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Abstract  

The removal of Na+ by a composite hydrated antimony pentoxide-sulfonated phenol-formaldehyde ion exchanger (C-HAP) from 4M HCl was studied using the breakthrough technique. The dynamic removal capacity for Na+ from 4M HCl is 12.3 mg Na+/g and 9.87 mg Na+/g at 0.2 ml/min and 0.8 ml/min, respectively. Height equivalent to a theoretical plate varies almost linearly with flow rate indicating particle diffusion control.

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Abstract  

Hydrolysates from chromed leather waste obtained in powdered form on an industrial scale by using biotechnical methods were analysed by TG an DSC techniques. Besides about 9% (mass/mass) of moisture, around 1% (mass/mass) of cyclohexylamine was found in the pulverized hydrolysates. Calorimetric measurement of the reaction heats of the reactions of the hydrolysates with commercially available aldehydes indicates that their reactivity decreases in the sequenceglutardialdehyde>>methylglyoxal≈acetaldehyde>>glyoxal>formaldehyde.

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Abstract  

Hexamethylene tetramine (HMTA) was determined in the presence of large quantities of urea, formaldehyde and ammonium hydroxide by potentiometric titration with perchloric acid solution using an autotitrator coupled to a personal computer. This analysis is required for the process control of the sol-gel method in the production of ceramic metal oxide (e.g., oxides and mixed oxides of Th, U and Pu) microspheres using the internal gelation route. Feed solution used for preparation of microspheres contains large quantities of urea. The washings of gel microspheres produced after the internal geletion process contain urea, formaldehyde, urea-formaldehyde complex and ammonium hydroxide. The presence of these constituents in the feed solution and washings seriously interfere in the commonly used methods for the determination of HMTA. Using this method the relative standard deviation was found to be 0.27% in eleven determinations of a typical feed solution (3.0M HMTA) when the aliquots contained 75 to 125 mg of HMTA. Time required for each titration was 5–7 minutes. Feed and effluent solutions of sol-gel process were analysed.

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The works reported in the literature (1994–2015) on the use of surfactants as separation modifiers of organic and inorganic compounds by thin-layer chromatography (TLC) is discussed. A number of adsorbents such as silica gel (plain and modified with surfactants and other compounds), stannous silicate, aminoplast, soil, urea-formaldehyde polymer with cellulose binder, and bismuth silicate have been used as layer materials. Surfactants used for the modification of the mobile and stationary phases in TLC have opened new opportunities for realizing novel separations of analytical importance. The salient features of TLC systems used in the analysis of organic and inorganic mixtures of substances have been provided in the tabular form.

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Singlet oxygen ( 1 O 2 )-catalyzed oxidation of water leads to a variety of oxidants (e.g. ozone, O 3 ) in host-parasite relationships as well. It can be detected indirectly in TLC or OPLC zones by use of the simple BioArena system and O 3 -eliminating molecules (e.g. d -limonene and indigo carmine) in the culture medium. It follows from these new findings that not only formaldehyde but also O 3 and related bioreactive compounds may play a crucial role in the mechanism of antibacterial activity of antibiotic-like compounds. The toxic potential of a molecule, however, originates from the ratio of the oxidants produced in the chromatographic spots.

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Abstract  

Properties and applications of composite ion exchangers developed in this Institute are described. The new sorbents consist of a selective inorganic ion exchanger, e.g., hexacyanoferrate of transition metals or hydrated antimony pentoxide, firmly incorporated into a resin matrix, e.g., phenol-formaldehyde, of various shapes. The composites have proved to be effective adsorbents for radionuclides of cesium, sodium, francium, elements 104 and 105, and some others. The sorbents were successfully tested as filter fillers for radiocesium removal from liquid radioactive wastes and from other solutions encountered in nuclear technology. They were also applied in radiochemical studies and in nuclear activation analysis.

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Abstract  

Chitosan was used as a sealant of knitted polyester vascular grafts. Three sterilization methods for chitosan-coated prostheses were tested: sterilization with ethylene oxide, formaldehyde and irradiation with gamma rays. Radiation sterilization was found to be the most promising of tested methods. The radiation-induced changes in chitosan irradiated in solid state were investigated. Main chain scission was found as the predominant effect of irradiation. Changes in IR and UV spectra were analyzed. Existence of some post-effects was detected. It seems that the observed increase in biocompatibility of chitosan surface caused by irradiation with sterilizing dose (25 kGy) is due to some structural factor connected with a decrease in molecular weight.

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Abstract  

The thermal and photochemical reactions of the methylal radical cation /I/ in freon matrices were studied using selective deuteration for elucidating the structure of the resulting species. /I/ has been shown to decay by unimolecular reaction upon heating to 140 K as well as upon photolysis in CFCl3 matrix and the product of decay has been assumed to be the complex of formaldehyde radical cation with CFCl3. Such decay reaction has been demonstrated for 1,3-dioxolan radical cation as well.

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Abstract  

The alkaline synthesis of porous phenol-formaldehyde polymers containing iminodiacetic acid is described. Porosity is induced by the addition of a finely divided solid material (template) that is insoluble under the reaction conditions. This template is removed by dissolution after the polymerization is complete. Silica gel, carbonate salts and various other salts are used as templates. Resins containing different phenols are synthesized and their effectiveness for the removal of radioactive cesium and strontium from alkaline concentrated sodium salt brines is examined. This matrix typifies the composition of soluble defense nuclear waste.

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Abstract  

New synthetic standard samples (SSB-1 and SSB-2), produced on the basis of phenol-formaldehyde resin in the shape of tablets are suggested. The samples are intended for INAA of biological materials. SSB-1 and SSB-2 samples contain Se, Cr, Au, Sb, Ag, Rb, Fe, Zn, Co and Ca, Ba, Hg, Sn, Br, Cs, Ni, Sc and Na. The concentrations of these elements are chosen so that the maximum statistical error of -quantum registration by the semiconductor detector should not exceed 3% when irradiating samples in a neutron flux of 1013 n·cm–2·s–1.

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