Copper Ferrocyanide Research Articles

REMOVAL OF RESIDUAL CONCENTRATIONS OF CESIUM IONS FROM LOW-LEVEL RADIOACTIVE SOLUTIONS

Because of mathematical modelling, the region of existence of the component composition of a complex inorganic sorbent designed to remove residual concentrations of cesium ions from low-level radioactive aqueous solutions was determined. The olay they limited by x1 – the number of nanoparticles of the iron oxide component from 18 to 19.5 ml, by x2 - the amount of copper ferrocyanide from 0.9 to 1.05 g, by x3 – the amount of Portland cement from 0.88 to 0.95 g. The determined concentrations of the complex inorganic sorbent provide for the removal of cesium ions from 98 to 100% and the capacity of the complex inorganic sorbent from 9 to 9.5 mg/g. According to the data on the frequencies of occurrence of the variation factors and their products in terms of their influence on the degree of cesium ion extraction from solution and the sorption capacity of the complex inorganic sorbent, they ranked in the following sequence, namely: х1х2х3>х1х2>х2х3>х1х3>х3>х2>х1. The influence of variation factors on other properties of the initial parameters is less relevant.

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.

Polymer–Zeolite Composites: Synthesis, Characterization and Application

Although the potential of natural minerals for purification of liquid radioactive wastes (LRW) from radionuclides has been widely studied, the use of hybrid polymer composites made of zeolite is still rather scarce. This article reports on the preparation of zeolite-based hybrid polymer composites using the in situ polymerization technique in the body of mineral matrix and its intercalated with copper ferrocyanide (CuFC) forms. This hybrid polymer composites have shown unique and enhanced properties for the removal of micropollutants from wasted water as compared to the individual mineral. The change in conventional properties of two mixed minerals, such as zeolite and bentonite, and their intercalated with CuFC forms were probed using techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and FT-IR analysis. The totality of analysis showed a coexistence of intercalated and percolated zeolite phases. The hybrid polymer composites exhibited both adsorption and ion-exchange properties in the removal of 134,137Cs+, 57,60Co2+ and 85Sr2+ radionuclides from LRW.

Application of alkali-activated cements for immobilization of dry low-level radioactive waste containing copper ferrocyanide

Summary: The possibility of using alkali-activated slag-Portland cement for immobilization of dry radioactive waste containing copper ferrocyanide they been confirmed. Because of optimization, the areas of existence of compositions that provide the criterion requirements for strength have been established. Introduction of magnetite additives in the amount of 14...15 wt. % (factor X1), zeolite in the amount of 6.5...7.5 wt. % (factor X2) and dry radioactive waste on the basis of copper ferrocyanide in the amount of 10...12 wt. % (factor X3) provides criterion requirements for compressive strength. The maximum value of strength – 13.2 MPa on the 28th day of hardening is characteristic for the above-mentioned quantities of additives, and it is 1.32 times higher than the standard level of strength. Introduction of zeolite for 6.5...7.5 wt. % allows to reduce the mass and density (1.07 times), radioactivity (1.09 times) of composites. Because of modelling of compound compositions, especially in the expected reactions, the factor X3 shows a weakening factor contributing to the reduction of values of output parameters. Therefore, the introduction of dry radioactive waste into the alkaline slag-Portland cement matrix containing copper ferrocyanide is limited to no more than 12 wt. %. The processes occurring in the volume of the material explain the reduction of mass, density and radioactivity of the compounds. The energy released during radioactive decay of cesium, strontium and other radionuclides is absorbed by magnetite and converted into heat. Heat promotes the removal of physically bound and partially chemically bound water from the structure of tobermorite-like low-basic calcium hydrosilicates, hydrogranates, alkaline-alkaline-earth zeolite-type hydroaluminosilicates, and copper ferrocyanide hydrate shell. However, the passage of radiolysis does not affect the kinetics of strength gain of the compounds, but contributes to the increase of their compressive strength by 1.87 times compared to the strength of the compounds on 7 days of curing

Hybrid Composite Materials for Immobilization of Radionuclides in Liquid Radioactive Waste

