Efficient cesium encapsulation from contaminated water by cellulosic biomass based activated wood charcoal

A new integrated circular economy index and a combined method for optimization of wood production chain considering carbon neutrality

The wood industry is potentially advantageous to applying the concepts of circular economy for sustainable development and can contribute to the commitment of carbon neutrality. This study developed an integrated circular economy index based on five different quantitative indicators for assessment of the wood production chain: heat recovery rate, CO2 sequestration rate, fossil fuel substitution rate, renewable electricity usage rate, and revenue increase from the by-products. A combination of best-worst method (BWM) and linear goal programming (LGP) techniques was investigated to develop an optimal circular economy model of wood processing chain for reduction in CO2 emission. The integrated circular economy index and the combined method were tested in a case-study of a rubberwood processing chain in Vietnam. The proposed model suggests that the woodchips and biomass from the harvesting and processing of rubberwood could be collected and treated using microwave thermolysis techniques; the enzyme hydrolysis technique is appropriate for bioethanol and biomethane recovery from the sawdust; and the hot air technique is preferable in the drying process. The proposed model could result in a significant reduction of the total net carbon emission from +552,750 tons CO2eq to -1,145,940 tons CO2eq per year. This could support the achievement of Vietnam's zero CO2 emission goal and hopefully contribute to the country's commitment to carbon emission neutrality by the year 2050.

PEI-coated Prussian blue nanocubes as pH-Switchable nanozyme: Broad-pH-responsive immunoassay for illegal additive

Nanozymes are commonly used in the construction of immunosensors, yet they are generally susceptible to pH condition, which greatly hindered their practical use. To break the limitation of pH conditions, polyethyleneimine-coated Prussian blue nanocubes (PBNCs@PEI) were synthesized as the pH-switchable nanozyme, which can show peroxidase-like and catalase-like activity in acidic and alkaline condition, respectively. Besides, the modification of PEI can largely improve the catalytic activity of PBNCs. Herein, the pH-switchable catalytic property of PBNCs@PEI was used to construct the dual-mode immunosensor for the detection of illegal additive, rosiglitazone. In acidic condition, PBNCs@PEI showed excellent peroxidase-like activity, which can trigger the colorimetric reaction of Au nanostars with TMB2+/CTAB. In alkaline condition, the catalase-like activity of PBNCs@PEI prevailed, thus the decomposition of H2O2 can generate O2 to initiate the aerobic oxidation of 4-chloro-1-naphthol (4-CN), which can decrease the fluorescence intensity of 4-CN. Based on the competitive immunoassay, both the localized surface plasmon resonance wavelength shift of Au nanostars and the fluorescence intensity change of 4-CN were quantitatively related with rosiglitazone concentration, thus shedding a new light on the construction of broad-pH-responsive immunosensor. Besides, a smart device was developed to transfer the chroma value of Au nanostars into the RSG concentration, making this sensor a promising method in on-site and point-of-care detection.

Integrating adsorption and in situ advanced oxidation for the treatment of organic wastewater by 3D carbon aerogel embedded with Fe-doped carbonitrides

Wastewater containing organic pollutants with high toxicity and poor biodegradability poses a considerable threat to human health and the ecosystem. Although adsorption and advanced oxidation processes (AOPs) are currently the most widely used technologies for wastewater treatment, limitations of these two independent processes make the treatment effect unsatisfactory. Herein, a system of integrating adsorption and subsequent in situ AOPs is established by a 3D carbon aerogel embedded with Fe-doped carbonitrides (Fe-NC/CAG). The SEM and BET analysis demonstrate that Fe-NC/CAG possesses porous structures with a specific surface area of 518.7 m²/g. The XRD result indicates the formation of Fe⁰ and Fe₃O₄ in Fe-NC/CAG. The impacts of operational parameters such as Fe-NC/CAG dosage, pollutants concentration, temperature, initial pH, and inorganic ions on the adsorption efficiency are investigated. The adsorption kinetics is predominantly based on the pseudo-second-order model. After adsorbing organic pollutants, the Fe-NC/CAG is immersed in peroxymonosulfate (PMS) solution. The adsorbed pollutants are in situ degraded by PMS-based AOPs, leading to the regeneration of Fe-NC/CAG. At optimum conditions, the integrating process established by Fe-NC/CAG achieves over 90% removal of antibiotics, phenolics, and dyes as well as keeps stable performance even after 6 cycles. This integrating adsorption and AOPs system is expected to open up a rich field for wastewater treatment.

