改性淀粉絮凝剂链结构形态对石材废水絮凝性能的影响
The effect of the chain architecture on the performance of the starch-based flocculants in flocculation of a stone wastewater
王禹洋 1罗章 2程智涵 1章龙管 2毕皓 1石鸿韬 2陈炜 1刁鹏 2胡潘 1杨琥1
作者信息
- 1. 南京大学环境学院,污染控制与资源化研究国家重点实验室,南京,210023
- 2. 中铁工程服务有限公司,成都,610083
- 折叠
摘要
石材废水具有高浊度特征,混凝/絮凝工艺是降浊净水的有效手段.本研究以绿色环保且价格低廉的天然高分子材料淀粉为原材,分别通过醚化和接枝共聚技术,合成了两种电荷密度相近,但链结构形态与电荷分布不同的阳离子改性淀粉絮凝剂:3-氯-2-羟丙基三甲基氯化铵改性淀粉(St-CTA,直链型)和淀粉接枝共聚丙烯酰胺-聚甲基丙烯酰氧乙基三甲基氯化铵(St-g-PAM-co-PDMC,接枝型).以泉州某石材加工厂废水为研究对象,详细考察并比较了两种阳离子改性淀粉絮凝剂对石材废水的絮凝性能,同时结合絮凝后上清液zeta电位、絮体结构的动态监测结果以及扩展DLVO理论等,探究其絮凝机理.研究结果表明,两种改性淀粉絮凝剂均表现出优于传统无机混凝剂聚合氯化铝的絮凝性能;除高效降低水体浊度,其对COD、氨氮、总磷及总氮均具有一定去除效果;改性淀粉絮凝剂絮凝过程主要是电中和与黏结架桥作用协同作用的结果.此外,St-g-PAM-co-PDMC由于具有丰富的接枝链结构,且阳离子基团随机分布在接枝链上,具有较高的阳离子基团利用效率及电中和混凝效果,表现出优于直链型St-CTA的除浊效果,具有较低的絮凝剂投加量、较大的絮体尺寸、较快的絮体生长速度、较高的絮体强度及更佳的破碎后絮体恢复性能.扩展DLVO理论结果也表明,St-g-PAM-co-PDMC的总相互作用低于St-CTA,有着更为高效的电中和混凝作用及降浊效果.两种电荷密度相近的改性淀粉絮凝剂絮凝性能的差异主要是由于其不同的链结构与电荷分布造成的,但其均具有优良的降浊净水效果及绿色环保等显著特征,其在石材废水等行业废水处理中应有着良好的应用前景.
Abstract
Stone wastewater has the characteristics of high turbidity,and coagulation/flocculation process is an effective technique to reduce the turbidity and purify this wastewater.In this study,two types of cationic starch-based flocculants,which have similar charge density but different chain architecture and charge distribution,have been designed and fabricated,those are,starch-3-chloro-2-hydroxypropyl triethyl ammonium chloride(St-CTA,linear polymer)and starch-g-poly(acrylamide-co-methacryloyloxyethyl trimethyl ammonium chloride)(St-g-PAM-co-PDMC,graft polymer).Stone wastewater from a stone processing plant of Quanzhou was taken as the research target,and the flocculation properties of these two types of cationic starch-based flocculants were investigated and compared in detail.The flocculation mechanisms were explored and discussed on the basis of the changes in the zeta potentials of supernatants after flocculation,the dynamic results of the flocs properties and the theoretic ones from the extended DLVO theory.The experimental findings show that both of the starch-based flocculants have better flocculation performance than the traditional inorganic coagulant,polyaluminum chloride.In addition to the efficient removal of the turbidity in wastewater,these two starch-based flocculants still have certain effect in removal of COD,ammonia nitrogen,total phosphorus and total nitrogen.The efficient flocculation effects of these two cationic starch-based flocculants are mainly ascribed to the synergistic effects of charge neutralization and bridging flocculation effects.Moreover,St-g-PAM-co-PDMC shows better flocculation performance than linear St-CTA because of its abundant branched chain structure and the random distribution of the cationic groups on the graft chains.Specifically,St-g-PAM-co-PDMC has a higher turbidity removal efficiency with a lower flocculant dosage,larger floc size,faster floc growth rate,higher flocs strength and better floc recovery performance.The results of the extended DLVO theory illuminate that the total interaction energy of St-g-PAM-co-PDMC to the colloidal particles is lower than that of St-CTA,and St-g-PAM-co-PDMC has more efficient charge neutralization and thus higher turbidity reduction effect.The difference in the flocculation performance of these two cationic starch-based flocculants with similar charge density is mainly ascribed to their different chain architecture and charge distribution.However,they both have good application potentials in the treatment of various wastewater samples including the stone wastewater due to their distinct features of efficient turbidity removal effect and environmental-friendliness.
关键词
石材废水/阳离子改性淀粉絮凝剂/链结构/絮凝性能/絮体性质/扩展DLVO理论/絮凝机制Key words
stone wastewater/starch-based flocculants/chain architecture/flocculation performance/floc properties/extended DLVO theory/flocculation mechanism引用本文复制引用
基金项目
国家自然科学基金(42061144014)
出版年
2024
NETL
NSTL
万方数据