Potassium Copper Hexacyanoferrate Research Articles

Amino-functionalized magnetic chitosan beads to enhance immobilization of potassium copper hexacyanoferrate for selective Cs+ removal and facile recovery.

Potassium copper hexacyanoferrate (KCuHCF)-incorporated magnetic chitosan beads (HMC) were synthesized for both selective Cs+ removal in aqueous solutions and facile recovery of the spent adsorbent. To disperse and immobilize large amounts of the KCuHCF, methyl acrylate and diethylenetriamine were sequentially grafted onto the one-step synthesized magnetic chitosan beads. The additional introduction of amino functionality led to the enriched Cu2+ ions on the bead surface to incorporate KCuHCF into the grafting matrix. Consequently, the HMC exhibited a high Cs+ capacity calculated to be 136.47 mg g−1 from the Langmuir model, and the equilibrium was established within 4 h. Moreover, the HMC exhibited excellent stability in a wide pH range from 4 to 11 and an outstanding Cs+ selectivity (>97%) in seawater (1.11 mg L−1 Cs+). From a practical point of view, the HMC was stable during five successive adsorption cycles and easily recovered by magnets, enabling continuous operation to decontaminate a large volume of wastewater.

Decontamination of very dilute Cs in seawater by a coagulation–precipitation method using a nanoparticle slurry of copper hexacyanoferrate

We examined the highly selective Cs adsorption ability of a potassium copper hexacyanoferrate (KCuHCF) nanoparticle slurry ink in seawater, i.e. very low Cs concentration in the presence of Na+, K+, Mg2+, Ca2+, and Cl− ions at high concentrations.

Modified biosorbent wood-decay fungus Fomes fomentarius for pre-concentration of 137Cs in water samples

The biosorbent used in this study was prepared from wood-decay fungus Fomes fomentarius. The chemical modification of biosorbent with potassium–copper hexacyanoferrate (KCuHCF) for cesium sorption in aqueous solutions studies was used. It was found that the biosorbent has a high 137Cs absorbability in the wide range of pH, even in the solutions with high ionic strength. The developed method for 137Cs determination by using modified bio-sorbent was applied to various types of water delivered by the Water Research Institute in Bratislava. 137Cs was measured on HPGe detector and 137Cs activity was less than the minimum detectable activity (5mBq L−1). The tested modified bio-sorbent is suitable for pre-concentration of 137Cs from water.

Immobilization of potassium copper hexacyanoferrate in doubly crosslinked magnetic polymer bead for highly effective Cs+ removal and facile recovery

A potassium copper hexacyanoferrate (KCuHCF) embedded magnetic hydrogel bead (HCF-Mbead) was synthesized via a facile double crosslinking methods of Fe3+ ionic binding and freeze-thaw for effective Cs+ removal. The HCF-Mbead had a hierarchical porous structure facilitating fast access of Cs+ ions to embedded active sites. The adsorbent showed enhanced Cs+ removal properties in terms of capacity (69.2mg/g), selectivity (Kd=4×104mL/g, 1ppm Cs+ in seawater) and stability (>99.5% removal in pH 3∼11) with rapid magnetic separation. This study further opens the possibility to develop an efficient material that links the integration of adsorption and recovery.

Rapid and highly efficient cesium removal by newly synthesized carbomer encapsulated potassium copper hexacyanoferrate composite

Copper hexacyanoferrate–carbomer composite (CuHCF-carbomer) was synthesized and used as an ion exchanger for the removal of hazardous cesium ion from aqueous solution. The composite composition, properties and morphology were characterized by several techniques namely, FTIR, SEM, EDX, XRD and TGA-DSC. The influence of pH of aqueous solution, initial concentration, shaking time and solution temperature on the adsorption of cesium onto CuHCF-carbomer composite were studied by batch technique. Maximum adsorption capacity value of 1.74 mmol g−1 of Cs+ on CuHCF-carbomer was obtained at pH 9, 9 mmolL−1 Cs+, and 25 °C. Adsorption isotherms, kinetic and thermodynamic parameters of the adsorption process were obtained and used to describe the adsorption of Cs+. In addition, column method was used in the same purpose of Cs+ ion removal. The effect of bed depth and flow rate on the adsorption characteristics of composite was examined at the optimum conditions of pH = 9 and initial Cs+ concentration = 5 mmoL−1. Thomas and Yoon–Nelson kinetic models were applied to evaluate column adsorption performance. Moreover, the prepared composite could be regenerated effectively by 2 M KCl and was used successfully for five times.

