Systematic activation of potassium peroxydisulfate with ZIF-8 via sono-assisted catalytic process: Mechanism and ecotoxicological analysis

Powerful and suitable combination of different advanced oxidation processes (AOPs) has raised a new challenge in recent years. Since the generation of synergistic phenomenon is vital in the final integrated process, there is still an urgent demand for developing a superior hybrid AOPs, which is synergistically effective, simply and economically prepared and operated. Herein, a novel combination of ZIF-8 nanomaterials (NMs) and sonolysis process was utilised for efficient activation of potassium peroxydisulfate (PDS), leading to the establishment of a novel combined sono-assisted indirect photocatalytic process. ZIF-8 NMs were fabricated by a facial and green synthesis method at room temperature. The XRD, TEM, and BET analyses confirmed the successful production of porous ZIF-8 nanomaterials with sodalite (SOD) topology and hexagonal shapes including the specific surface area of 1484.28 m²/g. Besides, the effects of operational parameters including pH, ZIF-8, and PDS, Acid Blue 7 (AB7) concentration and ultrasonic bath power (UBP) were investigated on three response parameters consisting of AB7 removal efficiency (RE (%)), pseudo-first-order kinetic rate constant (k_app) and synergistic factor (SF). Optimum operating conditions were determined as pH = 5, [ZIF-8] = 0.6 g/L, [PDS] = 0.6 mmol/L in which maximum SF of 1.45 was achieved. The concurrent decomposition of S₂O₈ ²⁻, HSO₅ ⁻, H₂O₂, and AB7 on the active sites of ZIF-8 NMs were responsible for degradation. Based on the identified by-products via GC–MS technique, the AB7 sonocatalytic degradation mechanism was proposed. Finally, valuable efforts were made to assess the ecotoxicological effects of AB7, ZIF-8 NMs and the produced intermediates under optimised operating conditions. Sono-assisted indirect photocatalytic process in the presence of ZIF-8 NMs activated PDS can be noticed as an acceptable and green integrated process due to its high SF and novel features.