Arsenate removal using titanium dioxide-doped cementitious composites: Mixture design, mechanisms, and simulated...

Arsenate (As(V)) in municipal wastewater leads to a public health problem due to its contamination of natural water sources. Here, we proposed to use sewer pipe made of TiO₂-doped cementitious composite (TCC) for As(V) removal from municipal wastewater. The optimum composition of TCC, the performance for As(V) removal in the simulated sewer system, and the molecular-level As(V) removal mechanisms were investigated. To obtain the optimum composition, variables were adjusted to maximize the As(V) removal using TCC. Results show that the TiO₂ and water contents were the dominant factors. Simulated sewer pipes made of TCC removed As(V) from 100 μg/L to <10 μg/L, which performed better than plain cementitious composite. Moreover, extended X-ray absorption fine structure (EXAFS) analysis indicates that both precipitation and adsorption contribute to the As(V) removal by TCC, while the adsorption is more significant with a lower As(V) concentration (i.e., 1 mg/L). This is the first study evaluating the feasibility to apply TCC for As(V) removal from sewer wastewater. The optimized composition, simulation results, and molecular-level mechanism gained from this study are useful to the future design of TCC for As(V) removal, especially for sewer systems.