Systematic Characterization of Different Quaternary Ammonium Salts to be Used in Organoclays

Barbosa, Renata; Souza, D. D.; Araújo, Edcleide Maria; Mélo, Tomás Jefférson Alves de

doi:10.4028/www.scientific.net/msf.727-728.1552

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“…While the release of adsorbed water until somewhat beyond 100 °C was largely similar, a significant shift of the main degradation event (corresponding to 34% mass loss) toward lower temperatures (350 °C → 260 °C) was obtained for the cationic product, which is in agreement with the literature. 66 This is presumably due to the well-known thermal degradation of quaternary ammonium salts to afford tertiary amines andin the case of the presence of a proton in the βposition relative to the ammonium nitrogenan alkene by an E2 Hofmann elimination mechanism. 67 Degradation between 300 and 380 °C accounts for about 24% weight loss.…”

Section: ■ Introductionmentioning

confidence: 99%

Cationization of Eucalyptus Kraft LignoBoost Lignin: Preparation, Properties, and Potential Applications

Figueiredo

Magina

Budjav

et al. 2022

Ind. Eng. Chem. Res.

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Current changes toward a more biobased economy have recently created tremendous renewed interest in using lignin as a valuable source for chemicals and materials. Here, we present a facile cationization approach aiming to impart kraft lignin water-solubility, with similar good features as lignosulfonates. Eucalyptus globulus kraft lignin obtained from a paper mill black liquor by applying the LignoBoost process was used as the substrate. Its reaction with 3-chloro-2-hydroxypropyl-trimethylammonium chloride (CHPTAC) in an aqueous alkaline medium was studied to assess the impact of different reaction conditions (temperature, time, educt concentration, molar CHPTAC-to-lignin ratio) on the degree of cationization. It has been shown that at pH 13, 10 wt % lignin content, 70 °C, and 3 h reaction time, a CHPTAC-to-lignin minimum molar ratio of 1.3 is required to obtain fully water-soluble products. Elemental analysis (4.2% N), size-exclusion chromatography (M w 2180 Da), and quantitative 13C NMR spectroscopy of the product obtained at this limit reactant concentration suggest introduction of 1.2 quaternary ammonium groups per C9 unit and substitution of 75% of the initially available phenolic OH groups. The possible contribution of benzylic hydroxyls to the introduction of quaternary ammonium moieties through a quinone methide mechanism has been proposed. Since both molecular characteristics and degree of substitution, and hence solubility or count of surface charge, of colloidal particles can be adjusted within a wide range, cationic kraft lignins are promising materials for a wide range of applications, as exemplarily demonstrated for flocculation of anionic dyes.

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Section: ■ Introductionmentioning

confidence: 99%