Valuable rubidium extraction from potassium reduced seawater brine

Extraction of rubidium (Rb) which is an economically valuable metal from seawater reverse osmosis (SWRO) brine is beneficial. However, potassium (K) in SWRO brine hinders Rb extraction. Natural clinoptilolite zeolite in powder form was able to selectively remove K from SWRO brine (Langmuir maximum sorption, Qmax (cal.) = 57.47 ± 0.09 mg/g). An integrated submerged membrane sorption reactor (SMSR) containing zeolite powder achieved 65% K removal from SWRO brine. Periodic replacement of zeolite in SMSR, coupled with membrane backwashing was effective in maintaining a high K removal efficiency and a stable transmembrane pressure. Less than 5% Rb losses occurred along with K sorption, establishing the high K selectivity by zeolite in SWRO brine. Utilization of K loaded zeolite as a slow release fertilizer would be beneficial for agriculture. In SWRO brine with reduced K contents, the Rb sorption efficiency of polymer encapsulated potassium copper hexacyanoferrate (KCuFC(PAN)) sorbent, increased significantly from 18% to 83%.

Removal of carcinogenic aromatic amines by metal hexacyanoferrates nanocubes synthesized via green process

Aromatic amines (AA) are a group of industrial and environmental pollutants with high thermodynamic stability and carcinogenicity. Their toxicity has raised concern worldwide and calls for the development of effective elimination methods based on nanomaterials. Recently, the high adsorbing and photocatalytic efficiency of widely used metal hexacyanoferrates was observed. To confirm this, potential of potassium zinc hexacyanoferrate (ZnHCF) and potassium copper hexacyanoferrate (CuHCF) were evaluated in remediation of simulated water containing selected hazardous AAs. Highly crystralline and sharp nanocubes of ZnHCF (∼50nm) and distorted nanocubes of CuHCF (∼100nm) were synthesized via green route using sapindus mukorossi (raw ritha) as a biosurfactant. Under optimized conditions—concentration of amine(1.0×10−4M), catalyst (25mg) and neutral pH, ZnHCF was found better with maximum degradation efficiency (90% of p-anisidine, 76% of p-toluidine, 71% of aniline and 70% of p-chloroaniline) followed by CuHCF (88%, 72%, 69% and 64%, respectively). This might be because of its higher zeta potential and BET surface area of ZnHCF. The highest adsorption (%) of p-anisidine on acidic surface of catalysts is probably due to its highest basicity. Statistical treatment of data fitted to various adsorption isotherms indicated the monolayer adsorption of AAs over surface of catalyst i.e., Langmuir with highest regression coefficient values (R2 more than 0.98 for all AAs). GC–MS analysis confirmed the formation of small, non-toxic by-products such as benzoquinone, hydroquinone, but-2-enal, 4-oxobut-2-enoic acid and malealdehyde. The potential of MHCF nanoparticles can be explored more effectively in removal of organic pollutants for solving the water pollution problems.

Analysis of Cs-adsorption behavior using a column filled with microcapsule beads of potassium copper hexacyanoferrate

ABSTRACTAsh-washing technology is a crucially important technology for removing radioactive Cs from contaminated ash. For that technology, Cs+ removal from the ash-washing solution by the adsorbent is necessary. This study was conducted to establish rapid preparation of appropriate adsorption columns for Cs+ uptake. A one-site model was not used for analysis because the model cannot accommodate sites with different adsorption speed. Results demonstrated that the adsorption behavior of the column filled with the granules of potassium copper hexacyanoferrate was well reproduced by a two-site adsorption model with parameters chosen through analysis of batch adsorption test results.

