Iodine Enrichment Research Articles

Dissimilatory Iodate-Reducing Microorganisms Contribute to the Enrichment of Iodine in Groundwater.

Iodate reduction by dissimilatory iodate-reducing microorganisms (DIRMs) plays a crucial role in the biogeochemical cycling of iodine on Earth. However, the occurrence and distribution of DIRMs in iodine-rich groundwater remain unclear. In this study, we isolated the dissimilatory iodate-reducing bacteriumAzonexus hydrophilusstrain NCP973 from a geogenic high-iodine groundwater of China for the first time. The analysis of genome, transcriptome, and heterologous expression revealed that strain NCP973 uses the dissimilatory iodate-reducing enzyme IdrABP1P2 to reduce dissolved or in situ sediment-bound iodate to iodide. The location of IdrABP1P2 in the conjugative plasmid of strain NCP973 implies that IdrABP1P2 could be spread by horizontal gene transfer and allow the recipient microorganisms to participate in the enrichment of iodide in aquifers. Based on the global iodine-rich groundwater metagenomes and genomes, the identification of idrA showed that phylogenetically diverse DIRMs are widely distributed not only in geogenic high-iodine groundwater of China but also in radionuclide-contaminated groundwater of USA as well as in subsurface cavern waters in Germany and Italy. Moreover, the abundance of idrA was found to be higher in groundwater with a relatively high iodine content. Collectively, these results suggest that terrestrial iodine-affected groundwater systems are another important habitat for DIRMs in addition to marine environments, and their activity in aquifers triggers the mobilization and enrichment of iodine in groundwater worldwide.

Coupled transformation pathways of iron minerals and natural organic matter related to iodine mobilization in alluvial-lacustrine aquifer

The complex of natural organic matter (NOM) and iron minerals in sediment is the main host and source of groundwater iodine. However, the transformation pathways of the complex remain unclear. The groundwater and sediment from the Hetao Basin were collected in this study to analyze multi-isotopes, NOM molecular characteristics, and iron mineral phases. The results showed that high-iodine groundwater was mainly observed in the discharge area, where biodegradation of NOM, sulfate reduction and methanogenesis occurred. Compared to the shallow clayey sediments, the confined sandy sediments had lower iodine content, a lower fraction of crystalline iron oxides, and a higher fraction of carbonate associated Fe(II) minerals, suggesting that the release of sediment iodine in the aquifer is related to the transformation of sediment Fe(III) hydroxides/oxides. Moreover, the molecular features of high-iodine groundwater NOM and sandy sediment NOM were characterized by a higher proportion of refractory compounds, suggesting that the reductive transformation of sediment Fe(III) hydroxides/oxides is fueled by degradable organic compounds. The microbial Fe-reducing and/or sulfate-reducing processes cause the enrichment of groundwater iodine in the form of iodide via the transformation of iodine species. These findings provide new insights into the genesis of high-iodine groundwater.

Spatial distribution and hydrogeochemical processes of high iodine groundwater in the Hetao Basin, China

To understand the genesis and spatial distribution of high iodine groundwater in the Hetao Basin, 540 groundwater samples were analyzed for the chemistry and isotope. Total iodine concentrations in groundwater range from 1.32 to 2897 μg/L, with a mean value of 159.2 μg/L. The groundwater environment was mainly characterized by the weakly alkaline and reducing conditions, with the iodide as the main species of groundwater iodine. High iodine groundwater (I > 100 μg/L) was mainly distributed in shallow aquifers (< 30 m) of Hangjinhouqi near the Langshan Mountain and the discharge areas along the main drainage channels. The δ18O and δ2H values ranged from −12.09 ‰ to −3.99 ‰ and − 91.58 ‰ to −52.80 ‰, respectively, and the correlation between groundwater iodine and isotopes indicates the dominant role of evapotranspiration in the enrichment of iodine in the shallow groundwater with depth <30 m. It was further evidenced by the correlation between groundwater iodine and Cl/Br molar ratio, and significant contributions of climate factors identified from the random forest and XGBoost. Moreover, irrigation practices contribute to high iodine levels, with surface water used for irrigation containing up to 537.8 μg/L of iodine, which can be introduced into shallow aquifer directly. The iodine in irrigation water can be retained in the soil or shallow sediment, and later leach into groundwater under favorable conditions.

A review of groundwater iodine mobilization, and application of isotopes in high iodine groundwater.

