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Abstract  

The extraction equilibrium of ternary ion-association complexes obtained during the reaction of tetrachloride complex of thallium(III) and monotetrazolium salts triphenyltetrazolium chloride (TTC) or thiazolyl blue (MTT) has been studied. The optimum conditions that are required to carry out the investigations have been found. As a result of using a developed chemical model, the constants of extraction, distribution and association, the distribution coefficients and the recovery factor of investigated ionassociates have been determined radiochemically.

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Abstract  

The extraction equilibrium of ternary ion-association complexes formed between the tetrachloro complexes of thallium(III) and ditetrazolium salts, neotetrazolium chloride (NTC)[2,2′,5,5′-tetraphenyl-3-3′-(p-biphenylene)ditetrazolium chloride] and nitrobluetetrazolium chloride (NBT)[3,3′-dianizole-4,4′-bis-2-(4-nitrophenyl-5-phenyltetrazolium chloride], has been studied. As a result, the extraction constants, the distribution constants, the association constants, the distribution coefficients of thallium(III) and the extraction indicators R, have been calculated. The results have been evaluated statistically. The relative standard deviations Sr have been calculated at a statistical certainty of 95%. The ratio ditetrazolium salts/TlCl 4 =1∶2 has been confirmed once again.

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Abstract  

The extraction equilibrium of the ternary ion-association complex of iodo-nitro-tetrazolium [3-(4-iodophenyl)-2-(4-nitrophenyl)-5-phenyltetrazolium chloride] with the chlorocomplex of thallium(III) is investigated radiochemically. The molar ratio of the ion-associate is found to be 1∶1, the association constant has a value of β=3.2·103 in aqueous solution and the distribution constant is KD=8.9. The extraction constant which gives a quantitative characterization of the equilibrium has a relative high value, E=2.3·104. This enables a convenient application of the investigated system for analytical purposes.

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Abstract  

Several commercially available 2H-tetrazolium salts (TS) {2,3,5-triphenyl-2H-tetrazolium chloride (TTC), 3-(1-naphthyl)-2,5-diphenyl- 2H-tetrazolium chloride (Tetrazolium Violet, TV), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) and 3,3′-(3,3′-dimethoxy-4,4′-biphenylene)-bis(2,5-diphenyl- 2H-tetrazolium) chloride (Tetrazolium Blue Chloride, BTC)} and their ion-associated complexes (IAC) with the Mo(VI) — 4-nitrochatechol (4-NC) anionic chelate [MoO2(4-NC)2]2− have been investigated by differential thermal analysis (DTA) and thermogravimetric analysis (TG). Some special features of the thermal behavior of the compounds have been discussed. The results show that the thermal stability of IAC depends on the factors determining the values of their association constants β: molecular mass and the presence of nitrophenyl substituent(s) in the tetrazolium ring.

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Abstract  

We attempted to determine the experimental conditions under which poplar plastocyanin iso-forms PCa and PCb undergo reversible thermal unfolding studied by differential scanning calorimetry (DSC). Our results indicate that an exothermic unfolding process exists always in the presence of molecular oxygen. Reversible unfolding and almost perfect two-state transitions were exhibited in the presence of TCEP under anaerobic conditions. This suggests that the second endothermic peak is due to copper-site disulfide dimmers formed during thermal denaturation. The conformational thermal stability of reduced PCbG (25 °C) = 33.9 kJ mol−1) has proven to be higher than that of reduced PCaG(25 °C) = 22.9 kJ mol−1).

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Thermal degradation of rice husks on a pilot plant

Utilization of the products as adsorbents for oil spill cleanup

Journal of Thermal Analysis and Calorimetry
Authors:
S. Genieva
,
S. Turmanova
,
A. Dimitrov
,
P. Petkov
, and
L. Vlaev

Abstract

This study is an attempt to establish the possibilities to obtain black rice husk ash (BRHA) and white rice husk ash (WRHA) via pyrolysis of wasted raw rice husks in a pilot plant fluidized-bed reactor at different conditions. The process course auto thermally, without outer fuel. The released heat may be used for steam obtaining or drying. The solid products obtained (BRHA or WRHA) are characterized using X-ray diffraction patterns, thermal analysis, and low temperature nitrogen adsorption. Using batch adsorption technique, the kinetics was studied and the adsorption capacities of crude oil and diesel fuel at different temperatures as well as some hydrocarbons at 298 K onto BRHA and WRHA are determined. It was established that BRHA have been higher adsorption capacity than WRHA. At a given temperature, BRHA sorbed more crude oil than diesel fuel. The results obtained showed that the material studied has high adsorption capacity and low cost and may successfully be used as an effective adsorbent to cleanup of bilge water and spills of oil and oil products in water basins. Because the saturated BRHA with crude oil, diesel fuel or different hydrocarbons are characterized with high calorific, they can be burnt in incinerators, industrial ovens or steam generators. By this way, we attain not only ecological but also economical effect.

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