聚合氯化钛铁盐混凝除砷性能研究

Performance of Arsenic Removal by Coagulation Process with Polymeric Titanium Ferric Chloride

采用微量滴碱法制备聚合氯化钛铁混凝剂(PTFC),并对其混凝除砷性能进行了初步探究。对聚合氯化钛/铁混凝剂粉末SEM图进行分析,并考察不同Ti/Fe比例、曝气氧化、碱化度、碱化剂、混凝剂投加量、pH值、共存离子等对除砷率的影响。结果显示:pH值为7.5时,As(Ⅲ)去除率随PTFC投加量的增加而增大;PTFC在弱酸性条件下对As(Ⅲ)的去除效果最佳。曝气氧化对PTFC除As(Ⅲ)有显著促进作用,Ti/Fe物质的量比为5/5时制备的碱化度为0.6的PTFC混凝后经曝气20 min,对As(Ⅲ)的去除率从55.3%提高到93.1%。碱化剂对PTFC混凝除砷的影响不大。共存阴离子SiO_3^(2-)对As(Ⅲ)的去除有明显抑制作用,但PO_4^(3-)对PTFC混凝去除As(Ⅲ)的影响相比较于单一金属盐较小,共存阳离子Ca^(2+)对PTFC去除As(Ⅲ)有促进作用。

This paper reported arsenic removal with coagulating by polymeric titanium ferric chloride（PTFC）, which was prepared by microinjection of base method. Complex coagulant of PTFC was analyzed by SEM. The effects of factors including different Ti/Fe ratio, aerated oxidation, basicity, different basifying agents, different coagulant dosages, the solution＇s pH value, co-existing ions on arsenic removal by the PTFC coagulation were investigated. The results of experiments showed that without changing pH in the coagulation process（pH=7.5）, As（ Ⅲ） removal efficiency increased with increasing dose of PTFC, and As（Ⅲ） removal efficiency by PTFC was high at weak acid conditions. Arsenic removal by PTFC was obviously promoted with aerated oxidation at 300 mL/min for 20 min. When titanium-iron mole ratio was 5 ∶5, B=0.6, arsenic removal reached 93.1%. The effect of alkalizer on As（Ⅲ） removal by PTFC was relatively weak. The phosphate ion had no obvious effect on arsenic removal compared with single metal salt, while presence of silicate anion in the solution would significantly inhibit the arsenic removal. Calcium ion play a positive role on arsenic removal.