Investigative Study of Chemical Characterization of Raphia Petiole Lignin by Soda and Kraft Pulping Processes

Soda lignins of raphia petiole have completely different structure from kraft lignins. Soda lignins have higher methoxyl content and fewer phenolic hydroxyl group. From nitro benzene oxidation, soda lignins have a higher percentage of syringaldhyde 18.20 and also a higher S/V molar ratio. This is the reason that soda lignin is composed mainly of syringyl units, while kraft lignin is composed of guaiacyl units. IR spectra show remarkable differences: soda lignins show the strongest bands at 1230-1330 cm −1 , attributed to syringyl nucleus; whereas kraft lignins show the strongest bands at 1030 cm −1 and 1270 cm −1 , which are attributed to the guaiacyl nucleus. NMR spectra were also studied.