Synthesis, Performance Measurement of Dy₂EuSbO₇/ZnBiDyO₄ Heterojunction Composite Catalyst and Photocatalytic Degradation of Chlorpyrifos within Pesticide Wastewater under Visible Light Irradiation

For the first time, a novel catalyst named Dy₂EuSbO₇ was successfully synthesized via the high-temperature solid-state sintering method (HTSSM). Dy₂EuSbO₇/ZnBiDyO₄ heterojunction photocatalyst (DZHP) was fabricated through the HTSSM for degrading chlorpyrifos (CPS) in the pesticide wastewater under visible light irradiation (VSLID). Under VSLID, DZHP could effectively degrade CPS in pesticide wastewater. The experimental outcomes suggested that the kinetic curve with the Dy₂EuSbO₇/ZnBiDyO₄ heterojunction (DZH) as a photocatalyst for the reduction of CPS under VSLID conformed to the first-order kinetics (FOKT). After VSLID of 156 min, the photocatalytic degradation (PTD) removal rate of CPS using DZH as photocatalyst was 1.12 times, 1.21 times, or 2.96 times that using Dy₂EuSbO₇ as a photocatalyst, ZnBiDyO₄ as a photocatalyst, or nitrogen-doped titanium dioxide as a photocatalyst. After VSLID of 156 min for four cycle degradation tests (FCDTS) with DZH as a photocatalyst, the removal rate of CPS reached 98.78%, 97.66%, 96.59%, and 95.69%, respectively. Above results indicated that the DZHP possessed high stability. Experiments with the addition of trapping agents showed that hydroxyl radicals (•OH) owned the strongest oxidative removal ability for degrading CPS compared with superoxide anions (•O₂⁻) or holes (h⁺). The oxidation capacity of three oxidation radicals for eliminating CPS was ranked in the ascending order as follows: h⁺ < •OH < •O₂⁻. Lastly, the possible degradation pathway and degradation mechanism of CPS were discussed in detail. A visible light responsive heterojunction catalyst with high catalytic activity and a photocatalytic reaction system which were capable of efficiently removing toxic organic pollutants from pesticide wastewater were obtained.