Intensification of micropollutant adsorption by activated carbon via short duration ultrasonic treatment

The integration of ultrasonic (US) cavitation with conventional adsorbents offers a transformative opportunity to upscale wastewater treatment processes. This study evaluates the synergistic effects of US on two distinct activated carbons in granular (GAC) and powder (PAC) forms for the removal of micropollutants (μPs) from both spiked deionized water and secondary effluent. Results demonstrate that within the first minute, US promotes a four-to-six-fold increase in μP removal for GAC, achieving levels equivalent to 30 min of conventional stirred adsorption. This time-parity effect offers the possibility of significant reduction in the required hydraulic retention time. During 1-min US application, Cycle Carbon 401 GAC removal of micropollutants increased between 1.5 and 4.3 times, on wastewater matrix. Between 1 and 30 min, the Pseudo-First Order model shows a k₁ increase between 1.2 and 1.6, for the different micropollutants, while long-term (96 h) experiments fitted to the Pseudo-Second Order model confirmed that US accelerates micropollutant adsorption to a maximum factor of 4, while the equilibrium capacity (q_e) remains unchanged. The efficacy of US is highly dependent on adsorbent morphology. While PAC showed negligible kinetic gains due to its inherently low mass-transfer resistance,and lack capacity of 20 kHz US to influence particles under 40μm, causing them to simply follow the fluid motion rather than overcome mass-transfer resistance, US significantly intensified the kinetics of GAC A (CC401). Due to its higher mesoporosity (S_meso), coal-based CC401 achieved 3-to-4-fold higher removal than the wood-based DL124, and US application bridged the performance gap between granular and powdered media ( [Formula: see text] ). Adsorbent characterization (BET, SEM, and DFT) confirmed that the GAC matrix remained structurally intact, suggesting that enhancements are kinetically driven by pore deblocking and the collapse of the stagnant boundary layer. Despite competitive interference from dissolved organic matter in wastewater, the enhancement ratio of US-assisted adsorption remains consistent across both water matrices. These findings provide a scalable roadmap for integrating ultrasonic-assisted processes into conventional treatment plants to maximize μP removal and achieve substantial operational co-benefits.