Effect of Binary and Ternary Nano‑Zeolite‑Based Flocculation Systems on the Properties of OCC Recycled Pulp and Paper

Background and Objective: The effective use of chemical as retention-drainage aiding systems in papermaking processes containing large amounts of fiber fines is inevitable from various product, economic, process and environmental aspects, and numerous complex systems have been proposed in these purposes. The use of nanoparticles in papermaking wet end and the interaction of these particles with cationic polyelectrolytes in the form of multi-component flocculation systems has received widespread attention in recent years in order to improve paper quality and its process characteristics. Cationic starch (CS) and cationic polyacrylamide (CPAM) are among the most widely used polyelectrolytes consumed in the papermaking industry. Zeolites, which are native, abundant, inexpensive and stable minerals at different pH of water, have found widespread and increasing applications in various applications. Benefits have also been reported for them as fillers in papermaking. Zeolites have the potential to be used as an anionic nanoparticle in complex flocculation systems of papermaking wet-end due to its specific surface area and high anionic charge.
Materials and Methods: OCC recycled pulp (CSF~315 ml) was prepared from a local mill without any additives. Nano Zeolite (NZ) with an average particle size of 38 nm (Pishgaman Mohit Zist Pak Co.), cationic starch with a degree of substitution (D.S) of 0.03 (Boyakhsaz Co.), and cationic polyacrylamide with a viscosity of 5500 cP (inventory of MWPI) were also prepared. Two-components flocculation addition sequence including CS and NZ, respectively; and three-components flocculation addition sequence including CS, CPAM and NZ, respectively were compared with each other and with the control sample. Addition strategies used at different levels were: CS at 1%, CPAM at 0.2% and 0%, and zeolite nanoparticles at 0, 0.1, 0.2, and 0.3%; all based on the pulp O.D. Pulp properties including total retention, drainage time during laboratory hand-sheet making, and drained volume of water in DDJ analyzer, as well as the laboratory recycled paper properties including thickness and tensile, burst, and tear strength indices were investigated according to TAPPI standards.
Results: Nano zeolite as part of the ternary system resulted in significant changes in the drainage time (up to -16%), drained volume of water (up to +8.5%), and total retention (up to +15%) of OCC recycled pulp compared to the control treatment. In the binary system, significant changes were also observed in the drainage time (up to -11%), drained volume of water (up to +7%), and total retention (up to +12%). Also, the thickness (up to +18%), tensile index (up to +55%), burst index (up to +101%), and tear index (up to +20%) of the paper produced from the ternary system were revealed compared to the control treatment. The binary system also had significant changes in the paper thickness (up to +8%), tensile index (up to +17%), burst index (up to +37%), and tear index (up to +6%) compared to the control treatment. Significant changes were observed with increasing addition levels of NZ in each of the binary and ternary complex systems. However, the addition level of NZ 0.2% was superior overall.
Conclusion: Due to its porosity, anionic and very high specific surface area, Nano Zeolite mainly showed statistically significant improvement in the performance of cationic starch and polyacrylamide polymers in OCC recycled pulp and paper. The improvement of micro flocculation of the pulp ingredients led to improved pulp retention and drainage and also the structural and strength properties of the paper. Its effectiveness in the presence of two polymers, CPAM and CS, was greater than its binary combination with cationic starch, where the three-component system had significant superiority in all pulp and paper properties compared to the two-component system.