Regeneration of an aqueous solution containing ferrous or ferric ions with hydrogen peroxide

• Main Authors: LECOMTE FABRICE, DEZAEL CLAUDE
• Format: Patent
• Language: English; French
• Published: 11.06.1999
• Edition: 6
• Subjects: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; COMPOUNDS THEREOF; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; THEIR RELEVANT APPARATUS; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

The regeneration of an aqueous solution containing ferrous ions complexed by chelating agents consists of contacting the aqueous solution with a liquid phase containing an oxidant, such as persulfate, sodium persulfate, peroxide or sodium peroxide, or hypochlorite or hydrogen peroxide. The hydrogen peroxide is used to oxidise the ferrous ions into ferric ions according to the equation: 2Fe<2+> (chelate) + 2H<+> + H2O2 = 2Fe<3+> (chelate) + 2H2O The quantity of the liquid phase is monitored by measuring the redox potential of the aqueous solution. The regeneration process is carried out as follows: (a) contacting the gas with the catalytic aqueous solution comprising of at least a polyvalent metal chelated by a chelating agent, in appropriate conditions to ensure the oxidation of hydrogen sulphide in elemental sulphur and the concomitant reduction of the metal of high valency to a metal of low valency. Part of the effluent judiciously freed of H2S is recovered as well as part of the reduced aqueous solution containing elemental sulphur, the reaction being in the form of H2S + 2Fe<2+> (chelate) = S + 2H<+> + 2Fe<2+> (chelate), (b) separating the elemental sulphur produced by the reduced aqueous solution, (c) regenerating at least part of the reduced purified aqueous solution, with a liquid phase containing an oxidant which allows the oxidation of complexed ferrous ions by chelating agents into ferric ions, the liquid phase comprising of persulfate, sodium persulfate, peroxide or sodium peroxide, or hypochlorite or hydrogen peroxide. - Procédé de régénération d'une solution aqueuse contenant des ions ferreux complexés où l'on met en contact ladite solution aqueuse avec une phase liquide ayant un pouvoir oxydant, telle que de l'eau oxygénée, dans des conditions choisies pour réaliser l'oxydation des ions ferreux en ions ferriques selon la réaction (CF DESSIN DANS BOPI) - Application à la régénération d'une solution aqueuse issue d'un procédé de désulfuration.