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1.
Environ Sci Pollut Res Int ; 20(5): 3224-31, 2013 May.
Article in English | MEDLINE | ID: mdl-23065604

ABSTRACT

The photocatalytic degradations of 4-chlorophenol (CP), 4-chloro-2-methylphenol (CMP), 4-chloro-3,5-dimethylphenol (CDMP) and 4-chloro-2-isopropyl-5-methylphenol (CIMP) were investigated in water and in simulated soil washing wastes containing Brij 35 (polyoxyethylene(23)dodecyl ether) in the presence of TiO2 dispersions. A neat inhibition of substrate decomposition proportional to their growing hydrophobicity was observed in the washing wastes for CP, CMP and CDMP, whereas CIMP showed a different behaviour. The mineralization of the organic chlorine of CP and CIMP was relatively fast and complete, whereas it was much slower for CMP and CDMP. Micellar solubilization and substrate adsorption onto the semiconductor play opposite roles on the degradation kinetics, and a breakpoint between the corresponding induced effects was evidenced when the pollutants become completely bound to the micellar aggregates.


Subject(s)
Chlorophenols/chemistry , Photolysis , Polyethylene Glycols/chemistry , Surface-Active Agents/chemistry , Water Pollutants, Chemical/chemistry , Water Pollution, Chemical/prevention & control , Adsorption , Chromatography, High Pressure Liquid , Chromatography, Ion Exchange , Kinetics , Micelles , Soil Pollutants/chemistry , Titanium/chemistry
2.
Chemosphere ; 86(4): 335-40, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22036015

ABSTRACT

Three alkylpolyoxyethylene surfactants bearing the same hydrophobic chain and a different number of oxyethylene groups were investigated as suitable candidates for the soil washing treatment of contaminated soil samples containing bentazone. Comparable good recoveries of the pesticide were obtained working with these surfactants. The photocatalytic treatment of the collected washing wastes, performed in the presence of suspended TiO(2) particles under irradiation with simulated sunlight, leads to the effective degradation of bentazone residues after a time depending on the nature and concentration of the chosen amphiphile. Brij 35 was found to be the best surfactant candidate, giving the faster abatement of the pesticide in the collected wastes. The overall treatment time depends on the bentazone mineralization kinetics, markedly slow in the presence of surfactants. Useful information about the photocatalytic degradation route was obtained from the HPLC-MS analysis of transient intermediates formed in water.


Subject(s)
Benzothiadiazines/chemistry , Environmental Restoration and Remediation/methods , Polyethylene Glycols/chemistry , Soil Pollutants/chemistry , Surface-Active Agents/chemistry , Benzothiadiazines/analysis , Environmental Monitoring , Photochemical Processes , Polyethylene Glycols/analysis , Soil/chemistry , Soil Pollutants/analysis , Surface-Active Agents/analysis
3.
Chemosphere ; 71(1): 59-65, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18061238

ABSTRACT

The possible application of two environmental remediation technologies - soil washing and photocatalysis - to remove and decompose various aromatic pollutants present in excavated soils of a contaminated industrial site has been investigated. Aqueous solutions containing the non-ionic surfactant Brij 35 were used to extract the contaminants from the soil samples. The photocatalytic treatment of the obtained washing wastes, performed in the presence of TiO(2) suspensions irradiated with simulated sunlight, showed a slow abatement of the toxic compounds due to the relevant concentrations of organics in the waste. A neat improvement of the process performances, obtained by operating in the presence of added potassium peroxydisulfate, suggests a feasible treatment route.


Subject(s)
Soil Pollutants/isolation & purification , Catalysis , Chromatography, High Pressure Liquid , Photochemistry
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