Sonophotocatalytic Degradation of Organic Pollutants

Sonophotocatalysis integrates ultrasonic irradiation with photocatalysis to harness synergistic physical and chemical effects for the removal of persistent organic contaminants. Ultrasound-induced cavitation generates transient microbubbles that collapse under extreme localised pressures and temperatures, producing radicals and enhancing mass transfer. Photocatalysts absorb light to excite charge carriers, which then react with water or oxygen to form reactive oxygen species such as hydroxyl radicals. The combined process accelerates degradation kinetics under mild conditions, achieving rapid mineralisation of dyes, pharmaceuticals, pesticides and other recalcitrant molecules. Recent advances in catalyst engineering—doping, heterojunction formation and exploitation of piezoelectric materials—have extended light absorption into the visible range, suppressed electron–hole recombination and improved quantum efficiencies. Optimisation of ultrasonic frequency, light intensity, catalyst loading and solution pH further tailors performance and energy consumption. By offering decentralised, chemical-free routes to water and wastewater treatment, sonophotocatalysis addresses global challenges in environmental remediation and supports sustainable development objectives.

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Sonophotocatalytic Degradation of Organic Pollutants publication trend

The graph below shows the total number of articles in sonophotocatalytic degradation of organic pollutants across all publications each year (not limited to Nature Index journals).

Technical terms

Sonophotocatalysis: A hybrid advanced oxidation process that combines ultrasonic cavitation with light-driven photocatalysis to enhance pollutant degradation through synergistic radical generation.

Cavitation: The formation, growth and abrupt collapse of microbubbles in a liquid under ultrasonic waves, creating hotspots that drive sonochemical reactions.

Reactive oxygen species (ROS): Highly reactive radicals and non-radical oxygen derivatives (e.g., •OH, O₂•–) produced during sonophotocatalysis which oxidise organic pollutants.

Synergy index: A dimensionless ratio comparing combined-process efficiency to the sum of individual processes, with values above one indicating synergistic enhancement.

Sonoluminescence: The emission of light from collapsing cavitation bubbles, which can contribute to photocatalyst excitation and additional radical formation.

References

1. Visible-light driven sonophotocatalytic removal of tetracycline using Ca-doped ZnO nanoparticles. Chemical Engineering Journal (2022).
2. Application of Photocatalysis and Sonocatalysis for Treatment of Organic Dye Wastewater and the Synergistic Effect of Ultrasound and Light. Molecules (2023).
3. Investigation of the Synergistic Effect of Sonolysis and Photocatalysis of Titanium Dioxide for Organic Dye Degradation. Catalysts (2020).
4. Advances on sonophotocatalysis as a water and wastewater treatment technique: efficiency, challenges and process optimisation. Frontiers in Chemistry (2023).