St. Kolaczkowski et al., WET AIR OXIDATION OF PHENOL - FACTORS THAT MAY INFLUENCE GLOBAL KINETICS, Process safety and environmental protection, 75(B4), 1997, pp. 257-265
Wet air oxidation is presented as a technique for removal of organic p
ollutants found in waste water streams. The oxidation of phenol has be
en achieved at moderate temperatures (T=473 K) and pressures (3.0 MPa
total pressure) with up to 95% destruction in less than 30 minutes. An
increase in either oxygen concentration or temperature has a positive
influence on reaction rate, with temperature following an Arrhenius d
ependence. The influence of pH is shown to be complex. For a 0.01 mol(
-1) phenol solution significant destruction was obtained; however, whe
n the initial pH was modified to either less than two or between neutr
ality and ten, practically no change in phenol concentration was obser
ved. When oxidation is carried out in strong alkali media (pH>12) reac
tion rate is enhanced significantly. Addition of small quantities of h
ydrogen peroxide resulted in enhanced rates of oxidation even at low t
emperatures (373 K). When hydrogen peroxide is added, oxygen plays a n
egligible role in the initial reaction, only becoming significant once
the hydrogen peroxide has been consumed. The nature and geometry of t
he reactor has been found to play an important role in free radical te
rmination steps, with metal surfaces likely to enhance significantly d
ecomposition of organic radicals.