SOME FACTORS CAUSING COLOUR IN ACETATE PULP AND CELLULOSE ACETATE

Many methods have been developed for determining the residual lignin in pulp. These methods are suited to the analysis of paper pulp and packing materials. In the latest methods attention has been paid not only to the precipitating lignin but also to low molecular lignin, which remains in solution in acid hydrolysis. The concentration of the acid soluble lignin is determined by the ultraviolet absorbance at a wavelength of 205 nm1-4. The absorbance maximum of the benzene ring of lignin occurs at this wavelength (Figure 1), and the concentration of soluble lignin can be calculated, for example, by a standard curve made with lignosuiphonic acid