Excessive intake of iodine will do harm to human health. In recent years, high iodine groundwater has become a global concern after high arsenic and high fluorine groundwater. A deep understanding of the environmental factors affecting iodine accumulation in groundwater and the mechanism of migration and transformation is the scientific prerequisite for effective prevention and control of iodine pollution in groundwater. The paper comprehensively investigated the relevant literature on iodine pollution of groundwater and summarized the present spatial distribution and hydrochemical characteristics of iodine-enriched groundwater. Environmental factors and hydrogeological conditions affecting iodine enrichment in aquifers are systematically summarized. An in-depth analysis of the hydrologic geochemistry, physical chemistry, biogeochemistry and human impacts of iodine transport and transformation in the surface environment was conducted, the results and conclusions in the field of high iodine groundwater research are summarized comprehensively and systematically. Stable isotope can be used as a powerful tool to track the sources of hydrochemical components, biogeochemistry processes, recharge sources and flow paths of groundwater in hydrogeological systems, to provide effective research methods and means for the study of high iodine groundwater system, anddeepen the understanding of the formation mechanism of high iodine groundwater, the application of isotopic technique in high iodine groundwater is also systematically summarized, which enriches the method and theory of high iodine groundwater research. This paper provides more scientific basis for the prevention and control of groundwater iodine pollution and the management of groundwater resources in water-scarce areas.

Optimizing Iodine Enrichment through Induced‐Fit Transformations in a Flexible Ag(I)‐Organic Framework: From Accelerated Adsorption Kinetics to Record‐High Storage Density (Small 28/2024)

Optimizing Iodine Enrichment through Induced‐Fit Transformations in a Flexible Ag(I)‐Organic Framework: From Accelerated Adsorption Kinetics to Record‐High Storage Density (Small 28/2024)

The flexible DADM-based covalent organic frameworks constructed by flexible knots and 4,4′-diaminodiphenylmethane as a linker for fluorescence sensing nitrophenol and adsorping iodine

Enrichment of nitro-aromatic compounds (NACs) and radioactive iodine seriously threatens the health of humans, therefore, trace detection of NACs and the efficient capture and storage of radioactive iodine have attracted a great deal of attention in recent years. Herein, we present two highly efficient flexible DADM-based covalent organic frameworks (DADM-based COFs) for the fluorescence sensing of o-nitrophenol (o-NP) and p-nitrophenol (p-NP) and reversible iodine capture, namely TDADM and HDADM. The resulting TDADM and HDADM have excellent thermal and chemical stability, some crystallinity and high BET surface areas of 1035 and 958 m2 g−1, respectively. For fluorescence sensing, TDADM and HDADM show high sensitivity to o-NP and p-NP with quenching constants (Ksv) of 6.77 × 103 and 3.39 × 104 L mol−1, respectively. The fluorescence quenching of TDADM is caused by the action of photo-induced electron transfer (PET) processes. The fluorescence quenching of HDADM is caused by the co-action of PET and resonance energy transfer (RET) processes. For iodine capture, TDADM and HDADM exhibit high iodine capture capacities, which are severally up to 4.08 and 5.32 g g−1. Such high iodine adsorption amounts are caused by the electron transfer of the electron-rich flexible DADM-based COFs to the electron-deficient I2 into the polyiodide anion complexes.

Optimizing Iodine Enrichment through Induced-Fit Transformations in a Flexible Ag(I)-Organic Framework: From Accelerated Adsorption Kinetics to Record-High Storage Density.

Efficient capture and storage of radioactive I2 is a prerequisite for developing nuclear power but remains a challenge. Here, two flexible Ag-MOFs (FJI-H39 and 40) with similar active sites but different pore sizes and flexibility are prepared; both of them can capture I2 with excellent removal efficiencies and high adsorption capacities. Due to the more flexible pores, FJI-H39 not only possesses the record-high I2 storage density among all the reported MOFs but also displays a very fast adsorption kinetic (124 times faster than FJI-H40), while their desorption kinetics are comparable. Mechanistic studies show that FJI-H39 can undergo induced-fit transformations continuously (first contraction then expansion), making the adsorbed iodine species enrich near the Ag(I) nodes quickly and orderly, from discrete I- anion to the dense packing of various iodine species, achieving the very fast adsorption kinetic and the record-high storage density simultaneously. However, no significant structural transformations caused by the adsorbed iodine are observed in FJI-H40. In addition, FJI-H39 has excellent stability/recyclability/obtainability, making it a practical adsorbent for radioactive I2. This work provides a useful method for synthesizing practical radioactive I2 adsorbents.

