Wet oxidation

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

Insight into spent caustic treatment: on wet oxidation of thiosulfate to sulfate

Abstract: Oxidation of thiosulfate to sulfate is often the rate controlling step during wet air oxidation (WAO) of spent caustic from the refinery and petrochemical industry and exhibits high Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). The kinetics of WAO of thiosulfate was studied in the absence and presence of a heterogeneous copper catalyst. Wet oxidation of thiosulfate to sulfate is a free radical reaction exhibiting an induction period. In non-catalytic oxidation, almost complete conversion of thiosulfate to sulfate was observed in 12 min at 150 °C and in 8 min at 120 °C in the presence of a heterogeneous copper catalyst at 0.69 MPa oxygen partial pressure. The presence of phenol accelerated thiosulfate oxidation. © 1999 Society of Chemical Industry

Activated Carbon from Macadamia Nut Shell by Air Oxidation in Boiling Water

Abstract: A high-yield activated carbon is produced from macadamia nut shell charcoal by (i) carbonization of the charcoal at 1173 K, (ii) air oxidation of the carbonized charcoal in boiling water (AOBW) at 503−553 K, and (iii) activation (a second carbonization) of the oxygenated carbon. In step ii, air is bubbled through a sparger to maintain a relatively high concentration of dissolved oxygen in the water, and the boiling water serves to control the temperature of the carbon during its gasification by the dissolved oxygen. Carbon dioxide is observed to be the only gaseous product of the oxidation chemistry. The oxidation results and the properties of the activated carbons from AOBW are similar to those obtained by controlled atmospheric air oxidation. However, the rate of CO2 formation is observed to increase with time to a plateau for AOBW, whereas the gasification rate decreases with time for atmospheric air oxidation. Multiple cycles, involving AOBW followed by activation, efficiently increase the specific su...

Ammonia passivation of metal gate electrodes to inhibit oxidation of metal

Abstract: A method and apparatus is provided for wet oxidation while passivating metal elements by adsorption of a passivating species. A transistor gate stack includes a metallic layer that exhibits catalytic behavior in the presence of the passivating species. In particular, ammonia adsorbs upon the metallic layer. During wet oxidation, such as source/drain reoxidation, the adsorbed ammonia inhibits oxidation of the metal, preserving conductive material.

Characterization of oxide films on 4H-SiC epitaxial (0001¯) faces by high-energy-resolution photoemission spectroscopy: Comparison between wet and dry oxidation

Abstract: Wet and dry oxide films-4H-SiC epitaxial (0001¯) C-face interfaces have been characterized by capacitance-voltage (C-V) measurements and soft x-ray excited photoemission spectroscopy (SX-PES) and hard x-ray excited photoemission spectroscopy (HX-PES) using synchrotron radiation. The interface state density for wet oxidation is much smaller than that for dry oxidation at any energy level. In the PES measurements, intermediate oxidation states such as Si1+ and Si3+ were observed. In addition, the areal densities of these states were found to be in a good correspondence with those of the interface states. The reasons for the good electrical characteristics of metal-oxide-semiconductor devices fabricated by wet oxidation are discussed in terms of the depth profiles of oxide films derived from the SX-PES and HX-PES results.

Near- and Supercritical Water

Abstract: Water is a benign media for processing, and possesses several interesting properties when used in a processing context. When water is subjected to high pressure and temperature its properties change significantly. Approaching the critical point, where gas and liquid phases can no longer be distinguished, brings changes to ion dissociation and dielectric constants due to factors such as changes in the amount of hydrogen bonding. The changes occurring at near- and supercritical conditions may be utilised in processing for degradation and conversion reactions. However, at these conditions several issues must be considered as well. Especially, the increased risk of corrosion due to a larger degree of auto-dissociation of water is a factor that must be considered when using near-critical water in processing plants. Also, the decreased dielectric constant may lead to precipitation and possible deposition of mineral salts in processing equipment, which in turn may lead to clogging of valves, etc. Furthermore, the application of near- and supercritical water in processes such as wet air oxidation of wastewater and liquefaction of biomass is discussed.