Sonophotocatalysis—Limits and Possibilities for Synergistic Effects

Abstract

Advanced oxidation processes are promising techniques for water remediation and degradation of micropollutants in aqueous systems. Since single processes such as sonolysis and photocatalysis exhibit limitations, combined AOP systems can enhance degradation efficiency. The present work addresses the synergistic intensification potential of an ultrasound-assisted photocatalysis (sonophotocatalysis) for bisphenol A degradation with a low-frequency sonotrode (f = 20 kHz) in a batch-system. The effects of energy input and suspended photocatalyst dosage (TiO2-nanoparticle, m = 0–0.5 g/L) were investigated. To understand the synergistic effects, the sonication characteristics were investigated by bubble-field analysis, hydrophone measurements, and chemiluminescence of luminol to identify cavitation areas due to the generation of hydroxyl radicals. Comparing the sonophotocatalysis with sonolysis and photocatalysis (incl. mechanical stirring), synergies up to 295% and degradation rates of up to 1.35 min−1 were achieved. Besides the proof of synergistic intensification, the investigation of energy efficiency for a degradation degree of 80% shows that a process optimization can be realized. Thus, it could be demonstrated that there is an effective limit of energy input depending on the TiO2 dosage.

Integrated Hydrogen Peroxide, Sono, and Heterogeneous Photocatalysis Technologies: A Novel Technique for Ammonia and Phosphorus Removal in Real Poultry Slaughterhouse Wastewater

“…According to the data presented in Figure 3(b) and Figure 4(b), there is a decline in phosphorus removal efficiency as the concentration of the catalyst is increased from 1.5 to 2.5 g/L. Consistent with prior research conducted by Dogdu (2022), our findings indicate that the effectiveness of degradation is significantly influenced by the extent of the available catalytic surface area and is constrained by the turbidity of the suspension, as noted by Paustian et al (2022). Dogdu (2022) and Khan et al (2023) both stated that an increase in the concentration of the catalyst results in a decrease in the propagation of ultrasonic waves inside the solution.…”

Fast and Efficient Piezo-Photocatalytic Mineralization of Ibuprofen by BiOBr Nanosheets under Solar Light Irradiation

“…However, low BiOBr dosage (0.125 g/L) was not adequate to promote a fast IBU degradation, not even combining piezocatalysis and photocatalysis because of the reduced catalytic surface available. , …”

“…However, low BiOBr dosage (0.125 g/L) was not adequate to promote a fast IBU degradation, not even combining piezocatalysis and photocatalysis because of the reduced catalytic surface available. 49,50 The kinetics of the three diverse processes (photocatalysis, piezocatalysis, and piezo-photocatalysis) was determined by a pseudo-first-order kinetic model. The corresponding plots (Figure S.13) confirm the synergistic effect of the coupling of the two techniques with respect to the single ones.…”