Abstract
Mid-high-frequency ultrasound (200-1000 kHz) eliminates organic pollutants and also generates H
O
. To take advantage of H
O
, iron species can be added, generating a hybrid sono-Fenton process (sF). This paper presents the possibilities and limitations of sF. Heterogeneous (a natural mineral) and homogeneous (Fe
and Fe
ions) iron sources were considered. Acetaminophen, ciprofloxacin, and methyl orange were the target organic pollutants. Ultrasound alone induced the pollutants degradation, and the dual competing role of the natural mineral (0.02-0.20 g L
) meant that it had no significant effects on the elimination of pollutants. In contrast, both Fe
and Fe
ions enhanced the pollutants' degradation, and the elimination using Fe
was better because of its higher reactivity toward H
O
. However, the enhancement decreased at high Fe
concentrations (e.g., 5 mg L
) because of scavenger effects. The Fe
addition significantly accelerated the elimination of acetaminophen and methyl orange. For ciprofloxacin, at short treatment times, the degradation was enhanced, but the pollutant complexation with Fe
that came from the Fenton reaction caused degradation to stop. Additionally, sF did not decrease the antimicrobial activity associated with ciprofloxacin, whereas ultrasound alone did. Therefore, the chemical structure of the pollutant plays a crucial role in the feasibility of the sF process.