The fraction of water-soluble lignin-carbohydrate complexes(LCC)containing sodium salt and low molecular weight(Mr)substances(<1 000)was isolated from alkali extracting liquor of wheat straw by a solvent-extraction method.A hollow-fiber ultrafiltrator was used to isolate sodium salt and low Mr substances in the LCC.The results indicate that sodium salts and low Mr substances can be removed effectively after a total of ten times ultrafiltration loops with pressure 0.10 MPa and concentration 0.5 % were perfor...