Removal Of Strontium Research Articles

Effective removal of strontium from wastewater using Co-doped layered sodium vanadosilicate.

The effective removal of strontium (Sr) from radioactive wastewater is essential for human health and ecological sustainability. However, due to the existence of a large number of coexisting ions, the selective removal of Sr2+ from it remains a significant challenge. Herein, three novel metal-doped sodium vanadosilicates were developed by structural regulation. It was found that Co-doping can not only significantly reduce the dissolution loss of vanadosilicate (NaVOSi) from the adsorbent in extreme environments by adjusting the orbital energy distribution, energy band structure, bond length, and bond energy of sodium vanadosilicate crystals, but also further enhance the adsorption performance by reducing its zeta potentials and agglomeration phenomenon. The maximum adsorption capacity of the developed adsorbent (Co-NaVOSi) was up to 319.10 mg·g-1 within 5 min. When applied to Sr2+ removal from simulated wastewater, the distribution coefficients of Sr2+ reached 2943.15 mL·g-1, and the separation coefficients between Sr2+ and coexisting ions were above 64. DFT calculations further revealed the highly selective removal mechanism of Sr2+ from wastewater. In addition, NaNO3 was proved to be an efficient eluent. The excellent properties above make NaVOSi an excellent candidate for effectively removing Sr2+ from wastewater.

Evaluation of Cs+ and Sr2+ sorption behaviour of synthetic NaA and NaP zeolite modified with graphene oxide

NaP and NaA zeolites are the promising materials for removal of cesium (Cs+) and strontium (Sr2+) from nuclear waste, and the effective utilisation of these relies on the appropriate modification to enhance their ion exchange properties. In this aim, zeolite (NaZ) containing both NaA and NaP zeolites, and the composite of zeolite and graphene oxide (GO-NaZ), were synthesised by hydrothermal process and characterized by varieties of techniques, like XRD, Raman spectroscopy, scanning electron microscopy (SEM), gas adsorption, and small angle X-ray scattering (SAXS). Presence of both NaP and NaA phases was confirmed from XRD and Raman spectroscopy. SEM, SAXS and gas adsorption studies indicated presence of extensive macropores and rough surfaces in the samples. The sorption behaviours of the samples were studied using solutions of radioactive tracer or inactive ions, and the sorption efficiencies were evaluated by equilibrium and kinetic studies. Equilibrium studies indicated that the composites have higher Cs+ exchange capacity than the pristine NaZ. However, opposite trend was observed for Sr2+ ions. Kinetic studies revealed that the Sr2+ and Cs+ uptake follow pseudo-2nd order kinetic model. It was also revealed that GO-NaZ composite shows better selectivity for Cs+ over Na+ at lower concertation of Cs+, and hence it can be a promising material for site decontamination.

Acyl-anchored metal-organic cages with interior cryptand-like recognition sites for selective removal of radioactive strontium(II).

Tailored design of organic linkers or metal nodes can introduce desirable functionalities into metal-organic cages (MOCs), significantly expanding their potential applications. In this study, we present a viable approach for engineering acyl-type metal nodes to create interior oxygen-rich sites within MOCs, enabling specific recognition of metal ions, including radioactive contaminants, while maintaining the structural integrity of the MOCs. A novel MOC featuring a uranyl-sealed calix[4]resorcinarene (C[4]R)-based multisite cavity, referred to as UOC, is synthesized as a prototype. In UOC, peroxide-bridged dimeric uranyl units at both ends of the coordination cage provide abundant oxygen sites for coordination, forming a cryptand-like cavity that facilitates efficient recognition and encapsulation of Sr2+ due to the size-matching effect. Additionally, hydrophobic binding cavities at both ends of UOC promote the co-inclusion of two different guest species. Inspired by the strong binding affinity of UOC for Sr2+, it is employed as a solid adsorbent for capturing low concentrations of Sr2+ in strontium-contaminated simulated groundwater. A removal efficiency of 99.7% for Sr2+ at an initial concentration as low as 0.013mmolL-1 is achieved, demonstrating its significant potential for the selective removal of trace amounts of radioactive 90Sr2+. This work demonstrates the feasibility of incorporating acyl-type metal nodes into MOCs for the recognition and encapsulation of metal ions, offering a novel strategy for developing new MOC-based functional materials.

