Showing papers on "Wet oxidation published in 1982"

The Oxidation of Shaped Silicon Surfaces

Abstract: Nonplanar silicon surfaces were prepared and oxidized at 900°–1100°C and the oxide morphology was studied by transmission electron microscopy of thin sections. A 30% decrease in oxide thickness at silicon step edges following 900° and 950°C wet oxidation is attributed to the effect of locally compressive intrinsic stress within the oxide on the solubility of oxygen. Oxidation inhibition becomes less at higher temperatures due to the relief of stress (during growth) by viscous flow of the oxide.

Fate of specific pollutants during wet oxidation and ozonation. Where do the pollutants wind up in oxidational purification processes? Here is a well documented experimental study

Abstract: The ability of wet oxidation and ozonation to destroy five typical priority pollutants (phenol, 2-chlorophenol, 1,2-dichloroethane, 4-nitrophenol, and dimethylphthalate) is reported. Particular attention has been paid to interpreting the batch kinetic data, exploring the influence of initial pH on ozonation and identifying and measuring the low-molecular weight organic acids produced. 28 references, 16 figures, 6 tables. (JMT)

Thermal oxidation of nickel disilicide

Abstract: The thermal oxidation characteristics of nickel disilicide on Si substrates have been investigated in the temperature range of 700–900 °C in dry oxygen and wet oxygen. A surface layer of SiO2 grows parabolically in time. The growth rate is independent on the crystalline structure (epitaxial or polycrystalline) and thickness of the NiSi2 layer. We surmise that the oxidation mechanism is dominated by oxygen diffusion through the growing SiO2. Activation energies for the dry and wet oxidation are 1.0±0.1 eV and 1.5±0.1 eV, respectively. NiSi2 layers on SiO2 oxidize with the same rate—resulting with progressively Ni-rich NiSi2. Preliminary measurements of the oxide quality yield dielectric strength of 2.1×10^6 V cm^−1, and a pinhole density of about 100 per cm2. A survey of oxidation data for Si and other refractory metal silicides shows that their oxidation does not draw similar kinetics to that of NiSi2.

The wet oxidation of organic compounds catalyzed by Co-Bi complex oxide.

Abstract: The wet oxidation of various organic compounds was carried out in the presence of the Co–Bi (5:1) complex oxide catalyst. The catalyst was especially effective for the oxidation of all refractory lower carboxylic acids, which are intermediates in the wet oxidation of many organic compounds.

An Evaluation of the Wet Oxidation Technique for Use in Determining the Energy Content of Seston Samples

Abstract: Many of the techniques available to determine energy content have problems inherent in their use on samples with a high proportion of inorganic minerals. One technique which may readily be used on such samples is wet oxidation, in which the sample is quantitatively chemically oxidized. However, this technique is infrequently used because of a potentially significant underestimation of energy content, due to incomplete oxidation of nitrogenous compounds. For a number of plant and animal tissues, wet oxidation with potassium dichromate gave values for energy content within ±3.0% of the value determined by bomb calorimetry.Seston samples on glass fiber filters may also be quickly and accurately analyzed using this procedure. The conversion from either weight loss on ignition or carbon and nitrogen content to energy content, using literature-derived conversion factors, is extremely inaccurate. Conversion of the wet oxidation values to carbon content gave inconsistent results, if the carbon content of the samp...

Surface oxides on porous carbon

Abstract: Wet oxidation of BPL porous carbon by H2O2 and HNO3 changes the pore structure and also increases the concentration of surface oxides. KOH uptake is increased by oxidation and is seen to be dependent on KOH concentration and to a lesser extent on inert electrolyte concentration. Enthalpy of immersion measurements have allowed the estimation of the enthalpy of hydration of the surface oxides and the enthalpy of neutralization of the easily accessible acid oxides.

Oxidation of titanium disilicide on polycrystalline silicon

Abstract: Oxidation mechanisms of titanium disilicide on polycrystalline silicon was investigated. Poly-Si was deposited on the oxidized Si wafer by CVD method, Ti was then deposited on the poly-Si by the electron beam gun and thus TiSi2 was formed by thermal annealing in vacuum. During the wet oxidation, Rutherford backscattering spectroscopy (RBS) results show a two-step oxidation process, namely, TiSi2 first dissociates and forms TiOx and SiO2, while after the formation of TiOx reaches the saturation level, the poly-Si rapidly diffuses through the TiSi2 to form SiO2. The calculated activation energy of reaction is 2.06 eV, and that of diffusion is 1.51 eV. Sheet resistances were measured and found to be consistent with the two-step oxidation model. Radioactive31Si was used as a marker to study the kinetics of the oxidation and found that during the diffusion process of oxidation, the poly-Si atoms transported through TiSi2 by grain boundary and/or interstitial diffusion.

Investigation on TiSi2 thin‐film oxidation by radioactive tracer technique

Abstract: The tracer technique using radioactive 31Si (T1/2 = 2.62h) was performed to study the oxidation kinetics of TiSi2 thin films on single and polycrystalline silicon. After depositing 1000‐A 31Si which had been activated in a nuclear reactor, radioactive TiSi*2 was formed by coating 500‐A Ti film in situ and then annealing at 850 °C for 45 min. On wet oxidation, the substrate silicon atoms transported through the TiSi*2 layer by grain boundary and/or interstitial diffusion. These results were confirmed by Geiger counting after etching the outer SiO2 layer step by step.

