碱化度对聚合氯化铝混凝除硅的影响

通过对实验室现有工业级聚合氯化铝进行碱化度分析,向多个化学试剂厂调研得出,现场常用聚合氯化铝的碱化度在1.5～2.7之间。通过合成不同碱化度(2.0～2.4)的聚合氯化铝,对模拟成垢水进行系统的混凝实验,考察碱化度对聚合氯化铝混凝除硅的影响。研究表明,碱化度会决定铝形态的分布,进而影响混凝除硅的效果。随着碱化度的升高,Al_a含量逐渐降低,Al_b含量先增大后减小,Al_c含量逐渐增加。对模拟污水处理后,残余硅酸形态有很大差异,用聚合氯化铝(2.0)除硅后Si_a含量变为32.1mg/L,Si_c含量变为15.3mg/L;聚合氯化铝(2.2)除硅后Si_a含量变为28.71mg/L,Si_c含量变为30.5mg/L;聚合氯化铝(2.4)除硅后Si_a含量变为22.4mg/L,Si_c含量变为41.2mg/L。聚合氯化铝(2.0)除硅后Si_a降低的比例最大,聚合氯化铝(2.4)除硅后Si_c降低的比例最大。随着碱化度的升高,全硅剩余含量依次为47.4mg/L、59.5mg/L、63.6mg/L,表明碱化度越低,除硅效果越好。

Influence of basicity of polyaluminum chloride on removal of silicon

By analyzing the alkalization degree of existing industrial-grade polymeric aluminum chloride in the laboratory and investigating several chemical reagent factories,we obtained that the alkalization degree of polymeric aluminum chloride commonly used on site is between 1.5—2.7. By synthesizing polymeric aluminum chloride with different alkalization degrees (2.0—2.4),we conducted a systematic coagulation experiment on the simulation of scale-forming water,and investigated the influence of alkalization degree on the coagulation silica removal of polymeric aluminum chloride. The results show that the alkalization degree will determine the distribution of aluminum speciation and therefore influence the effect of coagulation silicon removal. As the alkalization degree increases,the content of Al_a gradually decreases,the content of Al_b first increases and then decreases,while the content of Al_c gradually increases. After simulation of wastewater treatment,the residual silicate speciation is largely different. After silicon removal of polymeric aluminum chloride (2.0),the content of Si_a changes to 32.1mg/L,and the content of Si_c changes to 15.3mg/L;after silicon removal of polymeric aluminum chloride (2.2),the content of Si_a changes to 28.71mg/L,and the content of Si_c changes to 30.5mg/L;after silicon removal of polymeric aluminum chloride (2.4),the content of Si_a changes to 22.4mg/L,and the content of Si_c changes to 41.2mg/L. The proportion in the decrease of Si_a is the largest after silicon removal of polymeric aluminum chloride (2.0),and the proportion in the decrease of Si_c is the largest after silicon removal of polymeric aluminum chloride (2.4). With the increase of alkalization degree,the total residual silicon contents are respectively 47.4mg/L,59.5mg/L and 63.6mg/L. Within the author's scope of research,the lower the alkalization degree,the better the effect of silica removal.