Metal Ferrocyanides Research Articles

Regularities of cesium sorption by fibrous sorbents based on transition metal ferrocyanides

Regularities of cesium sorption by fibrous sorbents based on transition metal ferrocyanides

Magnetic hierarchical titanium ferrocyanide for the highly efficient and selective removal of radioactive cesium from water

Selective adsorption is the most suitable technique for eliminating trace amounts of 137Cs from various volumes of 137Cs-contaminated water, including seawater. Although various metal ferrocyanide (MFC)-functionalized magnetic adsorbents have been developed for the selective removal of 137Cs and magnetic recovery of adsorbents, their adsorption capacity for Cs remains low. Here, magnetic hierarchical titanium ferrocyanide (mh-TiFC) was synthesized for the first time for enhanced Cs adsorption. Hierarchical TiFC, comprising 2-dimensional TiFC flakes, was synthesized on SiO2-coated magnetic Fe3O4 particles using a sacrificial TiO2 shell as a source of Ti4+ via a reaction with ferrocyanide under acidic conditions. The resultant mh-TiFC exhibited the highest maximum adsorption capacity (434.8 mg g−1) and enhanced Cs selectivity with an excellent Kd value (6,850,000 mL g−1) compared to those of previously reported magnetic Cs adsorbents. This enhancement was attributed to the hierarchical structure, which reduced intracrystalline diffusion and increased the surface area available for direct Cs adsorption. Additionally, mh-TiFC (0.1 g L−1) demonstrated an excellent removal efficiency of 137Cs exceeding 99.85% for groundwater and seawater containing approximately 22 ppt 137Cs. Therefore, mh-TiFC offers promising applications for the treatment of 137Cs-contaminated water.

New Sorbents Based on Polyacrylonitrile Fiber and Transition Metal Ferrocyanides for 137Cs Recovery from Various Composition Solutions

For the first time, new sorbents based on polyacrylonitrile (PAN) fiber and transition metal ferrocyanides were obtained. The main difference between the obtained sorbents and the existing ones is the stage of preliminary preparation of the initial support by converting it into the forms PAN-Fe(OH)3 or PAN-MnO2, due to which additional ion exchange groups (carboxyl, carbonyl, etc.) are formed, which increases the amount of ferrocyanide fixed to the support. The best components and conditions for the synthesis of new sorbents were determined (concentration (0.1–0.2 mol/L), as well as pH (1 for sorbents based on PAN-Fe(OH)3, and 1–5—PAN-MnO2) of potassium ferrocyanide solution, concentration of transition metal salts (0.02 mol/L), temperature conditions). The influence of the studied solution composition (pH, concentration of Na+, K+, NH4+ ions) on the cesium distribution coefficients during its recovery by the obtained sorbents was assessed. The possibility of cesium recovery from solutions with pH 1–9 containing macro quantities of cations was demonstrated. The sorbents derived were characterized by modern structural methods such as infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy with EDS analysis. A study of the trace amount sorption of 137Cs was carried out in comparison with commercially available highly efficient sorbents (FNS-10 and Termoksid-35), and it was shown that the resulting sorbents are not inferior to industrial ferrocyanide sorbents and can be used for 137Cs selective sorption from technological solutions and natural waters.

Sugarcane bagasse decorated by metal (Fe3+/Cu2+) ferrocyanide for effective removal of cesium from aqueous solutions

In this work, we convert the biowaste materials (sugarcane bagasse) into wealth materials via combination with metal ferrocyanide through two steps to prepare (SCB-M-FC) composite for cesium removal from aqueous solutions. Firstly, SCB was modified to be amino silane (SCB-NH2) to provide amine binding sites. Secondly, the metal (M = Fe3+or Cu2+) ferrocyanide (FC) nanomaterials grow in situ on the surface of the modified -SCB to yield SCB-M-FC. Various techniques were used to characterize the prepared composite materials before and after the adsorption of cesium. The adsorption behavior of Cs+ by SCB, SCB-NH2, and SCB-M-FC under different conditions was studied and compared. We observed that the SCB-Cu-FC presents the experimental adsorption capacity for Cs+ (126.0 mg/g). Additionally, dynamic system for cleaning cesium from polluted water was also investigated. The excellent selective removal of Cs by SCB-M-FC was escorted by the liberation of K+ and diffusion mechanisms. The SCB-Cu-FC nanocomposite was found to be appropriate for the practical removal of cesium from contaminated aqueous solution.

