[Mechanism of As(Ⅴ)Removal from Water by Lanthanum and Cerium Modified Biochars].

Loaded lanthanum or cerium biochars were prepared by one step pyrolysis of La (NO3)3-laden or Ce (NO3)3-laden rice hulls and were employed for enhancing the adsorption of As (Ⅴ) from water. In contrast with BC and Ce-BC in this study, La-BC had better adsorption capacity in the acidic condition. The maximum adsorption capacity could reach 20.1 mg ·g-1. With increased pH, the adsorption capacity of La-BC was reduced. The highest adsorption capacity reached 39.1 mg ·g-1 (pH=5) and the lowest was 17.6 mg ·g-1 (pH=9). The resulting La-BC with As (Ⅴ) adsorption was characterized by SEM-EDS, FTIR, and XPS. There were two types of active adsorption sites for As (Ⅴ), oxygen-rich functional groups and lanthanum oxide. Although Ce-BC had oxygen-rich functional groups and cerium oxide, it was unable to participate in the adsorption of As (Ⅴ) from water.