Simultaneous Removal of Strontium, Manganese, Lead and Arsenate from Wastewaters Using a Green and Low-Cost Adsorbent Derived from Nut Residues

The potential of a nut residue, activated only by physical means, to simultaneously adsorb Sr2+, Mn2+, Pb2+ and As5+ from contaminated waters was investigated. Mono-metal and multi-metal adsorption behavior and adsorption capacities by the solid material were compared for a range of initial metals concentrations, adsorbent dose, contact time and solution pH. The mechanisms of adsorption were examined by conducting structural, mineralogical and chemical analyses and applying two isotherm models to simulate experimental data. In the case of mono-metal adsorption, the maximum uptake of Sr2+ by the biochar was 12.3, of Mn2+ 23.8, of Pb2+ 24.7 and of As5+ 12.4 mg/g. In the case of multi-metal adsorption, the uptake of each metal was enhanced as the total ion flux density increased, revealing that there was no competition between these ions for biochar’s sorption sites. For an adsorbent dose of 2 g/L, the maximum adsorption capacity of biochar for Sr2+, Mn2+, Pb2+ and As5+ could be raised up to 47.6, 49.9, 25 and 48.7 mg/g, respectively. Potential adsorption mechanisms were chemical complexation or electron coordination between the metals and the biochar matrix, as well as mineral precipitation on the adsorbent surface.

Development and characterization of kaolin-based PVA/alginate polymer composite (KPA) for removal of uranium and strontium from aqueous solutions

The present study used low-cost, abundant, and nontoxic kaolin and kaolin-based PVA/alginate composite (KPA) as adsorbents to remove U(VI) and Sr(II) ions from aqueous solutions. The characterization of the adsorbents was performed by several techniques. The results showed that PVA/alginate enhanced the functional groups and changed the surface morphology. Adsorption isotherm parameters were determined through both linear and non-linear regression analyses, from which it was inferred that the Langmuir model provides a better fit than other ones. The uranium removal capacity of KPA significantly improved as compared to that of kaolin, reaching 104.17 mg/g under the conditions of 30 min, pH 4.0, 298 K, and a solid-to-liquid ratio of 1.2 g/L. The strontium removal capacity of kaolin was significantly high as compared to that of KPA, reaching 68.96 mg/g under the optimum conditions. Removal of the radionuclides on both adsorbents was better described by the pseudo-second-order kinetic model, showing the ions to be immobilized on the adsorbents through chemical adsorption. Kaolin was not affected by interfering metals for U(VI) and Sr(II) adsorption, but KPA composite was influenced by the other metals. The adsorbents display potential as candidates to remove uranium and strontium from wastewater.

Optimization of strontium removal by Tetraselmis chui grown in bubble column photobioreactors

Green microalgae of the class Chlorodendrophyceae have recently attracted the interest of researchers due to their ability to form micropearls (intracellular inclusions of amorphous calcium carbonate) highly enriched in Sr. The marine species Tetraselmis chui (included in the class Chlorodendrophyceae) shows high uptake of both stable and radioactive Sr isotopes and has been suggested as a potential candidate for the development of new bioremediation tools regarding radioactive 90Sr pollution. In this study, we optimized Sr removal from seawater by growing T. chui in 1-L bubble column photobioreactors (PBRs) with and without CO2 supply. Culturing T. chui in bubble column PBRs greatly improves cell production and Sr removal compared to previous studies. Furthermore, the addition of 10 mL L−1 h−1 CO2 further accelerates T. chui growth and results in better Sr removal rates. This study presents promising results for the development of new bioremediation methods to treat 90Sr pollution.

