Edta Destruction Using The Solar Ferrioxalate Advanced Oxidation Technology (aot) Comparison With Solar Photo-fenton Treatment

Degradation of ethylenediaminetetraacetic acid (EDTA; in the mmol/l range) at pH 3 was studied by the ferrioxalate/H2O2 process under solar irradiation. A rapid total organic carbon (TOC) removal was attained in all cases, reaching almost 100% after 1 h solar exposure under the best conditions. In order to attain a high TOC removal yield, the pH must be rigorously controlled. The reaction rate increased with H2O2 concentration; but its effect was not very marked. The final extent of degradation was found to decrease with higher ferrioxalate concentrations, probably by competition of oxalate with EDTA or its degradation products. In the absence of oxalate, EDTA could also be degraded to a reasonably good extent, with a TOC removal only slightly lower than when using ferrioxalate, which constitutes a good advantage from the economical point of view. The intensity of solar light was found to be a very important factor to improve the reaction. © 2002 Elsevier Science B.V. All rights reserved.1511-3121127Babay, P.A., Emilio, C.A., Ferreyra, R.E., Gautier, E.A., Gettar, R.T., Litter, M.I., Oxidation Technologies for Water and Wastewater Treatment (II) (2001) Water Sci. Technol, 44, p. 179. , A. Vogelphol, S.U. Geissen, B. Kragert, M. Sievers (Eds.), ISSN 0273-1223, ISBN 1-84339-402-2Babay, P.A., Emilio, C.A., Ferreyra, R.E., Gautier, E.A., Gettar, R.T., Litter, M.I., (2001) Int. J. Photoenergy, 3, p. 193Hinck, M.L., Ferguson, J., Puhaakka, J., (1997) Wat. Sci. Technol, 35, p. 25Brauch, H.J., Schullerer, S., (1987) Vom Wasser, 69, p. 155Brauch, H.J., Schullerer, S., (1989) Vom Wasser, 72, p. 23Gilbert, E., Hoffmann-Glewe, S., (1990) Water Res, 24, p. 39Tucker, M.D., Barton, L.L., Thomson, B.M., Wagener, B.M., Aragon, A., (1999) Waste Manage, 19, p. 477Rodríguez, J., Mutis, A., Yeber, M.C., Freer, J., Baeza, J., Mansilla, H.D., (1999) Water Sci. Technol, 40, p. 267Krapfenbauer, K., Getoff, N., (1999) Rad. Phys. Chem, 55, p. 385Furlong, D.N., Wells, D., Sasse, W.H.F., (1986) Aust. J. Chem, 39, p. 757Low, G.K.C., McEvoy, S.R., Matthews, R.W., (1991) Environ. Sci. Technol, 25, p. 460Sabin, F., Türk, T., Vogler, A., (1992) J. Photochem. Photobiol. A: Chem, 63, p. 99Kagaya, S., Bitoh, Y., Hasegawa, K., (1997) Chem. Lett, p. 155Madden, T.H., Datye, A.K., Fulton, M., Prairie, M.R., Majumdar, S.A., Stange, B.M., (1997) Environ. Sci. Technol, 31, p. 3475Litter, M.I., Navío, J.A., (1994) J. Photochem. Photobiol. A: Chem, 84, p. 183Litter, M.I., (1999) Appl. Catal. B: Environ, 23, p. 89Navío, J.A., Colón, G., Litter, M.I., Bianco, G.N., (1996) J. Mol. Cat, 106, p. 267Navio, J.A., Testa, J.J., Djedjeian, P., Padrón, J.R., Rodríguez, D., Litter, M.I., (1998) Appl. Catal. A: Gen, 178, p. 191San Román, E.A., Navío, J.A., Litter, M.I., (1998) Adv. Oxid. Technol, 3, p. 261Botta, S., Restrepo, G.M., Navío, J.A., Litter, M.I., (1999) J. Photochem. Photobiol. A: Chem, 129, p. 89Su, Y., Wang, Y., Daschbach, J.L., Fryberger, T.B., Henderson, M.A., Janata, J., Peden, C.H.F., (1998) J. Adv. Oxid. Technol, 3, p. 63Sörensen, M., (1996), Dr.-Ing. Thesis, Faculty of Chemical Engineering, Fridericiana Karlsruhe University, GermanySörensen, M., Frimmel, F.H., (1995) Z. Naturforsh, 50 B, p. 1845Sörensen, M., Zurell, S., Frimmel, F.H., (1998) Acta Hydrochim. Hydrobiol, 26, p. 109Emilio, C.A., Litter, M.I., Magallanes, J.F., (2001) Helvetica Chim. Acta, 84, p. 799Legrini, O., Oliveros, E., Braun, A.M., (1993) Chem. Rev, 93, p. 67Pignatello, J.J., (1992) Environ. Sci. Technol, 26, p. 944Bossmann, S.H., Oliveros, B., Göb, S., Siegwart, S., Dahlen, E.P., Payawan L., Jr., Straub, M., Braun, A.M., (1998) J. Phys. Chem. A, 102, p. 5542Pignatello, J.J., Liu, Di., Huston, P., (1999) Environ. Sci. Technol, 33, p. 1832Safarzadeh-Amiri, A., Bolton, J.R., Cater, S.R., (1996) J. Adv. Oxid. Technol, 1, p. 18Hatchard, C.G., Parker, C.A., (1956) Proc. Roy. Soc. (London) A, 235, p. 518Zuo, Y., Hoigne, J., (1992) Environ. Sci. Technol, 26, p. 1014Nogueira, R.F.P., Jardim, W.F., (1999) J. Adv. Oxid. Technol, 4, p. 1Nogueira, R.F.P., Alberici, R.M., Mendes, M.A., Jardim, W.F., Eberlin, M.N., (1999) Ind. Eng. Chem. Res, 38, p. 1754Nam, S., Renganathan, V., Tratnyek, P.G., (2001) Chemosphere, 45, p. 59Kari, F.G., Hilger, S., Caronica, S., (1995) Environ. Sci. Technol, 29, p. 1008Sawyer, D.T., Kang, Ch., Llobet, A., Redman, Ch., (1993) J. Am. Chem. Soc, 115, p. 5817Nogueira, R.F.P., personal communicationUzumasa, Y., Nishimura, M., Seo, T., (1957) Bull. Chem. Soc. Jpn, 30, p. 438Balmer, M.E., Sulzberger, B., (1999) Environ. Sci. Technol, 33, p. 2418Draganic, I.G., Gal, O., (1971) Rad. Res. Rev, 3, p. 16

