Application of electrochemically generated ozone to the discoloration and degradation of solutions containing the dye Reactive Orange 122.
Aqueous solutions containing the commercial azo dye Reactive Orange 122 (RO122) were ozonated in acid and alkaline conditions. Ozone was electrochemically generated using a laboratory-made electrochemical reactor and applied using semi-batch conditions and a column bubble reactor. A constant ozone application rate of 0.25gh(-1) was used throughout. Color removal and degradation efficiency were evaluated as function of ozonation time, pH and initial dye concentration by means of discoloration kinetics and COD-TOC removal. Experimental findings revealed that pH affects both discoloration kinetics and COD-TOC removal. A single pseudo-first-order kinetic rate constant, k(obs), for discoloration was found for ozonation carried out in alkaline solutions, contrary to acidic solutions where k(obs) depends on ozonation time. COD-TOC removal supports degradation of RO122 is more pronounced for alkaline conditions. Evaluation of the oxidation feasibility by means of the COD/TOC ratio indicates that the ozonation process in both acid and alkaline conditions leads to a reduction in recalcitrance of the soluble organic matter.
Santana
Mário H P
MH
Institute of Chemistry - UFU, Laboratory of Electrochemistry, Campus Santa Mônica, Av. João Naves de Avila 2160, 38400-902 Uberlândia, MG, Brazil.
Da Silva
Leonardo M
LM
Freitas
Admildo C
AC
Boodts
Julien F C
JF
Fernandes
Karla C
KC
De Faria
Luiz A
LA
D001391:Azo Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010126:Ozone / Q000737:chemistry* / Q000378:metabolism; D013463:Sulfuric Acid Esters / Q000737:chemistry*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
D001391:Azo Compounds; D004396:Coloring Agents; D013463:Sulfuric Acid Esters; D014874:Water Pollutants, Chemical; C109260:reactive orange; D010126:Ozone