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 undrawn nylon 66 and model amides

Abstract: Undrawn nylon was found to be susceptible within a few days to degradation in wet or humid conditions at temperatures between 50 and 90°C. Model N-substituted amides, although not affected by these conditions, were attacked by hydrogen peroxide solutions. The degradation proceeded principally by rupture of the bond between the nitrogen of the amide and the carbon of its α-methylene group, consequent upon oxidation at this carbon. Unsubstituted primary amide, carboxyl, and aldehyde endgroups were formed, together with ammonia by hydrolysis of the oxidized amide. The bond between the α and β carbons of an N-methylene chain also suffered breakage, giving formic acid and carbon dioxide. The former could also arise by rupture of any initially produced N-formyl or N-formoyl amides. The appearance of lactic acid from butylacetamide showed that oxidation could proceed along the N-alkyl chain. Fragments of suitable size broken from the main chain of nylon became water-soluble and relatively stable to further attack by air or oxygen. These pieces essentially retained the nylon structure, but possessed two carboxylic ends and an average molecular weight of less than 600. A maximum oxygen uptake of about 30 moles per mole of original amide was calculated, corresponding to complete conversion into these soluble fragments. Significant degradation did not occur for many months at 60°C. in dry conditions or in solutions of 8-hydroxyquinoline, a process which has been patented. The latter was considered to function by chelating heavy metals into an inactive form and inhibiting peroxide formation.

Progress in performance and stability of a contactor-type Catalytic Membrane Reactor for wet air oxidation

Abstract: Catalytic Membrane Reactors combine a membrane that controls transfers and a catalyst that provides conversion. This paper focuses on the catalytic performance stability of interfacial contactor membranes in the wet air oxidation of formic acid. Stable catalytic membranes with high activity have been developed.

Coagulation as a post-treatment process for wet oxidation of pulp and paper mill circulation waters

Abstract: The present study tested the performance of coagulation after wet oxidation (WO) as a way to improve water quality, namely colour, and establish its viability as a secondary treatment process for water cycle closing. The experiments were carried out with model TMP (Thermomechanical Pulp) water concentrated by nanofiltration. The WO runs were conducted at a temperature of 453 K and p(O 2 ) of 1 MPa. Fe 2 (SO 4 ) 3 was chosen as the coagulant for the coagulation experiments. The experimental results showed that coagulation allowed 83% colour removal and 75% lignin reduction with a coagulant dose of 0.86 g Fe 3+ /L. Recirculation of sludge to the WO system improved the performance of the WO process. The dose needed to achieve the same results for the coagulation after the recirculation loop, i.e. coagulation after wet oxidation with coagulation sludge recycled to the WO system, was 0.78 g Fe 3+ /L. The Fe ion concentration remaining after coagulation was observed to be 0.91-0.95 mg/L, which could permit sludge-free water reuse in paper mills.

Effects of temperature and Cu2+ catalyst on liquid-phase oxidation of industrial wastewaters

Abstract: Wet air oxidation is a process in which partial oxidations arise in an aqueous medium. Elevated temperature and pressure have enhanced solvent power for both oxygen in air and organics in wastewaters. Oxidations have therefore been carried out either in a kinetic-controlling or in a diffusion-controlling operation. Spent caustic and neutralized wastewaters obtained from a petrochemicals-manufacturing process, were employed in this study for wet oxidation in a semi-batch reactor. Temperature was indicated by preliminary kinetic data to be the primary factor influencing a situation where there was little control by diffusion. The oxidation reactions of hydrocarbon organic compounds were demonstrated to be enhanced if Cu2+ was used as the catalyst. Designing and developing wet oxidation for processing industrial wastewaters was pursued in this present study by successfully adopting homogeneous kinetic models which were, subsequently, employed for calculating rate constants of oxidation reactions by correlating organics removal efficiency with oxidation time.