Modification of Ti3C2Tx nanostructure with KH2PO4 and chitosan for effective removal of strontium from nuclear waste.

Nanostructure titanium carbide MXene (Ti3C2Tx) was modified with KH2PO4 and chitosan to effectively remove strontium from nuclear wastewater. Nuclear waste includes radionuclides of uranium, thorium, strontium, and cesium, which are classified depending on the concentration of radionuclides. Nuclear waste with a high strontium concentration is the production waste of radiopharmaceutical production centers. Ti3C2Tx was synthesized from Ti3AlC2 using HF40% and HF in situ (MILD-Ti3C2Tx) in 24h at 313.15 and 333.15K. Morphology, structure, and functional groups were investigated using the XRD, SEM, EDS, FTIR, and BET analyses. The Sr(II)'s adsorption capacity on Ti3C2Tx-HF and Ti3C2Tx-HF in situ was obtained as 61.9 and 253.5mgg-1, respectively (temperature, 298.15K; pH, 7.00; contact time, 180min; and Sr(II) concentration, 150mgl-1). Ti3C2Tx-HF in situ showed fourfold adsorption due to more hydroxyl functional groups and larger interlayer spacing. Ti3C2Tx was modified with KH2PO4 and chitosan to investigate the mechanism of change of Sr(II)'s adsorption capacity, which increased to 370 and 284mgg-1, respectively. The structural results of modified Ti3C2Tx showed that the surface functional groups increased when modified with chitosan. In addition, modification with KH2PO4, through encapsulating large amounts of KH2PO4 between Ti3C2Tx layers, increased the possibility of Sr(II) diffusion between layers and electrochemical interactions with hydroxyl groups, and thus, increased its adsorption. Some experiments were designed to investigate the effect of parameters like initial concentration of Sr(II), contact time, temperature, and pH solution, as well as modified- and unmodified-Ti3C2Tx on adsorbent. The results revealed that the adsorption process of Sr(II) with pristine and modified-Ti3C2Tx follows pseudo-second-order kinetics and Freundlich heterogeneous isotherm model. Freundlich model isotherm indicates the presence of various functional groups on the surface and between the pristine and modified Ti3C2Tx layers. Electrostatic reactions and intra-sphere complexation were the two dominant mechanisms of the adsorption process.

Effective radioactive strontium removal using lithium titanate decorated Ti3C2Tx MXene/polyacrylonitrile beads

A lithium titanate-decorated Ti3C2Tx MXene (LTO-MX) composite was synthesized through etching and alkali processes, and subsequently immobilized using polyacrylonitrile (PAN) polymer via a phase inversion method. In the batch study, the strontium adsorption behavior followed the Redlich-Peterson isotherm and the pseudo-second-order kinetic models. The maximum adsorption capacity for strontium reached 24.05 mg/g. Furthermore, a continuous fixed-bed column study was performed using the LTO-MX PAN beads to remove strontium from aqueous solutions. The dynamic behavior of column adsorption was examined under various operating parameters such as initial strontium concentration, flow rate, and bed height. Dynamic modeling was employed to describe adsorption breakthrough properties based on these experimental data. Both the Thomas and Yoon-Nelson models accurately simulated the breakthrough curves. The proposed mechanisms for strontium adsorption included encapsulation, electrostatic attraction, cation exchange, and surface complexation. These results demonstrate the effectiveness of LTO-MX PAN beads as adsorbents for the continuous removal of strontium from radioactive wastewater.