Rubidium extraction from seawater brine by an integrated membrane distillation-selective sorption system

The ultimate goal of seawater reverse osmosis (SWRO) brine management is to achieve minimal liquid discharge while recovering valuable resources. The suitability of an integrated system of membrane distillation (MD) with sorption for the recovery of rubidium (Rb+) and simultaneous SWRO brine volume reduction has been evaluated for the first time. Polymer encapsulated potassium copper hexacyanoferrate (KCuFC(PAN)) sorbent exhibited a good selectivity for Rb+ sorption with 10–15% increment at 55 °C (Langmuir Qmax = 125.11 ± 0.20 mg/g) compared to at 25 °C (Langmuir Qmax = 108.71 ± 0.20 mg/g). The integrated MD-KCuFC(PAN) system with periodic membrane cleaning, enabled concentration of SWRO brine to a volume concentration factor (VCF) of 2.9 (65% water recovery). A stable MD permeate flux was achieved with good quality permeate (conductivity of 15–20 μS/cm). Repeated cycles of MD-KCuFC(PAN) sorption with SWRO brine enabled the extraction of 2.26 mg Rb+ from 12 L of brine (equivalent to 1.9 kg of Rb/day, or 0.7 tonne/yr from a plant producing 10,000 m3/day brine). KCuFC(PAN) showed a high regeneration and reuse capacity. NH4Cl air stripping followed by resorcinol formaldehyde (RF) resin filtration enabled to recover Rb+ from the desorbed solution.

Removal of radiocesium from low level radioactive effluents by hexacyanoferrate loaded synthetic zeolite: laboratory to pilot plant scale demonstration

Abstract Present paper reports removal of radiocesium from low level waste using a modified sorbent (13X-CFC) prepared by in-situ precipitation of potassium copper hexacyanoferrate(II) inside the macropores of a synthetic zeolite. The Cs exchange isotherm of the sorbent is established and it found to follow Fruendlich absorption isotherm equation. It is varified that presence of hexacyanoferrate on zeolite facilitates rapid Cs uptake performance. This is further confirmed in laboratory scale column tests, wherein excellent Cs removal performance from low level waste simulant was observed even at higher flow rates (40 bed volumes per hour). The utility of the sorbent is established through successful demonstration in a pilot scale (50 L) trial with almost complete removal of 137Cs from more than 14,000 bed volumes of actual low level waste. The sorbent, owing to its low cost and excellent 137Cs removal performance, is expected to find application in treatment of very low active waste streams.

Solvent-assisted synthesis of potassium copper hexacyanoferrate embedded 3D-interconnected porous hydrogel for highly selective and rapid cesium ion removal

Potassium copper hexacyanoferrate-embedded poly(vinyl alcohol)-citric acid hydrogel film (HPC) was prepared via a two-step method of Cu immobilization, followed by the diffusion of potassium hexacyanoferrate accelerated by acetone evaporation. The diffusion-derived KCuHCF formation in the preformed hydrogel facilitated the preservation of the 3D-interconnected hydrogel structure and dispersion of the KCuHCF nanoparticles. Using acetone as a non-solvent, reverse diffusion of the incorporated Cu in the hydrogel matrix was hindered; hence a large amount of KCuHCF was loaded in the matrix. The HPC exhibited substantially enhanced Cs+ removal properties in terms of adsorption capacity, kinetics and selectivity. From the adsorption isotherm, the HPC showed a very high Cs+ uptake of 667mg/g KCuHCF. Moreover, the adsorbent revealed stable and high Cs+ removal efficiency of 99.9% across a wide pH range from 2 to 10. The kinetics of Cs+ removal was remarkably rapid with 99.5% removal achieved within 30min from a dilute Cs+ solution (9.18ppm). When using seawater, the HPC exhibited almost unaltered Cs+ removal efficiency above 99.5%, and high distribution coefficient Kd value of 7.7×105ml/g at an extremely low Cs+ concentration (0.67ppm,V/m=1000ml/g), which highlighted the tremendous affinity for Cs+.

Organically modified clay with potassium copper hexacyanoferrate for enhanced Cs+ adsorption capacity and selective recovery by flotation

Organo-clay–HCF particles are used to remove Cs+ from aqueous environments. Cs-Loaded particles were subsequently separated via column flotation.

Nanostructured potassium copper hexacyanoferrate-cellulose hydrogel for selective and rapid cesium adsorption

Potassium copper hexacyanoferrate (KCuHCF) was synthesized and immobilized in a cellulose-based hydrogel made of carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) for the adsorption of cesium ions in aqueous solutions. The immobilization with the cellulose-based hydrogel facilitated the dispersion of nano-sized KCuHCF particles, showing the unprecedented adsorption capacity of the composite. In Cs+ removal experiments, KCuHCF-cellulose hydrogel composites (HCF-gels) exhibited exceptional Cs+ adsorption capacities (2.06–2.32mmolg−1) which was attributed to the presence of ion-exchangeable sites (COO−Na+) in the cellulose hydrogel. The HCF-gels also exhibited a rapid Cs+ removal (90.1% removal for 0.15mmolL−1 of Cs+ in 1h) with the uptake reaction kinetics expressed by a pseudo-second order kinetics model. Notably, the HCF-gels could adsorb Cs+ selectively (>90%) in seawater containing 0.11mmolL−1 Cs+. Such specificity with fast kinetics is due to the high ion accessibility from the inherent nature of hydrogels and the highly dispersed KCuHCF nanoparticles in the composites.

