Coprecipitation of microamounts of Cs with ferrocyanides of various metals

Abstract

Coprecipitation of microamounts of Cs with ferrocyanides of various metals, exhibiting a high sorption activity with respect to Cs ions, was studied. The distribution coefficients of 117 Cs were determined in coprecipitation with the ferrocyanides in 0.1 M NaNO 3 . The precipitated ferrocyanide was separated from solution by filtration through a Trumem metal!ceramic membrane. Cesium is recovered most efficiently with ferrocyanides of bivalent transition metals (Ni, Co, Cu, Fe, Cd).Utilization of liquid radioactive waste (LRW) of various activity levels implies selective isolation of long-lived radionuclides, in particular, 137 Cs having a long half-life of ;30 years and a high radiotoxicity.Cesium is isolated from multicomponent solutions by sorption, precipitation, extraction, membrane filtration, and other methods [1].Among these methods, precipitation is distinguished by easy procedure and simple implementation. A drawback of precipitation in LRW treatment is formation of abundant secondary waste, precipitates and pulps, whose utilization presents a fairly complex task. This drawback can be eliminated by precipitation or coprecipitation of LPW either on earlier formed precipitates or on precipitates freshly prepared in the solutions being treated, followed by filtration of the suspension through porous membranes with different pore sizes (micro, ultra-, and nanofiltration).In this work, we precipitated microamounts of Cs with ferrocyanides of various metals, which, according to published data, have a high sorption activity with respect to Cs ions [2, 3]. The resulting precipitates were separated from solution on a Trumem metal3ceramic membrane [4] with a pore size of 0.2 mm. EXPERIMENTAL Coprecipitation of microamounts of Cs with ferrocyanides of various metals was performed as follows. Into a model solution containing 0.1 M NaNO 3 (pH 6.0) and microamounts of 137 Cs (;100 Bq cm 33 ), solutions of potassium ferrocyanide and of a salt of the appropriate metal were introduced successively so that their final concentrations in solution were 2.86 0 10 35 and 3.81 0 10 35 M, respectively, at the Me n+ /Fe(CN) 6 43 molar ratio of 1.33 and the content of the resulting ferrocyanide precipitate of 8.5317.8 mg dm 33 . The resulting mixture was continuously stirred for 33 4 h and was then filtered in a vacuum through a Trumem metal3ceramic membrane with a pore size of 0.2 mm. In the resulting filtrate, we measured the specific activity of 137 Cs using an NRG-603 (Czech Republic) g-ray analyzer. Based on the measured activities, we calculated the distribution coefficients K d of 137 Cs and the purification coefficients K pur of the solution by the formulas K d = [(a 0 ! a eq )/a eq ](V/m),where a 0 and a eq are the initial and equilibrium specific activities of 137 Cs in solution, Bq cm 33 ; V, volume of solution, cm 3 ; and m, mass of the precipitated ferrocyanide, g.When calculating the mass of the metal ferrocyanide precipitated, we assumed formation of compounds with the composition K 1.33 Me II 1.33 Fe(CN) 6 in the c...

Determination of Cesium on Nickel Hexacyanoferrate‐Aluminum Oxide Modified Electrodes

“…Additionally, metal hexacyanoferrates are known to interchange Cs þ from aqueous solutions. Cs þ can be recovered from radioactive wastes by co-precipitation with those complexes [9,10]; they can adsorb almost 100% of the Cs þ from simulated radioactive wastes [10]. The above information suggests that Cs þ could be preconcentrated on a NiHCFe-Al 2 O 3 modified electrode.…”

Ferrocyanide Biosorbents Based on Lignocellulose Waste Products for Multifunctional Purpose

“…During the modification processes the fixing of ion exchange or complexing groups on the surface of the LC-matrix can take place. One way to obtain selective composite sorbents toward cesium ions is the impregnation of plant materials with the solutions of ferrocyanides of d-metals ([FC]M, where М -Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ) [5][6] that characterized by high selectivity with respect to cesium [7] that considered as the most hazardous among all radionuclides due to relatively long half-life, high toxicity and migration properties. Such composite materials based on plant raw material can also be used as enterosorbents to prevent pollutant accumulation in human and animal body.…”

Sorption of 137Cs from aqueous solutions onto layered double hydroxides containing the Fe(CN) 6 4− ion in the interlayer space

“…It was found that LDH-Mg-Al-Anion (Anion = CO 3 2-, NO 3 -) solid phases did not take up 131 I in the form of 131 Iand 131 IО 3 from aqueous solutions, whereas the efficiency of the 131 Iand 131 IО 3 removal from aqueous solution with SDO-Mg-Al exceeded 99%. Synthetic analogs of hydrotalcite of the composition LDH-Mg-Al-Nd-CO 3 and LDH-Mg-Nd-CO 3 allowed 90 Sr 2+ and 90 Y 3+ to be removed from aqueous solutions with more than 99% efficiency [2].…”

“…The compounds LDH-Mg-M 3+ -CO 3 (M 3+ = Al, Nd) remove 233,238 U(VI) from aqueous solutions of complex chemical composition with more than 99% efficiency [1]. 60 Со is efficiently sorbed from 10 -3 -10 -5 M aqueous Co(NO 3 ) 2 solutions onto LDH-Mg-Al and LDH-Mg-Nd with CO 3 2ions in the interlayer space. At the contact time of the solid and liquid phases (τ) of 15 min and V/m = 50 mL g -1 , K d exceeds 2 × 10 4 mL g -1 for LDH-Mg-Nd and does not exceed DOI: 10.1134/S1066362215010105 EXPERIMENTAL 5 × 10 3 mL g -1 for LDH-Mg-Al [1].…”

“…Inorganic sorbents containing ferrocyanide ions are widely used for removing cesium radionuclides from aqueous solutions [3][4][5]. Therefore, we prepared in this study samples of LDH-М 2+ -М 3+ -Fe(CN) 6 (М 2+ = Mg, Cu, Ni, Zn; М 3+ = Al, Fe) and determined their physicochemical properties, including the performance in the 137 Cs + sorption.…”