Synthesis of an anionic 2D → 3D interpenetration metal–organic framework for efficient removal of Sr2+

Rapid removal of radioactive strontium from solutions is of great significance for ecosystem conservation. Herein, a new Cu-Zn-MOF namely, [NH4]3[(Cu3Zn2(FDA)6(H2O)8Cl·3H2O] (Cu-Zn-MOF; H2FDA = 2,5-furandicarboxylic acid) is designed for the efficient adsorption of radioactive Sr2+ by ion exchange. The newly designed Cu-Zn-MOF possessed an anionic 2D → 3D interpenetration framework based trinuclear centers which are charge-balanced by amino cations. Kinetic studies showed that Cu-Zn-MOF rapidly removed Sr2+ (96.7 % in 4 h), and the kinetic data fitted well with the pseudo-second-order model. The adsorption isotherms were well described by Langmuir model and Cu-Zn-MOF exhibited high adsorption capacity (220.7 mg/g at 298 K), out-performing many state of the art adsorbents. More importantly, Cu-Zn-MOF exhibited intriguingly high selectivity for Sr2+ in solutions containing coexisting ions with good reusability. The findings of this study can provide key and useful information for the adsorptive removal of Sr2+ and other similar radioactive material with minimal processing and cost.

Waste-derived activated carbons for effective adsorptive removal of strontium, barium, and binary pollutants: A response surface methodology study

A double-pronged approach to pollution management is proposed by sustainably managing solid wastes and converting them to activated carbons that are then utilized for water treatment. In this study, gas-to-liquids (GTL) derived biosolids, carboard and their mixed samples are used to produce the activated carbons. In a laboratory batch study, a Box-Behnken experimental design was used with four factors and three levels to optimize the removal of single component strontium and barium, and the binary system of pollutants from an aqueous solution. The design incorporated response surface modeling (RSM) techniques with a total of 29 different experimental data points collected and analyzed in this study. The study was conducted considering four parameters: the initial pH of the solution (ranging from 4.0 to 8.0), temperature (ranging from 20 to 40 ℃), the percentage of cardboard (fixed at 0 %, 50 %, and 100 %), and the amount of adsorbent (between 0.05 and 0.5 g). These factors were assigned three levels, represented as −1, 0, and 1. A second-order polynomial regression equation was then developed to estimate the responses. The statistical significance of the independent variables and their interactions was assessed using analysis of variance (ANOVA) with a 95 % confidence level (α = 0.05). The results revealed that only temperature and dosage show significant effects on the responses and that optimum values of the selected parameters were obtained by solving the prediction equations, which were validated with less than 4 % error %. In an attempt to optimize the factors, a pH of 5.5, temperature of 40 ℃ and dose of 0.3 g is found for all three samples. Validation results for optimization also proved that varying the percentage cardboard showed little difference in the percentage removal of all the pollutants. The results from this study can be directly applied for any such systems trying to optimize these parameters and the prediction equations can be utilized effectively.

Simultaneous removal of caesium and strontium using different removal mechanisms of probiotic bacteria

When radioactive materials are released into the environment due to nuclear power plant accidents, they may enter into the body, and exposing it to internal radiation for long periods of time. Although several agents have been developed that help excrete radioactive elements from the digestive tract, only one type of radioactive element can be removed using a single agent. Therefore, we considered the simultaneous removal of caesium (Cs) and strontium (Sr) by utilising the multiple metal removal mechanisms of probiotic bacteria. In this study, the Cs and Sr removal capacities of lactobacilli and bifidobacteria were investigated. Observation using an electron probe micro analyser suggested that Cs was accumulated within the bacterial cells. Since Sr was removed non metabolically, it is likely that it was removed by a mechanism different from that of Cs. The amount of Cs and Sr that the cells could simultaneously retain decreased when compared to that for each element alone, but some strains showed only a slight reduction in removal. For example, Bifidobacterium adolescentis JCM1275 could simultaneously retain 55.7 mg-Cs/g-dry cell and 8.1 mg-Sr/g-dry cell. These results demonstrated the potentials of utilizing complex biological system in simultaneous removal of multiple metal species.