Thermal oxidation of cobalt disilicide

Abstract: The thermal oxidation kinetics of cobalt disilicide on Si substrates have been investigated in the temperature range of 650–1100 °C in dry oxygen and wet oxygen. A surface layer of SiO2 grows parabolically with time. The growth rate is independent of the substrate orientation (〈111〉 or 〈100〉) and thickness of the CoSi2 layer. We surmize that the oxidation mechanism is dominated by the diffusion of an oxidant through the growing SiO2. Activation energies for the dry and wet oxidation are 1.49±0.05 eV and 1.05±0.05 eV, respectively. The kinetics is exactly the same as for NiSi2 oxidation which suggest that the same mechanism controls the oxidation of these two similar suicides.

Oxygen injection nozzle for wet oxidation reactors

Abstract: An apparatus for injecting a mixture of pure oxygen or oxygen-enriched air (at least 25 percent oxygen) and purge water into a wet oxidation reactor operating at elevated temperature and pressure. An annular space between the oxygen carrying pipe and a second, larger pipe is filled with heat transfer resisting material, either maintained static or passed through the annular space to remove heat therefrom. The temperature of the oxygen and purge water is maintained at less than 250° F., preferably less than 150° F. to minimize evaporation of the purge water. Thus, backflow of organic matter into the oxygen pipe is prevented; plugging of the oxygen pipe by salts is also prevented.

Process for treating thiosulfate containing liquors

Abstract: A process for treating thiosulfate containing liquors such as coke oven gas scrubbing liquors by first adding acid, preferably sulfuric acid, to convert thiosulfate to elemental sulfur and bisulfite, separating and removing the elemental sulfur, and subjecting the remaining liquor to wet oxidation.

Wet oxidation of organic matter

Abstract: Forming an oxide ore slurry or ore concentrates containing organic matter by mixing with water and heating them at a temperature of at least about 230 C under an oxygen partial pressure at least about 25psi to oxidize organic matter. The process described in the present invention can be advantageously used in the treatment of tungsten concentrates and can be used for the digestion of tungsten concentrates with sodium carbonate solution or sodium hydroxide.

Treatment of waste liquid from wet desulfurization of coke oven gas

Abstract: PURPOSE:To alleviate the load and to miniaturize the equipment, by subjecting a liquid desulfurization waste to wet oxidation treatment to precipitate formed ammonium sulfate and then to an active sludge process. CONSTITUTION:A liquid waste from wet desulfurization of coke oven gas is subjected to wet oxidation treatment so as to selectively oxidize and decompose ammonium thiosulfate in a weakly acid or alkaline pH range at a temperature lower than 200 deg.C. Thereafter, formed ammonium sulfate is precipitated and separated, and the treated waste water is purified in an active sludge process. That is, the active sludge-process is carried out after precipitation and separation of ammonium sulfate. Consequently, the load for that part can be alleviated.

Method of and apparatus for re-extraction of oil

Abstract: A process for enhanced oil recovery by gas injection into oil-bearing formations which comprises wet oxidizing combustible carbonaceous materials with oxygen, air or a mixture of oxygen and air to obtain a gas comprising a mixture of water vapor and carbon dioxide (and nitrogen in the event air is used), substantially free of oxides of sulfur and nitrogen; injecting said gaseous mixture into an oil-bearing formation to produce a mixture of oil and water; extracting said mixture of oil and water from the oil-bearing formation; separating the water from the latter mixture; and recycling the water to the wet oxidation reactor Residual oil in the recycled water provides additional fuel for the wet oxidation reaction, and at the same time the need for costly water treatment is eliminated

The enrichment with impregnated polyurethane foam and spectrophotometric determination of trace thorium in natural water

Abstract: This paper reports the use of impregnated polyurethane foam for enriching trace thorium from natural water. The polyether type polyurethane foam was employed, which was impregnated with bis (2-ethylhexyl) phosphoric acid/tributyl phosphate/ carbon tetrachloride (2: 5: 93, V/V/V) mixture. The excess reagent was removed by filter paper. The impregnated foam thus prepared is dipped into the water sample and stirred for 20 minutes. The optimum conditions for enrichment are. sample should be adjusted to about pH 1 and temperature should be kept within 30～45℃. Distribution and phase ratios were calculated to be 4.26×10~4 and 2.01×10~4 respectively, assuming that the mixture and water are totally immiscible with each other. The actual values were all slightly greater than the calculated ones. After removing the foam from the sample, the former is washed with water and subjected to wet oxidation with concentrated nitric and perchloric acids. The residue is taken up with diluted hydrochloric acid. The thorium is spectrophotometrically determined with Arsenazo Ⅲ at 665 nm. The method is simple, rapid, accurate and inexpensive.

Off-site disposal eliminated with wet air oxidation

Abstract: This article focuses on a solution to Northern Petrochemical's Morris, Ill. plant problem of the spent scrubbing solution from an acid gas scrubber being so high in caustic and organics that, if discharged to the in-plant biological waste treatment system, frequent pH upsets and COD overloads would occur. The off-site disposal method was expensive, and increasingly stringent standards for such methods could only cause further increases in cost and possible curtailment. Therefore, Northern Petrochemical wanted to provide an on-site disposal system fully under their own control. A host of treatment, recycle, and disposal methods were studied, including deep well disposal, chemical fixation, caustic recovery/recycle, and chemical oxidation. Wet air oxidation (WAO) was selected for detailed pilot tests because, in a single-train continuous process operation, the major problems associated with treating spent caustic were expected to be solved. The sulfides would be oxidized to soluble sulfate salts, the trace cyanides oxidized, and pH and COD reduced. This would be done without chemical addition or the generation of a sludge or waste by-product requiring off-site disposal. All waste caustic is now treated in the system, thus eliminating off-site disposal. Net savings for the first six months of operation have been $675,000--an annualmore » rate of savings of $1.3 million.« less