Scintillation Response of Nd-Doped LaMgAl11O19 Single Crystals Emitting NIR Photons for High-Dose Monitoring

The Nd-doped LaMgAl₁₁O₁₉ single crystals were synthesized by the floating zone method, and the photoluminescence and scintillation properties were evaluated. Under X-ray irradiation, several sharp emission peaks due to the 4f-4f transitions of Nd³⁺ were observed at 900, 1060, and 1340 nm in the near-infrared range, and the decay curves show the typical decay time for Nd³⁺. The samples show good afterglow properties comparable with practical X-ray scintillators. The 1% and 3% Nd-doped LaMgAl₁₁O₁₉ samples show a good linearity in the dynamic range from 6-60,000 mGy/h.

Designer biochar with enhanced functionality for efficient removal of radioactive cesium and strontium from water

Radioactive elements released into the environment by accidental discharge constitute serious health hazards to humans and other organisms. In this study, three gasified biochars prepared from feedstock mixtures of wood, chicken manure, and food waste, and a KOH-activated biochar (40% food waste + 60% wood biochar (WFWK)) were used to remove cesium (Cs⁺) and strontium (Sr²⁺) ions from water. The physicochemical properties of the biochars before and after adsorbing Cs⁺ and Sr²⁺ were determined using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, extended X-Ray absorption fine structure (EXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). The WFWK exhibited the highest adsorption capacity for Cs⁺ (62.7 mg/g) and Sr²⁺ (43.0 mg/g) among the biochars tested herein. The removal of radioactive ¹³⁷Cs and ⁹⁰Sr exceeded 80% and 47%, respectively, in the presence of competing ions like Na⁺ and Ca²⁺. The functional groups present in biochar, including -OH, -NH₂, and -COOH, facilitated the adsorption of Cs⁺ and Sr²⁺. The Cs K-edge EXAFS spectra revealed that a single coordination shell was assigned to the Cs-O bonding at 3.11 Å, corresponding to an outer-sphere complex formed between Cs and the biochar. The designer biochar WFWK may be used as an effective adsorbent to treat radioactive ¹³⁷Cs- and ⁹⁰Sr-contaminated water generated during the operation of nuclear power plants and/or unintentional release, owing to the enrichment effect of the functional groups in biochar via alkaline activation.

Cesium removal from wastewater: High-efficient and reusable adsorbent K1.93Ti0.22Sn3S6.43

Efficient and quick removal of radioactive Cs⁺ from wastewater is significant for the safe use of nuclear energy and human health. A novel adsorbent K_1.93Ti_0.22Sn₃S_6.43 (KTSS) was developed for Cs⁺ removal from complex natural water systems. The working mechanism of KTSS for removing Cs⁺ was the synergistic effect of ion exchange and the Cs⋯S binding, which was proved by several characterization techniques. KTSS showed ultrafast kinetics for Cs⁺ adsorption within 1 min with a removal rate of 99%. Meanwhile, KTSS exhibited a higher adsorption capacity of 450.12 mg/g than many other adsorbents to remove Cs⁺ and possessed excellent chemical stability in a wide pH range of 3-12. Thanks to the natural affinity arising from the S^2- ligands, KTSS displayed excellent selectivity for Cs⁺ even in different complex water systems. The separation factors between Cs⁺ and the coexisting ions of Na⁺, K⁺, Mg²⁺, Ca²⁺ were ranged from 408.61 to 7448.20. Fortunately, by eluting with NaNO₃ the adsorbent could realize the green regeneration and cyclic utilization. Furthermore, it was found that KTSS had tremendous advantages in the removal of Cs⁺ in comparison with the other adsorbents. Consequently, it should be considered that KTSS obtained in this study has great potential in applying ultrafast and high-efficient removal of Cs⁺ from wastewater.

