Potassium Copper Hexacyanoferrate Research Articles

Fabrication of magnetite/GO/potassium copper hexacyanoferrate nanocomposite for removal of radioactive cesium ions

Metal hexacyanoferrates (MHCF) are a class of inorganic adsorbents used for wastewater management due to the presence of interstitial sites for capturing heavy metal ions. In present work, we are reporting the synthesis of magnetic nanocomposite of Fe3O4/graphene oxide/potassium copper hexacyanoferrate via wet chemical and coprecipitation approach. Potassium copper hexacyanoferrate (KCuHCF) and Graphene oxide (GO) both are marvelous adsorbents but their nano-size becomes a major obstacle in their separation process after the adsorption of the radionuclides. Thus, our synthesized nanocomposite Fe3O4/GO/KCuHCF enhances the recovery of KCuHCF even after radioactive Cs+ adsorption with adsorption capacity of 18 mg g−1 coinciding well with the Langmuir adsorption isotherm mechanism. The synthesized adsorbent is characterized thoroughly using UV–Visible spectroscopy, FT-IR, TGA, XPS, Raman spectroscopy, TEM-EDAX and XRD. This synthesized nanocomposite is used for the batch extraction of radioactive Cs+ from low level radioactive waste (LLW). The extraction kinetics followed pseudo-second-order kinetics mechanism.

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.

High-efficiently and rapidly capturing cesium from water with Prussian blue@expanded graphite as adsorbent

The removal of radioactive 137Cs from nuclear wastewater is still needed to mitigate their high radiological toxicity to living creatures. However, the industrial application of adsorbents is still challenging owing to the complex and costly preparation and slow adsorption rate for Cs wastewater with low concentration. Herein, cost-effective and fast removal of Cs+ is achieved by vermiform expanded graphite (EG) immobilized with potassium copper hexacyanoferrate (KCuHCF) via the in-situ synthesis method. We revealed that the nano-scale KCuHCF granules are dispersed homogeneously on the EG interlayers. With this design, it achieves an excellent Cs removal capacity of 16.24 mg/g within 30 min in ultralow Cs concentration and shows high selectivity among various competing ions. We systematically studied the associated adsorption mechanism by XPS and ICP, which revealed that ion exchange between the lattice K and Cs played critical roles. Our work paves the way for the design of economical adsorbents for radioactive Cs remediation.

Cation Co-intercalation in Potassium Copper(II) Hexacyanoferrates.

The cation-insertion solid state electrochemistry of a potassium copper(II) hexacyanoferrate in contact with LiClO4 /DMSO, NaPF6 /DMSO, and KPF6 /DMSO electrolytes has been theoretically and experimentally studied using the voltammetry of immobilized particles methodology. Voltammetric data, combined with SEM/EDS analysis permit to determine a K0.876 CuII 1.328 FeIII 0.049 [FeIII 0.318 FeII 0.682 (CN)6 ] stoichiometry for the synthesized solid. Separation of electronic and ionic contributions to Gibbs energy changes can be made based on cyclic voltammetric and open circuit potential measurements. These parameters can be combined to measure values of the Gibbs energy of cation-independent electron transfer of 7.2±0.4 (K+ ), 7.1±0.5 (Na+ ) kJ mol-1 , in close agreement with the expected independence of this parameter on the electrolyte cation. The reduction Fe(III) centers bound to cyano groups exhibit a cation-dependent, essentially Nernstian character which can be described in terms of Na+ and K+ insertion/deinsertion while in the case of Li+ electrolytes there is significant co-cation diffusion. Chronoamperometric data provide estimates of the diffusion coefficients of Na+ , and K+ ions through the solid around 10-9 cm2 s-1 .

