Pulp properties resulting from different pretreatments of wheat straw and their influence on enzymatic hydrolysis rate

Wheat straw was subjected to three different processes prior to saccharification, namely alkaline pulping, natural pulping and autohydrolysis, in order to study their effect on the rate of enzymatic hydrolysis. Parameters like medium concentration, temperature and time have been varied in order to optimize each method. Milling the raw material to a length of 4 mm beforehand showed the best cost–value-ratio compared to other grinding methods studied. Before saccharification the pulp can be stored in dried form, leading to a high yield of glucose. Furthermore the relation of pulp properties (i.e. intrinsic viscosity, KLASON-lignin and hemicelluloses content, crystallinity, morphology) to cellulose hydrolysis is discussed

Separation and characterisation of sulphur-free lignin from different agricultural residues

Wheat straw, as one of the most abundant agricultural residues in Europe, was subjected to alkaline pulping, microwave-assisted alkaline pulping and organosolv pulping using formic acid and hydrogen peroxide. The obtained lignins were characterised by means of Klason-lignin, FT-IR spectroscopy, elementary analysis, thioacidolysis, SEC and different wet chemical methods. The emphasis here was on their structural differences, especially the content of functional groups like total hydroxyl, phenolic hydroxyl, carboxyl, carbonyl and methoxyl groups.In addition, numerous agricultural residues, for example barley straw, maize straw, sunflower stalks and horse manure, were characterised and subjected to alkaline pulping, which was carried out based on the optimum parameters found for wheat straw: θ=. 160. °C, t=. 30. min and ω(NaOH). =. 3. wt%. The examined raw materials showed different suitability for lignin separation using this pretreatment. The resulting lignins were characterised with the methods described above and were classified into three groups within which lignins show similar characteristics. By this, lignin with interesting structural features could be proposed for further studies