The biphasic hybrid composite materials for immobilization and fixation of radionuclides of the Liquid Radioactive Waste (LRW) of the research water-water reactor KIR WWR-K have been studied. It was found that the hybrid compositions have a high synergistic effect regard to the sorption of radionuclides, especially 137Cs+ and 134Cs+ . The distribution coefficient of cesium radionuclides in the composite materials are 2 times higher in comparison with the those sorption activity in the mineral matrix. It has been established that the sorption of radionuclides by two-phase hybrid compositions is carried out by a combination of three mechanisms. Firstly, due to the electrostatic binding reaction between the functional groups of sorbents and metal ions stabilized by the system of coordination bonds with electron-donating nitrogen and oxygen atoms of the amino and carbonyl groups of the polymer matrix. Secondly, as a result of ion exchange between counterions of the mineral matrix and radionuclides ions in the environmental solution. Finally, due to the superequimolar absorption of radionuclides as a result of deformation of the crystal lattice of mineral fillers of the polymer matrix of bentonite and copper ferrocyanide, which increases their pore size. It has been shown that biphasic hybrid composite materials have an increased mechanical and radiation resistance while retaining elasticity even at high doses of electron irradiation, at which in despite on a noticeable decrease the value of deformation there is no significant decline in their compressive strength. The obtained information on the mechanism of binding of biphasic hybrid composite materials with various metal ions makes it possible to synthesize new classes of materials for selective sorption of certain types of radionuclides in the body of mineral and polymer matrices. This will allow us to use these materials as a highly effective sorption materials with a synergetic effect for the detection, identification, immobilization and fixation of LRW radionuclides.

DETERMINATION OF HYDRAULIC GRAIN SIZE OF NATURAL AND ARTIFICIAL SORBENTS FOR SIMULATION OF SETTLE FACILITY

In the conditions of progressive contamination of surface sources of water supply and inefficient wastewater treatment when using existing water treatment technologies, the research problem and the justification of the use of sorption materials for the retention of specific pollutants, in particular heavy metal ions and radionuclides, is urgent. The parameters that determine the efficiency of sorbents are indicators of their sedimentation rate. The purpose of the experiments was to determine the sedimentation rate indicators for bentonite and copper ferrocyanide, build sorbent sedimentation graphs, and establish the estimated sedimentation rate of sorbents in the sedimentation tank based on the studied data considering temperature regime. Deposition of the sorbent in settling tanks occurs with the non-stop movement of water at a low speed in the direction from the inlet to the outlet. The experiments are aimed at substantiating the efficiency and criteria of a universal facility, which is able to work equally effectively with sorbents in different aggregate states. The process of sorbent sedimentation in water is characterized by the kinetics of sorbent flakes conglomerates sedimentation. These processes are displayed in the form of deposition kinetics graphs. The experiment used powdered bentonite and a solution of copper ferrocyanide, consisting of yellow blood salt and copper sulphate in a given proportional ratio. In the course of the study the following parameters were determined: the hydraulic grain size of bentonite powdery clay, the dependence of the sedimentation rate on the temperature regime. The liquid layer was divided into layers that show changes in the amount of suspended substances depending on the depth, which made it possible to determine the dimensions of the settling tank, the height of the liquid overflow, which, in turn, made it possible to conduct simulation experiments on virtual machines with a full-scale clarifier-absorber in accordance to geometric parameters.

Desorption of Ammonia Adsorbed on Prussian Blue Analogs by Washing with Saturated Ammonium Hydrogen Carbonate Solution

Prussian blue analogs (PBAs) have been reported as promising ammonia (NH3) adsorbents with a high capacity compared to activated carbon, zeolite, and ion exchange resins. The adsorbed NH3 was desorbed by heating and washing with water or acid. Recently, we demonstrated that desorption was also possible by washing with a saturated ammonium hydrogen carbonate solution (sat. NH4HCO3aq) and recovered NH3 as an NH4HCO3 solid by introducing CO2 into the washing liquid after desorption. However, this has only been proven for copper ferrocyanide and the relationship between the adsorption/desorption behavior and metal ions in PBAs has not been identified. In this study, we investigated the adsorption/desorption behavior of PBAs that are complexes of first row transition metals with hexacyanometalate anions. Six types of PBAs were tested in this study and copper ferricyanide exhibited the highest desorption/adsorption ratio. X-ray diffraction results revealed high structural stability for cobalt hexacyanocobaltate (CoHCC) and nickel ferricyanide (NiHCF). The Fourier transform infrared spectroscopy results showed that the NH3 adsorbed on the vacancy sites tended to desorb compared to the NH3 adsorbed on the interstitial sites as ammonium ions. Interestingly, the desorption/adsorption ratio exhibited the Irving-Williams order.

