Self-irradiation of organic matter produces radiolytic gas. It is thought today that the release of radiolytic hydrogen may be inhibited by means of hydrogen reacting solids. In this work, the hydrogen trapping potential of a class of metal sulfides was studied by use of irradiation of mixtures from relevant inorganic compounds and model organics. Both organic and solid phases were thoroughly investigated before and after irradiation in order to elucidate the origin of the trapping effect. Aliphatic hydrocarbons and their mixtures with aromatics were irradiated by gamma rays at variable doses from 0.3 to 4 MGy. Crystalline and amorphous cobalt sulfides of different stoichiometry, oxygen containing cobalt compounds (Co(OH)2 and CoSO4), as well as sulfides of other metals (Mo, Ru and Ni) were used as admixtures. As follows from the experiments with the mixtures of aliphatic and aromatic hydrocarbons, transition metal sulfides do not influence the amounts of radiolytic hydrogen produced, nor the composition of organic matter after irradiation. Under experimental condition described above, this result shows that among the cobalt compounds investigated the amorphous precipitates of general composition CoOxSyHz.nH2O are efficient in inhibiting the hydrogen release, in comparison with closely related solids such as CoS, Co(OH)2 or CoSO4. On the whole, the amount and composition of organic radiolysis experimental data indicate that hydrogen is trapped within the solid. Indeed, even in the absence of irradiation, solids like CoOxSyHz.nH2O are able to absorb considerable amounts of hydrogen at ambient conditions.
(a) Institut de Recherches sur la Catalyse – CNRS UPR5401, 2 Av. A. Einstein, 69 626 Villeurbanne, France ;
(b) Institut de Radioprotection et de Sûreté Nucléaire, BP. 17, 92 262 Fontenay aux Roses, France -