Wet oxidation

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

Thermal oxidation of niobium silicide thin films

Abstract: Thermal oxidation of niobium silicide thin films on oxidized silicon substrates has been investigated. The silicide films were rf sputtered from a hot‐pressed alloy target of stoichiometric composition (Si/Nb∼2) onto heated (350 °C) substrates. Oxidation was carried out in dry and wet oxygen between 550 and 850 °C. From Rutherford Backscattering Spectroscopy (RBS) measurements, it was determined that the oxide films exhibited the same Si/Nb ratio as the initial silicide layer. While only Nb2O5 has been cleary identified, density considerations and experimental values of oxide thickness suggest that niobium and silicon oxides coexist. The composition of the remaining silicide layer did not change significantly during oxidation. The oxide growth was found to follow a (tox)nα (time) relationship, with n∼1.1 for dry oxygen and 1.4 for wet oxygen. Activation energies of 1.9 and 1.6 eV were determined for the dry and wet oxidation processes.

Wet Oxidation—An Option for Enhancing Biodegradability of Leachate Derived From Municipal Solid Waste (MSW) Landfill

Abstract: The present study reports the treatment of municipal solid waste (MSW) derived landfill leachate (initial pH = 7.82 and chemical oxygen demand (COD) = 6400 mg L−1) using catalytic wet oxidation (WO) process. The reaction was performed under moderate conditions (110−150 °C temperature and 0.7 MPa total pressures) in the presence of a CuSO4 catalyst. The effect of the promoter (Na2SO3) was also seen on the COD removal. The results were compared with that obtained for Fe2+ and H2O2 combination. Among all tested combinations, (CuSO4 + Na2SO3 + air) exhibited the best performance with ∼90% COD reduction at 150 °C temperature and 0.7 MPa pressures. Under these conditions, the biodegradability of the treated effluent was improved to 0.66 (from an initial value of 0.38). The average oxidation state of carbon (AOSC) value and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of carboxylic acids in the treated effluent.

Catalytic wet oxidation of quinoline over Ru/C catalyst

Abstract: In the present work, catalytic wet air oxidation of the model nitrogenous organic compound quinoline was studied in a slurry reactor over 5% Ru/C catalyst between 423 and 598 K temperature, 0.34 and 2.07 MPa oxygen (O2) partial pressure, and 0.025 and 0.1 kg m−3 catalyst loading. This catalyst was very effective, thereby suggesting its utility for the oxidative destruction of wastewaters polluted by nitrogenous organic compounds. From analysis of the mass transfer effects, it was found that the investigated reaction belonged to the kinetics-controlled reaction regime. Kinetic data on TOC destruction were fitted to a two-step first-order power law model: the first step was fast, whereas the second step was slow. The values of activation energy for the two steps were 29 and 93 kJ mol−1. Among the hyperbolic models tested, the model with a slow surface reaction between chemisorbed TOC and dissociatively adsorbed O2 was most appropriate. The fate of the nitrogen atom in the feed solution and its conversion to nitrite and nitrate ions, ammonia and nicotinic acid was established. Finally, it was corroborated that the reaction was fast when pyrex liner was used inside the reactor because free radicals were not destroyed by the reactor wall.