Two samples of the microporous titanosilicate ETS-10 synthesised by different preparation procedures were compared for their ability to take up uranium from aqueous solutions using a batch-type technique. The ETS-10 samples were synthesised using either TiO2 or TiCl3 as a titanium source. The uptake of uranium on the materials was compared by determining the distribution coefficient and percentage sorption as a function of contact time, uranium concentration, and sorbent concentration. It was found that the difference in the synthesis procedures of the materials had a significant influence on the uptake of uranium.
Authors:S. Sarri, P. Misaelides, M. Papanikolaou, and D. Zamboulis
The sorption of uranium from acidic aqueous solutions (pH 4.5, Cinit = 10 to 1000 mg U/L) by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa was investigated using a batch technique. The U-sorption onto Saccharomyces cerevisiae and Debaryomyces hansenii followed a Langmuir, while that onto Kluyveromyces marxianus and Candida colliculosa a Freundlich isotherm. The results demonstrated that all investigated biomasses could effectively remove uranium from acidic
aqueous solutions. From all sorbents, Saccharomyces cerevisiae appeared to be the most effective with a maximum sorption capacity of 127.7 mg U/g dry biomass.
nickel hexacyanoferrate, KNiFC, was incorporated in the porous matrix of
zeolites by successive impregnation with Ni(NO3)2 and
(CN)6.1 CFC and PFC exchangers were first prepared by
impregnating the potassium nickel hexacyanoferrate into the clinoptilolite and
the synthetic P zeolite, respectively. Ion-exchange isotherms and breakthrough
curves were plotted. Results showed that the CFC sorbent is suitable for
removal of Cs+ where PFC is more suitable for Sr2+.
Negative effect of Na+ as a competing ion in these exchangers was
less than in the parent zeolites. Isotherm plots fitted the Langmuir equation.
Authors:I. Sowa, D. Zajdel, R. Kocjan, M. Pizoń, and M. Wójciak-Kosior
The new obtained sorbent based on silica gel modified with polyaniline was used as a stationary phase in the ion chromatography of anions. NO3- and NO2- ions were analyzed by UV spectrophotometric detection (200 nm). It can be stated that the optimal mobile phase was a 0.05 M hydrochloric acid and the optimal flow speed was 0.3 mL min−1. The separation of both anions in the presented condition was satisfactory. The resolution factor (peak resolution) was 3.3. It suggests the possibility of the column application for simultaneous speciation analysis of nitrate ions.
Authors:W. Ciesińska, J. Zieliński, and T. Brzozowska
Coal-tar pitch was modified by addition of polystyrene, poly(ethylene terephthalate), unsaturated polyester and coumarone-indene
resin. The optimum conditions for production of homogeneous binary pitch-polymer blends containing 10% w/w of the polymer were established. Softening points, contents of toluene and quinoline-insoluble matters and rheological properties
of the blends were determined. The yield of solid fraction in semi-coking the blends was also found. The effect of polymers
on the coal-tar pitch blend properties was evaluated. Some pitch-polymer blends were then carbonized to carbon sorbents used
for purification of water and wastewater.
Iodide retention by AgCl, a potential sorbent in high-level waste (HLW) storage systems, was determined. The kinetics and
steady state sorption of iodide were determined in single and mixed electrolytes of NaNO3, and NaCl at ionic strengths of 25 and 50 mM. Iodide retention involved the conversion of AgCl to AgI. This conversion increased
rapidly within 0.02 hours, and retention maxima of 0.92 and 1.0 mol·l·mol−1 Ag occurred for low and high ionic strengths, respectively. These short-term studies indicated that AgCl would be an effective
scavenger of I− in HLW containment systems.
In this work, Cs+ ion sorption on some clays and zeolite were investigated. 137Cs was used as a tracer. Activities were measured with a NaI crystal gamma counter. The particle size distribution was determined
by a laser sizer. Surface area of the particles were determined by BET (Brunauer, Emmett and Teller method). Structure analysis
was made by using X-ray diffraction. The chemical compositions of the solid samples were determined using a ICAP-OE spectrometer.
