Combined adsorption-piezocatalytic removal of acid black 172 using Ce-MOF under aerobic conditions driven by flow-induced vibration

Cerium-based metal-organic framework (Ce-MOF) was synthesized via a solvothermal method and comprehensively characterized. Zeta potential analysis revealed a positive surface charge of +13.1 mV, indicating suitability for anionic dye adsorption. Nitrogen adsorption-desorption analysis showed a Brunauer-Emmet-Teller (BET) surface area of 505 m 2 /g with Type IVa/II composite isotherms, highlighting its significant adsorption potential. The material exhibited a measurable piezoelectric sensitivity of 0.073 mV/N, supporting its role in piezo-assisted catalysis. Ce-MOF was employed as an adsorptive-piezocatalyst for the removal of Acid Black 172 (AB172) under ambient light, operatingg solely with atmospheric oxygen, and eco-friendly, low-cost flow-induced mechanical energy. Control experiments confirmed that ambient light did not contribute to dye degradation, ensuring that the observed removal originated from adsorption-piezocatalysis rather than any photocatalytic effect. Scavenger tests were conducted to identify potential reactive oxygen species (ROS) in the reaction environment. Response Surface Methodology (RSM) using a Central Composite Design (CCD) optimized stirring speed, catalyst-to-dye weight ratio, and pH, achieving over 80 % dye removal under conditions of pH 8, catalyst-to-dye weight ratio above 60, stirring speed above 600 rpm, and 120 min reaction time. Reusability tests and structural stability analyses after cyclic reactions confirmed the robustness of Ce-MOF. Kinetic analysis suggested a combined pseudo-first-order (PFO)/pseudo-second-order (PSO) model for the adsorption, indicating parallel adsorption pathways.