Cloth catalysts in water denitrification: I. Pd on glass fibers

Fiber catalysts are easy to handle and free of mass-transfer resistance. This report is the first application of cloth catalysts to water denitrification. In this work, cloths woven from glass fibers (GF) of 7–10 mm in diameter, impregnated with Pd, were tested in a semi-batch reactor to evaluate their effectiveness in the catalytic liquid phase hydrogenation of nitrites and nitrates. The catalytic properties of Pd-GF cloths were evaluated as a function of Pd loading as well of chemical composition of the glass, specific surface area and weaving mode of the fibrous support. Investigated catalysts showed the same level of specific activity (per g Pd) as conventional powdered catalysts for liquid-phase hydrogenation of nitrites but their activity for nitrates was about one order of magnitude lower. The nitrite and nitrate removal activities were independent of the catalyst structure; the formation of ammonium ions was highly sensitive to reactant concentration. The stability of Pd-GF cloths is discussed

Tratamiento de efluentes acuosos contaminados con compuestos organoclorados

[ES] Los compuestos organoclorados son un tipo de residuos que han adquirido especial relevancia en los últimos tiempos, debido a sus características tóxicas y peligrosas, tanto para el medio ambiente como para los seres humanos. Su especial peligrosidad ha potenciado la búsqueda de alternativas para su tratamiento en las distintas corrientes donde se presentan. En este artículo se describe la problemática real de este tipo de compuestos, se exponen los principales contaminantes y se muestra una visión general de las alternativas para la eliminación de estos organoclorados de corrientes acuosas, detallándose en profundidad una de las alternativas de eliminación consideradas: la hidrodecloración catalítica en fase acuosa.Padilla Vivas, B.; Díez Sanz, FV.; Ordóñez García, S. (2005). Tratamiento de efluentes acuosos contaminados con compuestos organoclorados. Ingeniería del agua. 12(4):361-375. https://doi.org/10.4995/ia.2005.2571OJS361375124Alejandre A., Medina F., Rodríguez X., Salagre P., Cesteros Y., Sueiras J. E. (2000). Cu/Ni/Al layered double hydroxides as precursors of catalysts for the wet air oxidation of phenol aqueous solutions. Appl. Catal. B. 30:195-207Ali M., Sreekrishnan T. R. (2001). Aquatic toxicity from pulp and paper mill effluents: a reviewAdvances in Environmental Research. 5:175-196Aramendia M. A., Boráu V., García I. M., Jiménez C., Marinas A., Marinas J. M., Urbano F. J. (2002). Liquid-phase hydrodehalogenation of substituted chlorobenzenes over palladium supported catalysts. Appl. Catal. B.43:71-79Araujo J. (1993). Naturaleza y Ecología en España. La Muerte Silenciosa. Ed. Círculo de LectoresATSDR. Agency for Toxic Substances and Disease Registry (2002). ToxFAQs™. EEUU.Brauer H. (1985). Biotechnology Fundamentals of Biochemical Engineering. Volumen 2.Buitrón G., González A., López-Martín L. M. (1998). Biodegradation of phenolic compounds by an acclimated activated sludge and isolated bacteria. Water Science and Technology. 37:371-378Cuevas M. A. (1998). Jornadas sobre la contaminación de las aguas subterráneas: un problema pendiente. Valencia.Cybulski, Trawczynski J. (2004). Catalytic wet air oxidation of phenol over platinum and ruthenium catalysts. Appl. Catal. B. 47:1-13Debellefontaine H., Foussard J. (1999). Wet air oxidation for the treatment of industrial wastes. Chemical aspects, reactor design and industrial applications in Europe. Waste management. 20:15Energy Research Group (2003). Centre for Ecological Sciences, Bangalore, India.EPA (1998). The inventory sources of chlorinated pollutants in the United States (EPA/600/P-98/002Aa).EPA (1999). Integrated Risk Information System on 1,2,4-Trichlorobenzene.EPA (2003). Ground water primer, EPA region 5 and Agricultural & Biological Engineering. Purdue UniversityEuro Chlor (2002). Chloroform in the environment; Marine Risk Assessments (www.eurochlor.org)Felis V., Bellefon C., Fouilloux P., Schweich D. (1998). Hydrodechlorination and hydrodearomatisation of monoaromatic chlorophenols into cyclohexanol on Ru/C catalysts applied to water depollution: influence of basic solvent and kinetics of the reactions. Appl. Catal. B: Environ. 