Development and validation of an automated unit for the extraction of radiocaesium from seawater

An automated unit was developed for the in-situ extraction of radiocaesium (137Cs and 134Cs) from large volumes of seawater to achieve very low detection limits. The unit was designed for monitoring of Australian ocean and coastal waters, including at ports visited by nuclear-powered warships.The unit is housed within a robust case, and is easily transported and operated. It contains four filter cartridges connected in series. The first two cartridges are used to remove any suspended material that may be present in the seawater, while the last two cartridges are coated with potassium copper hexacyanoferrate for caesium extraction. Once the extraction is completed the coated cartridges are ashed. The ash is transferred to a small petri dish for counting of 137Cs and 134Cs by high resolution gamma spectrometry for a minimum of 24 h.The extraction method was validated for the following criteria: selectivity, trueness, precision, linearity, limit of detection and traceability. The validation showed the unit to be fit for purpose with the method capable of achieving low detection limits required for environmental samples. The results for the environmental measurements in Australian seawater correlate well with those reported in the Worldwide Marine Radioactivity Study (WOMARS).The cost of preparation and running the system is low and waste generation is minimal.

Pre-Concentration of Cs-137 Through Sorption: Low Level Analysis in Seawater

Comparative studies for the sorption of Cs-137 on silica coated potassium copper hexacyanoferrate and potassium cobalt hexacyanoferrate materials and an efficient method was optimized for its maximum sorption. The column sorption method was applied by packing synthesized material in specifically designed columns and low level/fallout level Cs-137 was sorbed on it from 2-4 L seawater sample (0.237 Bq/L). Higher sorption of Cs-137 was achieved on silica coated potassium copper ferrocyanate by optimizing the physical conditions at pH 8. Sorption potential of copper ferrocyanate was higher as compared to cobalt ferrocyanate under same optimized conditions. The developed method was, in field, applied for seawater sample collected from Arabian Sea, near the outfall of Karachi Nuclear Power Plant (KANUPP, Pakistan) by pumping 2-4L of seawater through synthesized material packed in columns. The results suggested that developed method was much precise and accurate as compared to conventional method. Keywords: Gamma spectrometer, hexacyanoferrate coated silica, low level Cs-137, sorption.

Efficient synthesis of size-controlled open-framework nanoparticles fabricated with a micro-mixer: route to the improvement of Cs adsorption performance

An efficient preparation of size-controlled nanoparticles of an open framework coordination polymer.

Supporting of Potassium Copper Hexacyanoferrate on Porous Activated Carbon Substrate for Cesium Separation

Activated carbon (AC) was chosen for carrying potassium copper hexacyanoferrate (KCuCF) to prepare a new Cs-selective material. The adsorbent was prepared by repetitious batch precipitation reaction of Cu2+ with [Fe(CN)6]4−. Characterization analyses identified the backbone formula of the activated carbon-supported KCuCF with K2Cu[Fe(CN)6], and shown the successful loading of KCuCF microcrystals on the porous carbon substrate with a loading percentage of 12.5 wt%, and with BET specific surface area and a total pore volume of 527.8 m2/g and 0.38 cm3/g for AC and 160.8 m2/g and 0.16 cm3/g for KCuCF-loaded activated carbon (KCuCF-AC), respectively. The optimal Cs adsorption capacity of about 0.46 mmol·g−1 was observed between the HNO3 concentration of 0.5–1.5 M, and the capacity even reached to 0.38 mmol·g−1 in the presence of a large amount of competing cations. The results indicate that activated carbon has no significant effect on the selectivity of the as-synthesized composite.

