Oxidation of Aqueous Dexamethasone Solution by Gas-Phase Pulsed Corona Discharge

The most widely used anti-inflammatory corticosteroid dexamethasone (DXM), frequently detected in waterbodies due to its massive consumption and incomplete removal in wastewater treatment processes, was experimentally studied for oxidation with gas-phase pulsed corona discharge (PCD) varied in pulse repetition frequency, pH, DXM initial concentration and additions of surfactant sodium dodecyl sulphate (SDS) and tert-butyl alcohol (TBA). The experimental study also included ozonation as compared to PCD in energy efficiency. The advantageous energy efficiency of PCD was observed in wide spans of pH and DXM initial concentrations surpassing ozonation by about 2.4 times. Identified transformation by- and end-products (fluoride and acetate), as well as the impact of radical scavengers, point to the prevalent radical oxidation of DXM. Somewhat increased toxicity observed on the course of PCD-treatment of high DXM concentrations presents a subject for further studies

Persulfate-based photodegradation of a beta-lactam antibiotic amoxicillin in various water matrices

<p>Amoxicillin (AMX), a widely used beta-lactam antibiotic, belongs to the World Health Organization’s list of essential medicines. This subsequently causes its long-term presence in the environment and therefore, affects different environmental compartments. In this research, the degradation and mineralisation of AMX by UVC-activated persulfate-based treatment in various aqueous media was assessed. The degradation of the target compound was in accordance with the pseudo-first-order reaction kinetics in all the UVC-induced systems. The results indicated that AMX degradation in any real water matrices is notably inhibited by the matrix properties. The trials with radical scavengers in ultrapure water proved the existence of and HO^., but mainly contributed to the degradation of AMX in the UVC/ and UVC//Fe²⁺ systems. It was shown that the parent compound disappeared during the treatment, but the mineralisation extent referred to the formation of transformation products the main of which were identified. The findings of this study could provide valuable information about the elimination of beta-lactam antibiotics from various environmental and processed waters.</p