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Wet oxidation

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


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Journal ArticleDOI
TL;DR: In this article, the use of novel CWAO catalysts, namely low cost, sewage sludge derived activated carbons was explored, and a strong correlation was found between surface area and phenol or TOC conversion, suggesting that surface area is a primary requisite for their performance in the first batch cycle.
Abstract: In this study the use of novel CWAO catalysts, namely potentially low cost, sewage sludge derived activated carbons was explored. Two types of municipal sludge were used: dewatered raw filter cake and dewatered mesophilic anaerobically digested sludge. The carbons were produced by: carbonisation; physical activation (steam or CO2) and chemical activation (K2CO3). Hydrochloric acid washing of some of the carbons was also investigated. The carbons were characterised in terms of their surface area, contact pH, propensity towards metal leaching, surface chemistry (via FTIR), ash content and inorganic elemental composition. Their CWAO performance was assessed at 160 °C and a partial oxygen pressure of 4.2 bar (25 bar of air) within a stirred batch reactor containing a 5 g/L phenol solution. All the carbons exhibited catalytic activity, with the K2CO3 activated and HCl washed carbons attaining a phenol and TOC removal that matched the performance of an activated carbon specifically manufactured for oxidative wastewater treatment applications. A strong correlation was found between surface area and phenol or TOC conversion, suggesting that surface area is a primary requisite for their performance in the first batch cycle. Thus, the oxidation of phenol is thought to proceed via a free radical driven mechanism. The active sites necessary to facilitate this mechanism, whether present as surface functional groups or active metals (e.g., Fe), were detected on all of the sludge based activated carbons. However, no clear correlation between phenol conversion and these active sites could be established.

83 citations

Journal ArticleDOI
TL;DR: It is shown that hydroxyl radicals (HO*) and hydrogen peroxide (H2O2) play the role of intermediates in the initial phase of the oxidation reactions.

83 citations

Journal ArticleDOI
TL;DR: In this paper, the authors performed wet-air oxidation of aqueous solutions of formic acid, acetic acid, and phenol in a trickle-bed reactor at T ǫ = −328 −523 K and total pressures up to 50 bar over various Ru/TiO 2 catalysts.
Abstract: Catalytic wet-air oxidation of aqueous solutions of formic acid, acetic acid and phenol was carried out in a trickle-bed reactor at T = 328–523 K and total pressures up to 50 bar over various Ru/TiO 2 catalysts. Complete oxidation of formic acid was obtained at mild operating conditions, and no catalyst deactivation occurred that could be attributed to the dissolution of active ingredient material. It was observed that besides oxidation route thermal decomposition contributes significantly to the removal of formic acid; Ru/TiO 2 catalysts could be thus efficiently used for transformation of HCOOH to H 2 and CO 2 in an inert atmosphere. Liquid-phase oxidation of acetic acid was found to be structure sensitive; the highest catalyst activity was obtained, when Ru phase on the catalyst surface prevailed in zero-valent state. Due to simultaneous oxidation of metallic Ru to RuO 2 during the reaction course, correspondingly lower conversion of acetic acid was measured in the reactor outlet. The employed Ru/TiO 2 catalysts enable complete removal of phenol and TOC at temperatures above 483 K; at these conditions, no carbonaceous deposits were accumulated on the catalyst surface. Apparent catalyst deactivation observed at temperatures below 463 K is attributed to strong adsorption of partially oxidized intermediates on the catalyst surface, which can be avoided by conducting the CWAO process at sufficiently high temperatures. The acute toxicity to Daphnia magna and Vibrio fischeri of end-product solutions compared with that of the feed solutions was significantly reduced by oxidative treatment over Ru/TiO 2 catalysts.

83 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the kinetics of WO of formic acid in the absence and presence of a cupric sulfate as catalyst in the temperature range 150−240 °C and oxygen partial pressure range 0.345−1.380 MPa.
Abstract: Oxidation of lower molecular weight carboxylic acids such as formic, acetic, glyoxalic, and oxalic acids is often the rate-controlling step during wet oxidation (WO) of an aqueous waste stream exhibiting very high chemical oxygen demand (COD). The kinetics of WO of formic acid was studied in the absence and presence of a cupric sulfate as catalyst in the temperature range 150−240 °C and oxygen partial pressure range 0.345−1.380 MPa. Wet oxidation of acetic acid was carried out in the presence of cupric sulfate in the temperature range 215−235 °C. Homogeneous copper sulfate was found to be a very good catalyst for oxidation of formic acid and acetic acid.

82 citations

Journal ArticleDOI
TL;DR: In this article, a new dry combustion method for the simultaneous determination of total organic carbon and nitrogen in seawater is presented, which yields CN ratios for total organic matter of 5 and 12 respectively.

82 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202314
202233
202171
202096
2019116
2018128