聚合氯化铝/聚丙烯酰胺复合改性凹凸棒土絮凝材料的制备及其除浊除藻效果

Preparation of polyaluminium chloride/polyacrylamide composite-modified attapulgite flocculation material and its removal effect of turbidity and algae

蓝藻水华已成为我国湖库面临的主要环境问题,而利用黏土治理有害藻华技术在我国应用已有十多年的历史,是国际上公认的最具发展前景的措施之一。通过选用凹凸棒土(AT)为原材料,聚合氯化铝(PAC)、聚丙烯酰胺(PAM)作为改性剂,制备新型复合絮凝材料凹凸棒土-聚合氯化铝-聚丙烯酰胺(AT-PAC-PAM)。比较不同原料配比条件下复合絮凝材料的除浊效果,并对絮凝材料改性前后微观形貌、物化性质进行表征分析,然后通过单因素实验对复合絮凝材料除浊除藻条件进行优化,最后采用电子显微镜观察不同絮凝材料处理藻液所生成的絮体形貌差异。研究结果表明:AT-PAC-PAM絮凝材料的最佳原料组分质量配比为m(AT)∶m(PAC)∶m(PAM)=100∶20∶0.2;材料改性后铝离子含量增加、表面积增加、孔径增大、空隙增多,使得吸附能力增强;在相同实验条件下,AT-PAC-PAM(20%)除浊除藻效果最优,其最佳条件为pH=7、复合絮凝材料质量浓度为60 mg·L^(-1)、藻液初始浊度50 NTU、慢搅转速100 r·min^(-1)、慢搅时间20 min、沉淀时间30 min;在对絮体微观观察中发现,复合絮凝材料AT-PAC-PAM加强了吸附架桥和网捕作用,使所形成的絮体密集紧实,从而促进藻-土复合絮体的沉降,具有很好的应用前景。

Cyanobacterial blooms have become the main environmental problems faced by lakes and reservoirs in our country,and the technology of using clay to control harmful algal blooms has been used for more than ten years,which is internationally recognized as one of the most promising measures.A new composite flocculation material,attapulgite-polyaluminum chloride-polyacrylamide(AT-PAC-PAM),was prepared by selecting attapulgite(AT)as the raw material and polyaluminum chloride(PAC)and polyacrylamide(PAM)as modifiers.The turbidity removal effects of the composite flocculation materials with different raw material ratios were compared,the microscopic morphology and physical and chemical properties of the flocculating materials were also characterized before and after modification.Then,the turbidity and algae removal conditions of the composite flocculation materials were optimized through single-factor experiments,and finally,electron microscopy was used to observe the differences in the morphology of the flocs produced by different flocculating materials treating algal solutions.The results showed that the optimum ratio of m(AT):m(PAC):m(PAM)was 100:20:0.2 for the AT-PAC-PAM flocculation materials;the modification of the materials increased the aluminium ion content,the surface area,the void space and the pore size,which enhanced the adsorption capacity.Under the same experimental conditions,AT-PAC-PAM(20%)had the most remove effects of turbidity and algae.The optimal conditions were following:pH7,composite flocculating material mass concentration of 60 mg·L^(-1),and the initial turbidity of the algae liquid of 50 NTU,slow stirring speed of 100 r·min^(-1),20 min slow stirring and 30 min settling.It was found that the composite flocculation material AT-PAC-PAM enhanced the adsorption bridging and net trapping effects,resulting in the formation of dense and compact flocs,thus promoting the settlement of algae-soil composite flocs,which has good application prospects.