Hydroxymethylation of a sodium lignosulfonate: molar mass distributions by SEC with dual detection.
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| Title: | Hydroxymethylation of a sodium lignosulfonate: molar mass distributions by SEC with dual detection. |
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| Authors: | Taverna, María E.1,2 (AUTHOR), Chiappero, Lucio R.2 (AUTHOR), Yossen, Mariana M.1 (AUTHOR), Estenoz, Diana A.1 (AUTHOR), Nicolau, Verónica V.2 (AUTHOR), Meira, Gregorio R.1 (AUTHOR) gmeira@santafe-conicet.gov.ar |
| Source: | Journal of Liquid Chromatography & Related Technologies. Jun-Aug2025, Vol. 48 Issue 11-15, p294-301. 8p. |
| Subjects: | Lignosulfonates, Molar mass, Analytical chemistry techniques, Distribution (Probability theory), Hydroxymethyl compounds, Lignins, Gel permeation chromatography, Phenolic resins |
| Abstract: | Lignosulfonates (LS) are employed as partial substitution of phenol in phenolic resins; but to increase their reactivity they require an initial hydroxymethylation reaction. Dual-detection size exclusion chromatography (SEC) is here employed for analyzing the evolution of the molar mass distributions (MMDs) along that reaction. The chromatograms were obtained with a UV detector at 254 nm, in series with a differential refractometer (DR). While the DR was assumed to detect the total instantaneous eluent, the UV signal was assumed to detect the aromatic rings of the lignin polymer, but not the low molar mass carbohydrate contaminants. The reactive lignin fraction exhibited a bimodal distribution, with two main components of different average molar masses. Along the reaction, only the reactive lignin fraction increased the molar masses, and the higher molar mass component also exhibited the higher reactivity. Deconvolution procedures were applied to estimate the MMDs of the contaminants, the total lignin, and the reactive lignin components. Double-detection size exclusion chromatography (SEC) was used for analyzing the evolution of the MMD along a hydroxymethylation of a sodium lignosulfonate contaminated by low molar mass carbohydrates. The UV sensor at 254 nm only responds to the (reactive and unreacted) phenolic groups of lignin, while the differential refractometer (DR) responds to the total blend. Deconvolution procedures enable to estimate the MMDs of the contaminants and the pure reactive lignin. The pure reactive lignin exhibited a bimodal MMD, with its higher molar mass component showing the higher reactivity. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Lignosulfonates (LS) are employed as partial substitution of phenol in phenolic resins; but to increase their reactivity they require an initial hydroxymethylation reaction. Dual-detection size exclusion chromatography (SEC) is here employed for analyzing the evolution of the molar mass distributions (MMDs) along that reaction. The chromatograms were obtained with a UV detector at 254 nm, in series with a differential refractometer (DR). While the DR was assumed to detect the total instantaneous eluent, the UV signal was assumed to detect the aromatic rings of the lignin polymer, but not the low molar mass carbohydrate contaminants. The reactive lignin fraction exhibited a bimodal distribution, with two main components of different average molar masses. Along the reaction, only the reactive lignin fraction increased the molar masses, and the higher molar mass component also exhibited the higher reactivity. Deconvolution procedures were applied to estimate the MMDs of the contaminants, the total lignin, and the reactive lignin components. Double-detection size exclusion chromatography (SEC) was used for analyzing the evolution of the MMD along a hydroxymethylation of a sodium lignosulfonate contaminated by low molar mass carbohydrates. The UV sensor at 254 nm only responds to the (reactive and unreacted) phenolic groups of lignin, while the differential refractometer (DR) responds to the total blend. Deconvolution procedures enable to estimate the MMDs of the contaminants and the pure reactive lignin. The pure reactive lignin exhibited a bimodal MMD, with its higher molar mass component showing the higher reactivity. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 10826076 |
| DOI: | 10.1080/10826076.2025.2467114 |
