been proposed according to characterization analyses of the composites after adsorption and subsequently been verified by adsorption under visible light experiments. 1.0%-Ag@Cu₂O (0.5%-Ag@Cu₂O, 0.2%-Ag@Cu₂O) shows a high iodide uptake efficiency of 98.5% (77.6%, 37.8%) in the visible light, much higher than that under the darkness (86.3%, 69.7% and 30.8%). In addition, the adsorbent showed excellent selectivity for I^- anions in the presence of large concentrations of competitive anions, eg. uptake efficiencies are 78.2%, 62.8%, 70.2% and 77.9% in the presence of the Cl^-, CO₃^2-, SO₄^2- and NO₃^- competitive anions, respectively, and could work in a wide pH range of 3-11. This study is hopefully to prompt Cu₂O to become a new and highly efficient adsorbent for iodide adsorb from solutions.

Gold-Nanoparticle-Immobilized Desalting Columns for Highly Efficient and Specific Removal of Radioactive Iodine in Aqueous Media

There has been worldwide attention on the efficient removal of radioactive iodine, because it is commonly released in nuclear plant accidents. Increasing concerns on environmental problems due to the radioactive iodine are leading us to develop stable and sustainable technology for remediation of radioelement contaminants. In this work, we report a highly efficient chromatographic method for specific and rapid capture of radioactive iodine. The gold nanoparticles immobilized dextran gel columns showed excellent removal capabilities of radioactive iodine in various conditions. These results suggested that our platform technology can be a promising method for the desalination of radioactive iodines in water.

Silver-based getters for 129I removal from low-activity waste

A prominent radionuclide of concern in nuclear wastes, 129I, is present in low-activity wastes (LAW) at the Hanford site. Several Ag-containing materials were tested as immobilization agents, or “getters”, for I (as iodide, I−) removal from deionized (DI) water and a liquid LAW simulant: Ag impregnated activate carbon (Ag–C), Ag exchanged zeolite (Ag–Z), and argentite. In anoxic batch experiments with DI water, the Ag–C and argentite were most effective, with maximum Kd values of 6.2 × 105 mL/g for the Ag–C and 3.7 × 105 mL/g for the argentite after 15 days. Surface area and Ag content were found to influence the performance of the getters in DI water. In the anoxic batch experiments with LAW simulant, Ag–Z vastly outperformed the other getters with Kd values of 2.2 × 104 mL/g at 2 h, which held steady until 15 days, compared with 1.8 × 103 mL/g reached at 15 days by the argentite. All getters were stable over long periods of time (i.e. 40 days) in DI water, while the Ag–Z and argentite were also stable in the LAW simulant. Ag–Z was found to have consistent I removal upon crushing to a smaller particle size and in the presence of O2, making it a strong candidate for the treatment of LAW containing I.

An investigation into the use of cuprous chloride for the removal of radioactive iodide from aqueous solutions

Cuprous chloride (CuCl) was examined as a precipitant to remove iodide (I(-)) from aqueous solutions. The effects of the dosage of CuCl, reaction time, initial concentrations of I(-) and bicarbonate (HCO3(-)) on I(-) removal were investigated. The results showed that the optimized removal efficiency of I(-) reached approximately 95.8% when the dosage was 150 mg/L, the initial I(-) concentration ranged from 5 to 40 mg/L and the reaction time was 15 min. The removal efficiency decreased from 95.8% to 76.0% with the addition of HCO3(-) at a concentration in the range of 0-107 mg/L. Furthermore, the dissociation of CuCl, the disproportionation reaction of Cu(+), the precipitation of cuprous iodide (CuI) and cuprous oxide (Cu2O), and the formations of copper sulfide (CuxS, 1≤x<2) were identified as the primary reactions using the PHREEQC software and the measurements of water quality parameters under various conditions. X-rays photoelectron spectroscopy (XPS) analysis was performed before and after the reaction, helping to elucidate the reaction mechanism. This study can provide a promising method to address radioactive I(-) pollution in water.

Selective capture of iodide from solutions by microrosette-like δ-Bi₂O₃

Radioactive iodine isotopes that are produced in nuclear power plants and used in medical research institutes could be a serious threat to the health of many people if accidentally released to the environment because the thyroid gland can absorb and concentrate them from a liquid. For this reason, uptake of iodide anions was investigated on microrosette-like δ-Bi2O3 (MR-δ-Bi2O3). The MR-δ-Bi2O3 adsorbent showed a very high uptake capacity of 1.44 mmol g(-1) by forming insoluble Bi4I2O5 phase. The MR-δ-Bi2O3 also displayed fast uptake kinetics and could be easily separated from a liquid after use because of its novel morphology. In addition, the adsorbent showed excellent selectivity for I(-) anions in the presence of large concentrations of competitive anions such as Cl(-) and CO3(2-), and could work in a wide pH range of 4-11. This study led to a new and highly efficient Bi-based adsorbent for iodide capture from solutions.

Facile low temperature solid state synthesis of iodoapatite by high-energy ball milling

High energy ball milled iodoapatite in the form of an amorphous matrix embedded with nanocrystals can be readily crystallized by subsequent low temperature thermal annealing, which greatly improves the thermal stability and iodine confinement.