Highly selective and easily regenerated porous fibrous composite of PSF-Na2.1Ni0.05Sn2.95S7 for the sustainable removal of cesium from wastewater

The removal of ¹³⁷Cs from radioactive wastewater remains a huge challenge due to the interference of many coexisting ions. Several tin chalcogenides (X₂Sn₃Y₇, XNa, K; YTe, Se, S) were synthesized and screened for highly selective cesium removal from radioactive wastewater. It was found that Na₂Sn₃S₇ showed the best adsorption performance for low cesium concentrations. Especially after nickel doping, the adsorption capacity and thermal stability of the adsorbent were significantly enhanced. Its maximum adsorption capacity reached 436.72 mg·g^-1 within only 5 min and adsorption performance kept active in the pH range of 2-12. After being coated with a porous polysulfone (PSF) fiber, the developed PSF-Na_2.1Ni_0.05Sn_2.95S₇ was applied to natural complex water with cesium concentration of 17.58 mg·L^-1. The separation factors between Cs⁺ and competitive ions ranged from 625.21 to 13123.21. It is noteworthy that NaNO₃ was an efficient regenerating agent and can be easily separated from the CsNO₃ mixture for cyclic utilization. Remarkably, only 45 min in each cycle of adsorption and desorption toward cesium was realized, and the adsorption properties hardly decreased even after 50 consecutive cycles. The above advantages make the proposed material an excellent candidate for efficient Cs⁺ removal and enrichment from wastewater.

Resource utilization of pig hair to prepare low-cost adsorbents with high density of sulfhydryl for enhanced and trace level removal of aqueous Hg(II)

Pig hair (PH), a keratinous waste, was modified by ammonium thioglycolate in a ball milling to promote its performance of Hg(II) sequestration. The ball milling broke the hydrophobic cuticle sheath and enhanced the reduction of disulfide bond, which increased the sulfydryl content of the modified PH (BTPH) from 0.07 to 11.05 μmol/g. BTPH exhibited a significantly higher capture capacity of Hg(II) (415.4 mg/g) than PH (3.1 mg/g), as well as the commercial activated carbon (219.7 mg/g), and persisted its performance over a wide range of solution pH. Meanwhile, BTPH with a distribution coefficient of 5.703 × 10⁵ mL/g could selectively capture Hg(II) from the water with the coexisting metal ions such as Mg(II), Cd(II) and Pb(II). Moreover, the low-cost BTPH could reduce the Hg(II) from 1.0 mg/L to well below the limit of drinkable water (2 μg/L) in real-world samples. Density functional theory (DFT) calculations and state-of-the-art characterizations illustrated that the binding of Hg(II) to sulfydryl groups was the main adsorption mechanism. Notably, BTPH decreased the mercury content of water spinaches from 24.1 to 0.50 mg/kg and thereby significantly reduced the phytotoxicity of Hg(II). This work therefore provides a sustainable way to utilize keratinous wastes for the remediation of aqueous Hg(II).

Advances in preparation, mechanism and applications of various carbon materials in environmental applications: A review

Carbon-related materials are now widely investigated in a various industrial field due to their excellent and unique qualities. It must be tailored to the application in such a way that it fits the application. At the same time, it needs to be generated in sufficient quantities for commercial use, and the synthesis method is the major sticking point here. Because most new materials are discovered by chance, the synthesis process described here may not be the most effective way to create them. The research is merely a steppingstone to discovering a different approach, and it will continue until the substance is no longer being used. If you're developing materials for any purpose, synthesis processes are essential. Fullerene, carbon nanotubes (CNT), graphene, and MXene are only a few of the carbon-based compounds discussed in this overview study, which also gives a brief prognosis on the materials future. Furthermore, the environmental application of these carbon materials was discussed and commented.