High-density immobilization of potassium copper hexacyanoferrate in poly(acrylic acid)/laponite hydrogel for enhanced Cs+ removal

As the risk of radioactive waste generated in large quantities is emerging, rapid and selective removal and decontamination of cesium ions (Cs+) from nuclear waste have become a significant issue for environmental protection and human health. Herein, a novel potassium copper hexacyanoferrate (KCuHCF)-embedded poly(acrylic acid)/laponite (PAAc/Lap-HCF) hydrogel has been developed by a facile and low-cost fabrication route for highly effective and selective Cs+ adsorption. The diffusion-derived KCuHCF formation in the nanocomposite hydrogel via layer-by-layer (LBL) assembly can facilitate the preservation of the 3D-interconnected hydrogel structure and the dispersion of KCuHCF particles, which contribute to high-density immobilization of stable KCuHCF (~57.73 wt%) in the matrix. The adsorbent shows enhanced Cs+ removal properties in terms of fast kinetics (>90% removal for 20 mg/L of Cs+ within 1 h), stability (>115 mg/g in wide pH value of 2–11), high adsorption capacity (146.22 mg/g) and selectivity (Kd = 1.3 ×105 mL/g, 1 mg/L Cs+ in highly competitive seawater). Such excellent characteristics with fast kinetics are mainly due to the high ion accessibility from the inherent nature of hydrogels and the highly loaded KCuHCF particles in the composites. The adsorption kinetics and isotherm obey the pseudo-second-order model and the dual-site Langmuir adsorption model, respectively. This nanocomposite hydrogel prepared in our work shows enhanced performance on removal of Cs+ in aqueous solution, which has a good application prospect in treating radioactive wastewater.

Graphene oxide/chitosan/potassium copper hexacyanoferrate(II) composite aerogel for efficient removal of cesium

Efficient removal of 137Cs from various radioactive wastewater and contaminated environment is much meaningful for nuclear energy sustainable development and public health. Herein we used chitosan (CS) to induce the self-assembly of graphene oxide (GO) into a hydrogel (GO/CS) possessing a three-dimensional macroporous structure and produced a type of ternary composite hydrogel/aerogel named GO/CS/Cu-PBA by in situ growing potassium copper hexacyanoferrate(II) (Cu-PBA) nanoparticles onto the GO/CS via simple leaching. The adsorption behaviors of Cs+ by GO, Cu-PBA, and GO/CS/Cu-PBA in various matrice was systematically studied and compared. It was found that the GO/CS/Cu-PBA exhibited satisfactory sorption capacity for Cs+ (64.7 mg/g) and ultrafast kinetics. In addition, a fixed-bed column system could be employed for the cleanup of Cs+ from contaminated groundwater. Further FT-IR, XRD, XPS, and EXAFS analyses clarified the interaction mechanism between Cs+ and GO/CS/Cu-PBA. Highly selective fixation of Cs+ by Cu-PBA was accompanied by the release of K+/Cu2+ and a crystalline phase transition. The adsorption of Cs+ by GO was mainly correlated with the electrostatic attraction by –COO− and C-OH groups. The confinement of Cu-PBA by GO/CS aerogel is of much potential for the practical treatment of cesium-containing radioactive wastewater.

High-Density Immobilization of Potassium Copper Hexacyanoferrate in Poly(Acrylic Acid)/Laponite Hydrogel for Enhanced Cs+ Removal

High-Density Immobilization of Potassium Copper Hexacyanoferrate in Poly(Acrylic Acid)/Laponite Hydrogel for Enhanced Cs+ Removal

Polydopamine-coated magnetic montmorillonite immobilized with potassium copper hexacyanoferrate for selective removal of Cs+ and its facile recovery

To address the challenges in remediating cesium contaminated aqueous environments, a low-cost, magnetically recoverable and superior composite adsorbent was fabricated based on the concept of magnetizing montmorillonite and entrapping potassium copper hexacyanoferrate that offers excellent selectivity for Cs+. The facile, green and scalable synthesis route involved exchanging the interlayer ions of montmorillonite with ferrous ions before oxidizing to form magnetic montmorillonite using a low-temperature hydrothermal method. The composite was then coated with polydopamine to be complexed with copper ions and subsequently reacted with the hexacyanoferrate precursor to in situ grow potassium copper hexacyanoferrate nanoparticles, thus forming the composite, D-Mt-Mag-HCF. The adsorbent exhibited excellent Cs+ sorption capacity (~159.2 mg/g) and Cs+ selectivity greater than 8.2 × 104 mL g−1 in concentrated brine. Moreover, the magnetic properties (17.4 emu/g) of the adsorbent facilitated its separation from contaminated aqueous environments once the adsorbent had removed Cs+. The current study demonstrates a novel and scalable production of a composite adsorbent that can be readily used to remediate contaminated water.

