V 600

The sonocatalytic activity of MXe/MIL-101(Cr) was assessed by measuring the decomposition of SD and AAP as pollutants in an aqueous solution at 25 °C. The entire sonocatalytic experiment was performed at 40 kHz in a MUJIGAE ultrasonic bath instrument (SD-D400H). Briefly, 25 mg of MXe/MIL-101(Cr) (1 g L^-1) was added to 25 ml of a 10 mg L^-1 solution of SD or AAP at pH 7.0. These mixtures were placed in the dark for 30 min to achieve adsorption–desorption equilibrium between the catalyst and the pollutant, and then H₂O₂ (2 ml, 2 mmol/L) was added. Following this, the sample was irradiated (180 W/L) using an ultrasonication bath at 303 K, and 1.5 ml volumes of the samples were collected and filtered at regular intervals through a 0.22 μm syringe filter. The filtrate adsorption intensities were then measured using a UV–Vis spectrophotometer (JASCO V-600) to determine pollutant concentrations. Experimental conditions such as pH (3–11), catalyst dosage (0.25–1.50 g/L), initial pollutant concentration (5–20 mg/L), H₂O₂ concentration (0.5–3 mM/L), radical scavenger species, ultrasonic irradiation power (90–225 W), and temperature (283–313 K) were varied to optimize the process. For recycling experiments, MXe/MIL-101(Cr) was washed thoroughly in DI water and dried at 60 °C in a vacuum for 6 h between cycles.

To quantify H₂O₂ evolution during sonocatalysis, a 2 ml sample of the reaction solution was filtered through a 0.22 μm syringe filter, and 1 ml of freshly prepared KI reagent (0.4 M KI, 0.05 M NaOH, and 1.6 × 10^-4 M (NH₄)₆Mo₇O₂₄·4H₂O) and 1 ml of 0.1 M KHC₈H₄O₄ were mixed with 1 ml of filtrate and aged for 2 min. Absorption was then measured at 350 nm using a UV–vis spectrophotometer (JASCO V-600). A trapping experiment was conducted to investigate the contributions made by reactive oxygen species (ROS) to the decomposition of organic compounds. The following four scavengers were added to the sono-reactor containing AAP: 5 mM of AgNO₃, an electron scavenger; EDTA, a hole scavenger; BQ, an O₂^•- scavenger; and t-BuOH, an •OH scavenger. In addition, different concentrations of humic acid (HA), t-BuOH (an •OH scavenger), and carbon tetrachloride (CCl₄, an •OH promoter) were also added to investigate the reaction kinetics.