Latex Particles Functionalized With Transition Metals Ferrocyanides for Cesium Uptake and Decontamination of Solid Bulk Materials

Abstract

Decontamination of spent ion-exchange resins, corrosion-unstable metal structures, soil, ground, and construction materials contaminated by fission, corrosion and transuranic radionuclides remains one of the most urgent and complicated ecological problems. Among the existing methods having different efficiencies in regard to such materials decontamination, application of selective sorbents put into a humid medium to be decontaminated (ground, bulk materials) appears to be rather extensive. However, the efficiency of such an approach is significantly limited by difficulties concerned with uniform sorbent distribution in porous media and completeness of spent sorbents removal for final disposal. In this paper we suggest a principally new approach to preparation of colloid-stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid-stable sorbents toward cesium ions were studied in solutions containing up to 200 g/1 sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.45–1.86 mol Cs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that makes them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed. Besides, functionalized latex particles can be used for preparation of carbon fiber/ferrocyanide composite materials for cesium uptake using electrodeposition method. Application of the carbon fibers as an inert support for ferrocyanides, in general, significantly improves the sorption kinetics, but washing out of ferrocyanide fines from the fiber surface limits the potential of such materials. When ferrocyanides are deposited in a form of nanocrystals stabilized by latexes which undergo electropolymerization on the fiber surface, the thin polymeric film formed substantially improves the stability of the composite and prevents loss of ferrocyanide during sorbent application. The effect of electrodeposition conditions on composite morphology, ferrocyanide loading and cesium distribution coefficient in media with different salinity has been discussed.

Immobilization of Metal Hexacyanoferrate Ion-Exchangers for the Synthesis of Metal Ion Sorbents—A Mini-Review

“…Table S4 (see Supplementary Materials) displays the different counter metals that were used for the synthesis of sorbents made of Prussian Blue analogues (including both precipitated particles and immobilized ion-exchangers). The most conventional hexacyanoferrates are incorporating: nickel [6,7,8,12,28,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66], copper [8,11,13,22,25,28,30,31,38,42,45,46,47,48,49,58,61,64,65,67,…”

“…Hexacyanoferrate-based sorbents are mainly oriented toward the recovery of Cs(I) [1,7,8,12,17,22,23,27,30,31,32,33,34,36,37,38,43,45,46,47,51,52,53,55,56,57,58,62,63,65,67,68,69,70,71,74,75,77,78,79,80,81,83,86,87,89,92,93,94,96,98,99,100,103,108,109,110,111,112,113,114,115,116,117,118,119,120,…”

“…Avramenko et al [30,31] reported the synthesis of latex colloid particles made of siloxane-acrylate emulsions (particle size close to 160 nm) mixed with metal (cobalt, copper or nickel) chloride salts (single-metal salt or combination of metal salts) with potassium hexacyanoferrate at pH 7. The composite emulsion is relatively stable (for at least 1 month); however, at high hexacyanoferrate content non-stabilized particles are formed and can be recovered by settling or filtration [31].…”

“…Comparing the potential of these materials for flocculation of radionuclides with the performances obtained by cesium precipitation in presence of the precursors (direct co-precipitation process) they point out that the most significant advantage is the remarkable reduction in the volume of the sludge produced by the treatment ( i.e. , 1% vs. 25%) [30]. They also reported the electrodeposition of cobalt hexacyanoferrate/latex emulsion at the surface of carbon fibers (with high specific surface area) [31].…”

Chitin-Prussian blue sponges for Cs(I) recovery: From synthesis to application in the treatment of accidental dumping of metal-bearing solutions

“…); and it is generally helpful immobilizing the IE in a suitable matrix (biopolymer, polymer) or at the surface of a specific mineral support (silica, activated carbon, zeolite etc.) [7][8][9][10][11][12][13]. These methods lead to materials that can be used in tank reactor, fixed-bed columns for the treatment of controlled contaminated water streams.…”