文化纸白水中溶解物质和胶体物质的来源分析及表征

Origin analysis and characterization of dissolved and colloidal substances from white water in fine paper mill

分析了高度封闭循环的文化纸生产线白水系统中溶解物质和胶体物质（ dissolved and colloidal substances，简称DCS）的来源，并对DCS的基本特性进行了表征。通过离心－抽提法分离白水中的DCS，用GC－MS分析其MTBE抽出物的化学组成，采用显微镜及激光粒度仪分析DCS的形态特征；利用凝胶渗透色谱法及热重分析仪研究DCS的分子质量分布及热失重特性。结果表明：造纸白水中的DCS主要来源于涂布胶乳、消泡剂、分散剂、表面施胶剂、荧光增白剂等湿部助剂的失效或水解产物，而木质素降解产物很少；DCS中的胶体物质主要以絮团形式分散在白水中或吸附在填料和纤维表面，粒径大多在500-4000 nm之间；DCS的分子质量主要分布在＜1400 u和＞12600 u两个区间，选用10 ku的超滤膜有望分离其中的大分子质量的物质；DCS热裂解温度为100-700℃。

The origin and characteristics of dissolved and colloidal substances （ DCS ） from a high closed white water system in fine paper mill were analyzed in this paper. The DCS were separated from white water by centrifugation.extrac.tion and the MTBE extracts were analyzed by gas chromatography mass spectrometry （ GC-MS） . The morphological char.acter of DCS was observed with microscope and laser particle size analyzer, and the molecular weight distribution and thermal weight loss properties of DCS were detected by gel permeation chromatography （ GPC） and thermogravimetry a.nalysis （ TGA） . The results showed that the DCS mainly originated from latex, paper additives and their ineffective prod.ucts such as defoaming agent, dispersant, surface sizing agent, brightening agent, but very few from lignin degradation. The particle size distribution of DCS was in the range of 500-4 000 nm, and the colloidal substance was dispersed in form of floc or absorbed on the surface of fines. The main molecular weight distribution area of DCS was〈1 400 u and〉12 600 u, and the macromolecular substances of DCS may be separated by ultrafiltration membrane with a cut off value of 10 ku. The DCS present obvious thermal weight loss during 100-700 ℃.