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Ghodbane H.,Laboratory of Environmental Engineering | Hamdaoui O.,Laboratory of Environmental Engineering
Chemical Engineering Journal | Year: 2010

In this work, the decolorization of C.I. Acid Blue 25 (AB25), a commercially important anthraquinonic dye, by direct UV irradiation alone and UV/H2O2 and UV/Fe(II) processes was investigated. Experiments were conducted in batch mode using a low-pressure mercury lamp emitting mainly at 253.7 nm. For direct UV photolysis, the decolorization rate increased with decreasing pH and initial dye concentration. The decolorization of AB25 was investigated using UV irradiation in the presence of H2O2 as function of hydrogen peroxide concentration, dye concentration and pH. Additionally, the effect of salts on the bleaching of this dye was also studied. Decolorization rate was increased in the presence of UV/H2O2 compared to UV irradiation alone. The results showed that the bleaching increases as the initial H2O2 concentration increased up to a certain limit at which hydrogen peroxide reduced the bleaching by scavenging the OH radicals. The bleaching of AB25 decreased when the dye concentration increased. Decolorization rate by means of Fe(II) homogeneous photocatalysis under UV irradiation was increased compared to direct UV irradiation alone. The best working condition was found for an initial Fe(II) concentration of 30 mg L-1. The results revealed that the tested advanced oxidation processes are very effective for the decolorization of AB25 in aqueous solutions. © 2010 Elsevier B.V. All rights reserved. Source

Chiha M.,Laboratory of Environmental Engineering | Hamdaoui O.,Laboratory of Environmental Engineering | Ahmedchekkat F.,Skikda University | Petrier C.,Joseph Fourier University
Ultrasonics Sonochemistry | Year: 2010

The aim of this work was to study the emulsification assisted by ultrasonic probe (22.5 kHz) and investigate the removal of copper(II) ions from aqueous solution using water-in-oil-in-water (W/O/W) emulsion liquid membrane process (ELM). The membrane was prepared by dissolving the extractant bis(2-ethylhexyl)phosphoric acid (D2EHPA) and the hydrophobic surfactant sorbitan monooleate (Span 80) in hexane (diluent). The internal phase consisted of an aqueous solution of sulfuric acid. Effects of operating parameters such as emulsification time, ultrasonic power, probe position, stirring speed, carrier (D2EHPA) and surfactant (Span 80) concentrations volume ratios of organic phase to internal striping phase and of external aqueous phase to membrane (W/O) phase, internal phase concentration and choice of diluent on the membrane stability were studied. With ultrasound, the W/O emulsion lifetime were much higher than those reported previously by mechanical agitation. The effect of carrier and Cu(II) initial concentration on the extraction kinetics was also investigated. Nearly all of the Cu(II) ions present in the continuous phase was extracted within a few minutes. Additionally, the influence of H2SO4 concentration on the stripping efficiency was examined. © 2009 Elsevier B.V. All rights reserved. Source

Merouani S.,Laboratory of Environmental Engineering | Hamdaoui O.,Laboratory of Environmental Engineering | Saoudi F.,Laboratory of Environmental Engineering | Chiha M.,Laboratory of Environmental Engineering | Petrier C.,Joseph Fourier University
Journal of Hazardous Materials | Year: 2010

The influence of bicarbonate and carbonate ions on sonolytic degradation of cationic dye, Rhodamine B (RhB), in water was investigated. As a consequence of ultrasonic cavitation that generates {radical dot}OH radicals, carbonate radicals were secondary products of water sonochemistry when it contains dissolved bicarbonate or carbonate ions. The results clearly demonstrated the significant intensification of sonolytic destruction of RhB in the presence of bicarbonate and carbonate, especially at lower dye concentrations. Degradation intensification occurs because carbonate radicals sonochemically formed undergo radical-radical recombination at a lesser extent than hydroxyl radicals. The generated carbonate radicals are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as RhB. Therefore, at low dye concentrations, carbonate radical presents a more selective reactivity towards RhB molecules than hydroxyl radical. In the presence of bicarbonate, degradation rate reached a maximum at 3 g L-1 bicarbonate, but subsequent addition retards the destruction process. In RhB solutions containing carbonate, the oxidation rate gradually increased with increasing carbonate concentration up to 10 g L-1 and slightly decreased afterward. Carbonate radicals sonochemically generated are suitable for total removal of COD of sonicated RhB solutions. © 2009 Elsevier B.V. All rights reserved. Source