Ionic Polyimine-Based Composite Membrane with Inductive and Complexation Synergistic Effects for Sensitive and On-Site Fluorescent Detection of Volatile Iodine.

Along with the development of nuclear power, concerns about radioactive emissions and the potential for nuclear leakage have been widely raised, particularly of harmful iodine isotopes. However, as a significant component of nuclear air waste, the enrichment and detection of air-dispersed gaseous iodine remain a challenge. In this work, it is focused on developing an attraction-immobilization-detection strategy-based fluorescence method for the on-site detection of volatile iodine, by employing a photoluminescent ionic polyimine network-polyvinylpyrrolidone (IPIN-PVP) composite membrane. This strategy synergizes ion-induced dipole interactions from IPIN and complexation effects from PVP, allowing effective iodine enrichment and immobilization. As a result, the optimized IPIN-PVP membrane exhibits rapid response times of 5 s and a low detection limit of 4.087 × 10-8m for gaseous iodine. It also introduces a portable handheld detection device that utilizes the composite membrane, offering a practical solution for real-time on-site detection of volatile iodine. This innovation enhances nuclear safety measures and disaster management by providing rapid and reliable iodine detection capabilities.

Localized foliar application of iodine on tomato: An effective approach for targeted agronomic biofortification

Iodine is an essential mineral for the human body and inadequate intake causes iodine deficiency disorders (IDDs) worldwide. Agronomic biofortification is a promising complementary approach to other strategies to avoid IDDs. It consists of the enrichment of fruit and vegetables with nutritional elements through preharvest techniques. Tomato is an important, nutritious, and widely consumed crop. Despite a poor iodine accumulation in the fruit, tomato is an iodine accumulator. Our research focused on iodine enrichment of two table tomato types (cherry and mini-plum) in a commercial mediterranean greenhouse. Potassium iodate (KIO3) was applied four times through foliar spray at three concentrations (0, 1, 5 mM) at two localized sites of application (at plant apex and at the three leaves above the target truss, “target leaves”) until the mature green stage of a target truss (untreated and the same for each treatment). The application of 1 mM KIO3 solution at the target leaves was the most suitable approach for adequate fruit enrichment. The accumulation of 110 μg∙100 g−1 of fresh weight (FW) in cherry and 130 μg∙100 g−1 FW for mini-plum tomato largely satisfy the iodine recommended dietary allowance for adults, pregnant and lactating women. Plant health, yield and commercial quality of fruit (color, size, dry matter content, total soluble solids, titratable acidity, pH) were not affected, while some carotenoids and total phenolics were slightly incremented, indicating a possible positive influence on the nutritional quality. In conclusion, foliar application of iodine for the preharvest enrichment of tomato was a successful approach to biofortification in a commercial greenhouse. That suggests further research is needed to investigate and improve the iodine biofortification techniques in different crops and systems.

Flake channels construction of hydroxyapatite/gelatin cryogel with excellent flame retardant properties for enhancing the capturing of iodine

Safe and efficient capturing of volatile radioiodine is of extremely important significance in the treatment of spent fuel. Herein, the flake channels in gelatin-hydroxyapatite (HAP@Ge) cryogel with excellent flame retardant properties were constructed by immobilizing hydroxyapatite nanorods (HAP) on Gelatin (Ge) cryogel for enhancing the capturing of iodine. The immobilization of HAP nanorods enhanced thermal stability, provided low rates of dynamic heat transfer and dissipation, and remarkably improved the flame retardant and smoke suppression properties of the Ge cryogel, which can effectively prevent the occurrence of safety incidents caused by further thermal degradation or combustion of this cryogel. More importantly, it was effective in improving the rapid enrichment of iodine, resulting in a high adsorption capacity. The maximum adsorption capacity of HAP@Ge cryogel for iodine vapor reached 2693 mg/g at equilibrium. The high adsorption capacity for iodine was attributed to the multi-scale porous structure in HAP@Ge cryogel, which offered effective channels for iodine diffusion, whereas the numerous complex and irregular flakes provided sufficient number of active sites for iodine capture. The adsorption process was chemical in nature and involved the -PO43−, –OH, –C=O, and –NHR groups on HAP@Ge cryogel. Moreover, the complex porous structure of HAP@Ge cryogel enhanced the physical capturing of iodine. These advantages, such as low-cost raw material, simple preparation method, good flame retardancy, and excellent capturing performance for iodine indicated that HAP@Ge cryogel is a potential candidate for the removal of radioactive iodine in the exhaust gas stream of post-treatment plants.Graphical