Magnetite-ferrocyanide-copper sorbents for recovery of cesium ions from low-activity liquid radioactive waters

The article is devoted to the development of nanoscale sorbents based on copper ferrocyanide and magnetites for the removal of cesium, strontium, and heavy metal ions in their simultaneous presence in a multicomponent two-phase low-level radioactive solution containing complexing agents and surfactants. It they noted that the highest values of cesium ion removal from low-level radioactive water - 99.96% and 99.62% - are obtained with sorbents based on 100% copper ferrocyanide and a mixture of copper ferrocyanide and industrial magnetite in a ratio of 2 to 1. The efficiency of the sorbents in terms of the distribution coefficient is 2394 and 1589.7 ml/g, which ensures the purification of radioactive water from trace concentrations of cesium ions to values of 2394 and 265.11. These sorbents provide water purification to values less than 2 Bq/cm3, which is typical for 1-4 classes of water quality in terms of radiation safety of groundwater and surface water as sources of centralised drinking water supply. It is noted that sorption of cesium ions on copper ferrocyanide and magnetite is carried out in the presence of water molecules and hydroxo groups. It is shown that artificial magnetite in its pure form exceeds the sorption capacity of industrial magnetite. This is due to the difference in the phase composition and particle size of the crystals. The results obtained will be use as components of the technological process in the Plasma-Sorb technology developed at the State Institution "The Institute of Environmental Geochemistry" of the National Academy of Sciences of Ukraine for the treatment of low- and intermediate-level radioactive water from Ukrainian nuclear power plants.

Freshwater Recovery and Removal of Cesium and Strontium from Radioactive Wastewater by Methane Hydrate Formation.

As human society has advanced, nuclear energy has provided energy security while also offering low carbon emissions and reduced dependence on fossil fuels, whereas nuclear power plants have produced large amounts of radioactive wastewater, which threatens human health and the sustainability of water resources. Here, we demonstrate a hydrate-based desalination (HBD) technology that uses methane as a hydrate former for freshwater recovery and for the removal of radioactive chemicals from wastewater, specifically from Cs- and Sr-containing wastewater. The complete exclusion of radioactive ions from solid methane hydrates was confirmed by a close examination using phase equilibria, spectroscopic investigations, thermal analyses, and theoretical calculations, enabling simultaneous freshwater recovery and the removal of radioactive chemicals from wastewater by the methane hydrate formation process described in this study. More importantly, the proposed HBD technology is applicable to radioactive wastewater containing Cs+ and Sr2+ across a broad concentration range of low percentages to hundreds of parts per million (ppm) and even subppm levels, with high removal efficiency of radioactive chemicals. This study highlights the potential of environmentally sustainable technologies to address the challenges posed by radioactive wastewater generated by nuclear technology, providing new insights for future research and development efforts.

Molten salt synthesis of MXene-derived hierarchical titanate for effective strontium removal

The removal and recovery of radioactive Sr(II) from wastewater and seawater has been of great concern due to the negative environmental impacts of nuclear energy development and the potential risk of nuclear accidents. Herein, a facile molten salt synthesis strategy was developed to systematically investigated the reaction of different types of MXenes with nitrates. Among the products, K+ intercalated hierarchical titanate nanostructures (K-HTNs) obtained from the direct chemical transformation of multilayered Ti3C2Tx exhibited unique layered structures, good physicochemical properties, and outstanding adsorption performance for Sr(II). The maximum adsorption capacity of Sr(II) by K-HTNs reached 204 mg·g−1 at ambient temperature, and the good regeneration and reusability of the titanate was also demonstrated. K-HTNs showed preferential selectivity for Sr(II) in different environmental media containing competing ions, and the removal efficiency of Sr(II) in real seawater was as high as 93.3 %. The removal mechanism was elaborated to be the exchange of Sr2+ with K+/H+ in the interlayers of K-HTNs, and the adsorbed Sr(II) had a strong interaction with Ti−O− termination on the titanate surface. Benefiting from the merits of rapid and scalable synthesis and excellent adsorption performance, MXene-derived K-HTNs have broad application prospects for the purification of 90Sr-contaminated wastewater and seawater.

