聚合氯化铝铁的制备、使用及混凝机制研究

Preparation,application and coagulation mechanism of polyaluminium ferric chloride

以氯化铝和氯化铁为原料制备出一系列不同铝铁物质的量比及碱化度的无机高分子混凝剂——聚合氯化铝铁(PAFC),并应用于地表水的混凝处理过程。考察PAFC的混凝效能及产生的絮体特性,进而对其使用条件进行优化并分析混凝机制。结果表明,PAFC为多羟基桥连的铝铁聚合物,水解后发生电中和作用使胶粒脱稳,而后通过羟桥和氧桥联接产生架桥和卷扫沉淀作用,混凝效果优异。PAFC的pH适用范围较宽,但铝铁物质的量比对其水解过程影响较大,在铝铁物质的量比为7∶1、碱化度为0.5、投加量为10 mg/L时,絮体的粒度及生长速度最大,此时浊度和UV254的去除率分别达84.93%和78.52%。此外,正交实验的结果表明水力条件对PAFC的混凝效能影响显著,其最佳使用条件为:快搅时间为20 s、快搅速度为200 r/min、慢搅时间为15 min、慢搅速度为40 r/min。

With aluminium chloride and ferric chloride as raw materials,a series of inorganic polymer coagulants-polyaluminium ferric chloride(PAFC) with different amount-of-substance ratio of Al/Fe and basicity were prepared,and then used in coagulation process of surface water.The coagulation efficiency and floc characteristics of PAFC were studied to optimize its application conditions,and meanwhile coagulation mechanisms were also analyzed.Results showed that synthesized PAFC possess a variety of hydroxy bridged aluminum-iron polymers.Colloidal particles became destabilization due to the charge neutralization mechanism of PAFC hydrolysate,and then the bridge between hydroxyl and oxygen could promote the bridging and sweeping precipitation action.The coagulation effect was excellent.The pH range of PAFC was wide,but the amount-ofsubstance ratio of aluminum to iron had a great influence on the hydrolysis process.The amount-of-substance ratio of Al/Fe was 7∶1,the alkalinity was 0.5 and the dosage was 10 mg/L.Under the conditions,particle size and growth rate of flocs were the largest,and the removal rates of turbidity and UV254 reached 84.93% and 78.52%,respectively.In addition,coagulation efficiency of PAFC was greatly influenced by hydraulic conditions.The optimum parameters were as follows:the fast stirring time was 20 s,the fast stirring speed was 200 r/min,the slow stirring time was 15 min and the slow stirring speed was 40 r/min.