Paradoxes and paradigms: Observations on pyrohydrolytic decomposition of fluorine-containg materials and accompanying thermochemistry

Abstract

Pyrohydrolysis is a fast, reliable and convenient method for the decomposition of solid samples. It is widely used for decomposition of samples containing fluorine. The efficiency of different accelerators for pyrohydrolytic decomposition and subsequent determination of fluoride in some raw materials, industrial products and pure CaF 2 was studied. A brief discussion on thermochemistry of these reactions is provided.

Effects of airborne fluoride on soil and vegetation

“…Samples of soil for determination of F t were decomposed by weighing approximately 100 mg (AE0.05 mg) of soil into a platinum crucible and mixing together with approximately 50 mg of WO 3 [18]. The crucible was inserted into the platinum reaction tube and heated for approximately 30 min at 1100 8C in the presence of a superheated water steam stream with a flow rate ranging from 0.5 to 1 ml min À1 .…”

Fluoride in Human Health and Nutrition

“…138,139 Reactions proceeding during decomposition of metal fluorides by pyrohydrolysis, oxygen bomb combustion and alkaline carbonate fusion and their related thermochemistry were discussed in our recent papers. 140,141 Calcium and magnesium fluoride, which can be in variable amounts present also in human, animal, vegetation and other environmental samples, were suggested as the most resistant ones to decompose among all the metal fluorides studied.…”

“…In our laboratory classical analytics used for determining the composition of bulk material of synthesised compounds containing fluorine 118,[276][277][278][279][280][281][282][283] was extended to thermochemical investigations, 118,140,141,[280][281][282][284][285][286][287] measurement uncertainty evaluation, 171 determination of fluorine in food 149,183 and environmental samples 7,288,289 and nanomaterials. [290][291][292][293][294] Principles of thermochemistry were used for the estimation of the entropies of formation of fluorine containing aqueous anions 285 and to discuss ions containing solely fluorine atoms 286 and oxidation potential of fluorine.…”

“…Based on this investigation some of the most resistant fluoride minerals towards the total decomposition were suggested. 140,141 The importance of evaluating the MU according to the GUM in research laboratories was addressed and a procedure for the MU evaluation for determination of F in vegetation was suggested. 171 Our study on fluorine contents in total diet samples is important, since it is one of the few studies on the intakes of fluoride from food in adults which is based on duplicate diet technique.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 17, 2006) and the discipline

“…? Ponikvar and Liebman [48] in the following article report about their study on the use of high temperature hydrolysis (pyrohydrolysis), with the use of WO 3 and U 3 O 8 as accelerators, for the purpose of decomposition and subsequent determination of fluorine in some fluorine containing industrial products and pure CaF 2 . These determinations are of crucial importance due to possible harmful effects of fluorine on health and environment.…”