Strontium isotopes as tracers for water-rocks interactions of groundwater to delineate iodine enrichment in aquifer of Datong Basin, northern China

Groundwater iodine has direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin. Iodine affected aquifer system in Datong Basin of North China was studied with a focus on strontium isotopes and major ion chemistry, in order to estimate the controlling hydrological and geochemical processes. The data revealed a rather complicated mixing pattern of various groundwater source end-members that were subject to different water-rock interactions, such as silicate weathering, evaporite and carbonate dissolution. Groundwater from the recharge area of east margin was characteristic by 87Sr/86Sr ratios higher than 0.71643, which implied the silicate weathering process. Groundwater from the discharge area and west margin might be originated from evaporite and carbonate dissolution processes with low 87Sr/86Sr ratios. Mixing models of three end-members based on Sr isotope and contents reflected that the type of water-rock interactions shifted from silicate weathering towards evaporite dissolution along the groundwater flow path from east margin to basin center. Abundant iodine and natural organic matters (NOMs) were discovered in groundwater located at the discharge area with Sr isotopic values between 0.710 and 0.717, implying evaporite dissolution governing iodine and NOMs enrichment in groundwater. Silicate weathering process had negligible influence on iodine and NOMs enrichment in groundwater. While carbonate dissolution made negative contribution for iodine releasing to aqueous phases. The PHREEQC inverse modeling results illustrated that dissolution of halite, calcite, gypsum and kaolinite and cation exchange significantly changed chemical composition of groundwater along the groundwater paths from the two basin margins to central area.

Iodine enrichment in the groundwater in South China and its hydrogeochemical control

In North China, iodine-rich groundwater has been extensively studied, but few in South China. This study aimed to investigate the characteristics of iodine-rich groundwater in South China and identify potential contamination sources. The results revealed that the average concentration of iodine in groundwater was 890 µg/L, with a maximum concentration of 6350 µg/L, exceeding the permitted levels recommended by the World Health Organization (5–300 µg/L). Notably, the enrichment of iodide occurred in acidic conditions (pH = 6.6) and a relatively low Eh environment (Eh = 198.4 mV). Pearson correlation and cluster analyses suggested that the enrichment of iodide could be attributed to the intensified redox process involving Mn(II), iodine (I2), or iodate (IO3−) in the soil. The strong affinity between Mn(II) and I2/IO3− facilitated their interaction, resulting in the formation and mobilization of I− from the soil to the groundwater. Leaching experiments further confirmed that reducing substances (such as sodium sulfides, ascorbic acids, and fulvic acids) in the soil with low dissolved oxygen (DO) levels (< 1.0 mg/L) enhanced the dissolution of iodine species. Conversely, higher DO content (> 3.8 mg/L) promoted the oxidation of I− into I2 or IO3−, leading to its stabilization. This research provides new insights into the characteristics and mechanisms of I− enrichment in groundwater in South China, and emphasizes the significance of the redox reactions involving Mn(II) and I2/IO3−, as well as the influence of soil properties in regulating the occurrence and transportation of iodine species within groundwater systems.

Porous Triptycene Network Based on Tröger's Base for CO2 Capture and Iodine Enrichment.

A three-dimensional rigid "six-connected" porous triptycene network based on Tröger's base (TB-PTN) was synthesized by using triptycenes as connectors and Tröger's base as linkers. With characteristics of a high surface area of 1528 m2 g-1, nitrogen-enriched groups, and superior thermal stability, TB-PTN displays a high CO2 uptake of 22.3 wt % (273 K, 1 bar) and excellent iodine vapor adsorption (240 wt %).

Biotechnological Aspects of Iodine Enrichment of Bakery Products

In case of potential radiological contamination of territories, preventive intake of iodine-containing products before the arrival of iodine radionuclides is effective. The paper presents the results of the influence of changes in the recipe composition of the bakery product, namely the use of the additive iodocasein on the physico-chemical and organoleptic characteristics of bread. The use of iodocasein for bread enrichment is justified. The influence of technological parameters on the preservation of the iodine trace element in bread is investigated. Doses of iodine-containing additives are calculated in the technological process. It is proved that the iodine in bread is preserved in the product for 90 hours. The nutritional value of the developed bread recommended for preventive nutrition is evaluated.

