Degradation of pharmaceuticals by ultrasound-based advanced oxidation process

Abstract

Water pollution by pharmaceutically active compounds is an emerging issue. Toxicological studies reveal that pharmaceuticals are indeed toxic for living organisms. The lack of suitable treatment technology for the complete removal of pharmaceuticals is therefore a major challenge. Advanced oxidation processes are emerging removal techniques that have many advantages versus conventional technologies. Many studies indicate that advanced oxidation processes, either in single or in combination with other degradation techniques, can enhance the degradation of pharmaceuticals in aqueous solutions. Here, we review the degradation of pharmaceuticals by sonolysis, an oxidation processes using ultrasound. In this technique, hydroxyl radicals are generated by pyrolytic cleavage of water molecules. We review the influence of operational parameters, additives and hybrid techniques on the degradation of pharmaceuticals. The maximum degradation of organic compounds was observed in the frequency range of 100-1000 kHz, which is in the high-frequency medium-power ultrasound. Even though almost all the experiments presented more than 90 % removal and good biodegradability of the target compound, good mineralization and the toxicity removal were hardly achieved. The efficiency of the degradation varies with water matrixes and varying pH. Major pathways of degradation are hydroxylation, dehalogenation, demethylation, decarboxylation, deamination, etc. More hybrid techniques have to be developed to scale up the application of ultrasound.

Sonolysis and sono-Fenton oxidation for removal of ibuprofen in (waste)water

“…Despite growing interest for sono-Fenton process in the literature, information about optimum US frequency is still scarce, because previous studies [10,13,23] usually operated at a single value (in the 20-40 kHz range). Sonochemical effects being suspected in the enhanced ferrous iron regeneration, two high US frequencies (580 and 862 kHz) were investigated.…”

“…Several works have investigated the coupling of ultrasound and Fenton oxidation for the elimination of various organic compounds such as dyes, phenolic compounds and pesticides [13,19,20], and more recently pharmaceuticals [21][22][23]. However, to our knowledge, this latter mechanism (Eq.…”

Optimization of ciprofloxacin degradation in wastewater by homogeneous sono-Fenton process at high frequency

“…Hydroxyl radicals can (i) degrade organic compounds, (ii) react with H2O2 (especially when they are in large excess) forming less active species according to Equation 8 [36,54,55] (iii) or recombine with different radicals according to Equations 9-11. [56][57][58] H2O2 Then, another set of experiments was carried out in order to study the effect of H2O2 addition on CIP sonolysis. The stoichiometric amount of the required H2O2 for the complete oxidation of CIP in aqueous solution was calculated according to Equation 12:…”

Emerging Pollutants – Part II: Treatment

“…Therefore, the study on combination of ultrasonic degradation process with other advanced oxidation processes is another major research direction (Rayaroth et al 2016). Rao et al (2016) investigated the degradation of Carbamazepine (CBZ) in pure water and secondary effluent wastewater by Ultrasound and UV/Ultrasound processes.…”