introduction: In modern papermaking systems, addressing the issue of anionic impurities has already become an inevitable problem. Regarding this problem, AMAZON offers the most effective solutions and a variety of options.
Papermaking wet end chemistry issues and the importance of Anionic Trash Catcher (ATC)
The development of papermaking technology has made the wet end chemistry complex and the concentration of anionic garbage accumulation high. Adding anionic garbage capture agent before adding cationic additives to the pulp can improve its effect and improve the wet end condition. An effective way to reduce the impact of anionic impurities is to pretreat the pulp with anionic garbage capture agent or fixative.
The working principle of Anionic Trash Catcher (ATC)
Anionic trash catchers are generally linear low-molecular-weight polymers with high cationic charge density, including inorganic and organic types. The principle of action is through the role of charge neutralization or adsorption bridging. Anionic trash catchers with high cationic charge density form very small pairs with soluble anionic impurities. After flocculation, they are retained and fixed on fibers and fillers. The addition point is usually before adding other cationic additives to the pulp. Sometimes it needs to be added as early as possible to control the cationic demand of the system. Moreover, the type of anionic trash catcher has an important influence on the use effect. Organic ATCs have more advantages in reducing the cationic demand of interfering substances and are preferred for this purpose.
Types of Anionic Trash Catcher (ATC)
1）Aluminum sulfate:
– It is cheap and widely used. It is prepared by the reaction of aluminum hydroxide, kaolin or bauxite ore with sulfuric acid. Its composition is Al₂(SO₄)₃·nH₂O.
– However, as the papermaking system turns to alkaline, it gradually loses its positive charge and is no longer suitable as an anionic trash catcher.
2）Polyaluminum chloride (PAC):
– It is a water-soluble inorganic polymer between aluminum chloride and aluminum hydroxide. Its general formula is Alₙ(OH)ₘCl₃ₙ₋ₘ. It exists in the form of high cationic charge. When added to water, it can form a high cationic charge aluminum polymer. It contains more aluminum ions than aluminum sulfate and can maintain high chargeability in a wide pH range.
– When used as an anionic trash catcher, its performance is better than that of aluminum sulfate and is more suitable for the alkaline papermaking trend.
3）Polyethyleneimine (PEI):
– It is a colorless or light yellow viscous liquid with a polymerization degree of about 100. It is a water-soluble cationic polymer obtained by ring-opening polymerization of ethyleneimine in an acidic medium. It has branched structures containing primary amine, secondary amine, and tertiary amine.
– Its performance can be improved by modification methods such as reaction with epichlorohydrin. It is cationic in aqueous solution and has the best effect when pH = 6 – 9. It can capture anionic trash, act as a retention aid, and is beneficial to the closed circulation of white water. It is a better anionic trash catcher for alkaline papermaking systems.
4）Poly(diallyldimethylammonium chloride) (PolyDADMAC):
– It is a water-soluble cationic polymer with special functions. Homopolymers and copolymers have high positive charge density, good water solubility, high efficiency, non-toxicity, and low cost.
– It is stable in the pH range of 0.5 – 14 at room temperature and partially hydrolyzes in alkaline media. A small amount of addition can balance the charge and improve the filler retention rate, but excessive addition will reverse the charge and affect the retention rate.
5）Others:
– Bentonite can be combined with cationic polyacrylamide to remove anionic waste; polyaluminum silicate sulfate is a good adsorbent but rarely used in papermaking; polyethylene oxide is an excellent scavenger and retention aid in high-yield pulp systems, and its working principle is adsorption bridging, and the effect is more obvious when the system contains phenolic hydroxyl substances.
Regarding the treatment of anionic trash and the selection of Anionic Trash Catcher (ATC), you are welcomed to discuss more technical information and application guidelines with us.