Selective removal and immobilization of cesium from aqueous solution using sludge functionalized with potassium copper hexacyanoferrate: a low-cost adsorbent

Selective removal and immobilization of cesium from aqueous solution using sludge functionalized with potassium copper hexacyanoferrate: a low-cost adsorbent

Urushiol-resourced dopamine analogue as a trigger to construct clay-hexacyanoferrate hydrogel for cesium removal

To guarantee the sustainable development of the nuclear industry, it is vital to have a low-cost, green, and scalable route developed to synthesize efficient adsorbents for rapid and effective remediation of nuclide-contaminated water. In this study, a natural catechol derivative with unsaturated alkyl chain, urushiol, was aminated by mildly thiol-ene click with cysteamine to form a dopamine analogue, which can self-polymerize and trigger the formation of silicate plates into hydrogel framework and in-situ immobilize the potassium copper hexacyanoferrate, an efficient adsorbent, when hexacyanoferrate and excess Cu2+ were present in the silicate suspension. The chelation between Cu2+, poly-urushiol and hexacyanoferrate that assemble the hybrid hydrogel was confirmed by SEM and XPS and the performance of this hydrogel was evaluated in terms of adsorption capacity (214 mg g−1), selectivity (Kd>106 mg L−1), kinetics and reversible self-healing behavior with pleasing results obtained. The economic and nature-sourced property of the urushiol offers a green and novel concept to develop a satisfying adsorbing system for Cs+ removal.

Densification of non-radioactive porous siliceous particles loaded with cesium potassium copper hexacyanoferrate by spark plasma sintering

In the development of a conditioning process for cesium-bearing sorbents from the decontamination of aqueous waste streams, the treatment of a granular material composed of (Cs,K)2CuFe(CN)6 loaded onto mesoporous silica particles has been investigated in an additive-free two-step conditioning process involving (i) calcination at 1000 °C to remove volatile species and (ii) densification by spark plasma sintering. A 92.0 % dense pellet was obtained after 10 min sintering at 850 °C under 100 MPa. Density and microstructural measurements indicate that densification is first driven by the viscous flow of a vitreous phase containing Cs, formed during calcination. The density of the sample then increases further during sintering by grain boundary diffusion. However, a limited but non negligible part of cesium is lost during densification.

Adsorptive removal of cesium by electrospun nanofibers embedded with potassium copper hexacyanoferrate

As the risk of radioactive waste generated in large quantities is emerging, rapid and selective cesium ion decontamination has become a significant issue for waste volume reduction. This study demonstrates a novel immobilization strategy to synthesize a composite adsorbent embedding potassium copper hexacyanoferrate (KCuHCF) for effective cesium ion separation. Through an electrospinning technique, a nanofiber matrix was fabricated from a polymer blended with poly-vinyl alcohol and sodium alginate, and in situ immobilization of KCuHCF was achieved via the coordination effect of carboxylate functionality. The immobilized KCuHCF nanoadsorbent content and uniformity were optimized by controlling the ratio of the polymers, which was systematically analyzed through electron microscopy and spectroscopic analyses. The composite adsorbent in the batch experiment exhibited a high adsorption capacity of 114 mg g−1 and selectivity for cesium showing distribution coefficients on the order of 104–105 mL g−1, even under seawater conditions where large amounts of competitive cations coexist. A membrane filtration experiment using the composite as a membrane at a pressure of 2 bar showed efficient decontamination by removing 180 mg cesium per 1 m2 with a high flux of about 148 L m−2 h−1. Thus, the deposition of KCuHCF nanoadsorbent on the surface of the nanofiber and the adsorption filtration method could be a practical alternative in the radioactive wastewater treatment.