Enhanced Strontium Removal through Microbially Induced Carbonate Precipitation by Indigenous Ureolytic Bacteria.

Microbial ureolysis offers the potential to remove metals including Sr2+ as carbonate minerals via the generation of alkalinity coupled to NH4+ and HCO3- production. Here, we investigated the potential for bacteria, indigenous to sediments representative of the U.K. Sellafield nuclear site where 90Sr is present as a groundwater contaminant, to utilize urea in order to target Sr2+-associated (Ca)CO3 formation in sediment microcosm studies. Strontium removal was enhanced in most sediments in the presence of urea only, coinciding with a significant pH increase. Adding the biostimulation agents acetate/lactate, Fe(III), and yeast extract to further enhance microbial metabolism, including ureolysis, enhanced ureolysis and increased Sr and Ca removal. Environmental scanning electron microscopy analyses suggested that coprecipitation of Ca and Sr occurred, with evidence of Sr associated with calcium carbonate polymorphs. Sr K-edge X-ray absorption spectroscopy analysis was conducted on authentic Sellafield sediments stimulated with Fe(III) and quarry outcrop sediments amended with yeast extract. Spectra from the treated Sellafield and quarry sediments showed Sr2+ local coordination environments indicative of incorporation into calcite and vaterite crystal structures, respectively. 16S rRNA gene analysis identified ureolytic bacteria of the genus Sporosarcina in these incubations, suggesting they have a key role in enhancing strontium removal. The onset of ureolysis also appeared to enhance the microbial reduction of Fe(III), potentially via a tight coupling between Fe(III) and NH4+ as an electron donor for metal reduction. This suggests ureolysis may support the immobilization of 90Sr via coprecipitation with insoluble calcium carbonate and cofacilitate reductive precipitation of certain redox active radionuclides, e.g., uranium.

Molten salt mediated single-step synthesis of reusable nanostructured CaTiO3 for the removal and recovery of Sr2+: A potential adsorbent for the contaminated water bodies

The facile synthesis approach for the adsorbent preparation and recyclability during decontamination of radioactive pollutants is a significant concern in water treatment. The objective of this study is to, synthesis via solid-state reaction of the nanostructured CaTiO3 for the removal and recovery of strontium (Sr2+) from the various water sources. The influence of the adsorption-dependent parameters including, initial concentration, adsorbent dose, pH, contact time and co-existing ions interference were investigated. The prepared adsorbent was characterized by different analytical techniques like FT-IR, SEM with EDAX, TEM, TGA-DTG, Powder XRD and BET surface analysis. The kinetic models were also used, and according to the kinetic models, a pseudo-second-order kinetic model (R2 = 0.999) was better fitted to the adsorption of Sr2+ ions onto CaTiO3 rather than pseudo-first-order kinetics, which could properly represent the observed adsorption of Sr2+. For the isotherm study, the results are best fitted to the Langmuir isotherm model (R2 = 0.98) with a maximum adsorption capacity of 102.04 mg/g. The common ions (Na+, Mg2+, Ca2+, and K+) and Sr2+ having a concentration of 1:2, 1:3, and 1:4, where 82.8, 79.5, and 68.2 % removal was achieved of Sr2+ in each respective matrix. In addition, the adsorption and corresponding recovery and removal for the different Sr2+spiked matrices in deionized water, tap water, well water, lake water, and seawater were investigated with 97, 65.6, 76.5, 73.9 and 17.8 % removal respectively. Also, the CaTiO3 showed excellent recyclability with minimal loss even after 5 consecutive recyclability cycles and >90% removal of strontium achieved. Hence, prepared nanostructured CaTiO3 could be considered a promising adsorbent for the removal and recovery of Sr2+ions from contaminated water bodies.

