CONCLUSION
A series of Kraft lignin samples from the
black liquor of Eucalyptus camaldulensis Dehn
were precipitated with concentrated sulphuric acid
at various pH levels (2, 4, and 6). It was concluded
that there are clear differences between the lignin
samples obtained at different pH levels, according
to their yields and ash content. The precipitationat pH 4 gave the highest yield and the lignin
obtained exhibited similar properties to that
precipitated at pH 2. Selective extractions for low
MW lignin were further performed on the lignin
obtained, using various organic solvents
(dichloromethane, acetone and methanol). The low
MW lignin samples extracted from acetone and
methanol possessed the same properties as the
starting lignin. In contrast, extraction with
dichloromethane produced lignin with a lower
molecular weight (about 940 g mol-1), leading to
lower Td (about 360°C) and Tg (about 80°C).