Kinetics of ester-105 degradation by La/TiO₂ photocatalysis

Lanthanum-doped titanium (La/TiO₂) nano-photocatalysts were prepared using the sol-gel method and characterized by X-ray diffraction (XRD), zeta potential, and low-temperature nitrogen adsorption analyses. Ester-105, a flotation collector from beneficiation wastewater, was chosen as the target pollutant. The influence of the initial ester-105 concentration, pH, and photocatalyst dosage on the photocatalytic degradation of ester-105 was investigated. To examine the kinetics of the adsorption and photocatalytic degradation of ester-105, a Langmuir adsorption model and Langmuir-Hinshelwood kinetic models were established and discussed. The synthesized photocatalyst comprised anatase-phase TiO₂, with an isoelectric point of pH = 6.5, specific surface area of 56.1626 m²·g^-1, and average pore size of 7.78 nm. The maximum adsorption and the adsorption equilibrium constant of La/TiO₂ for ester-105 were determined as 0.338 mg·g^-1 and 1.008 L·mg^-1, respectively. The first-order kinetic reaction rate constant (k) exhibited a linear relationship with the initial ester-105 concentration. The optimal pH for ester degradation was theoretically determined to be 6.95, and the optimum photocatalyst dosage was found to be 0.2739 g·L^-1. Experiments confirmed that the photocatalytic degradation of ester-105 using La/TiO₂ followed the Langmuir-Hinshelwood kinetics model, thereby providing a theoretical foundation for the photocatalytic degradation of ester-105 for industrial application.