EVALUATION AND TESTING OF INORGANIC ION EXCHANGE SORBENTS FOR THE REMOVAL OF CESIUM-137 FROM ACTUAL IDAHO NUCLEAR TECHNOLOGY AND ENGINEERING CENTER ACIDIC TANK WASTE

Three inorganic ion exchange sorbents were evaluated for 137Cs removal from the Idaho Nuclear Technology and Engineering Center (INTEC), acidic tank waste. A commercially available, Russian manufactured, potassium copper hexacyanoferrate (FS-2), crystalline silicotitanate (IONSIV IE-911), manufactured by UOP, and ammonium molybdophosphate-polyacrilonitrile composite sorbent (AMP-PAN), produced at the Czech Technical University, Prague, were tested. Approximately 800 mLs of actual radioactive tank waste were used to evaluate the FS-2 and IONSIV IE-911 sorbents. Feed flowrates of 6-7 mLs/hr through a 1 cm3 column were used for both tests. Initial 137Cs breakthrough with IONSIV IE-911 was observed at approximately 100 mLs and 50 % breakthrough was observed at 660 mLs. A 137Cs breakthrough of 20 % was observed after 775 mLs of waste was processed through the column containing FS-2. Tests were also performed with both of these sorbents using simulated tank waste. Results for the IONSIV IE-911 compare well for both tests; however, there are some slight discrepancies with the FS-2 results. These discrepancies are believed to be the result of mercury sorption arising from different mercury speciation between the actual and simulated waste feeds. Over 80 wt% of the cesium loaded onto the FS-2 sorbent was eluted with 8 M HNO3, while no attempt was made to elute cesium from the IONSIV IE-911 sorbent. The AMP-PAN test used a 1.5 cm3 column, 1600 mLs of actual radioactive waste, and a flowrate of 40 mLs/hr (26 bed volumes/hr). Initial 137Cs breakthrough was observed after processing 600 mLs, and 0.15 % breakthrough was observed after processing 1550 mLs of waste. Over 83 % of the cesium was eluted using 44 mLs of 5 M NH4NO3. Two loading and elution cycles were performed with simulated waste and AMP-PAN. Approximately 4800 mLs (3200 BV) of simulant were processed before 50 % breakthrough was observed. Over 70 % of the cesium was eluted in 85 mL (57 BV). Only 4050 mLs (2700 BV) of simulant were processed before 50 % breakthrough was observed in the second loading cycle and 50 % of the cesium was eluted in 117 mL (78 BV). The results indicate that AMP-PAN has the highest capacity for cesium and sorption appears to not be affected by the presence of mercury in the waste, giving it clear advantages over IONSIV IE-911 and the FS-2 sorbent. The AMP may also be easily dissolved from the PAN binder using sodium hydroxide.

In vitro Study of 137Cs Sorption by Hexacyanoferrates(II)

We synthesized a varicty of colloidal and non-colloidal mixed hexacyanoferrate(II) complexes of Fe. Cu. Co. Ni. Zn. Mn and studied ihe cesium Sorption in vitro under physiological conditions (artificial gastric juice. pH 1.2 and artificial duodenal juice. pH 6.8). All of the hexaeyanoferrates under study (except cesium iron(III) hexaeyanoferrate CsFeHCF) sorb tracer amounls of 13 Cs quantitatively. Differences in the sorption capacity become obvious by offering substantial amounts of cesium. Potassium copper hexacyanoferrate(II) (KCuHCF) and potassium zinc hexa- cyanoferrate(II) (KZnHCF) are most efficient in cesium sorption at pH 1.2 and at pH 6.8. The sorption capacities of KCuHCF and KZnHCF (2.3-3.0 mmol Cs'g HCF) are twice as high as for coiloidai Prussian blue (KFeHCF; 1.0-1.3 mmol Cs/g HCF) and insoluble Prussian blue (FeHCF: 1.0-1.6 mmol Cs/g HCF). The most promising Compounds. KCuHCF and KZnHCF. should be further investigated in in vivo studies for 137 |l4cesium decorporation. Evidence indicate that the sorption mechanism for most of the Compounds under study is a cesium/potassium ion-exehange reaction. In the case of insoluble Prussian blue (FeHCF). a cesium/proton exchange was observed. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ On laboratory scale. 137 |V4Cs-contaminated whey dry powder. produced from South German cow milk in summer 1986 was almost completely decontaminated by dialysing a whey Suspension against buffer Solution containing FeHCF. The 117 "JCs'-ions. completely bound by FeHCF. can be isolatcd from the buffer Solution by simple filtration. The buffer Solution and the FeHCF can