Removal of strontium by nanofiltration: Role of complexation and speciation of strontium with organic matter

Strontium (Sr) removal from water is required because excessive naturally occurring Sr exposure is hazardous to human health. Climate and seasonal changes cause water quality variations, in particular quality and quantity of organic matter (OM) and pH, and such variations affect Sr removal by nanofiltration (NF). The mechanisms for such variations are not clear and thus OM complexation and speciation require attention. Sr removal by NF was investigated with emphasis on the role of OM (type and concentration) and pH (2–12) on possible removal mechanisms, specifically size and/or charge exclusion as well as solute-solute interactions. The filtration results show that the addition of various OM (10 types) and an increase of OM concentration (2–100 mgC.L−1) increased Sr removal by 10-15%. The Sr-OM interaction was enhanced with increasing OM concentration, implying enhanced size exclusion via Sr-OM interaction as the main mechanism. Such interactions were quantified by asymmetric flow field-flow fractionation (FFFF) coupled with an inductively coupled plasma mass spectrometer (ICP-MS). Both extremely low and high pH increased Sr removal due to the enhanced charge exclusion and Sr-OM interactions. This work elucidated and verified the mechanism of OM and pH on Sr removal by NF membranes.

In-situ synthesis of potassium copper hexacyanoferrate−expanded graphite for effective removal of strontium from water

Radiostronium remediation is highly demanded for ecological conservation, nuclear energy sustainability, and human health. However, industrial applications of 90Sr removal adsorbents remain challenging due to the issues of efficient adsorbent exploitation and costly synthesis processes. Herein, we report a low-cost adsorbent for the removal of Sr2+ ions from water by in-situ synthesis and immobilization of potassium copper hexacyanoferrate (KCuHCF) onto expanded graphite (EG). The XRD, FTIR, SEM, and TEM results indicated that the nanoscale KCuHCF granules were homogenously distributed on EG interlayers. It showed excellent Sr2+ adsorption capacities of 6.05 mg·g−1 in water with ultralow Sr2+ concentrations and high selectivity even in the presence of various disturbing ions, including K+, Na+, Mg2+, and Ca2+ ions. The adsorption data were well-fitted by the pseudo-second-order kinetic model and the Langmuir isotherm model, suggesting the nature of heterogeneous monolayer chemisorption. Ion exchange between Sr2+ and lattice Fe2+ dominated the adsorption process. Compared with other state-of-the-art adsorbents that suffer the issues of complex and expensive synthesis processes, this work offers a facile and economical KCuHCF−EG adsorbent for the efficient removal of Sr2+ ions from radioactive wastewater.

Removal of chromium and strontium from aqueous solutions by adsorption on laterite

Removal of chromium and strontium from aqueous solutions by adsorption on laterite

A comparison of various XAD-Amberlite resins impregnated with dicyclohexyl-18-crown-6 for strontium removal

In the present study, four different varieties of Amberlite resin impregnated with dicyclohexyl-18-crown-6 were employed as an adsorbent for the selective extraction of strontium ions (Sr2+) from nitric acid solutions and dicyclohexyl-18-crown-6 impregnated in XAD-4 resin shows highest adsorption of Sr2+ from nitric acid solution. The effect of important parameters such as concentration of nitric acidic in the medium, adsorbent dosage, contact time, initial Sr (II) concentration and temperature were investigated in a batch system. The results demonstrated that the adsorption rate is high in the first 30 min and equilibrium was achieved after 300 min at 3 mol/L nitric acid medium. The results of the kinetic evaluations fit excellently with the pseudo-second-order model with a correlation coefficient R2 = 0.998. The prepared adsorbent extracts Sr (II) by following the Langmuir isotherm with a maximum adsorption capacity of 9.17 mg/g. Thermodynamic investigations indicated that the Sr (II) adsorption is an exothermic and spontaneous process. Strontium ions desorbed from resin in an acceptable percentage (98.9%) with double distilled water. In addition, the adsorption capability of the adsorbent in real water samples and also the effect of the existence of coexisting ions on the extraction of Sr (II) were assessed.