Structure analysis and cesium adsorption mechanism evaluation of sodium copper ferrocyanide

Structure analysis and cesium adsorption mechanism evaluation of sodium copper ferrocyanide

Синтез, структура и особенности формирования бифазных гибридных композиций на основе бентонита

The synthesis, structure and features of the formation of biphasic hybrid polymer compositions based on natural ionite (bentonite – BT), its intercalated complex (ICC) with a solid solution of copper ferrocyanide K4-хCux[Fe(CN)6] and a synthetic rare cross-linked acrylamide-acrylic acid copolymer were studied. The mechanism of formation of biphasic intercalated and percolated structures was analyzed by means of X-ray diffraction, X-ray fluorescence analysis, IR-Fourier spectroscopy and stress-strain curves. It is shown that the impregnation of the mineral bentonite filler into the polymer matrix, including its intercalated complex {BT:K4-xCux[Fe(CN)6]} is accompanied by an increase of non-uniformity of the structure of the hybrid composite material. It has been established that the main factor characterizing the deformation stability of the composite is the adhesive strength at the interface between the mineral filler and the polymer matrix. Under uniaxial tension of the P[AA-AA]{BT} composition and the percolated complex P[AA-AA]{BT:K4-xCux[Fe(CN)6]} their internal structure is rearranged resulting in stretching of agglomerates of solid fillers along polymer chains, which is determined by the adhesion force between polymer chains and mineral particles at the phase boundary. It is proposed to consider such biphasic hybrid composite materials as a promising class of interpenetrating networks with valuable applied properties.

Synthesis of hollow mesoporous silica spheres functionalized with copper ferrocyanide and its application for Cs+ removal.

In this study, the potassium copper ferrocyanide-functionalized hollow mesoporous silica spheres was successfully prepared. SEM, FTIR, XRD, EDS, and XPS techniques were used to characterize the structure of materials before and after functionalization. The synthesized functionalized hollow mesoprous silica was applied to remove cesium from aqueous solution. The applicability of the adsorbent for the removal of cesium ions was assessed and the effective parameters such as solution pH, contacting time, initial Cs+ concentration, and competitive ions effect were evaluated systematically under the batch mode. The experimental results showed that the adsorbent exhibited high Cs+ selectivity even in the highly concentrated coexisting ions solution, which makes them to be used as potential adsorbents for the removal of cesium from nuclear wastewater or contaminated groundwater.

Cationic (Basic) dye complex pigments

Abstract Cationic (or basic) dye complex pigments are classical organic pigments obtained from water-soluble cationic dyes for textiles, mainly of triarylmethine (arylcarbonium ion) types, which are precipitated using large inorganic counterions, especially those derived from heteropolyacids such as phosphotungstomolybdic acid or, to a certain extent, using the counteranion derived from copper ferrocyanide. This range of pigments includes red, violet, blue and green products, offering brilliant shades, high color strength and good transparency. They are well suited to printing ink applications, although they provide only moderate levels of fastness properties. The pigments are synthesized by treating aqueous solutions of the dyes under highly controlled conditions with solutions of the heteropolyacids, prepared in situ. The copper ferrocyanide salts are obtained by treatment of potassium ferrocyanide with sodium sulfite in water, and subsequently with solutions of the cationic dye and copper (II) sulfate. The pigments are primarily used in inks for packaging and advertising materials. However, they have little use outside printing inks. Reflex or alkali blue pigments are structurally related cationic dye derivatives which are inner salts of the dye structures and are also used in printing inks.

Method for Modification of Vermiculite with Copper Ferrocyanide for Selective Extraction of 137Cs from Liquid-salt Media

Method for Modification of Vermiculite with Copper Ferrocyanide for Selective Extraction of 137Cs from Liquid-salt Media

Copper ferrocyanide chemically immobilized onto a polyvinylidene fluoride hollow-fibre membrane surface for the removal of aqueous cesium

ABSTRACT A method of chemically bonding copper ferrocynide (CuFC) to the surface of a PVDF hollow-fibre membrane (PVDF-CuFC) was designed and the resulting PVDF-CuFC was applied to the effective removal of aqueous cesium (Cs). In order to chemically immobilize CuFC on the surface of the PVDF hollow-fibre membrane, carboxyl groups were introduced onto the membrane surface (PVDF-COOH) to peptide bond with amine groups from CuFC. The introduction of the carboxyl group onto the surface of the PVDF hollow-fibre membrane was confirmed by Fourier-transform infrared spectroscopy (FT-IR), while the immobilization of CuFC was confirmed by scanning electron microscopy with energy dispersed spectroscopy, FT-IR, and thermogravimetric analysis. The PVDF-CuFC showed higher Cs adsorption kinetics and adsorption capacity than PVDF-COOH. Moreover, as the initial pH increased, the amount of Cs adsorption by PVDF-CuFC also increased. However, the amount of Cs adsorption at pH 10 was slightly less. The applicability of PVDF-CuFC as a filter type adsorbent for the treatment of a Cs-contaminated water source is demonstrated by continuous filtration experiments.