Estimation of 137Cs Distribution and Recovery Using Various Types of Sorbents in the Black Sea Surface Layer

Monitoring 137Cs in seawater is necessary for the timely detection of radioactive contamination. The possibility of sorption and the sorption efficiency of 137Cs from seawater were studied for the first time during several cruises of the R/V (research vessel) Professor Vodyanitsky using various types of sorbents based on transition metal ferrocyanides (Anfezh, Niket, Uniket, FSS, FD-M, FIC, Termoxid 35, NKF-C) and zirconium phosphate (Termoxid 3A). The influence of the seawater flow rate and volume of the sorbent used for the recovery of 137Cs was estimated. The ferrocyanide sorbents Niket, Uniket, Termoxid 35, and FIC showed the best sorption efficiency (60–100%) at a seawater flow rate of 2–4 column volumes per minute. The data obtained during three cruises on the R/V Professor Vodyanitsky were analyzed. A detailed (28 sampling points) spatial distribution of 137Cs in the Black Sea along the southern coast of Crimea was studied using the sorbents that showed the best characteristics. An increase in 137Cs activity in the study area was not found, and the average activity was 9.01 ± 0.87 Bq/m3.

A highly efficient metal ferrocyanide adsorbent based on zinc phytate for cesium removal

Human health and sustainable development of nuclear energy pose new challenges for cesium removal. Herein, exploiting a novel metal ferrocyanides (MFCs) adsorbent is highly desirable for efficiently eliminate Cs+ from contaminated water. Based on zinc phytate (Zn-PA), the newly synthesized hybrid material of ZnFC-PA exhibits top-class adsorption capacity (qm = 559.76 mg/g) and excellent stability in a wide range of pH. The rapid adsorption kinetics and superior selectivity in the existence of numerous competing ions confirm the outstanding performance for cesium separation. Furthermore, the adsorption performance is roughly static after several cycles, and the distribution coefficient Kd still remains at a high level (3.3 × 104 mL/g) even in practical geothermal water. The excellent adsorption performance and reusability make it a promising Cs+ adsorbent to remediate the environment.

Synthesis of N-Bases from Primitive Earth Gases in presence and absence of Metal Ferrocyanides

The action of heat on Acetylene, Ammonia and Water vapour in presence and absence of metal ferrocyanides at 90±5°C under simulated sea beach conditions has been investigated for the plausible formation of nucleic acid bases. Paper chromatography (PC) and High-Performance Liquid Chromatography (HPLC) analysis of the reaction concentrate heated up to 200hrs revealed purine and pyrimidine bases viz. cytosine, uracil, adenine, thymine and hypoxanthine were formed and confirmed with the data of authentic samples.

Synthesis of Inorganic Compounds in the Matrix of Polysaccharide Chitosan.

Data related to the fabrication of hybrid materials based on the polysaccharide chitosan were systematized and reviewed. The possibility of using chitosan as a “host” matrix for in situ synthesis of inorganic compounds for the preparation of various types of composite materials were investigated. Coprecipitation of metal oxides/hydroxides (Fe, Ni, Al, Zr, Cu and Mn) with chitosan was carried out through the alkalinization of solutions containing metal salts and chitosan, with the addition of ammonia or alkali solutions, homogeneous hydrolysis of urea, or electrophoretic deposition on the cathode. The synthesis of transition metal ferrocyanides and hydroxyapatite was achieved from precursor salts in a chitosan solution with simultaneous alkalinization. The mechanism of composite formation during the coprecipitation process of inorganic compounds with chitosan is discussed. Composite materials are of interest as sorbents, coatings, sensors, and precursors for the production of ceramic and electrode materials.

Remediation of cesium-contaminated fine soil using electrokinetic method

In this study, electrokinetic remediation equipment was used to remove cesium (Cs) from clay soil and waste solution was treated with sorption process. The influence of electrokinetic process on the removal of Cs was evaluated under the condition of applied electric voltage of 15.0-20.0 V. In addition to monitoring the Cs removal, electrical current and temperature of the electrolyte during experiment were investigated. The removal efficiency of Cs from soil by electrokinetic method was more than 90%. After electrokinetic remediation, Cs was selectively separated from soil waste solution using sorbents. Various adsorption agents such as potassium nickel hexacyanoferrate (KNiHCF), Prussian blue, sodium tetraphenylborate (NaTPB), and zeolite were compared and KNiHCF showed the highest Cs removal efficiency. The Cs adsorption on KNiHCF reached equilibrium in 30 min. The maximum adsorption capacity was 120.4 mg/g at 0.1 g/L of adsorbent dosage. These results demonstrated that our proposed process combined electrokinetic remediation of soil and waste solution treatment with metal ferrocyanide can be a promising technique to decontaminate Cs-contaminated fine soil.

