Analysis of characteristic of dissolved and colloidal substances in poplar APMP

White water in papermaking systems can contain many Dissolved and Colloidal Substances (DCS). With the recycling of white water, DCS will accumulate in the papermaking system, resulting in serious deposit problems on papermaking equipments, and product qualities are likely to be suffered. In this paper, the physicochemical properties of DCS from poplar alkaline peroxide mechanical pulp (APMP) were studied. The dissolved substances (DS) and colloidal substances (CS) in the DCS have different contributions to the DCS properties. The results showed that the DS contributed as much as 77% to the total DCS, while the CS only contributed to the other 23%. It is obvious that the carbohydrates in the DCS are much more than the lipophilic resin substances. But the cationic demand (CD) of CS was higher than DS, so the main contributor to the CD was from CS which is composed of more anionic substances. The conductivity of the DS was quite similar to that of the DCS, indicating DS had a key effect on the DCS conductivity. The DCS was determined by GC-MS (Gas Chromatography-Mass Spectrum) qualitatively, and three compounds of the resin acid components, seven compounds of the fatty acid components, seven compounds of the saccharide components and two compounds of the indicans components were identified in DCS.