20:91-100Fernández J., Maruthamuthu P., Kiwi J. (2004). Photobleaching and mineralization of Orange II by oxone and metal-ions involving Fenton-like chemistry under visible light. Journal of Photochemistry and Photobiology A: Chemistry. 161:185-192Fortuny A., Bengoa C., Font J., Castells F., Fabregat A. (1999). Water pollution abatement by catalytic wet air oxidation in a trickle bed reactor. Catalysis Today. 53:107-114Fritsch D., Kuhr K., Mackenzie K., Kopinke F. (2003). Hydrodechlorination of chloroorganics compounds in groundwater by Pd catalysts. Part 1. Development of polymer-based catalysts and membrane reactor tests. Catalysis Today. 82:105-118García Ara L. J. (2002). Actuaciones para la minimización del impacto del vertido de sustancias peligrosas en la industria química. (www.eic.es)Glaze W., Kenneke J., Ferry J. (1993). Chlorinated by-products from the TiO2-mediated photodegradation of trichloroethylene and tetrachloroethylene in water. Environ. Sci. Technol. 27:177-184Heinrichts B., Schoebrechts J. P., Pirard J. P. (2001). Palladium-silver sol-gel catalysts for selective hydrodechlorination of 1,2-dichloroethane into ethylene. Part III. Kinetics and reaction mechanism. Part IV. Deactivation mechanism and regeneration. Journal of Catalysis. 200:309-320Hoke J. B., Gramiccioni G. A., Balko E. N. (1992). Catalytic hydrodechlorination of chlorophenols. Appl. Catal. B: Environ. 1:285-296Janssen D. B., Oppentocht J. E., Poelarends G. J. (2001). Microbial dehalogenation. Environmental Biotechnology. 12:254-258Jechorek M., Wendlandt K. D., Beck M. (2003). Cometabolic degradation of chlorinated aromatic compounds. Journal of Biotechnology. 102:93-98Kargi F., Eker S. (2004, in press, corrected proof). Removal of 2,4-dichlorophenol and toxicity from synthetic wastewater in a rotating perforated tube biofilm reactor. Process BiochemistryKim Y. H., Carraway E. R. (2000). Dechlorination of pentachlorophenol by zero valent iron and modified zero valent irons. Environ. Sci. Tec. 34:2014-2017Kopinke F., Mackenzie K., Köhler R. (2002). Catalytic hydrodechlorination of groundwater contaminants in water and in the gas phase using Pd/Al2O3. Appl. Catal B: Environ. 1349:1-10Kovenklioglu S., Cao Z., Farrauto R. J., Balko E. N. (1992). Direct catalytic hydrodechlorination of toxic organics in wastewater. AIChE J. 38:1003-1012Lin S. S., Chen C. L., Chang D. J., Chen C. & C. (2001). Catalytic wet air oxidation of phenol by various CeO2catalysts. Water research. 36:3009-3014Lomnicki S., Lichtenberger J., Xu Z., Waters M., Kosman J., Amiridis M. D. (2003). Catalytic oxidation of 2,4,6-trichlorophenol over vanadia/titania-based catalysts. Appl. Catal. B: Environ. 46:105-119López E., Ordóñez S., Díez F. V. (2003). Inhibition effects of organosulphur compounds on the hydrodechlorination of tetrachloroethylene. Catalysis Today. 84:121-127Lowry G. V., Reinhard M. (1999). Hydrodehalogenation of 1- to 3- carbon halogenated organic compounds in water using a palladium catalyst and hydrogen gas. Environ. Sci. Technology.33:1905-1910Lowry G. V., Reinhard M. (2000). Pd-catalyzed TCE dechlorination in groundwater: solute effects, biological control and oxidative catalyst regeneration. Environ. Sci. Technology. 34:3217-3223Malato S., Blanco J., Vidal A., Richter C. (2002). Photocatalysis with solar energy at a pilot-plant scale: an overview. Appl. Catal. B: Environ. 37:1-15Matatov-Meytal Y. I., Sheintuch M. (1998). Catalytic abatement of water pollutants. Ind. Eng. Chem. Res. 37:309-326Matatov-Meytal Y. I., Sheintuch M. (2000). Catalytic regeneration of chloroorganics-saturated activated carbon using hydrodechlorination. Ind. Eng. Chem.Res. 39:18-23Matatov-Meytal Y. I., Sheintuch M. (2002). Hydrotreating processes for catalytic abatement of water pollutants. Catalysis Today. 75:63-67Matheson L. J., Tratnyek P. G. (1994). Reductive dehalogenation of chlorinated methanes by iron metal. Environ. Sci. Technology. 28:2045-2053McNab W. W., Ruiz R., Reinhard M. (2000). In-situ destruction of chlorinated hydrocarbons in groundwater using catalytic reductive dehalogenation in a reactive well: testing and operational experiences. Environ. Sci. Technol. 34:149-153Ministerio de Medio Ambiente (2001). Medio Ambiente en España 2000. Ed. Direc. Gral. de Medio Ambiente.Muftikian R., Fernando Q., Korte N. (1995). A method for the rapid dechlorination of low molecular weight chlorinated hydrocarbons in water. Water Research. 