Wet oxidation of salicylic acid solutions.
Salicylic acid is a frequent pollutant in several industrial wastewaters. Uncatalyzed wet air oxidation, which is a promising technique for the treatment of phenolic effluents, has not been analyzed yet for the removal of salicylic acid. The effect of different conditions of pH (1.3-12.3), pressure (1.0-4.1 MPa), temperature (413-443 K), and initial concentrations (1.45-14.50 mM) on the wet oxidation of salicylate/salicylic acid solutions have here been investigated. The pH value of the reaction media was found to be a key parameter for the rate of the oxidation process with an optimum at pH 3.1, when the concentrations of salicylic acid and salicylate were similar. The oxidation reaction followed pseudofirst-order kinetics with respect to salicylic acid and 0.82 order with respect to dissolved oxygen. Additionally, the evolution of the color during the wet oxidation was analyzed and discussed in relation with the formation of intermediate compounds. Then, a reaction pathway for the noncatalytic wet oxidation of the salicylic acid was proposed.
Collado
Sergio
S
Department of Chemical Engineering and Environmental Technology, University of Oviedo, E-33071 Oviedo, Spain.
Garrido
Laura
L
Laca
Adriana
A
Diaz
Mario
M
D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D011312:Pressure; D020156:Salicylic Acid / Q000032:analysis / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
D012996:Solutions; D014874:Water Pollutants, Chemical; D020156:Salicylic Acid