effect of nano silica and cationic polyacrylamide on retention, drainage and strength properties of recycled paper from occ

various kinds of chemicals are used in papermaking to enhance paper properties and to improve efficiency of the production process. in the presence of cationic starch as an anionic charge catcher, effects of nano silica/cationic polyacrylamide complex on retention, drainage time, water volume drained by dynamic drainage jar and properties of paper recycled from old corrugated container were investigated. the results revealed that individual addition of cpam is more efficient than the individual addition of anionic nano silica, regarding to the investigated properties, increase all characteristics compared to the situation without these addition. higher volume of drained water (up to 6%) and lesser time needed for the sheet formation (up to 10%) combined with retention increment (> 2%) have been achieved by flocculation and consolidation of fines and fibers via bridging and network flocculation of pulp ingredients and contributing to charge neutralization of anionic surfaces, more and more, resulted in bigger flocs which could be retained by papermaking wire. the mentioned mechanism contributed to better bonding of paper network resulted in tensile and burst indicates improvement up to > 45% and >50%, respectively. influence of silica anionic nanoparticle on strengthening of the flocs formed by cpam, made higher energy requirements (> 12%) for paper tearing. in addition to higher yield of production, application of cpam/nano silica complex resulted in a paper with higher value from quality and application point of view.