Studing the effect of reducing agents (sodium borhydrade and sodium dithionite) on chemical structures of poplar kraft and bagasse soda alkali lignin by FT-IR spectroscopy

In this study, the chemical changes of functional groups (C=O) and double bond (C=C), induced in the structures of poplar kraft lignin and bagasse soda lignin were investigated. The reducing effect of sodium borohydride and sodium hydrosulfite, followed by the UV irradiation on these two compounds were determined using FT-IR spectroscopy. Results showed that, reduction of the lignin by reducing chemical imparted stability in lignin structure against UV light. The FT-IR spectroscopy showed that, the major light stabilizing phenomenon that is responsible for this stability is the conversion of carbonyl groups (C=O) alcohol group (C-OH) and double bonds (C=C) to single bonds (C-C). Between the two reducing compound, sodium borohydride showed better performance than sodium hydrosulfite.