基于非对称场流分离技术的水环境腐殖酸聚集特性研究

The study of aggregation properties of aqueous humic acid based on asymmetric flow field-flow fractionation

腐殖酸的聚集特性是影响其去除率及与其它污染物相互作用的重要因素,本文采用非对称场流分离技术对腐殖酸组分进行分离,配合示差折光检测器及多角度激光光散射器,对腐殖酸分子量的分布规律进行研究,探讨了水环境的化学条件对腐殖酸荷电状态和聚集状态的影响规律.结果表明,腐殖酸具有自我凝聚的特性;在p H较低和溶液离子强度较高时,腐殖酸胶粒的Zeta电位绝对值减小而分子量增大,腐殖酸胶粒聚集程度增大;随腐殖酸浓度增大,腐殖酸胶粒的Zeta电位绝对值减小,腐殖酸分子发生聚集而使胶粒分子量增大.当离子强度达到0.08mol·L-1,或浓度达到15 mg·L-1时,腐殖酸分子不仅靠氢键聚集在一起,还可能发生分子间的缔合.

Aggregation properties of aqueous humic acid strongly influence its removal efficiency and the interaction with other pollutants.In this study,asymmetric field flow fractionation technique was used to isolate humic fractions,coupled with a differential refractive index detector and a multi-angle laser light scattering device for studying the distribution of molecular weight of humic acid.Then,the effect of chemical conditions on the states of the charge and aggregation of the humic acids（HAs） was discussed.The results show that the HAs had the property of self-flocculation.With the lower p H and the relatively higher ionic strength,the absolute values of Zeta potential for the HA colloidal particles decrease while the molecular weight increased,thereby the polymerization degree increased.Moreover,with the increasing of the HA concentration and subsequently the decrease of the absolute values of Zeta potential,the molecular weight of the HA colloidal particles increased due to the micelle aggregation.When the ionic strength is up to 0.08 mol·L-1,or the concentration is greater than 15 mg·L-1,there will be not only hydrogen bonds,but also intermolecular association between humic acid molecules.