Electro-ultrasonic coupled for enhanced removal efficiency of toxic fine particles from biomass combustion: Performance optimization and synergistic mechanisms.

Biomass combustion emits fine particulate matter (PM2.5) rich in toxic substances that pose severe respiratory health risks; however, conventional control technologies exhibit low collection efficiency for submicron particles due to their high mobility and stable dynamics. This study proposes an electro-ultrasonic coupled agglomeration technology to bridge this gap. A segmented continuous-flow experimental platform integrating macro-performance testing, micro-characterization, and numerical simulations was established. Under optimized parameters (bipolar charging at ±16 kV, AC electric field of 300 V/400 Hz, and ultrasound at 16 kHz/142 dB), the coupled field achieved a light transmittance of 86.4%-exceeding single electric and acoustic fields by 33.1 and 67.2 %age points, respectively-with the extinction coefficient reduced to 0.9 m⁻¹ , confirming a genuine "1 + 1 > 2" synergistic enhancement. Particle trajectory simulations revealed that spatiotemporal coupling transforms linear particle motion into three-dimensional helical paths, increasing cumulative displacement by over 445.9% and substantially elevating collision probability. SEM observations confirmed the formation of compact block-like agglomerates (15-20 μm). Three synergistic mechanisms-motion intensification, charge-state regulation, and structural stabilization-are identified. This electro-ultrasonic coupled approach offers a high-efficiency, low-noise pretreatment strategy for PM2.5 mitigation in industrial biomass combustion, with scalable potential for reducing downstream filtration burden and particle-bound toxin emissions.