湿部化学系统中无机盐对纤维素纤维吸附CPAM的影响

Effects of Inorganic Salt on Cellulose Fiber Adsorption of CPAM in Wet End Chemistry System

白水循环导致湿部化学系统中无机盐的积累,回用时影响纤维与阳离子助剂的吸附。在无盐条件下,纤维吸附CPAM符合Langmuir等温吸附方程,是一种单分子层吸附,纤维吸附CPAM的过程即是纤维表面逐渐被CPAM分子覆盖的过程。本文采用三种无机盐模拟了其对湿部化学系统的影响。研究表明三种无机盐对纤维吸附CPAM的影响不同,随Na2SO4浓度的增加,CPAM的吸附量增大,当Na2SO4浓度超过一定值时,CPAM的吸附量开始下降。高电荷密度的CPAM2能适应更高浓度的无机盐环境。二价的Mg2+和Ca2+则会与纤维上的羧基、酚羟基发生络合吸附,占据了CPAM吸附到纤维上的作用点,导致CPAM分子不易吸附到纤维上,吸附量下降。

White water system closure leads to the accumulation of inorganic salts in the wet end system of paper machine, which will affect the pulp fiber adsorption of cationic additives when white water reuses. Under the condition of no salt in the wet end system, pulp fiber adsorption of CPAM is a kind of monolayer adsorption and accords with Langmuir isothermal adsorption equation. In the process of pulp fiber adsorption, the fiber surface is covered by CPAM molecular gradually. Three different kinds of inorganic salt were added in the wet end system and the influences on the fiber absorption of CPAM were researched. Results showed that with the increasing of the concentration of Na2SO4, CPAM adsorption quantity increased, and when the concentration of Na2SO4 exceeded a certain value, the adsorption quantity of CPAM began to decline. High charge density of CAPM2 can adapt to the higher concentration of inorganic salt conditions. Bivalent Mg2＋ and Ca2＋ can complex adsorption with the carboxyl group and phenolic hydroxyl on the fiber, which will occupy the CPAM adsorption point and lead to CPAM molecules not easy to be adsorpted on the fiber.