Degradation of phenol by mechanical activation of a rutile catalyst

Cotto, María; Emiliano, A.; Nieto, Santander; Duconge, José; Roque‐Malherbe, R.

doi:10.1016/j.jcis.2009.07.016

Cited by 7 publications

(4 citation statements)

References 66 publications

(123 reference statements)

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“…The mechanochemical degradation rates for Safranin T, expressed via the rate constant K d , are different for different oxides (see the table), but in all the cases (with one exception) strongly exceed that for phenol (1.6 × 10 -5 s -1 according to [6]). Upon MChT with fairly well water-soluble molybdenum and vanadium oxides Safranin T did not exhibit its characteristic absorption at 520 nm, but other bands were observed.…”

Section: Methodsmentioning

confidence: 99%

“…This phenomenon may be associated with their specifi c structure: These samples are not mechanical mixtures of phases; by contrast, they are characterized by extremely close contact of phases in the bulk of the primary crystallites, as pointed out in [8][9][10]. A mechanism suggested for the mechanocatalytic process in [6] is similar to those accepted for UV and microwave radiation-induced oxidation processes [1,9]. Possibly, the specifi c structure of the biphase samples facilitates all the stages of the MChT process, from generation of an electron-hole pair to the oxidation reaction proper.…”

Section: Methodsmentioning

confidence: 99%

“…This has resulted in the search for alternative approaches, among which there are some recently developed technologies, e.g., advanced oxidation processes [3] based on nonconvective energy transport to the media being treated, often with the use of typical photocatalysts. One of these technologies, mechanochemical treatment (MChT) [4,5], was applied for water treatment purposes in only one published study [6] dedicated to phenol decomposition in the presence of rutile. Specifically, that study demonstrated that pollutant degradation via supply of mechanical energy to the system is possible in principle.…”

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Mechanochemical degradation of Safranin T catalyzed by oxides

et al. 2012

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Mechanochemical treatment of aqueous solutions of Safranin T in the presence of oxides as catalysts was studied.Ultraviolet radiation-induced photodegradation of pollutants in aqueous media using semiconductor catalysts (typically, titanium and zinc oxides) is considered to be the most effi cient route, but suffers from several drawbacks [1,2]. This has resulted in the search for alternative approaches, among which there are some recently developed technologies, e.g., advanced oxidation processes [3] based on nonconvective energy transport to the media being treated, often with the use of typical photocatalysts. One of these technologies, mechanochemical treatment (MChT) [4,5], was applied for water treatment purposes in only one published study [6] dedicated to phenol decomposition in the presence of rutile. Specifically, that study demonstrated that pollutant degradation via supply of mechanical energy to the system is possible in principle.Here, we examined degradation of Safranin T whose aqueous solutions were subjected to mechanochemical treatment in the presence of several oxides possessing different physicochemical characteristics. EXPERIMENTALDegradation of Safranin T in solutions with the concentrations of 0.005 and 0.01 g l -1 was carried out at the catalyst:solution ratio 0.2-2.0 mg : 30 ml. As catalysts served the oxides whose characteristics are presented in the table. Mechanochemical treatment was effected in a Pulverisette 6 (Fritsch GmbH) planetary ball mill at a rotation speed of 300 rpm for 5-90 min. The degradation of the dye was monitored by analyzing both the solution proper (on a Heλios γ Thermospectronic, spectrophotometer, Poland) and the spent catalyst. The catalysts before and after operation were examined by X-ray diffraction and thermogravimetric (DTA-TG) analyses, as well as by IR spectroscopy, mass spectrometry, and nitrogen adsorption method.It should be noted that Safranin Т is degraded in the presence of all the oxides examined, as illustrated by the electronic spectra obtained for the dye solution before and after the MChT in the presence of these catalysts (Fig. 1). The spectra demonstrate a dramatic decrease in optical density at 520 nm due to mechanocatalysis. Based on the spectral data obtained we plotted the kinetic degradation curves for Safranin T in the ln D 520 -τ coordinates, where D 520 is the optical density at 520 nm, and τ, MChT duration, s (Fig. 2). It is seen that, like in the case of many photocatalytic processes, the degradation of Safranin T is adequately described by a fi rst-order kinetic equation [1] [at the same time, Safranin T proved to be resistant to mechanical impact in the absence of a catalyst for 1.5 h (Fig. 2, curve 1)].The mechanochemical degradation rates for Safranin T, expressed via the rate constant K d , are different

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Mechanochemical degradation of Safranin T catalyzed by oxides

et al. 2012

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“…Several efforts to degrade phenol have been undertaken using various techniques but some important methods involve the application of electromagnetic [47,48], laser [49,50] photocatalytic [51][52][53][54], mechanochemical [55], electro-catalytic [56][57][58][59], photo-electrocatalytic [60], biodegradation [61][62][63][64][65][66][67][68][69][70][71], advanced oxidation process [72] and glow discharge plasma [73][74][75] processes. However, in the following section, various sonochemical methods, used for the degradation of phenol in aqueous solutions, would be discussed.…”

Section: Remediation Methods Of Phenolmentioning

confidence: 99%

Sonochemical Degradation of Phenol in the Presence of Inorganic Catalytic Materials

Pankaj

Verma²

2010

Theoretical and Experimental Sonochemistry Involving Inorganic Systems

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Degradation of phenol in its aqueous solutions, using various techniques, including ultrasound, have been examined and discussed to better understand the mechanisms involved therein and the advantages as well as the disadvantages associated with the use of inorganic catalytic materials. IntroductionSonochemical degradation of organic molecules [1], employing cavitational effect is not new. Many simple [2] and complex molecules [3] from modest to very high toxicity levels, polluting the aquatic life and the environment have been successfully reduced to relatively non-toxic or lesser harmful species, if not degraded completely by the ultrasound. Although the degree of degradation and the duration of sonication varied considerably, depending upon the nature of moieties, but the sonochemical degradation undergoes either without the addition of extra chemicals or involves the minimum amounts of non-toxic chemicals such as photocatalyst TiO 2 , Fenton's reagent etc., hence can be termed as a green technology. The purpose of this article is to review the sonochemical degradation of phenol, under different experimental conditions and in the presence of several other active chemicals to understand better the mechanisms involved in all such processes.Phenol is an important chemical, from the point of its industrial and commercial applications, but is of great environmental apprehension due to its toxicity. Its chemical name is hydroxybenzene which is more acidic compared to aliphatic alcohols hence is also known as carbolic acid [4]. At ambient temperature and pressure it is a hygroscopic crystalline solid, which is colourless when pure [5] but

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