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Autori: C.F. Petre and F. Larachi
Editorial: Industrial and Engineering Chemistry Research, 46, p.1990-1999, 2007.
The oxidation of methyl mercaptide by Fe/Ce oxide-hydroxide was studied as a potential approach to deal with the methyl mercaptan contamination from total reduced sulfur (TRS) emissions in the pulp and paper industry. The reaction was studied in aqueous solutions at 22oC and different alkaline pH values (10.5-12) both in anoxic and oxic conditions. Mercaptide reactivity was strongly dependent on pH in anoxia, whereas in oxic conditions it was noticeably higher but tributary of dissolved oxygen (DO2). Interference with bisulfide co-mixed with mercaptide caused an inhibition in the conversion for both pollutants. Such inhibition was due to the incipient polysulfides formed via bisulfide oxidation. On the contrary, the mercaptide conversion was found to improve at the expense of bisulfide when large quantities of exogenous polysulfides were present initially in the reaction medium. The conversion of mercaptide was unaffected with the co-mixing of dimethyl sulfide. The oxidation of methyl mercaptide by the O2/Fe/Ce oxide-hydroxide system did not affect the re-oxidative regeneration of surface Fe(III) by DO2. This feature pinpoints the sine qua none condition for a redox process based on the O2/Fe/Ce oxide-hydroxide system to remove methyl mercaptan in the pulp and paper emissions.
Cuvinte cheie: Pulp and paper industry; total reduced sulfur; methyl mercaptan; dimethyl sulfide; dimethyl disulfide; bisulfide; polysulfides; iron/cerium oxide-hydroxide; dissolved oxygen