P. Ormad

TiO2-CATALYSED OZONATION OF RAW EBRO RIVER WATER

Abstract This paper presents the results obtained with heterogeneous catalytic ozonation in which raw Ebro river (Spain) water is ozonated in the presence of titanium dioxide supported on alumina as a solid catalyst at two different O 3 :C weight basis ratios. The influence of catalytic ozonation on the trihalomethane (THM) formation during drinking-water treatment is also studied. It is shown that using this catalyst during ozonation of the natural water allowed reductions in THM formation. Characterization of the raw, ozonated and chlorinated water was made by concentrating the sample through liquid–liquid extraction, along with the gas chromatography/mass spectrometry (GC/MS). A total of 66 different organic compounds were identified, mainly carboxylic acids, aromatics, aldehydes, ketones and alcohols. The percentage of elimination or formation levels reached during ozonation and chlorination are discussed.

Degradation of organochloride compounds by O3 and O3H2O2

This paper presents the results obtained from oxidation with O3 and O3H2O2 of a residual water coming from the production of dicofol and tetradifon pesticides, where chlorobenzenes, DDTs and its metabolites and other organochloride compounds were found. The oxidation processes were carried out using ozone (O3) in basic medium (pH 9.4) at low dosage (0–1.5 g O3 g−1 initial TOC) and in the presence of hydrogen peroxide (H2O2), with a 0.5 H2O2O3 molar ratio. During the treatment, many compounds were removed (dichlorobenzophenone, tetradifon, chlorobenzene, trichlorobenzene) and their change in concentration at different ozonation contact time was monitored. Other compounds like DDE remained practically invariable. This study investigated the formation of first ozonation by-products (FOBPs) in the wastewater, specifically chlorophenols, by means of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/electron capture detection (GC/ECD) analysis in terms of the amount of time the O3 has been in contact with the processed sample. o-Chlorophenol, p-chlorophenol, benzenemthanol, n-chlorohydroxibenzaldehyde, n-chlorobenzenemethanol, chlorobenzoic acid, etc., were formed during the treatment, due to the mechanism of fast and non-selective oxidation which ozone has through OH radicals, formed by the decomposition of the O3 molecule and accelerated by the presence of H2O2 in water

Heterogeneous Catalytic Ozonation with Supported Titanium Dioxide in Model and Natural Waters

Abstract This paper presents the results obtained with heterogeneous catalytic ozonation in which model and natural waters are ozonated in the presence of supported titanium dioxide (TiC2) as a solid catalyst. The conditions in preparing the supported catalyst are experimentally optimized. The efficiencies of three catalyst supports (attapulgyte, alumina and silica gel) for organic matter oxidation have been compared. The TiC2 supported in alumina calcined at 500[ddot]C compacted to granular form with a particle diameter about 2-4 mm is demonstrated to be the best catalyst on the removal total organic carbon (TOC) by ozone.

Comparative Efficiency of the Systems O3/High pH And 03/catalyst for the Oxidation of Chlorobenzenes in Water

Abstract The objective of this study was to investigate the use of advanced oxidation processes to oxidize an industrial wastewater in which chlorobenzenes were found in the range of 1 mg/L to 5 mg/L and a solution of chlorobenzenes whose concentration was 0.03 mg/L, which was prepared from stock solutions. Ozone in a neutral medium (pH=7) was compared with ozone in presence of metallic ions, such as Fe (II), Fe(III) and Mn(II) at concentration of 610-5 M.

Wastewater from the manufacture of rubber vulcanization accelerators : characterization, downstream monitoring and chemical treatment

The content of wastewater resulting from the manufacture of rubber antioxidants and accelerators by a factory situated in the Ebro basin (Spain) has been determined using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The change in the pollutants was studied in the riverbed via two modules which continuously gathered pollutants on various solid supports (activated carbon and XAD-2 resins). These modules were located in Bocal Station, lying a further 100 km downstream from the factory, and from the Zaragoza water supply. Forty-six different compounds were identified at Bocal Station, the majority resulting from the production of rubber additives. Due to the immunity of different waste substances, and to the toxic nature of some, we studied their reaction when subjected to techniques of chemical oxidation using ozone.

Catalytic Ozonation with Supported Titanium Dioxide. The Stability of Catalyst in Water

Abstract This paper presents the results obtained with heterogeneous catalytic ozonation in which model and natural waters are ozonated in the presence of titanium dioxide (TiO2) supported on alumina. In this work the stability of the catalyst is investigated. Four consecutive ozonations with the same catalyst revealed no reduction in the organic matter oxidation. The results obtained in natural waters with catalysts that had been previously used indicated that the applied catalysts did not appear to lose any of their efficiency after use.

Characterization of organic micropollutants in the River Cinca (Spain) by using granular activated carbon and liquid-liquid extraction

The results obtained in the characterization of the micropollutants in the River Cinca by adsorption on granular activated carbon (GAC) and liquid-liquid (LL) extraction are presented. Gas chromatography-mass spectrometry was used for the identification of the various components in the water. Nineteen organochloride compounds [the complete series of chlorobenzenes, DDTs and their metabolites, dichlorobenzophenone (DCBF) and tetradifon] were quantified by gas chromatography-electron-capture detection. In the River Cinca, 229 and 74 compounds were identified by GAC and LL extraction, respectively, fifteen of which appear in the group of substances in List I of the 76/464/EEC European Council Directive as Priority Pollutants.

Study Of The Advanced Oxidation Processes Of Chlorobenzenes In Water

Abstract The focus of this study was to investigate the use of advanced oxidation processes to oxidize a residual water in which chlorobenzenes were found in the range of 1 mg/L to 10 mg/L and whose TOC was about 1,000 mg/L, and a solution of chlorobenzenes whose concentration was 0.03 mg/L, which was prepared from stock solutions. Ozone in basic medium (pH = 9) and ozone in the presence of hydrogen peroxide (H2O2) were compared.