Wet Oxidation of Salicylic Acid Solutions

Abstract

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.

Fenton’s Oxidation Kinetics, Pathway, and Toxicity Evaluation of Diethyl Phthalate in Aqueous Solution

“…This observation was supported by the fact that the toxicity originated from the remaining DEP and the oxidation products accumulating as the reaction progressed. Toxicity tests on the effects of associated intermediate products to Photobacterium phosphoreum have been reported in previous studies (37). The EC50 (i.e., concentration for 50% maximal effect) followed the sequence, acetic acid (2.17 mM) > ethyl 2-hydroxybenzoate (1.55 mM), which explains that the toxicity effect of intermediate products in the mineralization process was different.…”

Application of a Non-thermal Atmospheric Pressure Plasma Jet to the Decomposition of Salicylic Acid to Inorganic Carbon

“…This small amount of phenol indicates that excess OH radical decomposed phenol as soon as it was generated. The mechanism of degradation by the radicals was proposed by Collado et al 30 They reported that salicylic acid is first converted to phenol, followed by further conversion to hydroquinone or catechol.…”

Oxidative degradation of salicylic acid by sprayed WO3 photocatalyst

“…and also it is used as a raw material. This contaminant has to be removed from the wastewater and spreading in environment should be avoided [5,6]. Heterogeneous photocatalytic oxidation is one of the promising processes among the AOP which is successfully employed for degradation of various OC.…”