Removal and recovery of chloride ions in concentrated leachate by Bi(III) containing oxides quantum dots/two-dimensional flakes.

The high concentration of chloride (Cl-) ions in leachate often has negative effects in their harmless treatments, and the common treatments containing the ion exchange method consume excessive antichlors due to their large particle sizes and unfavorable morphologies. Herein, the antichlors of the Bi(III) containing oxides with quantum dots (QDs) or two-dimensional (2D) structures are first explored for the removal and recovery of Cl- ions in concentrated leachate. By using the QDs/2D flakes constructed antichlors of Bi2O3 and the magnetite Bi-Ti composite, the maximum Cl- removal rates of 61.8% and 66.1% are respectively achieved under the optimum conditions. The higher removal efficiency of the magnetite Bi-Ti composite is contributed by its less stable crystal phases of Bi25FeO40/Bi12TiO20, which can proceed more deeply in the removal of Cl- ions compared with that of Bi2O3. The recovered terminal magnetite Bi-Ti precipitate with Bi2O3/BiOCl heterostructure exhibits excellent photocatalytic activity in the degradation of the dechlorinated leachate, where a total organic carbon removal rate of 87.2% is achieved under UV-vis-near-infrared irradiation. Therefore, the selection of Bi(III) containing oxides opens a promising and high-value method for the removal and recovery of Cl- ions in leachate and other waste waters.