Synthesis of potassium metal ferrocyanide/Al-MCM-41 with fast and selective adsorption of cesium

In this work, low-cost and non-toxic diatomite was used as the silicon source and aluminum source to synthesize Al doped MCM-41 (Al-MCM-41), and Cs+ adsorbents has been prepared by immobilizing the potassium metal ferrocyanide (KMeFC, Me = Cu2+, Ni2+, Zn2+, Co2+, and Fe3+) on Al-MCM-41. The adsorbents have high surface area from 471.7 to 685.8 m2 g−1, and their Cs+ adsorption performance has been detailed investigated. The max Cs+ adsorption capacity is 1.1602 mmol g−1, 1.092 mmol g−1, 0.8174 mmol g−1, 0.6973 mmol g−1, and 0.4541 mmol g−1 for KZnFC/Al-MCM-41, KNiFC/Al-MCM-41, KCoFC/Al-MCM-41, KCuFC/Al-MCM-41, and KFeFC/Al-MCM-41, respectively. The KZnFC/Al-MCM-41 presents the highest adsorption capacity, and it can reach adsorption equilibrium with 10 min. The pH experiment results show the KZnFC/Al-MCM-41 can keep a higher adsorption capacity in pH range from 2 to 11. What more, the KZnFC/Al-MCM-41 present good adsorption selectivity against to K+, Na+, Ca2+, and Mg2+. The adsorption mechanism was also discussed, and the adsorption results show the adsorption process of Cs+ by KMeFC/Al-MCM-41 conforms to pseudo-second-order kinetics and Langmuir isotherm adsorption model, and the thermodynamic experiments confirmed the adsorption process of Cs+ by KMeFC/Al-MCM-41 are endothermic and spontaneous. The FT-IR, XRD, and XPS of KZnFC/Al-MCM-41 before and after adsorption of Cs+ inferred that the adsorption process of the adsorbents mainly completed by the exchange between Cs+ and K+. This work provide a novel strategy to synthesis of KZnFC/Al-MCM-41 in low-cost and green route, and the adsorbent as-synthesized in this work is an efficient candidate for removing or extracting Cs+ from radioactive wastewater and mineral resources.

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.

Chitosan-based biosorbents: immobilization of metal hexacyanoferrates and application for removal of cesium radionuclide from aqueous solutions

Composite M (M—Cu, Ni) potassium ferrocyanide chitosan-based materials were prepared via co-precipitation methods using chitosan as a matrix for adsorption of cesium from alkaline solutions. The materials were fabricated using a suspension or in situ formation of ferrocyanides of transition metals in a chitosan matrix with simultaneous chitosan deposition. The synthesis products were characterized by the methods of scanning electron microscopy with energy-dispersive analysis (SEM–EDX) and X-ray diffraction (XRD). In the process of sorption of radiocesium from alkaline solutions under static conditions, the stability of composite sorbents compared with the pristine powders of transition metal ferrocyanides was estimated. The boundary values of the pH and time, at which the destruction of the composite sorbent is observed, are determined. The stabilizing effect of chitosan on the resistance of Ni-K ferrocyanide (FCN) complexes in alkaline mineralized solutions has been shown on the example of Ni-K FCN/chitosan composite sorbents.

Effect on Cs removal of solid-phase metal oxidation in metal ferrocyanides

Abstract Metal ferrocyanides (MFCs) have been studied for many years and are regarded as efficient adsorbents for the selective removal of radioactive cesium (Cs) from contaminated aqueous solutions. Although their efficiency has been demonstrated, various investigations on the physicochemical, thermal, and radiological stability of the solids of MFCs are required to enhance the applicability of MFCs in the treatment process. We observed that the Cs adsorption efficiencies of cobalt and nickel ferrocyanides decreased as their aging period increased, while the Cs adsorption efficiencies of copper and zinc ferrocyanides did not decrease. The tendencies of these ferrocyanides were accelerated by exposure of the solids at a higher temperature for a longer time. Our comprehensive analyses demonstrated that only the oxidizable metals in the MFCs can be oxidized by aging time and increasing temperature; also, this affects the Cs removal efficiency by decreasing the exchangeable sites in the solids. The chemical stability of MFCs is very important for the optimization of the synthesis and storage conditions.

