PMID- 19816729
OWN - NLM
STAT- MEDLINE
DCOM- 20100331
LR  - 20211020
IS  - 1614-7499 (Electronic)
IS  - 0944-1344 (Linking)
VI  - 17
IP  - 3
DP  - 2010 Mar
TI  - Oxidative degradation of chlorophenol derivatives promoted by microwaves or power 
      ultrasound: a mechanism investigation.
PG  - 674-87
LID - 10.1007/s11356-009-0253-y [doi]
AB  - BACKGROUND, AIM, AND SCOPE: Phenols are the most common pollutants in industrial 
      wastewaters (particularly from oil refineries, resin manufacture, and coal 
      processing). In the last two decades, it has become common knowledge that they 
      can be effectively destroyed by nonconventional techniques such as power 
      ultrasound (US) and/or microwave (MW) irradiation. Both techniques may strongly 
      promote advanced oxidation processes (AOPs). The present study aimed to shed 
      light on the effect and mechanism of US- and MW-promoted oxidative degradation of 
      chlorophenols; 2,4-dichlorophenoxyacetic acid (2,4-D), a pesticide widespread in 
      the environment, was chosen as the model compound. MATERIALS AND METHODS: 2,4-D 
      degradation by AOPs was carried out either under US (20 and 300 kHz) in aqueous 
      solutions (with and without the addition of Fenton reagent) or solvent-free under 
      MW with sodium percarbonate (SPC). All these reactions were monitored by gas 
      chromatography-mass spectrometry (GC-MS) analysis and compared with the classical 
      Fenton reaction in water under magnetic stirring. The same set of treatments was 
      also applied to 2,4-dichlorophenol (2,4-DCP) and phenol, the first two products 
      that occur a step down in the degradation sequence. Fenton and Fenton-like 
      reagents were employed at the lowest active concentration. RESULTS: The effects 
      of US and MW irradiation were investigated and compared with those of 
      conventional treatments. Detailed mechanisms of Fenton-type reactions were 
      suggested for 2,4-D, 2,4-DCP, and phenol, underlining the principal degradation 
      products identified. MW-promoted degradation under solvent-free conditions with 
      solid Fenton-like reagents (viz. SPC) is extremely efficient and mainly follows 
      pyrolytic pathways. Power US strongly accelerates the degradation of 2,4-D in 
      water through a rapid generation of highly reactive radicals; it does not lead to 
      the formation of more toxic dimers. DISCUSSION: We show that US and MW enhance 
      the oxidative degradation of 2,4-D and that a considerable saving of oxidants and 
      cutting down of reaction times is thereby achieved. The results support the 
      interpretation of previously published data and improve the understanding of the 
      factors of direct degradation along different pathways. CONCLUSIONS: Oxidative 
      pathways for 2,4-D, 2,4-DCP, and phenol were proposed by a careful monitoring of 
      the reactions and detection of intermediates by GC-MS. RECOMMENDATIONS AND 
      PERSPECTIVES: The understanding of the factors that affect chlorophenols 
      degradation along different pathways may facilitate the optimization of the 
      treatment. Type of energy source (US or MW), power, and frequency to be applied 
      could be designed in function of the operative scenario (amount of pollutant in 
      soil, water, or oils).
FAU - Cravotto, Giancarlo
AU  - Cravotto G
AD  - Dipartimento di Scienza e Tecnologia del Farmaco, University of Turin, 10125, 
      Turin, Italy. giancarlo.cravotto@unito.it
FAU - Binello, Arianna
AU  - Binello A
FAU - Di Carlo, Stefano
AU  - Di Carlo S
FAU - Orio, Laura
AU  - Orio L
FAU - Wu, Zhi-Lin
AU  - Wu ZL
FAU - Ondruschka, Bernd
AU  - Ondruschka B
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20091009
PL  - Germany
TA  - Environ Sci Pollut Res Int
JT  - Environmental science and pollution research international
JID - 9441769
RN  - 0 (Chlorophenols)
RN  - 0 (Fenton's reagent)
RN  - 0 (Free Radicals)
RN  - 0 (Herbicides)
RN  - 0 (Water Pollutants, Chemical)
RN  - 2577AQ9262 (2,4-Dichlorophenoxyacetic Acid)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - E1UOL152H7 (Iron)
SB  - IM
MH  - 2,4-Dichlorophenoxyacetic Acid/*chemistry
MH  - Chlorophenols/*chemistry
MH  - Environmental Restoration and Remediation/*methods
MH  - Free Radicals/chemistry
MH  - Herbicides/chemistry
MH  - Hydrogen Peroxide/chemistry
MH  - Iron/chemistry
MH  - Kinetics
MH  - *Microwaves
MH  - Models, Chemical
MH  - Oxidation-Reduction
MH  - Ultrasonics
MH  - Water Pollutants, Chemical/*chemistry
EDAT- 2009/10/10 06:00
MHDA- 2010/04/01 06:00
CRDT- 2009/10/10 06:00
PHST- 2009/05/02 00:00 [received]
PHST- 2009/09/24 00:00 [accepted]
PHST- 2009/10/10 06:00 [entrez]
PHST- 2009/10/10 06:00 [pubmed]
PHST- 2010/04/01 06:00 [medline]
AID - 10.1007/s11356-009-0253-y [doi]
PST - ppublish
SO  - Environ Sci Pollut Res Int. 2010 Mar;17(3):674-87. doi: 
      10.1007/s11356-009-0253-y. Epub 2009 Oct 9.