Efficient enrichment of iodine by supported ionic liquid with three effective adsorption sites: Heteroatoms, fused aromatic rings and ionic bond

With the continuous development of nuclear energy, radioactive iodine in nuclear waste would be hazardous to human health and environment. Therefore, it is of great significance to develop an efficient adsorbent for iodine capture. In this study, a novel ionic liquid ([N4444]4PTC) was prepared which combines three effective adsorption sites of heteroatom, fused aromatic ring and ionic bond for iodine capture. To make full use of the iodine capture capacity of [N4444]4PTC, [N4444]4PTC@MF composite was fabricated by using MF as a carrier which is cheap and readily available. The hydrogen bond between MF and PTC4– increases the surface charge density of MF, and endows [N4444]4PTC with high porosity. Thus, the iodine adsorption capacity (5.81 g g−1) and adsorption rate of [N4444]4PTC@MF was significantly improved. This synergistic effect-based iodine capture system was demonstrated to convert iodine molecules into polyiodide anions via charge-transfer (CT) mechanism at electron-rich sites. The formed anionic specie was effectively stabilized by the abundant quaternary ammonium cations in the system, making it easier to take place the adsorption process and increase the stability of the captured iodine. The adsorption–desorption test showed that the composite material exhibits excellent recycling performance and was suitable for multiple use in practical applications.

Novel insight into iodine enrichment in alluvial-lacustrine aquifers: Evidence from stable carbon and iron isotopes

Reductive dissolution of Fe (oxyhydr)oxides triggered by biodegradation of organic matter (OM) are considered to be key processes controlling iodine (I) release in groundwater systems. However, the precise mechanisms involved in release from organic matter degradation and from Fe (oxyhydr)oxides are unclear. In this study, dual stable isotope analysis (δ13C and δ56Fe) was combined with ultraviolet–visible spectral characterization of dissolved organic matter to elucidate the mechanisms of iodine enrichment in groundwater of the central Yangtze River basin, China, which represents Quaternary alluvial-lacustrine floodplains. High iodine groundwater mainly occurs along the Yangtze River (YR) and Han River (HR), with a maximum concentration of 1220 μg/L. The results suggest that methanogenesis driven by the biodegradation of high molecular weight organic compounds can promote the reductive dissolution of amorphous Fe (oxyhydr)oxides, which is the predominant process controlling iodine enrichment in the YR groundwater system. In addition, fermentation accompanied by sulfate reduction can also trigger the release of iodine into groundwater. The reductive dissolution of crystallized Fe (oxyhydr)oxides driven by the fermentation of small-molecule organic compounds is the dominant process responsible for iodine enrichment in the HR groundwater system. This study provides novel insight into the mechanisms of iodine enrichment in Quaternary alluvial-lacustrine aquifers.

Effect of Hypertension on EPR effect Induced by Polymer Nanomicelles in Renal Cell Carcinoma in vitro.

To investigate the effect of hypertension on the (enhanced permeability and retention, EPR) effect induced by polymer nanomicelles in renal cell carcinoma in vitro. A total of 80 patients with renal cell carcinoma treated at the Department of Urology Surgery in the Dept. of Urology of the Affiliated Hospital of Hebei University from Oct. 2019 to Oct. 2020, were analyzed retrospectively. The hypertension group (experimental group) included 40 patients, and the normal blood pressure group (control group) included 40 patients. The diagnosis of renal clear cell carcinoma was confirmed by preoperative auxiliary examinations, such as ultrasonography and CT combined with postoperative pathological analysis. All patients underwent laparoscopic radical nephrectomy for renal cell carcinoma. Polymer nanomicelles (loaded with prolonium iodide) were perfused into the resected kidney specimens within the specified time. The iodine enrichment of polymer nanomicelles in renal tumors was assessed by CT scanning. The peak EPR effect and the time to the peak were statistically compared between the two groups. No significant differences were found in age, sex, location of kidney disease, tumor location or tumor size between the two groups (p> 0.05). The peak (χ̄±S) of the EPR effect in experimental group was 3.60±0.95 ug/cm3 and 3.01±0.96 ug/cm3 in control group, respectively. There was significant difference between the two groups (p< 0.05). The time to the peak of the EPR effect was 3.76±0.75 h in experimental group and 3.82±0.93 hour in control group, respectively. No statistically significant difference was found in the time to the peak of the EPR effect between the two groups (p> 0.05). Hypertension has a certain effect on the EPR effect induced by polymer nanomicelles in renal cell carcinoma in vitro.

