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The bacterial inactivation of E. coli by cotton TiO2/Cu DC-magnetron sputtered thin films was investigated in the dark and under low-intensity actinic light. The TiO2/Cu sputtered layers revealed to be sensitive to actinic light showing the spectral characteristics of Cu/CuO. This indicates that Cu does not substitute Ti4+ in the crystal lattice. Under diffuse actinic light (4 mW/cm2), the hybrid composite TiO2/Cu sample lead to fast bacterial inactivation times

Photo-Fenton process was explored as photochemical pre-treatment to improve the biodegradability of a wastewater coming from a textile industry located in the south of France, which was characterized as very biorecalcitrant by means of Zahn–Wellens biodegradability test. The effect of H2O2, Fe(III) and temperature on the photo-mineralization processes have been studied and the optimal conditions were found. Experiments were made to obtain information concerning the evolution of the biodegradability of the treated effluent after 40 and 70% of photo-mineralization. The photo-treated effluent is not biocompatible and its complete mineralization cannot be performed by biological means. UV–VIS and high-performance liquid chromatography (HPLC) analyses show that aromatic intermediates remain in the effluent after the photo-treatment, which have been identified as the principal reason of the biorecalcitrance.

The electrochem. oxidn. of phenol for wastewater treatment was studied on doped SnO2 anodes. Anal. of reaction intermediates and a C balance showed that the main reaction is oxidn. of phenol to CO2. This unexpected behavior of the SnO2 anode is explained by a change of the chem. structure of the electrode surface during anodic polarization. [on SciFinder (R)]

A detrimental effect on the survival of bacteria Escherichia coli KI2 was observed after photocatalytic exposure. The reactions have been carried out in a batch photoreactor using mainly titanium dioxide (TiO2) P-25 Degussa as a catalyst. Illumination was produced by a Hanau Suntest lamp. Some parameters, such as light intensity, extend of continuous irradiation, catalyst concentration and temperature have a positive effect on disinfection. Intermittent illumination results in an increase in the time required for E. coli inactivation. No bacterial growth was observed after illumination of a contaminated TiO2 suspension. In contrast, without catalyst, illuminated bacteria recovered its initial concentration after 3 h in the dark. Bacterial inactivation in the absence of catalyst was more affected than that with catalyst when increasing light intensity from 400 to 1000 W/m(2). TiO2 concentrations higher than 1 g/l do not significantly increase the initial inactivation rate for both intensities. However, at 1000W/m(2) a modification of TiO2 concentration ranging between 0.25 and 1.5g/l did not affect the total inactivation time, as with 400 W/m(2). Water turbidity negatively affects the photocatalytic inactivation of bacteria. TiO2 immobilized on Nafion((R)) membranes inactivates E. coli with efficiencies close to those observed for bacterial suspension containing the same concentration of suspended TiO2. For fixed TiO2 on glass, the dose (W min/m(2)) necessary for the total inactivation decreases by increasing the fixed TiO2 amount. Fixed TiO2 P-25 was more active to photocatalytic inactivation when compared with immobilized rutile and anatase. However fixed rutile enhances E. coli inactivation as anatase. The effect of temperature and turbidity were made using wastewater sample. (C) 2003 Elsevier Science B.V. All rights reserved.

This study evaluates the use of the Fe(III)-EDDS complexing agent as an alternative to conventional acidic pH photo-Fenton for the treatment of the pesticide imidacloprid in natural water. The main objective is to estimate whether Fe(III)-EDDS is a viable alternative when treating waters containing high concentrations of contaminants. To this end, the mode of action of Fe(III)-EDDS is examined in the presence of carbonates, at different aeration conditions and at different temperatures. The role of HO2 center dot/O-2(center dot-) radical species and some aspects of the Fe(III)-EDDS complexation mechanism are discussed. Degradation kinetics and toxicities of generated intermediates are compared between Fe(III)-EDDS and conventional photo-Fenton treatment. An overview of the benefits and limitations of the process is presented. (C) 2015 Elsevier B.V. All rights reserved.

The bacterial inactivation of Escherichia coli on Ag–cotton textiles were investigated under different experimental conditions with novel Ag-nanoparticles fixed on cotton textiles. The evaluation of the bactericide performance of the Ag–cotton was compared with the one observed for Ag–TiO2–cotton loaded textiles. The procedure used allowed us to prepare highly dispersed Ag-cluster species, 2–4 nm in size, as observed by transmission electron microscopy (TEM). By depth profile analysis, the X-ray photoelectron spectroscopy (XPS) revealed that the Ag profile in the 15 topmost layers remained almost constant before and after E. coli inactivation. The cotton loading was fairly low and of the order of 0.10 wt.% Ag/wt. of cotton. By infrared spectroscopy no modification of the Ag–cotton could be detected before or after E. coli inactivation due to the small absorption coefficient of Ag and the very low metal loading of Ag on the cotton. The E. coli was completely abated on Ag–cotton textiles immediately after the contact took place, due to the strong bacteriostatic effect of the dispersed silver clusters on the cotton surface.

he electrochemical oxidation of phenol for waste water treatment was studied at a platinum anode. Analysis of reaction intermediates and a carbon balance has shown that the reaction occurs by two parallel pathways; chemical oxidation with electrogenerated hydroxyl radicals and direct combustion of adsorbed phenol or/and its aromatic intermediates to CO2.