Chiha M.,Laboratory of Environmental Engineering | Merouani S.,Laboratory of Environmental Engineering | Hamdaoui O.,Laboratory of Environmental Engineering | Baup S.,LEPMI | And 2 more authors.
Ultrasonics Sonochemistry | Year: 2010

Sonochemical degradation of phenol (Ph), 4-isopropylphenol (4-IPP) and Rhodamine B (RhB) in aqueous solutions was investigated for a large range of initial concentrations in order to analyze the reaction kinetics. The initial rates of substrate degradation and H2O2 formation as a function of initial concentrations were determined. The obtained results show that the degradation rate increases with increasing initial substrate concentration up to a plateau and that the sonolytic destruction occurs mainly through reactions with hydroxyl radicals in the interfacial region of cavitation bubbles. The rate of H2O2 formation decreases with increasing substrate concentration and reaches a minimum, followed by almost constant production rate for higher substrate concentrations. Sonolytic degradation data were analyzed by the models of Okitsu et al. [K. Okitsu, K. Iwasaki, Y. Yobiko, H. Bandow, R. Nishimura, Y. Maeda, Sonochemical degradation of azo dyes in aqueous solution: a new heterogeneous kinetics model taking into account the local concentration OH radicals and azo dyes, Ultrason. Sonochem. 12 (2005) 255-262.] and Seprone et al. [N. Serpone, R. Terzian, H. Hidaka, E. Pelizzetti, Ultrasonic induced dehalogenation and oxidation of 2-, 3-, and 4-chlorophenol in air-equilibrated aqueous media. Similarities with irradiated semiconductor particulates, J. Phys. Chem. 98 (1994) 2634-2640.] developed on the basis of a Langmuir-type mechanism. The five linearized forms of the Okitsu et al.'s equation as well as the non-linear curve fitting analysis method were discussed. Results show that it is not appropriate to use the coefficient of determination of the linear regression method for comparing the best-fitting. Among the five linear expressions of the Okitsu et al.'s kinetic model, form-2 expression very well represent the degradation data for Ph and 4-IPP. Non-linear curve fitting analysis method was found to be the more appropriate method to determine the model parameters. An excellent representation of the experimental results of sonolytic destruction of RhB was obtained using the Serpone et al.'s model. The Serpone et al.'s model gives a worse fit for the sonolytic degradation data of Ph and 4-IPP. These results indicate that Ph and 4-IPP undergo degradation predominantly at the bubble/solution interface, whereas RhB undergoes degradation at both bubble/solution interface and in the bulk solution. © 2010 Elsevier B.V. All rights reserved. Source

Daas A.,Laboratory of Environmental Engineering | Hamdaoui O.,Laboratory of Environmental Engineering
Journal of Membrane Science | Year: 2010

In this work, the extraction of bisphenol A (BPA), an endocrine disrupting compound, from aqueous solutions by emulsion liquid membrane (ELM) was studied. Liquid membrane consists of a diluent (hexane) and a surfactant (Span 80). 0.05N sodium hydroxide solution was used as internal aqueous phase. Effects of experimental conditions that affect the stability such as surfactant concentration, emulsification time, internal phase concentration and volume ratio of internal phase to membrane phase was investigated. The important variables governing the permeation of BPA were examined. These variables are sulfuric acid concentration in external phase, acid type in external phase, internal phase concentration, type of internal phase, surfactant concentration, stirring speed, volume ratio of internal phase to membrane phase, treatment ratio, BPA concentration, diluent type and presence of salt. This study also investigated the effect of NaOH concentration in the internal phase on the stripping of BPA. The results showed that by appropriate selection of the extraction and stability conditions, it was possible to extract nearly all of BPA molecules from the feed solution even in the presence of high concentration of salt. Under optimum conditions, very good stripping efficiency (98%) can be achieved. © 2009 Elsevier B.V. All rights reserved. Source

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