Functionalized geopolymer foams for cesium removal from liquid nuclear waste

Geopolymer foam hosting a 3D network of interconnected pores was synthetized and functionalized with a potassium copper hexacyanoferrate [K2CuFe(CN)6] in order to decontaminate radioactive liquid waste containing cesium. The Geopolymer Foam (GF) and Functionalized Geopolymer Foams (FGF) were characterized using a panel of characterization techniques (SEM, TEM, XRD …) before studying their capacity to remove selectively cesium from the solution. K2CuFe(CN)6 homogeneously precipitates on the pore walls of the foam and into the mesoporous network. Exploiting kinetic and adsorption isotherms in various solutions (deionized water, fresh water and fresh water with excess of sodium), a comparative study between the GF and FGF was undertaken. In presence of competitive ions into the solution, the capacity of both materials decreases with respect to the deionized water. The mechanism of exchange is Na+ ↔ Cs+ and K+ ↔ Cs+ for GF and FGF respectively. Although the GF material presents some very high performances in term of ion exchange, in excess of sodium ions, the GF material completely loses its capacity with respect to the FGF that remains constant up to 1 mol/l−1. FGF is therefore very selective with regard to the cesium if other cations coexist into the solution. This is also confirmed by experiments performed in radioactive environment for very low concentration of radioactive cesium where the distribution coefficient (Kd) for the FGF reaches in average 3.5 105 ml g−1 that is ten times higher than for the GF material.

Practical Aqueous Calcium-Ion Battery Full-Cells for Future Stationary Storage

There is a pressing need for high rate cycling, and cost-effective stationary energy storage systems in concomitance with the fast development of solar, wind and other types of renewable sources of energy. Aqueous rechargeable Ca-ion batteries have the potential to meet the growing demands of stationary energy storage devices because of their natural abundance, safety, low-cost proposition and higher volumetric capacity. In this study, a low cost, safe aqueous Ca-ion battery based on low potential, lower specific weight in-situ polymerized polyaniline as an anode and a high redox potential open framework structured potassium copper hexacyanoferrate as a cathode is demonstrated. The charge-discharge mechanism of this battery include dopind/dedoping of NO3- at the anode and intercalation and deintercalation of Ca-ion at the cathode. This Ca-ion battery works successfully in 2.5 M Ca(NO3)2 aqueous electrolyte, exhibiting 70 Wh kg-1 specific energy at 250 W kg-1 and even maintains 53 Wh kg-1 at 950 W kg-1 attributing to a good rate capability. At 0.8 A g-1 the battery provides an average specific capacity of 130 mAh g-1, exhibiting high Coulombic efficiency (~ 96%), with 95% capacity retention over 200 cycles life span, acquiring a new achievement in the electrochemical performance of aqueous Ca-ion batteries. Furthermore, the calcium-ion storage mechanism is investigated using high-end XANES and EXAFS measurements. Thus, this significant electrochemical performance of anode and cathode makes the battery as a promising candidate for grid-scale storage applications.

Effective removal of cesium from wastewater via adsorptive filtration with potassium copper hexacyanoferrate-immobilized and polyethyleneimine-grafted graphene oxide

As an attractive alternative to radioactive cesium removal, we introduced an adsorptive filtration method using a composite membrane consisting of potassium copper hexacyanoferrate (KCuHCF) and graphene-based support. Polyethyleneimine-grafted reduced graphene oxide (PEI-rGO), used as an immobilizing matrix, was effective not only in distributing KCuHCF inside the composite with the aid of abundant amino-functionality, but also in achieving high water flux by increasing the interlayer spacing of the laminar membrane structure. Due to the rapid and selective cesium adsorption properties of KCuHCF, the fabricated membrane was found to be effective in achieving complete removal of cesium ions under a high flux (over 500 L m−2 h−1), which is difficult in a conventional membrane utilizing the molecular sieving effect. This approach offers strong potential in the field of elimination of radionuclides that require rapid and complete decontamination.

Structural effects of calcination on Cs-exchanged copper hexacyanoferrate (Cs,K)2CuFe(CN)6 loaded on mesoporous silica particles

Porous silica particles functionalized by potassium copper hexacyanoferrate (KCu-HCF@silica) are investigated as selective sorbents to remove radioactive cesium from contaminated effluents. This article reports the thermal behavior of Cs:KCu-HCF@silica particles at the laboratory scale, in view of developing hot isostatic pressing processes to compact the Cs-loaded particles into dense waste forms. The data show that the spent particles cannot be hot-pressed directly because the release of volatile compounds does prevent compaction. Preliminary calcination in air leads to (i) the decomposition of Cs:KCu-HCF, (ii) the closure of the mesopores of silica and a reduction in the particles’ specific surface area, (iii) the crystallization of silica into cristobalite, all without significant Cs loss. This retention of Cs is due to the in-situ formation of a Cs based silicate glass with the siliceous particles.

Elimination of Cs+ from aquatic systems by an adsorbent prepared by immobilization of potassium copper hexacyanoferrate on the SBA-15 surface: kinetic, thermodynamic, and isotherm studies.

