Hardwood kraft pulp fibre oxidation using acidic hydrogen peroxide

Abstract

Gaining insight into the oxidation of hardwood kraft fibres using hydrogen peroxide at mildly acidic conditions was the main aim of this study. The oxidized hardwood pulp had an increased number of carbonyl groups and, when formed into sheets, an enhanced durability in water was seen due to the formation of cross-links, known as hemiacetals. The carbonyl groups formed were found to be mainly ketones with the exception of the case with longer reaction times (60–90 minutes) at 85 °C, where aldehydes were detected. Through compositional analysis it was found that mainly xylan was oxidized, likely due to the higher amount of xylan close to the surface of the fibre wall. The influence of xylan on the oxidation process was investigated using cold caustic extraction (CCE) performed prior to oxidation. When the CCE pulp was oxidized, there was an increased rate of introduced carbonyl groups and degradation was more pronounced. This is likely due to the accessible surface area being increased, caused by the formation of pores when the lower molecular weight xylan was being extracted during CCE.

Study of oil biodegrading by expanded perlite Loaded by oil-eating bacteria

“…The culture medium, as speci ed in Table 1, encompassed both primary and secondary elements in accordance with their relevance for microbial growth. The pH of the sample was adjusted to 7.2 using a NaOH solution (Martinsson et al 2021). Approximately three liters of this solution were initially prepared and stirred for ten minutes.…”

Nanocellulose by Ammonium Persulfate Oxidation: An Alternative to TEMPO-Mediated Oxidation

“…29,36,37 The peroxyl radical may also form carbonyls with secondary alcohols, ultimately contributing to the formation of hemiacetal cross-links when dried; however, Leung demonstrated using Fourier transform infrared (FTIR) and NMR that this reaction does not occur. 38,39 The byproduct of the oxidation reaction is the formation of sulfate ions and sulfuric acid. Leung determined that these were in the molar ratio of 4:6 in the residual liquor.…”

“…The subsequent decomposition reactions, eqs and , are the rapid formation of hydrogen sulfate, HSO 4 – , sulfate-free radical SO 4 •– , and peroxyl radical, HO • . The sulfate-free radical oxidizes the C6 to its aldehyde form, followed by peroxyl radical oxidation to form carboxylic acid groups on the nanofiber surface. ,, The peroxyl radical may also form carbonyls with secondary alcohols, ultimately contributing to the formation of hemiacetal cross-links when dried; however, Leung demonstrated using Fourier transform infrared (FTIR) and NMR that this reaction does not occur. , The byproduct of the oxidation reaction is the formation of sulfate ions and sulfuric acid. Leung determined that these were in the molar ratio of 4:6 in the residual liquor.…”