纳米MnO_2强化过滤去除水中痕量铊

Removal of Trace Tl from Drinking Water by Enhanced Filtration Using Nanosized MnO_2

利用纳米Mn O_2强化石英砂和锰砂过滤去除水中痕量重金属铊,考察了去除效能以及竞争性Ca^(2+)和络合性腐殖酸(HA)对强化过程的影响。投加48μmol/L的纳米Mn O_2对常规石英砂过滤体系具有良好的强化效果,出水水质能达到国家饮用水标准;由于锰砂本身具有良好的过滤去除效能,在相同的纳米Mn O_2投加量下并没有表现出很好的强化能力。竞争性Ca^(2+)和络合性HA对强化混凝有一定影响,投加5 mmol/L的Ca^(2+)在一定程度上降低了对痕量重金属的去除效能,10 mg/L的腐殖酸则显著抑制了重金属的去除,大大增加了出水中残余Tl的浓度。总体来看,高价态铊由于受到腐殖酸的络合作用,强化过滤去除效能较低,即氧化过程不利于强化过滤去除痕量铊。

The removal of trace thallium i. e. Tl （ Ⅰ ） and T1 （ Ⅲ）, from drinking water by enhanced quartz sand filtration and manganese sand filtration was investigated using nanosized MnO2, as well as the impacts of competitive Ca^2＋ and humic acid. Removal efficiency of trace Tl（ Ⅰ ） and Tl（ Ⅲ） was significantly improved by 48 μmol/L MnO2, and met drinking water standard of China. Due to higher density of adsorption activity site on manganese sand, it could remove trace thallium efficiently. Competitive Ca^2＋ and complex HA could reduce trace T1 removal to a certain extent. Ca^2＋ additive resulted in a lower removal of trace Tl. Similarly, the introduction of humic acid led to a significant increase in residual Tl. Generally, the removal of higher valence T1 was lower due to the higher complex activity of HA with Tl（ Ⅲ ） than that of Tl（ Ⅰ ）. This study provides a potential strategy for drinking water treatment polluted by trace thallium.