Significantly improving trace thallium removal from surface waters during coagulation enhanced by nanosized manganese dioxide

• Published in: Chemosphere (Oxford) Vol. 168; pp. 264 - 271
• Main Authors: Huangfu, Xiaoliu, Ma, Chengxue, Ma, Jun, He, Qiang, Yang, Chun, Jiang, Jin, Wang, Yaan, Wu, Zhengsong
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2017
• Subjects: Adsorption; Calcium; China; Drinking water; Enhanced coagulation; Fresh Water; Humans; Humic Substances; Hydrogen-Ion Concentration; Manganese Compounds - chemistry; Nanoparticles; Nanosized manganese dioxide; Oxides - chemistry; Thallium - analysis; Thallium - isolation & purification; Trace thallium removal; Water - chemistry; Water Pollutants, Chemical - isolation & purification; Water Purification - methods; Enhanced coagulation; Drinking water; Nanosized manganese dioxide; Trace thallium removal
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2016.10.054

Thallium (Tl) is an element of high toxicity and significant accumulation in human body. There is an urgent need for the development of appropriate strategies for trace Tl removal in drinking water treatment plants. In this study, the efficiency and mechanism of trace Tl (0.5 μg/L) removal by conventional coagulation enhanced by nanosized manganese dioxide (nMnO2) were explored in simulated water and two representative surface waters (a river water and a reservoir water obtained from Northeast China). Experimental results showed that nMnO2 significantly improve Tl(I) removal from selected waters. The removal efficiency was dramatically higher in the simulated water, demonstrating by less than 0.1 μg/L Tl residual. The enhancement of trace Tl removal in the surface waters decreased to a certain extent. Both adjusting water pH to alkaline condition and preoxidation of Tl(I) to Tl(III) benefit trace Tl removal from surface waters. Data also indicated that competitive cation of Ca2+ decreased the efficiency of trace Tl removal, resulting from the reduction of Tl adsorption on nMnO2. Humic acid could largely low Tl removal efficiency during nMnO2 enhanced coagulation processes. Trace elemental Tl firstly adsorbed on nMnO2 and then removed accompanying with nMnO2 settling. The information obtained in the present study may provide a potential strategy for drinking water treatment plants threatened by trace Tl. •High removal of trace Tl from surface waters through coagulation enhanced by nMnO2.•Both high pH and high valence of elemental Tl may benefit trace Tl removal.•Competive cations of Ca2+ and constituents of HA can reduce removal.•Trace elemental Tl adsorbed on nMnO2 and removed accompanying with nMnO2 settling.