Aqueous phase (catalytic) wet air oxidation of ammonia: Thermodynamic considerations

Recent Progress and Prospects in Catalytic Water Treatment

“…Ammonia is produced in various applications and can form as undesired side product during the mineralization processes . Thermodynamic considerations of the equilibrium between soluble/gas ammonia and speciation in liquid phase is an important issue and is a preliminary step before establishing reliable kinetic model . It has been found that the fraction of solubilized ammonia largely exceeds that of ammonium ions, which could explain the high efficiency of catalytic wet oxidation reaction process because ammonia in its molecular form is more reactive than NH 4 + .…”

“…104 Thermodynamic considerations of the equilibrium between soluble/gas ammonia and speciation in liquid phase is an important issue and is a preliminary step before establishing reliable kinetic model. 105 It has been found that the fraction of solubilized ammonia largely exceeds that of ammonium ions, which could explain the high efficiency of catalytic wet oxidation reaction process because ammonia in its molecular form is more reactive than NH 4 + . As already indicated, CWAO needs more severe conditions compared to ozonation conditions with temperature in the range 150−320 °C and higher pressure in the range 0.5−20 MPa to increase oxygen dissolution in water and fulfill coverage conditions in terms of adsorbed oxygen species.…”

Enhanced Wet Air Oxidation of Benzene by the Addition of Phenol

“…Wet air oxidation (WAO) that refers to liquid phase reactions between organic pollutants and oxygen under subcritical conditions (i.e., 125–320 °C, 0.5–22 MPa of air) was first patented by Zimmermann, by oxidizing them into small molecules, nontoxic or low toxic substances . WAO has been extensively employed for the degradation of a number of organic compounds such as phenol, − acetic acid, ammonia, and paracetamol . In the current study, benzene is chosen as the representative VOCs because of its high toxicity and photochemical activity.…”

“…To increase the effectiveness of the WAO, numerous methods have been reported. One of these methods is the catalytic wet air oxidation in which either homogeneous or heterogeneous catalysts were used to enhance the degradation of organic compounds. − ,, …”

“…One of these methods is the catalytic wet air oxidation in which either homogeneous or heterogeneous catalysts were used to enhance the degradation of organic compounds. [18][19][20]22,23 The performance of the wet oxidation method can also be enhanced by using ozone 25 or hydrogen peroxide 26−28 as an oxidizing agent. Supercritical oxidation 29 was also found to improve the oxidation of some compounds.…”