UV/vis Lignin Analysis Neutral Spectra The neutral ultraviolet and visible (UV/vis) spectra were measured in a 2:1 2-methoxyethanol/water (v/v) solvent and according to standard literature

The neutral ultraviolet and visible (UV/vis) spectra were measured in a 2:1 2-methoxyethanol/water (v/v) solvent and according to standard literature procedures. The UV/vis data was acquired using a Lambda 900 UV spectrometer. Briefly, the absorption spectra were recorded from 200 to 800 nm using a pathlength of 10 mm, a bandwidth of 1.0 nm and a scan speed of 250 nm/min. Only matched cuvettes were used when obtaining the spectra. The spectra were determined by adding 5 mL of the lignin solution (0.06 g/L in 2:1 v/v 2-methoxyethanol and deionized water) to 1 mL of phosphate buffer at pH 6.5. This lignin solution was placed in the sample cell. The reference cell was prepared by adding 5 mL of a solvent solution (2:1 v/v 2-methoxyethanol and deionized water) to 1 mL of phosphate buffer at pH 6.5.