A New Methodology to Elucidate Lignin Structure-Properties-Performance Correlation

Unveiling the interrelation between the lignin structure, its properties and performance in specific applications is of primary importance for lignin engineering for high-value products. Herein, we suggest a new efficient methodology to quantitatively evaluate the roles of lignin specific functionalities in selected applications. The method is based on changing only one structural variable at a time, while keeping all others constant prior to performance evaluation. Indulin AT (a softwood Kraft lignin) was subjected to a set of chemical modifications by selectively masking its aliphatic (AlipOH), phenolic OH (PhOH), carboxyl (COOH) and carbonyl (CO) groups. The property-performance correlation was demonstrated by measuring the glass transition temperatures (Tg) of the modified lignins. The effect of the modifications on the adsorption performance of the modified lignins was evaluated towards methylene blue. This approach clearly demonstrated that PhOH and AlipOH groups have about equal contribution (50% each) to the lignin adsorption capacity, while the role of the other functional groups is insignificant.