Lignins, which are heterogeneous cross-linked polyphenolic macromolecules present in the cell walls of plants, are the most important bio-source of phenolic structures on Earth and represent 30% of non-fossil organic carbon.In the paper industry using bisulfite pulping, lignins from wood are transformed into sulfonated lignin derivatives by-products. Also known as lignosulfonates, these phenolic polymers are commonly used in industrial applications as plasticizers and dispersants but are also promising greener substitutes for phenols (e.g., in phenol-formol resins).To efficiently use these complex and heterogeneous bio-based phenolic polymers in industrial applications, it is important to control and quantify the free phenols to determine their chemical reactivity. In this aim, we developed a quick, straightforward and reliable UV analytical method to rapidly and easily quantify free phenol content in raw lignosulfonate materials.Through quantitative ClO2 titration and UV analysis of synthetic lignosulfonate model compounds and industrial lignosulfonates in acidic and basic media, we determined an average molar extinction coefficient of lignosulfonate solutions. With this coefficient and a couple of UV analysis, one can readily obtain reliable and accurate free phenol contents for any industrial lignosulfonate solution.This UV-based analytical method is quicker than the phosphorylation technique and is a promising alternative for routine quantitative analysis of raw lignosulfonate materials.

Quick and reliable UV spectroscopy-based free phenol quantification in lignosulfonates

248th National Meeting (2014)

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