Heterogeneous photocatalysis of Cr(VI) in the presence of citric acid over TiO2 particles : relevance of Cr(V)-citrate complexes

International audienceTiO2-photocatalytic reduction experiments of Cr(VI) (0.8 mM) under near UV (366 nm) irradiation in the presence of citric acid (0 ≤ [citric acid] (mM) ≤ 40) were performed at pH 2 under air bubbling. Addition of citric acid facilitates Cr(VI) reduction, hindering the electron-shuttle mechanism taking place in pure water. TOC monotonously decreases until all Cr(VI) was reduced. The maximum rate of Cr(VI) reduction was attained for an initial citric acid/Cr(VI) molar ratio, R, equal to 1.25, a further increment in R being detrimental; however, Cr(VI) decay in the presence of citric acid was always faster than in its absence. Cr(VI) reduction takes place through Cr(V) species, readily complexed by citrate and detected by EPR spectroscopy. Quantitative EPR determinations indicate that an important fraction (nearly 15%) of the reduced Cr(VI) is transformed to Cr(V)-Cit, which also undergoes a photocatalytic transformation. The detrimental effect taking place at high conversions for R > 1.25 can be ascribed to secondary steps, i.e., the competition between Cr(VI) and Cr(V) complexes for conduction band electrons or to the competition of Cr(V)-Cit and Cit for holes

Adsorption of Boron by Metallurgical Slag and Iron Nanoparticles

Boron is a problematic pollutant because of the difficulty involved in removing it from water with an acceptable cost-to-benefit ratio, especially at extremely high concentrations (600 mg B/l). It is also necessary to remove the pollutant to comply with the quality criteria for drinking water (1 mg B/l) and even for agricultural irrigation purposes (0.5–15 mg B/l depending on crop tolerance). Although some newly proposed water-treatment technologies use economical adsorbents, they are unable to achieve the residual concentrations. The aim of this work is to show that adsorption using metallurgical slags (SL) can be used either as a pre-treatment of the zero-valent iron nanoparticles (nano-Fe 0 ) or as a final treatment itself for removing boron at high concentrations to obtain effluents complying with the standards established for drinking water and wastewater reuse. Adsorption tests (kinetics and isotherms) were carried out for both adsorbents. The slags showed good results as an adsorbent for boron removal in the pre-treatment and final treatment stages, with a very low cost compared with nano-Fe 0 . The use of slags instead of expensive commercial adsorbents makes adsorption of water with high boron concentrations feasible, and allows obtaining treated wastewater for agricultural irrigation of very tolerant crops

