Assessment of Degradation Behavior for Acetylsalicylic Acid Using a Plasma in Liquid Process

Abstract

Acetylsalicylic acid (ASA) is a pharmacologically active compound. In this study, ASA was decomposed effectively using a plasma in liquid phase process with hydrogen peroxide and TiO2 photocatalyst. Increasing the electrical power conditions (frequency, applied voltage, and pulse width) promoted plasma generation, which increased the rate of ASA decomposition. The added hydrogen peroxide increased the rate of ASA degradation, but injecting an excess decreased the degradation rate due to a scavenger effect. Although there was an initial increase in the decomposition efficiency by the addition of TiO2 powder, the addition of an excessive amount inhibited the generation of plasma and decreased the degradation rate. The simultaneous addition of H2O2 and TiO2 powder resulted in the highest degradation efficiency. We suggest that ASA is converted to salicylic acid through demethylation by hydroxyl radicals and is finally mineralized to carbon dioxide and water via 2,4-dihydroxy benzoic acid and low molecular acids.

Proof of Principle of Wastewater Treatment using Plasma Discharge to Reduce the Amount of Methylparaben

“…The GS-MS results indicated that the methylparaben was completely decomposed to a certain extent, with carbon dioxide and water as the presumed end products. The decomposition presumably takes place here due to the highly reactive environment and the strong radical formation (Cui et al 2018, Abramov et al 2021, Bang et al 2019. However, even with the longest treatment period, elimination was not even close to 100%.…”

“…13.3 kWh, the price of a single cycle treatment would be over 1 €/m3 (Considering the average electricity price of 0.3263 €/kWh in Germany in 2021 (Umwelt Bundesamt 2021)), however, parts of the consumption are also due to external pumps and here lies a potential for cost savings. The use of oxidizing agents, such as hydrogen peroxide, would also be conceivable (Bang et al 2019), to heighten the efficiency and reduce the number of cycles needed. An extension of the monitoring equipment for an actual industrial plant would also make sense in order to be able to ensure a constant plasma intensity.…”

Non-Thermal Plasma-Assisted Catalytic Reactions for Environmental Protection

“…Moreover, it was observed that the increase of the number or size of the pores enhances both the volume and surface discharges. The addition of a heterogeneous TiO 2 -based catalyst can be efficient in the degradation of pharmaceutical compounds present in aqueous solution such as acetylsalicytic acid [10]. Furthermore, the addition of hydrogen peroxide increased the rate of acetylsalicytic acid degradation, but injecting an excess decreased the degradation rate due to a scavenger effect.…”