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The interactions between three polynuclear aromatic htydrocarbons (PAHs), namely fluorene, naphthalene and anthracene, and three fractions of a soil, namely fulvic acid (FA), humic acid (HA) and humidinorganic fractions, were studied experimentally. Prepared PAH + soil fraction binary mixtures, with PAH concentrations ranging over 0.8-7 mass%, were tested using a differential scanning calorimeter (DSC) over a temperature range of 20-390°C.The DSC thermograms for the PAH + HA mixtures showed distinctly different characteristics compared to mixtures with the other two soil fractions, where the endothermic peak for the vaporization of the PAH was absent. With the aid of vapour-liquid flash calculations, the lack of the boiling point peak is interpreted to be due to the liquid-phase miscibility of the PAHs and the HA fraction. Implications of the DSC results on the design and performance of the thermal desorption process are discussed.On a ttudit exp6rimentalement les interactions de trois tiydrocarbures aromatiques polynuclkaires (PAH), soient le fluorhe le naphtakne et I'anthrdne et de trois fractions cle sol, soient d'acide fulvique (FA), d'acide humique (HA) et des fractions humiqueslinorganiques. Des mtlanges binaires de PAH+fraction de sol, avec des concentrations en PAH de 0,8-7% en masse. ont 6d tesds au moyen d'un calorim&re difftrentiel h balayage (DSC), dans une gamme de ternp6ratures de 20 ZI 390 "C. Les thermogrammes du DSC pour les mtlanges PAH+HA montrent distinctement difftrentes caracdristiques, comparativement aux mtlanges faits ZI partir des deux autres fractions de sol, IS oh le pic endothermique correspondant S la vaporisation du PAH est absente. Avec I'aide des calculs de ponts flashs liquidevapeur, on interprkte I'ahsence de pic de point d'tbullition h la miscibilit6 en phase liquide des PAH et de la fraction HA. On analyse les implications des rtsultats du DSC sur la conception et la performance du proddt de dtsorption thermique.

Most of the bountiful literature on the calculation of effectiveness factors for catalyst particles deals with relatively simple reactions and kinetics. The performance of catalyst particles in the industrially important, modified Claus reaction introduces multiple reactions, sulphur vapour equilibria, non‐linear kinetics and limiting thermodynamic conversions into the calculation of local effectiveness factors. This analysis demonstrates a means for generating local effectiveness factors, during reactor design calculations by the use of a single calculated curve of versus a modified Thiele parameter for spherical particles.

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