高、低电导率体系中荧光增白剂的吸附行为研究

Study the Adsorption of Fluorescent Whitening Agent in High Conductivity and Low Conductivity Systems

考察了荧光增白剂(FWA)在不同电导率情况下吸附于BCTMP纤维的情况。体系的电导率分别用NaCl或CaCl2调节为高、低两个水平(5000和500μs/cm),采用紫外可见光谱法测定FWA的残存量从而获得吸附量信息。结果表明,不论是氯化钠还是氯化钙体系,高电导率条件下FWA的吸附率均高于其在低电导率条件下的吸附率。将氯化钠体系与氯化钙体系相比较,相同的FWA用量条件下,CaCl2体系中FWA的吸附率高于其在NaCl体系中的吸附率。纸张浸渍法也表明,相比于低电导率条件,高电导率条件下FWA的增白效果更佳。低电导率条件下,钙离子促进增白的效果明显好于钠离子,但增至高电导率条件后,钠离子促进增白的效果与钙离子相近。

The adsorption of a fluorescent whitening agent（FWA） on a bleached chemi-thermomechanical pulp（BCTMP） fiber at different conductivity conditions was investigated.Two levels of conductivities,a low one and a high one,corresponding to 500 or 5000μs/cm each,were adjusted by adding different amount of sodium chloride（NaCl） or calcium chloride（CaCl2） into distilled water which was used to dilute pulp slurry.Ultraviolet-visible spectroscopy was applied to measure the residual amount of FWA in pulp water,from which the adsorbed amount of FWA on fiber could be obtained.It was found that no matter in the NaCl-adjusted or the CaCl2-adjusted system,the adsorption of FWA on fibers under high conductivity level was always higher than that under the low one.When comparing the NaCl-adjusted with the CaCl2-adjusted system under the same conductivity levels,it was found that the adsorption of FWA onto fiber in the CaCl2-adjusted system was always higher than that in the NaCl-adjusted one.Further demonstration by paper dipping method showed that the whitening effect of FWA under high conductivity treatment was better than that under the low conductivity one.Also found was that calcium ion promoted the whitening effect of FWA to a higher degree than sodium ion under the low conductivity level,however,under the high conductivity level,the promoting effects were almost the same for the two ions.