Kinetic and thermodynamic parameters were determined. Due to very high uptake results; clay and zeolite can be proposed as
a good sorbents in waste management considerations.
Authors:N. Zaitseva, C. Deptula, Kim Khan, O. Knotek, P. Mikeć, and V. Khalkin
Absorption of carrier-free T1 from nitric acid solutions of lead by ammonium 12-molybdophosphate fixed in the matrix of porous Teflon (AMP-sorbent) has been investigated. Effective separation of T1 and Pb is shown to take place. Elution processes of T1 from AMP-sorbent have been investigated. It is found that complete extraction of T1 is achieved upon dissolving AMP in concentrated ammonia. Further purification and concentration of T1 are performed by means of cation exchange chromatography on Dowex-50 or KU-2 resins. Investigation of high temperature behaviour of T1 ultramicroamounts in Pb melt showed that T1 is quantitatively separated out into the gas phase when fluorinating additions of PbF2 or NaF solid salts covering the melt surface are used. The volatile compounds of radiothallium formed were transported by a stream of inert gas (He or N2) from the evaporation zone to the thermochromatographic column, where they were sorbed on the surface in a limited zone with the maximum at 240 °C. Liquid and gas thermochromatographic methods for separation of carrier free radiothallium from protonirradiated lead material have been developed. The radiochemical, chemical and radionuclidic purity of T1 samples complies with requirements of nuclear medicine for201T1 product. Both methods ensure 95% chemical yield of T1 and take about two hours each.
The preparation of the OASIS®-HLB sorbent based solid phase extraction (SPE) resins and their application for the 177Lu radioisotope separation were investigated. Di-(2-ethylhexyl) orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent
based SPE resins (OASIS-HDEHP) were successfully developed from this investigation. The wettable porosity structure of the
moderately extractant impregnated OASIS-HDEHP resins is favorable for the effective diffusion of polar and ionic solutes giving
good separation performance. Its good wetting ability offers ease of packing into conventional chromatographic columns. Their
off-gassing-free operation makes OASIS-HDEHP columns good for long term use with highly consistent elution dynamics (several
dozens of separations perfectly achievable on the same column). The simple method for the capacity factor (k’) evaluation was developed to facilitate the characterization of the SPE chromatographic resin column. A competent procedure
using OASIS-E30RS resin (one member of the OASIS-HDEHP resin group) for the separation of no-carrier added (n.c.a) 177Lu from the bulk amount of Yb target was developed. This separation procedure has showed very good performance with several
prominent advantages such as the much shorter separation time (5–6 hours) and high reproducibility. Its high adsorption capacity
for Yb and Lu makes it ideal for the separation of the bulky sample (50 mg Yb target for the 20 g weight resin column) for
the production of the several Ci of 177Lu radioactivity.
Authors:G. Gradev, M. Milanov, Y. Prodanov, and G. Stephanov
The sorption of monovalent ions (cesium, silver, thallium, mercury), bivalent ions (strontium, barium, lead, copper, cobalt,
zinc) and polyvalent ions (cerium) on calcium clinoptilolite under dynamic conditions has been studied. Both the dynamic exchange
capacities in the different break-through of the ions and the degree of the exchanging ions in sorption of different metal
cations have been determined. The good selectivity of calcium clinoptilolite in relation to cesium and strontium is displayed
in the presence of sodium. The influence of various factors on the sorption the thermal and radiation treatment of the sorbent,
the pH and concentration of solutions, equilibration time, presence of alkali and alkali earth ions deactivating agents—EDTA,
citric acid tartaric acid, and boric acid in solution has been studied. The optimum conditions of sorption have been determined.
Experiments for the desorption of cesium and strontium have been carried out. The possibility to use calcium clinoptilolite
for the purpose of deactivation of radioactive wastes is shown. The better sorption properties of that sorbent, compared to
calcium clinoptilolite, can be explained by the higher aluminium content, as well as by a prevalence of calcium and magnesium
in its ion exchange complex.