Prospects of titanium carbide-based MXene in heavy metal ion and radionuclide adsorption for wastewater remediation: A review

Contamination of water sources with various organic and inorganic non-biodegradable pollutants is becoming a growing concern due to industrialization, urbanization, and the inefficiency of traditional wastewater treatment processes. Transition Metal Carbides/Nitrides (MXenes) are emerging as advanced nanomaterials of choice for treating contaminated water owing to their excellent conductivity, mechanical flexibility, high specific surface area, scalable production, rich surface functionalities, and layered morphology. MXenes have demonstrated enhanced ability to adsorb various organic and inorganic contaminants depending upon their surface terminal groups (-OH, -F, and -O) and interlayer spacing. Titanium carbide (Ti₃C₂T_x) is most researched to date due to its ease of processing and stability. Ti₃C₂T_x has shown excellent performance in absorbing heavy metal ions and radioactive heavy metals. This review summarizes state-of-the-art Ti₃C₂T_x synthesis, including selective etching techniques, optimization of the desired adsorption features (controlling surface functional groups, intercalation, sonication, and functionalization), and regeneration and adsorption mechanism to remove contaminants. Furthermore, the review also compares the adsorption performance of Ti₃C₂T_x with other commercial adsorbents (including chitosan, cellulose, biomass, and zeolites). Ti₃C₂T_x has been found to have an adsorption efficiency of more than 90% in most studies due to its layered structure, which makes the functional groups easily accessible, unique and novel compared to other conventional nanomaterials and adsorbents. The challenges, potential solutions, and prospects associated with the commercial development of Ti₃C₂T_x as adsorbents are also discussed. The review establishes a framework for future wastewater treatment research using MXenes to address the global problem of water scarcity.

U(VI) adsorption by green and facilely modified Ficus microcarpa aerial roots: Behavior and mechanism investigation

Uranium (U)-containing wastewater poses serious pressure to human health and environmental safety. The treatment of U-bearing wastewater using green and facilely fabricated materials is considered a promising alternative. Herein, the raw and modified aerial roots of Ficus microcarpa (RARF and MARF, respectively) were prepared and applied to the treatment of synthesized U-containing wastewater. The results showed that the adsorption process was spontaneous and chemically controlled, which was in good accordance with the pseudo-second-order kinetic and the Redlich-Peterson isotherm adsorption model. The adsorption mechanisms were proposed to be the complexation between U(VI) and oxygen/phosphorus-containing functional groups on MARF.

Hyper-crosslinked tetraphenylborate as a regenerable sorbent for Cs+ sequestration in aqueous media through cation-π interactions

Practical adsorbents that could efficiently collect radioactive Cesium (Cs⁺) are critically important in achieving proper management and treatment measures for nuclear wastes. Herein, a hyper-crosslinked tetraphenylborate-based adsorbent (TPB-X) was prepared by reacting TPB anions as Cs⁺ binding sites with dimethoxymethane (DMM) as crosslinker. The most efficient TPB-X synthesis was attained at 1:4 TPB/DMM mole ratio with sorbent yield of 81.75%. Various techniques such as FTIR, TGA-DTG, N₂ adsorption/desorption and SEM-EDS reveal that TPB-X is a water-insoluble, thermally stable and highly porous granular sorbent. Its hierarchical pore structure explains its very high BET surface area (1030 m² g^-1). Sequestration of Cs⁺ by TPB-X involves its exchange with H⁺ followed by its binding with the phenyl rings of TPB through cation-π interactions. The Cs⁺ adsorption in TPB-X is endothermic and spontaneous, which adheres to the Hill isotherm model (q_m = 140.58 mg g^-1) and follows pseudo-second order kinetics (k₂ = 0.063 g mg^-1 h^-1). Calculations from the density functional theory reveal that the binding of TPB anion is strongest for Cs⁺. Thus, TPB-X was able to selectively capture Cs⁺ in simulated surface water containing Na⁺, K⁺, Mg²⁺, and Ca²⁺ and in HLLW containing Na⁺, Rb⁺, Sr²⁺, and Ba²⁺. Hyper-crosslinking was found beneficial in rendering TPB-X reusable as the sorbent was easily retrieved from the feed after Cs⁺ capture and was able to withstand the acid treatment for its regeneration. TPB-X exhibited consistent performance with no sign of chemical or physical deterioration. TPB-X offers a practical approach in handling Cs⁺ contaminated streams as it can be repeatedly used to enrich Cs⁺ in smaller volume of media, which can then be purified for Cs⁺ reuse or stored for long-term natural Cs⁺ decay process.

