Oxidation of 4-chloro-3-methylphenol in pressurized hot water in liquid and vapor phases

摘要

4-Chloro-3-methylphenol (c = 2.0 mM), representing a model pollutant, was oxidized both in liquid and vapor phases. The oxidant (hydrogen peroxide) was used in an amount equivalent to 10 times that of the model pollutant. Space times were 10-60 s; temperatures, 250-390 ℃; and pressures 228-311 bar (liquid and supercritical states), or 4-13 bar (vapor phase). The effect of preheating the capillaries delivering the organic matter and oxidant was studied. Excellent oxidation results for 4-chloro-3-methylphenol were obtained in both the vapor and liquid phases, but there was less corrosion (nickel and chromium concentrations in the effluent) in the vapor phase. Better oxidation efficiencies were obtained at lower temperatures and shorter space times, and the formation of reaction products was lower with non-preheated capillaries, i.e. when hydrogen peroxide was not decomposed before entering the reaction zone.