Arsenic removal from groundwater of the Chaco-Pampean Plain (Argentina) using natural geological materials as adsorbents

Use of natural geological materials for arsenic (As) removal is an emerging solution at a household level for poor people in remote rural settlements, especially when the materials are locally available and can be collected by the local population. Their low or zero cost makes these materials very attractive compared with synthetic or commercial materials. Sometimes, this may be the only option to provide safe water to very poor settlements. Their suitability for As removal from water is mainly due to adsorption, co-precipitation and ion exchange processes involving Fe-and Al-rich minerals and clay minerals present in the soils or sediments. In the present study, various clay-rich soils from the Santiago del Estero province (SDE, NW Argentina) and, for comparison, a laterite from the Misiones province have been tested as adsorbents for As in shallow naturally contaminated groundwaters of the Rio Dulce alluvial aquifer in SDE. Batch adsorption experiments showed higher As(V) removal for the Misiones laterite sample (99 %) as compared with the soils from SDE (40-53 %), which can be related to lower contents of water-soluble and oxalate extractable Al and Fe in the last samples. These results suggest the application of the Misiones laterite soil as an alternative for As removal. However, high transportation costs from Misiones to SDE can be an economical restriction for the low-income population of SD

Solar Energy Based Water Potabilization: Low-cost Technologies For Isolated Regions Of Latin America And The Caribbean

Low-cost technologies, based on the use of solar energy, are proposed in the framework of the OAS/AE/141/2001 project to provide safe drinking water in isolated rural populations of Latin America and the Caribbean, with scarce hydric and economical resources. The offered technologies are Solar Disinfection in Individual Units (SODIS-DSAUI), Arsenic Removal by Solar Oxidation (SORAS-RAOS) and Solar Heterogeneous Photocatalysis with Titanium Dioxide (HP). It was found that DSAUI can be applied in all cases for disinfection, although HP can treat simultaneously bacterial and chemical contamination. RAOS is efficient in synthetic samples but the applicability to real waters is very dependent on the water matrix. All results are described and discussed together with actions to impulse the application by disseminating the methods and educating the population.428742879Litter, M.I., Mansilla, H., (2001) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/aguapura/default.htm, Solar water disinfection in rural communities of Latin America, Project OEA/AE141. ISBN 987 43 6942 6, La PlataNavntoft, C., Dawidowski, L., Paladini, A., Blesa, M.A., Assessment of a simple UV radiation model for applications in photocatalytic systems in Argentina (2004) 12th SolarPACES Int. Symp., , Oaxaca, Mexico, OctoberWegelin, M., (2000) EAWAG News, 48. , 11-12, SeptemberWater & Sanitation in Developing Countries, , http:/www.sodis.ch, EAWAG-SANDECBlesa, M.A., Eliminación de contaminantes por fotocatálisis heterogénea (2001) CYTED VIII-G Network, , http://www.cnea.gov.ar/xxi/ambiental/CYTED/default.htm, Digital Grafic, La PlataHug, S., (2000) EAWAG News, 49. , 18-20, DecemberWegelin, M., Gechter, D., Hug, S., Mahmud, A., Motaleb, A., http://www.sandec.ch/WaterTreatment/Documents/SORAS.pdfLitter, M.I., (2002) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/aguapura/default.htm, Prospect of rural communities of Latin America for the application of low-cost technologies for water potabilization, Project OEA/AE141, La PlataIbáñez, J.A., Litter, M.I., Pizarro, R.A., (2003) J. Photochem. Photobiol. A: Chem., 157, p. 81Litter, M.I., Mansilla, H.D., (2003) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/aguapura/default.htm, Sunlight assisted arsenic removal in rural communities of Latin America, Project OEA/AE141, La PlataLitter, M.I., Jiménez González, A., (2004) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/agua-pura/default.htm, Advances in low-cost solar technologies for disinfection, decontamination and arsenic removal in waters of rural communities of Latin America (HP and RAOS methods), Project OEA/AE141, La PlataGarcía, M.G., D'hiriart, J., Giulitti, J., Lin, H., Custo, G., Del Hidalgo, M.V., Litter, M.I., Blesa, M.A., Solar light induced removal of arsenic from contaminated groundwater: The interplay of solar energy and chemical variables (2004) Solar Energy, 77, p. 60