The adsorption-photocatalytic cooperative mechanism for efficient degradation of methylene blue by SDBS modified ZnTi-LDH

Abstract

With the development of global industry, the treatment technology of water pollutants has become increasingly important. In this paper, ZnTi-LDH photocatalysts with synergistic effects of adsorption and photocatalysis were synthesized by a simple hydrothermal method and applied to the removal of methylene blue (MB) from water. The synthesized ZnTi-LDH with sodium dodecyl benzene sulfonate (SDBS) modification (ZT-0.4) had improved adsorption and photocatalysis properties, thus greatly enhancing the removal rate of MB. ZT-0.4 was able to remove 98.1 % of MB in the static system and stabilized to remove about 76 % of MB in the dynamic system, both of which were substantially improved compared to unmodified ZnTi-LDH. Zeta potential analysis and Electrochemical tests indicated that the addition of SDBS enhanced the electrostatic adsorption capacity of ZnTi-LDH on MB, shortened the carrier transport path, and increased the electron-hole pair separation efficiency, which substantially improved the pollutant removal rate. The photocatalytic activity of ZT-0.4 remained a MB removal efficiency of 71.3 % after five consecutive cycles. ZT-0.4 also demonstrated enhanced removal rates for other dyes such as Rhodamine B (94.4 %) and Congo Red (100 %). Quenching experiment and electron paramagnetic resonance (EPR) indicate that ·OH, ¹O₂ and ·O₂^- radicals are the main active substances for photocatalytic degradation. In this work, efficient and stable ZnTi-LDH photocatalytic materials were developed by constructing an adsorption-photocatalytic synergistic mechanism, which provides a novel photocatalytic material design strategy for the dynamic removal of pollutants in wastewater.