For elimination of cesium from aqueous solutions, mesoporous SBA-15 was synthesized and employed as the support for immobilization of potassium copper hexacyanoferrate. The synthesized adsorbent was characterized by various techniques and was used for adsorption of cesium. The results indicated that its adsorption capacity was 174.80mg/g and superior to many studied adsorbents. The adsorbent represented good selectivity in the presence of some studied co-existing. The Temkin, Redlich-Peterson, Sips, Langmuir, and Freundlich isotherm models were used to evaluate the experimental data. The error analysis performed by EABS, ERRSQ, and HYBRID methods showed that the data was in good agreement with the Langmuir model indicating that the process was monoenergetic and the uptake of cesium forwarded through monolayer process. The pseudo-second-order model was recognized as the adequate model to describe the kinetic data of the adsorption process. The adsorption process was endothermic and spontaneous. The regeneration tests revealed that the adsorbent retained most of initial capacity after recovery.

Integrated submerged membrane distillation-adsorption system for rubidium recovery

Seawater reverse osmosis (SWRO) brine management is essential for desalination. Improving brine recovery rate with resource recovery can enhance the overall desalination process. In this study, an integrated submerged membrane distillation (S-MD) with adsorption (granular potassium copper hexacyanoferrate (KCuFC)) was evaluated for improving water recovery from brine while extracting valuable Rb. The thermal S-MD process (55 °C) with a continuous supply of Rb-rich SWRO brine enabled Rb to be concentrated (99% rejection) while producing fresh water. Concentrated Rb in thermal condition enhanced Rb extraction by granular KCuFC. An optimum dose (0.24 g/L) KCuFC was identified based on 98% Rb mass adsorption (9.78 mg as Rb). The integrated submerged MD-adsorption system was able to achieve more than 85% water recovery and Rb extraction in continuous feed supply (in two cycles). Ca in SWRO brine resulted in CaSO4 deposition onto the membrane and surface of KCuFC, reducing recovery rate and Rb adsorption. MD water recovery significantly improved upon Ca removal while achieving a total of 6.65 mg of Rb extraction. In comparing the performance of different KCuFC forms (granular, particle and powder), the particle form of KCuFC exhibited 10–47% higher capacity in terms of total adsorbed Rb mass and adsorption rate.

Highly Reversible and Rechargeable Safe Zn Batteries Based on a Triethyl Phosphate Electrolyte.

Zinc metal is an attractive anode material for next-generation batteries. However, dendrite growth and limited Coulombic efficiency (CE) during cycling are the major roadblocks towards the widespread commercialization of batteries employing Zn anodes. In this work we report the novel adoption of triethyl phosphate (TEP) as a solvent and co-solvent with aqueous electrolytes to obtain a highly stable and dendrite-free Zn anode. Stable Zn plating/stripping for over 3000 h was obtained, accompanied by a CE of 99.68 %. SEM images of the Zn anodes revealed highly porous interconnected dendrite-free Zn deposits. The electrolyte displayed good compatibility with both Zn anodes and potassium copper hexacyanoferrate (KCuHCf) cathodes for Zn ion batteries (ZIBs). The full cell showed a long cycling stability and high rate capability. The present work is a contribution towards cost-effective and safe battery systems.

Highly Reversible and Rechargeable Safe Zn Batteries Based on a Triethyl Phosphate Electrolyte

AbstractZinc metal is an attractive anode material for next‐generation batteries. However, dendrite growth and limited Coulombic efficiency (CE) during cycling are the major roadblocks towards the widespread commercialization of batteries employing Zn anodes. In this work we report the novel adoption of triethyl phosphate (TEP) as a solvent and co‐solvent with aqueous electrolytes to obtain a highly stable and dendrite‐free Zn anode. Stable Zn plating/stripping for over 3000 h was obtained, accompanied by a CE of 99.68 %. SEM images of the Zn anodes revealed highly porous interconnected dendrite‐free Zn deposits. The electrolyte displayed good compatibility with both Zn anodes and potassium copper hexacyanoferrate (KCuHCf) cathodes for Zn ion batteries (ZIBs). The full cell showed a long cycling stability and high rate capability. The present work is a contribution towards cost‐effective and safe battery systems.