DUAL APPLICATION OF FIXING AGENT AND RETENTION AID ON CONTROLLING DISSOLVED AND COLLOIDAL SUBSTANCES IN PULP

摘要

A polyamine(PA)fixing agent and a cationic polyacrylamide(CPAM)retention aid were used singly as well as in dual sequence to treat an old newspaper pulp.Focused beam reflectance measurement(FBRM)was utilized to measure the quantity,size and size distribution of the colloidal particles resided in the pulp filtrate.The objective was to elucidate the dual effect of fixing agent and retention aid on controlling dissolved and colloidal substances(DCS)in papermaking.The results show that when the PA was used singly,some colloidal agglomerates were formed,but part of the agglomerates,being either not fixed onto fiber or not trapped in fiber mat,resided in the pulp filtrate; when the CPAM was used singly,due to the fact that its charge was neutralized easily by the DCS,its ability to reduce the quantity of colloidal particles in the pulp was greatly decreased,as a result its formation of larger colloidal agglomerates was not obvious; when the PA and the CPAM were used in sequence as a dual system,those agglomerates formed by the PA but would have resided in the aqueous phase were further retained onto fiber by the CPAM,thus better effect in reducing the quantity of the colloidal particles and less residue of larger colloidal agglomerates in pulp filtrate were resulted in.