Photocatalytic degradation of two different types of dyes by synthesized La/Bi2WO6

Abstract

A lanthanum doped Bi₂WO₆ composite (La/Bi₂WO₆) was prepared using a simple hydrothermal method. The synthesized samples were well characterized using XRD, SEM, TEM, UV-vis DRS, XPS, and BET analysis methods. The photocatalytic activities of La/Bi₂WO₆ on reactive brilliant red X-3B (X-3B) and rhodamine B (RhB), under simulated solar irradiation, were systematically investigated. As a result, the doped Bi₂WO₆ samples possessed a higher specific surface area than pure Bi₂WO₆, but still retained the crystalline phases, morphology and visible light absorption properties of pure Bi₂WO₆. The initial concentrations of dyes, the dosage of catalyst and H₂O₂ all displayed the same effects on the degradation of the two dyes. However, pH showed different effects on X-3B and RhB because X-3B is an anionic dye while RhB is a cationic dye. Moreover, among all the inorganic ions studied (Na⁺, K⁺, Ca²⁺, Mg²⁺, NO₃⁻, HCO₃⁻, Cl⁻, SO₄²⁻), the addition of Cl⁻ significantly affected the adsorption and degradation of the two dyes; Cl⁻ inhibited the total removal efficiency of X-3B, but enhanced the removal efficiency of RhB. The effects of inorganic cations were attributed to the effect of Cl⁻ because the four metal ions were used as their chloride salts.