From laboratory insights to industrial applications in continuous flow sonophotocatalytic abatement of persistent pollutants enabled by a broad-spectrum S-scheme photocatalyst

The rapid pace of industrialization has resulted in the alarming discharge of detrimental chemicals into the environment, prompting the scientific community to rethink conventional wastewater treatment technologies. Sonophotocatalysis, a synergistic green approach, harnessing the combined forces of ultrasound and visible light, has emerged as a promising frontier in environmental remediation. Leveraging the exceptional surface area, porosity, and coordination flexibility of zeolitic imidazole frameworks (ZIF-67), a type of metal-organic framework (MOF), makes it an excellent scaffold for catalyst design. Forming the core of this approach, a CoWO₄-decorated ZIF-67 hybrid nanocomposite was developed and utilized as a sonophotocatalyst to degrade tetracycline (TC) under dual-energy exposure. The CoWO₄/ZIF-67 catalyst achieved an unprecedented TC degradation efficiency of 98% within 75 min, outperforming standalone sonocatalytic and photocatalytic treatment, with excellent reusability. Mechanistic insights, supported by theoretical studies, revealed a strong interaction between the structural and physicochemical properties of the catalyst and energy-induced reactive oxygen species (ROS) generation. A large-scale continuous-flow sonophotocatalytic reactor of 20 L was fabricated to evaluate the performance of the synthesized catalyst on real wastewater samples containing interfering ions. The system achieved an 85% reduction in total organic carbon (TOC), demonstrating excellent scalability and practical applicability, offering a promising approach for treating emerging organic pollutants in an efficient and environmentally friendly manner.