From production to product: Part 1. Solution states of alkaline bagasse lignin solution

The viscosity of alkaline solutions of bagasse lignin (BL) derived from the effluents of a soda pulping process was studied dependently on the lignin concentration and solution pH. A concentration-driven aggregation of lignin at a fixed pH was recognized by means of a change in the slope of the viscosity–concentration relationship. Furthermore, pH-driven aggregation phenomena of lignin were identified due to the balance of protonation and deprotonation of phenol functionalities in the lignin molecule. The correlation of both principal aggregation phenomena of lignin in alkaline solution by changing lignin concentration and alkalinity leads to a simplified model of four solution states. Product testing for specific applications should be performed covering these four solution states.