Silver oxide nanocrystals anchored on titanate nanotubes and nanofibers: promising candidates for entrapment of radioactive iodine anions

Iodine radioisotopes are released into the environment by the nuclear industry and medical research institutions using radioactive materials. The (129)I(-) anion is one of the more mobile radioactive species due to a long half-life, and it is a great challenge to design long-term management solutions for such radioactive waste. In this study, a new adsorbent structure with the potential to efficiently remove radioactive iodine anions (I(-)) from water is devised: silver oxide (Ag2O) nanocrystals firmly anchored on the surface of titanate nanotubes and nanofibers via coherent interfaces between Ag2O and titanate phases. I(-) anions in fluids can easily access the Ag2O nanocrystals and be efficiently trapped by forming AgI precipitate that firmly attaches to the adsorbent. Due to their one-dimensional morphology, the new adsorbents can be readily dispersed in liquids and easily separated after purification; and the adsorption beds loaded with the adsorbents can permit high flux. This significantly enhances the adsorption efficiency and reduces the separation costs. The proposed structure reveals a new direction in developing efficient adsorbents for the removal of radioactive anions from wastewater.

Titanate-based adsorbents for radioactive ions entrapment from water

This feature article reviews some titanate-based adsorbents for the removal of radioactive wastes (cations and anions) from water. At the beginning, we discuss the development of the conventional ion-exchangeable titanate powders for the entrapment of radioactive cations, such as crystalline silicotitanate (CST), monosodium titanate (MST), peroxotitanate (PT). Then, we specially emphasize the recent progress in the uptake of radioactive ions by one-dimensional (1D) sodium titanate nanofibers and nanotubes, which includes the synthesis and phase transformation of the 1D nanomaterials, adsorption ability (capacity, selectivity, kinetics, etc.) of radioactive cations and anions, and the structural evolution during the adsorption process.

Removal of radioactive iodine from water using Ag2O grafted titanate nanolamina as efficient adsorbent

Emergency treatment of radioactive material leakage and safety disposal of nuclear waste is a constant concern all along with the development of radioactive materials applications. To provide a solution, titanate with large surface area (143 m(2)g(-1)) and a lamina morphology (the thickness of the lamina is in range of tens of nanometers) was prepared from inorganic titanium compounds by hydrothermal reactions at 433 K. Ag(2)O nanocrystals (5-30 nm) were deposited onto the titanate lamina. The surface of the titanate lamina has crystallographic similarity to that of Ag(2)O nanocrystals. Hence, the deposited Ag(2)O nanocrystals and titanate substrate join together at these surfaces, forming a well-matched phase coherent interface between them. Such coherence between the two phases reduces the overall energy by minimizing surface energy and anchors the Ag(2)O nanocrystals firmly on the external surface of the titanate structure. The composite thus obtained was applied as efficient adsorbent to remove radioactive iodine from water (one gram adsorbent can capture up to 3.4 mmol of I(-) anions). The composite adsorbent can be recovered easily for safe disposal. The structure changes of the titanate lamina and the composite adsorbent were monitored by various techniques. The isotherm and kinetics of iodine adsorption, competitive adsorption and column adsorption using the adsorbent were studied to assess its iodine removal abilities. The adsorbent exhibited a capacity as high as 3.4 mmol of iodine per gram of adsorbent in 1h. Therefore, Ag(2)O deposited titanate lamina is an effective adsorbent for removing radioactive iodine from water.

Structural studies of copper sulfide films: effect of ambient atmosphere

We examined the structural properties of copper sulfide films as a function of the sulfurization time of 70-nm-thick Cu films. Copper sulfide films with various phases such as mixed metallic Cu-chalcocite, chalcocite, roxbyite, and covellite phases were formed with increasing sulfurization time. To evaluate the structural stability of various films, all the films were exposed to the ambient atmosphere for the same amount of time. Although the phase structure and stoichiometry of the films were maintained at a greater depth, the near-surface region of the films was oxidized and covered with overlayers of oxide, hydroxide, and/or sulfate species due to the exposure and reaction with the ambient atmosphere. The oxygen uptake and its reactivity with the copper sulfide film surfaces were enhanced with increasing sulfur content of the films. In addition, the type of divalent state of copper formed on the film surfaces depended on the phase structure, composition, and stoichiometry of the films.

XPS and XAS studies of copper(II) sorbed onto a synthetic pyrite surface

Compounds containing copper are likely candidates to delay iodide migration in environmental media through the formation of sparingly soluble phases. Preliminary experiments showed that iodide was neither sorbed onto chalcopyrite nor by a binary system pyrite/copper(II), although significant amounts of copper were present at the pyrite surface. In the present study, spectroscopic studies (XPS, XANES and EXAFS) were thus performed to determine the nature of sorbed copper species. Although introduced as Cu(II), copper was mainly present at the oxidation state (I) on the pyrite surface suggesting a heterogeneous reduction process. Moreover, copper appeared tetrahedrally coordinated to two sulfur and two oxygen atoms onto the pyrite surface, a chemical environment, which seemingly stabilized the metal and made it unreactive towards iodide.