Functionalized layered double hydroxides composite bio-adsorbent for efficient copper(II) ion encapsulation from wastewater

In this study, naturally abundant and inexpensive bamboo was used to make cheaper activated charcoal for efficient encapsulation of toxic copper (Cu(II)) ion from wastewater. The functionalized bamboo charcoal-Layered double hydroxides (BC-LDHs) composite bio-adsorbent was prepared using co-precipitation method. The composite bio-adsorbent was exploited to eliminate Cu(II) ion with high sensitivity and selectivity from contaminated water. The adsorption parameters including the effect of pH, contact time, adsorbent dose, and effect of initial concentration were optimized in systematic way and the adsorption kinetics and isotherms were investigated for potential use in real sample treatment. The physicochemical properties and morphological structure of the adsorbent were examined using X-ray Diffraction, Scanning Electronic Microscopy, Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis to understand the Cu(II) ion adsorption mechanism. The adsorption results revealed that the BC-LDH could remove almost 100% of Cu(II) ion from aqueous solution at pH range between 3.0 and 6.0 within 30 min. The maximum monolayer adsorption capacity was determined to be 85.47 mg/g based on the Langmuir isotherm. The adsorption equilibrium data were well-fitted by the Langmuir isotherm model (R² = 0.998) and the experimental kinetic data were supported by the pseudo-second order model (R² = 0.999). The BC-LDH could be reused without losing its adsorption performance in several cycles after successful regeneration with 0.10 M HCl. The Cu(II) ion removal mechanism was postulated with intercalated ion exchange, surface precipitation and interaction between BC-LDH and surface functionalities. Therefore, the highly functional BC-LDH composite could be a promising adsorbent for efficient Cu(II) ion removal from wastewater.

Decontamination of radioactive cesium-contaminated soil/concrete with washing and washing supernatant- critical review

We reviewed washing of radioactive Cs-contaminated concrete and soil based on the fate of Cs in concrete and soil, including sorption materials for treatment of supernatant solution. In non-aged cement materials (the calcium silicate hydration (C-S-H) phase), it was possible to decontaminate Cs using ion exchange with monovalent cations, such as NH₄⁺. The clay components in the soil and aggregates were important factors in optimization of the efficiency and mechanism for Cs decontamination with washing solution. The parameters (reagent component, pH, and temperature) of the washing solution should be determined considering soil mineral type (here, weathered biotite (WB) with vermiculite), since monovalent cations such as NH₄⁺ and K⁺ can inhibit Cs decontamination due to collapse of the hydrated and expanded interlayer regions with cation exchange. In this case, hydrothermal treatment or H₂O₂ dosing was necessary to expand the collapsed interlayer region for Cs removal by washing with cation exchange or organic acids. Acid and a chelating agent significantly enhanced Cs-release with dissolution of the adsorbent layer containing iron and aluminum oxides. The important characteristics of important and emerging sorption materials for treatment of the radioactive Cs-contaminated supernatant after washing treatment are discussed. Sorbents for treatment of washing supernatant are divided in to two main categories. Clay minerals, metal hexacyanoferrates, and ammonium molybdophosphates are discussed in the inorganic class of materials. Hypercrosslinked polymers, supramolecular sorbents, carbon nanotubes, and graphene oxide are covered in the carbon-based sorbents for Cs removal from water.

