关键词: 秸秆, 絮凝分离, 预处理碱液, 木质素

Abstract: Straw is a representative lignocellulose resource, and its pretreatment is a key factor in its separation and the application of its constituents. Based on SO₃ micro-thermal explosion and alkali treatment, an efficient separation of three major constituents of rice straw was achieved. In this paper, in order to recover the lignin and recycle the lye, the flocculation-separation through ion exchange of lignin was explored by learning from ion exchange separation. With the screening of metal ion, CaCl₂ was chosen to separate lignin in the lye. Also, the effects of different factors, such as adding amount of CaCl₂, flocculation time, temperature, rotating speed and pH, on lignin isolated yield were explored. The result shows CaCl₂ flocculation of lignin can be greatly improved by dialysis treatment. Meanwhile, the yield of lignin in the flocculation was investigated. The optimal condition is as follows:1% of CaCl₂ adding amount, 6h, 50℃, 150r/min and pH 11. Under above condition, lignin isolated yield could reach 61.08%. With the detection of flocculate, the analysis of IR and XPS, the existence of lignin in the flocculate was determined. Further, the mechanism of flocculation-separation of lignin by Ca²⁺ in the lye was analyzed preliminarily.

Key words: straw, flocculation separation, pretreatment lye, lignin