Rational Design of Polyamine-Based Cryogels for Metal Ion Sorption.

Here we report the method of fabrication of supermacroporous monolith sorbents (cryogels) via covalent cross-linking of polyallylamine (PAA) with diglycidyl ether of 1,4-butandiol. Using comparative analysis of the permeability and sorption performance of the obtained PAA cryogels and earlier developed polyethyleneimine (PEI) cryogels, we have demonstrated the advantages and disadvantages of these polymers as sorbents of heavy metal ions (Cu(II), Zn(II), Cd(II), and Ni(II)) in fixed-bed applications and as supermacroporous matrices for the fabrication of composite cryogels containing copper ferrocyanide (CuFCN) for cesium ion sorption. Applying the rate constant distribution (RCD) model to the kinetic curves of Cu(II) ion sorption on PAA and PEI cryogels, we have elucidated the difference in sorption/desorption rates and affinity constants of these materials and showed that physical sorption contributed to the Cu(II) uptake by PAA, but not to that by PEI cryogels. It was shown that PAA cryogels had significantly higher selectivity for Cu(II) sorption in the presence of Zn(II) and Cd(II) ions in comparison with that of PEI cryogels, while irreversible sorption of Co(II) ions by PEI can be used for the separation of Ni(II) and Co(II) ions. Using IR and Mössbauer spectroscopy, we have demonstrated that strong complexation of Cu(II) ions with PEI significantly affects the in situ formation of Cu(II) ferrocyanide nanosorbents leading to their inefficiency for Cs+ ions selective uptake, whereas PAA cryogel was applicable for the fabrication of efficient monolith composites via the in situ formation of CuFCN or loading of ex situ formed CuFCN colloids.

Rapid enrichment of cesium ions in aqueous solution by copper ferrocyanide powder

In this study, copper ferrocyanide (CuFC) powder was first prepared by co-precipitation method, and the removal rate, sorption capacity and mechanism of sorption cesium on CuFC was investigated. Before and after sorption, the surface morphology and structure of CuFC were characterized systematically by the Fourier transform infrared spectrometer, the X-ray diffraction (XRD), the scanning electron microscope (SEMEDS), and the thermogravimetric analysis. Batch adsorption experiments were carried out to investigate the effects of adsorbent dose, contact time, solution pH, different initial Cs+ concentrations, temperature and the effect of competitive ions on Cs+ adsorption. The FTIR spectrum demonstrated that the product had characteristic absorption peaks such as –C≡N, Fe(II)–C≡N and C≡N–Cu(II), and the XRD spectrum was consistent with the CuFC standard spectrum, indicating that the CuFC was was synthesised successfully. And it can be seen from SEM and EDS that the adsorbent exhibits the same regular cubic crystal structure as the metal ferrocyanide. Kinetic parameters were fitted by the pseudo-second order model (R2 = 0.999), and the adsorption process by the CuFC was chemical adsorption. The adsorption isotherms data of CuFC were well-fitted to the Langmuir (R2 = 0.974). The CuFC effectively captured the Cs+ ion in the presence of K+ by the effect of competitive ions. Therefore, the CuFC could be effectively used as a potential adsorbent for Cs+ adsorption from wastewater.

Study on the immobilization of cesium absorbed by copper ferrocyanide using allophane through pressing/sintering method

The development of the Cs stable immobilization method contributes to the treatment of insoluble ferrocyanide sludge containing radioactive Cs (Cs–CuFC) generated by the Fukushima nuclear accident. Cs–CuFC begins to decompose at 200 °C, and Cs in Cs–CuFC volatilizes after being oxidized to Cs2O in air at high temperature. Therefore, Cs has an immobilization ratio of less than 4% at 1000 °C. Meanwhile, Cs–CuFC generates poisonous gases, such as HCN, NO, and NH3, and the release of HCN is suppressed in active atmosphere. For the stable immobilization of Cs, a pressing/sintering method that used allophane as an additive was examined. Allophane was mixed uniformly with Cs–CuFC in a mass ratio of 1:1, and the mixture was sintered at different temperatures to obtain solidified bodies. A stable crystal called pollucite was formed after sintering above 900 °C, and the immobilization ratio of Cs was approximately 100%. Part of pollucite was concentrated on some spots on the surface of solidified bodies. These bodies had good mechanical properties for geological storage. The leaching percentage of Cs for the solidified bodies sintered at 1100 °C in distilled water was less than 0.01% and 0.4% at 25 °C and 90 °C, respectively, thereby indicating that the solidified bodies had excellent immobilization properties and chemical stability.