Selective Separation of Radiocesium from Complex Aqueous Matrices Using Dual Solid-Phase Extraction Systems

The release of radiocesium (r-Cs) into natural aqueous systems is of concern because of its extended solubility as an alkaline metal ion and its facile incorporation into living beings. A technique for the selective separation of Cs from an aqueous matrix using dual solid-phase extraction (SPE) systems in a series is proposed in this paper. The SPEs equipped with chelates (Nobias Chelate-PA1 and Nobias Chelate-PB1), an ion-exchange resin (Nobias Ion SC-1), or macrocycles (MetaSEP AnaLig Cs-01 and MetaSEP AnaLig Cs-02) were evaluated in terms of selectivity and retention/recovery behavior toward Cs and other potentially competing ions (Li, Na, K, Rb, Ba, Ca, Mg, and Sr). The simulated solution of ¹³³Cs, a chemical analog of r-Cs, was used to optimize the separation process. Operating parameters such as pH (3-13), flow rate (0.2-5.0 mL min^-1), and elution behavior (HCl, 0.1-5.0 mol L^-1) were optimized to ensure maximum removal of Cs from the aqueous matrices. The dual SPE system comprised Nobias Chelate-PB1 that minimized the competing impact of ions, while selective Cs retention was attained with MetaSEP AnaLig Cs-02. The proposed process was verified using real r-Cs-contaminated water from Fukushima, Japan, to observe the quantitative separation and preconcentration of r-Cs from the complex matrices.

Effective removal of 137Cs ions from radioactive wastewater by Melamine-Styrene based Polymer (MSP)

Cesium (Cs) is a major product of uranium fission, which is one of the most existed radionuclides in radioactive wastes. Removal of Cs-137 has a critical role in the decontamination of liquid radioactive waste due to its half-life of 30.17 years. Concordantly, melamine styrene based conjugated polymer (MSP) was designed, synthesized, and characterized with FTIR, TGA, SEM and BET measurements. The novelty of the study is that the MSP adsorbent is designed as a highly conjugated structure to have better interaction with Cs over the Cs-π bond of the benzene groups of the adsorbent. In this work, the adsorption behavior and rate of MSP were investigated as parameters of adsorbent amount, pH, contact time, particle size, initial Cs⁺ concentration, and temperature. Besides, the adsorption efficiency of Cs-137 was examined by Gamma Spectroscopy. Adsorption results were fitted to three different isotherms which were Freundlich, Langmuir and Dubinin-Radushkevich (D-R). The maximum adsorption capacity of polymer for Cs⁺ ion was found from Langmuir isotherm as 78 mg g^-1. As a part of kinetic parameters, pseudo first and second orders were investigated and in terms of the correlation coefficient pseudo second order was much more appropriate for adsorption of Cs-137 onto MSP.

Novel micro-structured carbon-based adsorbents for notorious arsenic removal from wastewater

The contamination of groundwater by arsenic (As) in Bangladesh is the biggest impairing of a population, with a large number of peoples affected. Specifically, groundwater of Gangetic Delta is alarmingly contaminated with arsenic. Similar, perilous circumstances exist in many other countries and consequently, there is a dire need to develop cost-effective decentralized filtration unit utilizing low-cost adsorbents for eliminating arsenic from water. Morphological synthesis of carbon with unique spherical, nanorod, and massive nanostructures were achieved by solvothermal method. Owing to their intrinsic adsorption properties and different nanostructures, these nanostructures were employed as adsorption of arsenic in aqueous solution, with the purpose to better understanding the morphological effect in adsorption. It clearly demonstrated that carbon with nanorods morphology exhibited an excellent adsorption activity of arsenite (about 82%) at pH 3, remarkably superior to the two with solid sphere and massive microstructures, because of its larger specific surface area, enhanced acid strength and improved adsorption capacity. Furthermore, we discovered that iron hydroxide radicals and energy-induced contact point formation in nanorods are the responsible for the high adsorption of As in aqueous solution. Thus, our work provides insides into the microstructure-dependent capability of different carbon for As adsorption applications.