29:2434-2439Ordóñez S., Díez F. V., Sastre H. (2003). Hydrodechlorination of tetrachloroethylene over Pd catalysts: influence of process conditions on catalyst performance and stability. Appl. Catal. B. 40:119-130Peres, J. A., Beltrán de Heredia J. (2004). Integrated Fenton's reagent coagulation/flocculation process for the treatment of cork processing wastewaters. Journal of Hazardous Materials. 107:115-121Perrone L., Prati L., Rossi M. (1997). Removal of chlorinated organic compounds from water by catalytic dehydrohalogenation. Appl. Catal. B: Environ. 15:241-246Portela J. R., Bernal J. L., Sanz E. N., Martínez de la Ossa E. (1997). Kinetics of wet air oxidation of phenol. Chem. Eng. J. 67:115-121Rivas F. J., Kolaczkowski S. T., Beltrán F. J., McLurgh D. (1998). Development of a model for the wet air oxidation of phenol based on a free radical mechanism. Chemical Engineering Science. 53:2575-2586Schmidt L. M., Delfino J. J., Preston J. F., St. Laurent G. (1999). Biodegradation of low aqueous concentration pentachlorophenol (PCP) contaminated groundwater. Chemosphere. 38:2897Schreier C. G., Reinhard M. (1995). Catalytic hydrodehalogenation of chlorinated ethylenes using palladium and hydrogen for the treatment of contaminated water. Chemosphere. 31:3475-3487Schüth C., Disser S., Schüth F., Reinhard M. (2000). Tailoring catalysts for hydrodechlorinating chlorinated hydrocarbon contaminants in groundwater. Appl. Catal. B: Environ. 28:147-152Schüth C., Reinhard M. (1998). Hydrodechlorination and hydrogenation of aromatic compounds over palladium on alumina in hydrogen-saturated water. Appl. Catal. B: Environ. 18:215-221Shindler Y., Matatov-Meytal Y. I., Sheintuch M. (2001). Wet hydrodechlorination of p-chlorophenol using Pd supported on an activated carbon cloth. Ind. Eng. Chem.Res. 40:3301-3308Sweeny K. H. (1981). The reductive treatment of industrial wastewaters. AIChE Symp.Series. 77:67-78Torrades F., Pérez M., Mansilla H. D., Peral J. (2003). Experimental design of Fenton and photo-Fenton reactions for the treatment of cellulose bleaching effluents. Chemosphere. 53:1211-1220Trabuco E., Ford P.C. (1999). Hydrodechlorination of 1,2-dichloroethane by rhodium catalysts under water gas shift reaction conditions. Journal of Molecular Catalysis A: Chemical. 148:1-7Young K., Daniel J., Lewis S. (2002). Kinetic and inhibition studies for the aerobic cometabolism of 1,1,1-trichloroethane, 1,1-dichloroethylene and 1,1-dichloroethane by a butane-grown mixed culture. Biotechnology and Bioengineering. 80:498-508Yuan G., Keane M.A. (2003a). Liquid phase catalytic hydrodechlorination of 2,4-dichlorophenol over carbon supported Pd: an evaluation of transport limitations Chemical Engineering Science. 58:257-267Yuan G., Keane M.A. (2003b). Liquid phase catalytic hydrodechlorination of chlorophenols at 273 K. Catalysis Communications. 4:195-201Yuan G., Keane M.A. (2003c). Catalyst deactivation during the liquid phase hydrodechlorination of 2,4-dichlorophenol over supported Pd: influence of the support. Catalysis Today. 88:27-3

Effect of pH on the Nitrite Hydrogenation Mechanism over Pd/Al2O3 and Pt/Al2O3: Details Obtained with ATR-IR Spectroscopy

It is well-known that activity and selectivity to N2 during nitrite hydrogenation over noble metal catalysts in water depend on the pH of the solution, but mechanistic understanding is lacking. Attenuated total reflection infrared (ATR-IR) spectroscopy is an ideal tool to perform detailed studies on catalytic surfaces in water. In this paper, the influence of pH was studied on adsorption and subsequent hydrogenation of nitrite in water between pH 5 and 9 over Pd/Al2O3 and Pt/Al2O3, using ATR-IR spectroscopy. On both catalysts, pH clearly influenced the surface coverage and reaction rates of intermediates. For Pt/Al2O3, lowering the pH induced the increasing surface coverage of key reaction intermediates like NOsteps1620 cm−1 and “HNO”(ads)1540 cm−1, as well as increased hydrogenation rates, explaining the higher TOF at lower pH as reported in the literature. For Pd/Al2O3, the effect of pH on selectivity is controlled by the rate constants of the formation and hydrogenation of the most stable reaction intermediates to N2 (NO(ads)1720 cm−1) and NH4+ (NH2(ads)1510 cm−1)