Jean-Marie Herrmann

Bio: Jean-Marie Herrmann is an academic researcher from University of Lyon. The author has contributed to research in topics: Photocatalysis & Catalysis. The author has an hindex of 44, co-authored 74 publications receiving 12508 citations. Previous affiliations of Jean-Marie Herrmann include École centrale de Lyon & Claude Bernard University Lyon 1.

Photocatalytic degradation pathway of methylene blue in water

Abstract: The TiO2/UV photocatalytic degradation of methylene blue (MB) has been investigated in aqueous heterogeneous suspensions. In addition to a prompt removal of the color, TiO2/UV-based photocatalysis was simultaneously able to oxidize the dye, with an almost complete mineralization of carbon and of nitrogen and sulfur heteroatoms into CO2 ,N H4 + ,N O3 − and SO4 2− , respectively. A detailed degradation pathway has been determined by a careful identification of intermediate products, in particular aromatics, whose successive hydroxylations lead to the aromatic ring opening. These results suggest that TiO2/UV photocatalysis may be envisaged as a method for treatment of diluted waste waters in textile industries. © 2001 Elsevier Science B.V. All rights reserved.

Photocatalytic degradation of various types of dyes (alizarin s, crocein orange g, methyl red, congo red, methylene blue) in water by uv-irradiated titania

Abstract: The photocatalytic degradation of five various dyes has been investigated in TiO 2 /UV aqueous suspensions. It was attempted to determine the feasibility of such a degradation by varying the chemical structures, either anthraquinonic (Alizarin S (AS)), or azoic (Crocein Orange G (OG), Methyl Red (MR), Congo Red (CR)) or heteropolyaromatic (Methylene Blue (MB)). In addition to a prompt removal of the colors, TiO 2 /UV-based photocatalysis was simultaneously able to fully oxidize the dyes, with a complete mineralization of carbon into CO 2 . Sulfur heteroatoms were converted into innocuous SO 4 2− ions. The mineralization of nitrogen was more complex. Nitrogen atoms in the −3 oxidation state, such as in amino-groups, remain at this reduction degree and produced NH 4 + cations, subsequently and very slowly converted into NO 3 − ions. For azo-dye (OG, MR, CR) degradation, the complete mass balance in nitrogen indicated that the central NN azo-group was converted in gaseous dinitrogen, which is the ideal issue for the elimination of nitrogen-containing pollutants, not only for environmental photocatalysis but also for any physicochemical method. The aromatic rings were submitted to successive attacks by photogenerated OH radicals leading to hydroxylated metabolites before the ring opening and the final evolution of CO 2 induced by repeated subsequent “photo-Kolbe” reactions with carboxylic intermediates. These results suggest that TiO 2 /UV photocatalysis may be envisaged as a method for treatment of diluted colored waste waters not only for decolorization, but also for detoxification, in particular in textile industries in semi-arid countries.

Synergy effect in the photocatalytic degradation of phenol on a suspended mixture of titania and activated carbon

Abstract: The photocatalytic degradation of phenol, chosen as an aromatic model molecule, has been performed at room temperature (20°C) in contact with a suspended mixture of titania and of activated carbon (AC). Non-additive adsorption capacities were observed when the solids were mixed, and this was ascribed to a strong interaction, involving half of the surface of titania and ca. 14% of that of AC. A synergy effect was observed with an increase of the first order rate constant by a factor of 2.5. As for neat titania, the same main intermediate products (hydroquinone and benzoquinone) were found but in much smaller quantities and during a much smaller lifetime, suggesting that the same reaction mechanism occurred in the presence of photoinactive AC. The synergy effect was ascribed to an extended adsorption of phenol on AC followed by a transfer to titania where it is photocatalytically degraded. The synergy effect could not be improved by previous physical treatments of the solid mixture such as grinding and sonication. Some phenol remained adsorbed on AC when no traces of organic compounds were detected in the purified water. This adsorbed phenol could be destroyed by illuminated titania while maintaining UV-irradiation. This combined photocatalytic system may appear as a new performing one, more efficient with a shorter time necessary for decontaminating diluted used waters.

Influence of chemical structure of dyes, of pH and of inorganic salts on their photocatalytic degradation by TiO2 comparison of the efficiency of powder and supported TiO2

Abstract: Anionic (Alizarin S (AS), azo-Methyl Red (MR), Congo Red (CR), Orange G (OG)) and cationic (Methylene Blue (MB)) dyes were degraded, either individually or in mixtures, by using UV-irradiated TiO 2 in suspension or supported on glass and on paper. The influence of the chemical structure of different dyes as well as that of pH and of the presence of inorganic salts on the photocatalytic properties of TiO 2 has been discussed. The role of adsorption is suggested, indicating that the reaction occurs at the TiO 2 surface and not in the solution. S and N hetero-atoms are respectively mineralized into SO 4 2− , NO 3 − and NH 4 + , except azo-groups which mainly formed N 2 which represents an ideal case for a decontamination reaction. The fate of nitrogen strongly depends on its initial oxidation degree. High photocatalytic activities have been found for TiO 2 coated on glass by the sol–gel method. Its efficiency was intermediate between those of PC-500 and P-25 powders. The efficiency of PC-500 TiO 2 sample, fixed on paper by using a binder, is slightly less important than that of the powder. The presence of a silica-binder with an acidic pzc is suggested to be at the origin of the decrease in efficiency.

Understanding TiO2 photocatalysis: mechanisms and materials.

Abstract: Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China