目的 研究ζ电位对于甘草水提液絮凝效果的影响, 优选甘草水提液的最佳絮凝工艺。方法 采用天然高分子絮凝剂壳聚糖对甘草水提液进行絮凝除杂处理。通过单因素试验、正交试验及粒度试验, 证明ζ电位与药液絮凝率之间存在的深层关系。结果 在单因素条件影响下, 药液的絮凝率均是在体系的ζ电位绝对值最低、最接近等电点时达到最高。通过正交试验确定甘草水提液絮凝的最佳工艺条件为壳聚糖投加量0.347 g/L, pH值为6, 温度30 ℃, 此条件下体系的ζ电位为-1.67 mV, 在所有试验组中最接近等电点, 药液的絮凝率高达95.29%。絮凝前原液的ζ电位为-14.78 mV, 药液中颗粒的平均粒径为17.12 μm;絮凝后上清液的ζ电位为-1.67 mV, 颗粒平均粒径为6.77 μm。ζ电位的变化改变着溶胶体系中的颗粒行为, 并最终影响药液的絮凝率。结论 在甘草水提液絮凝的过程中, ζ电位对药液的絮凝率有着重要的影响:ζ电位的绝对值越低, 越接近等电点, 药液的絮凝率越高。同时由于ζ电位更能反映絮凝过程的本质, 因此可为絮凝条件的选择提供强有力的依据。

Objective Study on the influence of ζ potential on flocculating rate of Chinese herbs water-extract liquid. Methods Chitosan of natural macromolecule flocculant was adopted to remove the flocculation impurity of the herb licorice (Glycyrrhizae Radix) extract, and the deep connection between ζ potential and liquid flocculating rate was proved by single factor experiment, orthogonal experiment, and granularity. Results Under the influence of single factor conditions, absolute value of ζ potential of the system is lower, while the flocculation rate is higher. Based on orthogonal experiment, the optimum process condition of flocculating licorice extract is determined to be the flocculant dosage quantity of 0.347 g/L, pH value of 6, temperature of 30 ℃, and the system ζ potential of -1.67 mV, which is close to the isoelectric point among all the experiment. Whereas the flocculating rate was as high as 95.29%. The ζ potential of solution before flocculation is -14.78 mV, the average particle size is 17.12 μm; After the flocculation the ζ potential of clear liquid is -1.67 mV, the average particle size is 6.77 μm. The change of ζ potential affected the particle behavior of sol system and ultimately affected the liquid flocculating rate. Conclusion In the process of flocculating herb licorice extract, the ζ potential has the important influence on the flocculation of herb extract. Absolute value of ζ potential of the system is lower, closer to the isoelectric point, the flocculation rate is higher. The ζ potential that reflects the flocculation essence provides a strong justification for the selection of flocculation conditions.

国家自然科学基金资助项目"壳聚糖絮凝-螯合法去除中药液中重金属离子及胶体杂质的研究"(21406142);国家自然科学基金资助项目"基于激光测量技术的双多组浸没撞击流流场特性的非线性研究"(21476141)