Researchers have developed bio-based aldehyde-amine curing agents for bisphenol A epoxy resin coatings by isolating and converting multiple chemical fractions from pulping black liquor. In the investigation, the research team demonstrated that both lignin and saccharide-rich fractions separated from this pulping by-product can be successfully transformed into functional curing agents, offering an experimental route for the high-value utilization of all components found in black liquor.
To isolate the distinct constituent materials from the pulping black liquor, the experimental procedure began with acid precipitation to separate the lignin fraction. Following the removal of lignin, the researchers treated the remaining supernatant liquid through either acidolysis or dialysis. These treatment pathways allowed the authors to isolate separate saccharide-rich fractions from the black liquor byproduct alongside the recovered lignin.
The isolated lignin and the various saccharide-rich fractions were subsequently subjected to the Mannich reaction to synthesize bio-based aldehyde-amine curing agents. Following chemical synthesis, the resulting curing agents were evaluated using spectroscopic techniques. Specifically, Fourier transform infrared spectroscopy and proton nuclear magnetic resonance suggested the successful synthesis of both the lignin-based and saccharide-based aldehyde-amine curing agents.
The synthesized curing agents were then applied to cure bisphenol A epoxy resin, specifically designated as E901, to prepare protective epoxy coatings. Within the evaluation of coating performance, curing agents prepared from the acidolysis supernatant—identified as MIAAA and MIBAA—exhibited superior performance when compared directly against the curing agents derived from lignin. Furthermore, the researchers observed that inorganic salts retained within the isolated lignin and saccharide-rich fractions served as functional fillers, contributing to enhanced mechanical properties in the cured epoxy coatings.
Quantitative testing demonstrated specific property advantages depending on the formulation derived from the acidolysis supernatant. The epoxy coating formulated and cured with the MIAAA curing agent achieved a maximum tensile strength of 57.0 MPa. Meanwhile, the coating cured using the MIBAA curing agent demonstrated optimal corrosion protection, recording an impedance modulus value of log|Z|0.01 Hz of 7.31 after two hours of immersion in a 3.5 weight percent sodium chloride solution. Overall, the findings indicate the feasibility of converting black liquor lignin and saccharides into effective curing agents for epoxy coatings.
The authors noted that data will be made available on request.
Subject of Research: Bio-based epoxy curing agents synthesized from pulping black liquor components
Article Title: Preparation of bio-based curing agents utilizing various components isolated from pulping black liquor for application in epoxy coatings
Article References: Ye, J., Song, W., Zhu, W., Lin, H., Fan, Q., & Li, X. (2026). Preparation of bio-based curing agents utilizing various components isolated from pulping black liquor for application in epoxy coatings. Journal of Materials Science, 61(40), 31338-31357. https://doi.org/10.1007/s10853-026-13408-1
Image Credits: AI Generated
DOI: 10.1007/s10853-026-13408-1
Keywords: black liquor, lignin, saccharide fractions, curing agents, epoxy coatings, Mannich reaction, acidolysis, materials science, Preparation, bio-based, curing, agents
News Source: Denise Maddox. (November 10, 2026). Researchers Develop Bio-Based Epoxy Curing Agents From Pulping Black Liquor Components. Scienmag.
