Atmospheric acetic acid pulping of rice straw IV: Physico-chemical characterization of acetic acid lignins from rice straw and woods. part 2. Chemical structures

Acetic acid lignins from rice straw (RLs), birch (BL) and fir (FL) were che mically characterized by means of elementary analysis, functional groups an alysis, alkaline nitrobenzene and permanganate oxidation, Mannich reactivit y and other techniques. The results showed that RLs had higher contents of residual polysaccharide and protein, and remarkably fewer acetyl groups tha n BL and FL. Results of nitrobenzene and permanganate oxidation indicated t hat RLs were remarkably more condensed than the native lignin in rice straw . In addition, the results of Mannich reactivity showed that RLs were more reactive toward modification than BL and FL, and might be a good raw materi al for lignin derivatives, such as lignin adhesives and chelating resins.