Wet oxidation

About: Wet oxidation is a research topic. Over the lifetime, 3094 publications have been published within this topic receiving 61536 citations.

Wet oxidation of AlAs grown by molecular beam epitaxy

Abstract: A 1 μm thick n‐type GaAs layer with Si doping density of 1×1017/cm3 and a 1000 A thick undoped AlAs layer was subsequently grown by molecular beam epitaxy on the n+ GaAs substrate. To perform selective oxidation of the AlAs layer, the wafer was oxidized in N2 bubbled H2O vapor ambient at 370 °C, 400 °C, and 430 °C, each for 3 hours. It is found that the defect‐free selective oxidation of AlAs is very critically dependent on oxidation temperature. Both GaAs and AlAs layers were oxidized at the oxidation temperature of 430 °C, and some defects were found by scanning electron microscopy (SEM) on the surface oxidized at 370 °C. Oxidation was, however, stopped at the AlAs/GaAs interface at the oxidation temperature of 400 °C, and no defects were found on the surface. By the slow ramp rate (5 mV/sec) high frequency (100 kHz) C‐V measurement, the fixed charge density was estimated to be about 1×1011/cm2 for the metal‐oxide‐semiconductor (MOS) capacitor fabricated from the oxidized sample at 400 °C.

Photocatalytic Oxidation as a Secondary Treatment Method following Wet Air Oxidation

Abstract: Photocatalytic oxidation is investigated as a potential secondary treatment method to follow wet air oxidation (WAO). The rates of photocatalytic oxidation of acetic acid and 2-chlorobiphenyl in aqueous solution were studied under continuous flow conditions in a small diameter cylindrical borosilicate reactor packed with highly porous TiO2 particles at temperatures up to 160 °C and pressures up to 20 atm. These compounds are of particular interest because they are recalcitrant to conventional WAO. Specific attention is paid to the effects of oxygen concentration, pH, and temperature on reaction rates. Results show that solution pH may play an important role in the selective oxidation of a compound in a mixed waste stream. 2-Chlorobiphenyl was selectively oxidized in the presence of much higher concentrations of acetic acid by maintaining a neutral to basic pH. Moreover, the dependence of the rate of mineralization of acetic acid on oxygen is strongly influenced by pH. At low pH, high dissolved oxygen conc...

Scale-up and Modeling of Fixed-Bed Reactors for Catalytic Phenol Oxidation over Adsorptive Active Carbon

Abstract: The wet air oxidation of phenol over a commercial active carbon catalyst has been studied in laboratory-scale and pilot-plant fixed-bed reactors at mild temperatures and oxygen partial pressures of 120−160 °C and 0.05−0.2 MPa, respectively. The performances of the fixed-bed reactors have been assessed and compared to each other for both up- and downflow operation mode. Depending on the flow mode and reactor scale, distinct phenol destruction rates have been observed in the experiments. A series of batch experiments are carried out to obtain phenol removal kinetics, which are subsequently implemented in the modeling of the pilot-plant fixed-bed reactor. A one-dimensional, nonisothermal piston dispersion model is developed to describe in detail the interplay of reaction kinetics, gas−liquid hydrodynamics, and heat and mass transfer in both flow directions. The model predicts reasonably well the experimental data, thus allowing for a thorough explanation of the observed pilot-plant reactor performance.