First-principles modeling of metal (ii) ferrocyanide: electronic property, magnetism, bulk moduli, and the role of C ≡ N− defect

The ferrocyanide structures of transition metals (M) Ti2+, Cr2+, Mn2+, or Co2+ are investigated using a first-principles modeling approach. The crystal structure of cobalt ferrocyanide is found to resemble previous experimental data with good accuracy (~1% error). The considered porous structures possess magnetic moments of 8.00 µB/cell, 8.00 µB/cell, 4.00 µB/cell, and 4.00 µB/cell given by the [TiFe(CN)6]2−, [CrFe(CN)6]2−, [MnFe(CN)6]2−, and [CoFe(CN)6]2− frameworks, respectively. There is only one spin-state occupation at the Fermi level, which leads to the conclusion of semi-metallicity of the four structures. To verify the reliability of the electronic and magnetic properties, linear-response DFT + U calculations are performed and establish excellent agreement with the conventional DFT calculations. Then, the mechanical strength is evaluated by estimating the bulk moduli of the four structures, which fall in the range of 114 GPa–133 GPa. Upon the consideration of one C ≡ N− linker defect, the magnetic moments of cobalt ferrocyanide and manganese ferrocyanide rise dramatically to 8 µB/cell, while that of the titanium structure drops to 6 µB/cell. In light of the electronic structure evidence, we believe that the low-spin Fe cation nearby the C ≡ N− defect has an indirect effect on spin polarization of the four Co cations in the unit cell.

Development and Evaluation of Adsorption Block of Radiocesium

The removal of radioactive cesium from water solutions with some concrete blocks was investigated. When the concrete blocks were prepared by mixing zeolites, the ability of holding and transmitting water was greatly increased. The cesium ions were adsorbed to a certain extent in these concrete blocks. Moreover, when the mixtures of zeolite and metal ferrocyanide were used, the radioactive cesium could be highly removed. In particular, the residual rate of cobalt ferrocyanide was attained to 90% or above.

Effect of the chemical nature of different transition metal ferrocyanides to entrap Cs

Transition metal ferrocyanides are used since many years to selectively entrap radio-cesium from nuclear contaminated effluents. We investigate the cesium sorption properties on a series of ferrocyanides containing different transition metal ions (Ni2+, Co2+ and Cu2+) and outline the role of the chemical nature of the bivalent metal ion, the iron oxidation state, the presence of K+ in the structure and the grain size of the powders on the equilibrium time and efficiency of the Cs+ sorption.

Removal of p-aminophenol and p-nitrophenol from aqueous solution through adsorption on bismuth, lead, and manganese ferrocyanides and their relevance to environmental issues

Removal of p-aminophenol (PAP) and p-nitrophenol (PNP) from aqueous solution have been studied through adsorption on bismuth, lead and manganese ferrocyanides (125 μm British Sieve Standard mesh size) at pH range 1.0–10.0 and room temperature (27 ± 1°C). The progress of adsorption was followed spectrophotometrically by measuring the absorbance of PAP and PNP solutions at their corresponding λmax = 220 and 330 nm, respectively. At neutral pH, PNP was found to more adsorbed than PAP on all three metal ferrocyanides studied. Manganese ferrocyanide and bismuth ferrocyanide were found to have maximum and minimum adsorption, respectively for both adsorbents. The adsorption followed the Langmuir type of adsorption in the concentration range of 10−4 to 10−5 mol/L of PAP and PNP solutions.

The use of composite ferrocyanide materials for treatment of high salinity liquid radioactive wastes rich in cesium isotopes

Abstract The use of composite materials based on metal ferrocyanides combined with natural mineral sorbents for treatment of high salinity Cs-containing liquid radioactive waste (LRW) was investigated. The study indicated that among the investigated composites, the best sorption characteristics for Cs were shown by materials based on copper ferrocyanide. Several factors affecting the removal of cesium from LRW, namely total salt content, pH and organic matter content, were also investigated. High concentrations of complexing organic matter significantly reduced the sorption capacity of ferrocyanide sorbents.

Highly efficient removal of 137Cs in seawater by potassium titanium ferrocyanide functionalized magnetic microspheres with multilayer core–shell structure

Transition metal ferrocyanides were deposited on silica encapsulated magnetite particles for the effective decontamination of radiocesium.

Sorption of cesium radionuclides with composite carbon fibrous materials

Sorption of composite sorbents produced by a combined method of thermal treatment and electrochemical and chemical deposition of transition metal ferrocyanides stabilized with latex emulsions onto a fibrous carbon matrix for cesium radionuclides was studied.