Assessing of cesium removal from wastewater using functionalized wood cellulosic adsorbent

Sustainable materials are urgently desired for treatment of radioactive cesium (Cs) contaminated water to safe-guard the public health. Apart from the synthetic ligand-based materials, the Mangrove charcoal modified adsorbent was fabricated for assessing of Cs removal from waste sample. The raw charcoal was oxidized using nitrification approach and diverse oxygen containing carboxyl, carbonyl and hydroxyl functional groups were introduced. After modification, the adsorbent characteristics were drastically changed as compared to the charcoal during the measurement of FTIR, N₂ adsorption-desorption isotherms and SEM micrographs. The data clarified that charcoal modified adsorbent was exhibited high Cs transport through the inner surface of the adsorbent based on bonding ability. The adsorbent was shown comparatively slow kinetics to Cs ion; however, the adsorption capacity was high as 133.54 mg/g, which was higher than the crown ether based conjugate materials. The adsorption data were followed to the Langmuir adsorption isotherms and the monolayer coverage was possible due to the data presentation. The presence of high amount of Na and K were slightly interfered to the Cs adsorption by the charcoal modified adsorbent, however; the Na and K concentration was 350-600 folds higher than the Cs concentration. Then the proposed adsorbent was selective to Cs for the potential real radioactive Cs contaminated water. The volume reduction was established rather than desorption and reuses advantages. More than 99% volume reduction was measured by burning of Cs adsorbed adsorbent at 500 °C for ensuring the safe storage and disposal of used adsorbent. Therefore, the charcoal modified adsorbent may open the new door to treat the Cs containing wastewater.

Ion-Imprinted Polymers: Synthesis, Characterization, and Adsorption of Radionuclides

Growing concern over the hazardous effect of radionuclides on the environment is driving research on mitigation and deposition strategies for radioactive waste management. Currently, there are many techniques used for radionuclides separation from the environment such as ion exchange, solvent extraction, chemical precipitation and adsorption. Adsorbents are the leading area of research and many useful materials are being discovered in this category of radionuclide ion separation. The adsorption technologies lack the ability of selective removal of metal ions from solution. This drawback is eliminated by the use of ion-imprinted polymers, these materials having targeted binding sites for specific ions in the media. In this review article, we present recently published literature about the use of ion-imprinted polymers for the adsorption of 10 important hazardous radionuclides-U, Th, Cs, Sr, Ce, Tc, La, Cr, Ni, Co-found in the nuclear fuel cycle.

Dual Ion-Imprinted Mesoporous Silica for Selective Adsorption of U(VI) and Cs(I) through Multiple Interactions

Separation of uranium and cesium from low-level radioactive effluents (LLRE) is of great significance for sustainable development of the nuclear industry and for the environment. However, high salinity and massive coexisting ions of LLRE are giant challenges for the separation. To address the challenges, we report a strategy for efficient and simultaneous separation of uranium and cesium from a high-salt environment by dual ion-imprinted mesoporous silica based on multiple interactions. The as-prepared adsorbents can reach equilibrium for uranium and cesium within 1 h with a maximum capacity of 221.7 mg U g^-1 and 34.5 mg Cs g^-1. The sorption mechanism demonstrates that the highly active phenolic hydroxyl groups of imprinted cavities can extract uranium and cesium effectively through multiple interactions, including coulomb attraction, redox, ion exchange, and complexation. The synergism of multiple interactions and imprinted cavity endows the sorbent with good selectivity for uranium and cesium over other cations and with excellent salt tolerance. This work demonstrates a new strategy of selective extraction of nuclides by multifunction adsorbent through multiple interactions.