Laboratory-scale studies on the removal of cesium with a submerged membrane adsorption reactor

This study developed a submerged membrane adsorption reactor system and conducted laboratory scale experiments to remove cesium using copper ferrocyanide (CuFC). The differences in cesium removal efficiency and membrane fouling by using a countercurrent two-stage adsorption (CTA) process and the conventional adsorption process were discussed. The 144 h of the continuous experiment showed that the effluent concentration remained constant with time, and the highest value of the decontamination factor approached 103. The CTA process possesses a higher concentration of suspended CuFC and a lower membrane fouling rate.

A remotely steerable Janus micromotor adsorbent for the active remediation of Cs-contaminated water.

We report the development of magnetically steerable self-propelled micromotors that selectively remove radioactive Cs from contaminated water. Mesoporous silica microspheres were functionalized with the highly Cs-selective copper ferrocyanide, and half of the adsorptive particle surface was then coated with ferromagnetic Ni and catalytic Pt layers to fabricate Janus micromotors. The micromotor adsorbent displayed random propulsion in an H2O2 solution via catalytic bubble evolution from the Pt surface, and the micromotor adsorbent self-propulsion resulted in an 8-fold higher Cs removal compared to the stationary adsorbent within one hour. The ferromagnetism of the Ni layer allowed the micromotor adsorbent to be magnetically and remotely steerable, and the propulsion speed under a magnetic field was ˜11-fold greater than it was in the absence of the magnetophoretic force. The adsorption of Cs by the self-propelling micromotor adsorbent and the subsequent magnetic recovery of the adsorbent enabled the successful removal of radioactive 137Cs from aqueous solutions. More than 98% of the radioactive 137Cs ions were removed from solution, even in the presence of competing ions, such as Na+ (1000 ppm).

Fabrication of a novel polyvinylidene fluoride membrane via binding SiO2 nanoparticles and a copper ferrocyanide layer onto a membrane surface for selective removal of cesium.

A novel polyvinylidene fluoride (PVDF) membrane was fabricated through chemical binding SiO2 nanoparticles (NPs) and copper ferrocyanide (CuFC) layers onto a membrane surface simultaneously to improve the removal efficiency of Cs. The results indicated that the SiO2 NPs were strongly deposited onto the membrane surface, and the CuFC layer was firmly attached on the surface of SiO2 NPs and the membrane. CuFC/SiO2/PVDF membrane remained stable after the acidic solution and sonication stress treatments. CuFC/SiO2/PVDF membrane showed good permeate flux and high selectivity on removal of Cs, and adsorbing capacity reached 1440.4 mg m-2 for Cs. The membrane remained high rejections of Cs in a wide pH, and could be regenerated well by H2O2 and N2H4. Selective adsorption and electrostatic interaction govern the rejection of Cs. The coexisting cations decreased the rejection of Cs mainly in accordance to the order of cations' hydration radii as K+ > Na+ > Ca2+ > Mg2+. In addition, the rejection of Cs could still reach 99.4% in 8 h in the filtration of humic acid solution and natural surface water. The membrane could removal of Cs from water effectively by directly rapid filtration, suggesting it can be applied as promising technology for radioactive wastewater treatment.

Investigation of coagulation as a pretreatment for microfiltration in cesium removal by copper ferrocyanide adsorption

An adsorption–coagulation–microfiltration (A–C–MF) hybrid process using copper ferrocyanide (CuFC) as the adsorbent was developed in this study for the removal of cesium from water. The effect of coagulant on cesium removal by CuFC adsorption was investigated. A simpler calculation method for determining the CuFC dosage was established based on the Freundlich adsorption isotherms. Although the volume of treated water was 1.32 times higher for the A–C–MF process than the adsorption–microfiltration (A–MF) process, the cake layer and membrane pore resistances in the former were both lower than those in the latter due to the coagulation process.