Active ion-exchangeable Bi2O(OH)2SO4 synthesized by ball milling for effective iodine enrichment: Insight into the pathway

Effective capture of radioactive iodine and iodine enrichment from dilute source are highly desirable but still remain as significant challenges. Based on mechanochemical activation of Bi oxide (Bi2O3) toward iodine incorporation by forming BiOI, we report a new approach to functionalize Bi2O3 with several anion groups just by simply co-milling with Bi sulfate. Several analytical methods were used to characterize the reaction products and its high efficiency for iodine enrichment inside. Compared with activation just for α-Bi2O3 itself, formation of Bi2O(OH)2SO4 was confirmed to allow a tremendous increase in adsorption capacity up to 335.57 mg/g towards iodine with the product, due to effect by ion-exchange with three anion groups (SO42−, CO32−, OH−) to form BiOI with a stable structure of Bi-O layer, demonstrating obvious advantages as a newly developed typical anionic adsorbent. Iodine can be recovered by heating BiOI to give back Bi2O3 for recycling. As a cost-effective and environmental-friendly process to produce an efficient material for iodine enrichment, this research may open a promising way to effectively remove radioactive iodine and recover iodine resources.

Mechanisms of iodine enrichment in the pore-water of fluvial/lacustrine aquifer systems: Insight from stable carbon isotopes and batch experiments

• High iodine groundwater occurs in discharge area of fluvial/lacustrine aquifer systems. • Local transformation of sediment Fe minerals explains the enrichment of pore-water iodine in the deep sediments. • Iodine-rich pore-water in the shallow sediments near the coastal area is related to the marine transgressions. The wide occurrence of high iodine groundwater is posing negative effects on human health. The land subsidence due to groundwater over-exploitation causes the release of iodine-rich pore-water trapped in clayey sediment into groundwater, however, the mechanisms of iodine enrichment in pore-water were still unclear. In this study, we selected the Datong Basin (DB) and North China Plain (NCP) with few and severe land subsidence, respectively, to understand the contributions of complex hydro-biogeochemical processes on the enrichment of iodine in groundwater and pore-water by using the inorganic/organic carbon isotope and batch experiments. The results showed that at the DB, the range of groundwater iodine was 4–2175 µg/L, and the enrichment of groundwater iodine is mainly related to the transformation of iron oxyhydroxides triggered by microbial degradation of organic matter, which was reflected by the more depleted δ 13 C DIC signatures of groundwater and gradual increasing trend of ratio of HCl-extractable Fe(II)/sediment Fe total and sediment δ 13 C DOC signatures with depth. In comparison, groundwater iodine at the NCP had the range of 2–1106 µg/L, and pore-water rich in iodine preserved in the clayey sediment serves as the main source. The depth profiles of sediment iron mineral fractions and δ 13 C DOC signatures suggested that the NCP sediments experienced lower degree of reductive transformation of iron minerals and microbial degradation of natural organic matter. At some specific depths higher than 300 m, the evident higher ratios of HCl-extractable Fe(II)/sediment Fe total indicate that the local transformation of iron minerals can explain the pore-water rich in iodine at deep sediments, which was supported by the results of microbial batch experiments. The pore-water with high iodine concentration preserved in the shallow sediment is more likely related to the marine transgressions. This study helps to improve our understanding of the mechanisms of high iodine groundwater, which may provide some new insights on further groundwater management.

High efficient and continuous recovery of iodine in saline wastewater by flow-electrode capacitive deionization

Iodine (I) is a non-renewable and important scarce resource and an essential trace element for human body. Meanwhile, the low concentration radioactive iodine produced by the nuclear industry can cause serious harm to the environment and human beings. The purpose of this study is to investigate the removal and recovery of low-concentration iodine in wastewater by flow-electrode capacitive deionization (FCDI) technology to achieve sustainable utilization of iodine. We systematically investigate the effect of FCDI on iodine enrichment performance under different operating parameters. The results indicate that compared with Cl−, I− is preferentially removed. Cl− and I− have different removal behaviors from brackish water to brine concentration, but I− show a better removal behavior and has a higher selectivity. The iodine removal efficiency remains above 96% after continuous100 cycles under the optimal operating parameters of the FCDI unit with high charge utilization efficiency. Long-term batch experiments show that the low-concentration feed iodine solution (100 mg/L) can be effectively concentrated to 18 times after 24 h operation, with the final iodine concentration dropping to 8.2 mg/L in the feed water chamber and rising to 1818.5 mg/L in the concentration chamber. Overall, the excellent concentration effect, high removal efficiency, and low-energy consumption of the FCDI system in the iodine removal and recovery make it a promising method for the treatment of iodine-containing wastewater.