海藻酸钠基复合\复配混凝剂去除“纳米颗粒物-腐植酸复合污染物”的作用过程及机制研究

With the accelerating introduction of engineered nano materials into commercial products, it is inevitable that these materials will ultimately reside at some level in our recreational and drinking waters and form contamination of nano particles (NPs). The NPs are most likely to bind Humic acid （HA） to form NPs-HA combined pollutant, which would harm to people's health. Because that there is no conventional coagulants that can absolutely protect the consumer from exposure to NPs either through recreational use or consumption of drinking waters, this Project use composite \ compound coagulants based on Sodium alginate to treat NPs-HA combined pollutant. In water, composite \ compound coagulants based on Sodium alginate could produce "egg-box" crosslinked network, which could bind the nanoparticle clusters together and form large and compact flocs. This would improve the removal efficiency of NPs by coagulation. Moreover, composite \ compound coagulants based on Sodium alginate could produce detachable liquid layer on the surface of ultrafiltration membrane. This liquid layer would prevent NPs from fouling the surface and interior of ultrafiltration membrane, which would reduce the adverse effect of NPs-HA combined pollutant on subsequent depth treatment. Moreover, the action between composite \ compound coagulants based on Sodium alginate and NPs-HA combined pollutant and the mechanism of coagulation and restricting membrane fouling would be revealed by studying migration dynamics, coagulation behavior and flocs properties. This project will provides technical support for using mature process to control nano particle pollution, which is important for controlling water environment pollution in our country.

随着纳米材料的广泛使用，纳米颗粒物不可避免地进入水体,与腐殖酸作用形成"纳米颗粒物-腐殖酸复合污染物"，危害人体健康。本课题针对传统混凝剂无法有效去除"纳米颗粒物-腐植酸复合污染物"的缺陷，利用海藻酸钠基复合\复配混凝剂形成的"egg-box" 交联网络结构网捕"纳米颗粒物-腐殖酸复合污染物"，形成大粒径密实絮体，实现纳米颗粒物混凝去除。同时，利用海藻酸钠基复合\复配混凝剂形成的可脱离式液状层，阻止混凝残余的纳米颗粒物对后续膜截留工艺的污染，降低其对混凝后续深度处理工艺的不利影响。此外，本课题通过对聚集动力学、混凝动力学及絮体性质的研究，阐明海藻酸钠基复合\复配混凝剂去除"纳米颗粒物-腐植酸复合污染物"的作用过程及机制，明确海藻酸钠基复合\复配混凝剂对纳米颗粒物造成膜污染的抑制机理。本课题将为利用成熟工艺控制纳米颗粒物污染提供技术支撑，具有十分重要的理论和实用价值。

进入水体的纳米颗粒物将与腐植酸形成复合污染物，其会危害生态环境和人体健康。针对这一情况，本课题成功制备出了海藻酸钠基复合\复配混凝剂，利用其线性的大分子结构及其“egg-box”网状交联结构，高效去除了不同特性水体中的"纳米颗粒物-腐殖酸复合污染物"，并阻止了混凝残余的纳米颗粒物对后续膜截留工艺的污染，降低了其对混凝后续深度处理工艺的不利影响。混凝实验结果表明，对于不同纳米颗粒物，海藻酸钠基复配\复合混凝剂均能够有效的去除。在最佳条件下，纳米氧化铜（CuO NPs）、纳米二氧化钛（TiO2 NPs）、纳米银（Ag NPs）颗粒物的混凝去除效率可高达80%以上。聚集动力学及混凝动力学研究表明，海藻酸钠基复配\复合混凝剂提高了"纳米颗粒物-腐殖酸复合污染物"聚集速度，使其形成大粒径、结构松散、恢复度高的絮体。“混凝-超滤膜联用实验”表明， CuO NPs 、TiO2 NPs 和Ag NPs在海藻酸钠基复配\复合混凝剂作用下聚集为大颗粒物，其几乎完全可以被后续超滤膜截留。同时，海藻酸钠基复配\复合混凝剂可以大幅度减轻后续超滤膜污染。海藻酸钠基复合\复配混凝剂处理后水样所形成的膜阻力仅为同等条件下PAC处理后水样的30% ，更为重要的是膜内不可逆污染降低了90%。絮体特性研究表明改性海藻酸钠与TiCl4复配处理纳米银水样所得絮体可以再生为银掺杂型二氧化钛，其表现出了更好的光催化效果。.本课题共取得了11篇论文和2项发明专利的成果，其中分别在Chemical Engineering Journal、Journal of Hazardous Materials、Desalination等杂志发表论文9篇（一区SCI论文5篇），另有再投文章2篇，授权2项发明专利。本课题的研究结果将为利用成熟工艺控制纳米颗粒物污染提供技术支撑，具有十分重要的理论和实用价值。