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Study on the Stickies Deposition and Its Enzymatic Control in Secondary Fibers Recycling

Author: LiuCongXiang
Tutor: LiZongQuan
School: Shandong Institute of Light Industry
Course: Pulp and Paper Engineering
Keywords: Secondary stickies Stability Deposition performance Filler Pectinase
CLC: TS75
Type: Master's thesis
Year: 2011
Downloads: 134
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Abstract

Waste Paper Recycling is one of the most important raw material in the pulp and paper industry in China. The waste paper recycling process occurs stickies deposition affect machine operation and product quality. According to previous studies, using a pressure-sensitive adhesive (PSA) as secondary stickies model compounds to study the stability of the secondary stickies and deposition performance. And explore the effects using pectinase treatment DCS to improve the cationic polymer and a method of controlling the deposition of stickies. The results show that the presence of calcium ions can cause instability and will lead to deposition of stickies. With the increase of the concentration of calcium ions, the stability of stickies decline, stickies deposition aggravated. This is because the calcium ions are added such that the increase in the ionic strength of the colloidal system, the electric double layer of the colloidal particles surrounding compression causes instability and deposition of stickies. Cationic polymers such as cationic polyacrylamide (CPAM), polyethylene imine (PEI), will lead to instability of stickies and generates deposition. With the increase of the concentration of the cationic polymer, the amount of stickies deposition increases first and then decreased. In other words, a low amount of a cationic polymer will cause the the Instability and deposition of stickies, high amount of a cationic polymer of the instability of stickies is adsorbed to the fiber surface, so that the deposition amount is reduced. In the presence of calcium ion, the cationic polymers of low dosage CPAM in, the PEI will aggravate the deposition of stickies. The high dose of cationic polymer is to reduce the deposition of stickies. Fillers such as talc, calcium carbonate is an important part of the adhesive mass in sediments. Precipitated calcium carbonate, talc, can be adsorbed to the adhesive mass, and lead to the destabilization of adhesive particles. The presence of the cationic polymer will exacerbate secondary stickies instability. Compared with talc, calcium carbonate can adsorb more stickies particles, due to the instability the CPAM triggered the stickies particles can absorb, and absorb more stickies as adsorption centers, exacerbated by CPAM of glue The adherend flocculation role. In a higher amount of cationic polymer, these flocculated stickies particles can be adsorbed to the fibers, this time will reduce the deposition of stickies. Separate surface active agent on the stability and deposition performance of the adhesive mass is not a significant impact, after adding a filler in the system, the presence of a surfactant will reduce the deposition of stickies. The same surfactant concentration, a high concentration of filler caused by the deposition amount is also high. The presence of dissolved and colloidal substances (DCS), would weaken the effects of the cationic polymer, aggravate the deposition of stickies, and pectic acid is the main substance in the DCS. Pressure sensitive adhesive PSA as a secondary stickies model compound, research bleached hot mill chemical mechanical pulp (BCTMP) in the DCS, pectate pectinase treatment cationic polymer and stickies deposition. The results showed that, in the DCS of BCTMP will weaken the effects of the cationic polymer, aggravate the deposition of stickies. Pectinase treatment DCS is conducive to the control of the adhesive deposition, This is mainly because the pectic acid the major anionic trash in the DCS, pectinase processing consequences of glue acids are degradation and improve the effects of the cationic polymer, more The more stickies is adsorbed to the fibers, thus reducing the deposition of stickies.

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