Evaluation of water matrix effects, experimental parameters, and the degradation pathway during the TiO₂photocatalytical treatment of the antibiotic dicloxacillin

Abstract

The photocalytic degradation of dicloxacillin (DXC) using TiO2 was studied in synthetic and natural waters. The degradation route and the effect of different experimental variables such as pH, applied power, and the initial concentrations of DXC and the catalyst were investigated. The best performances were achieved at a natural pH 5.8 and using 2.0 g L(-1) of TiO2 with 150 W of applied power. The photodegradation process followed Langmuir-Hinshelwood kinetics. The water matrix effect was evaluated in terms of degradation efficiency in the presence of organic compounds (oxalic acid, glucose), Fe(2+) ion and natural water. An increase in degradation was observed when ferrous ion was part of the solution, but the process was inhibited with all evaluated organic compounds. Similarly, inhibition was observed when natural water was used instead of distilled water. The extent of degradation of the process was evaluated following the evolution of chemical oxygen demand (COD), antimicrobial activity (AA), total organic carbon (TOC) and biochemical oxygen demand (BOD5). Total removal of DXC was achieved after 120 min of treatment and 95% mineralization was observed after 480 min of treatment. Additionally, the total removal of antimicrobial activity and a high level of biodegradability were observed after the photocalytical system had been operating for 240 min.

Treatment technologies for emerging contaminants in water: A review

“…For example, dicloxacilin degradation has been attempted using UV photolysis [155,163], the decomposition of hydrogen peroxide [156] or ozone [155,[157][158][159] using UV radiation, titanium dioxide photocatalysis [177] and sono-chemical oxidation [175]. A range of studies have reported that dicloxacilin is inert to UV radiation alone, slightly degradable by photocatalysis, but highly sensitive to sono-chemical conditions [175,176]. This is attributed to the fact that long wavelength UV radiation may not be able to generate any change in the chemical structure of the ECs and could explain the persistence in the environment of some of the compounds.…”

Degradation of the antibiotic oxacillin in water by anodic oxidation with Ti/IrO 2 anodes: Evaluation of degradation routes, organic by-products and effects of water matrix components

“…Ozonation, electrochemical, Fenton/photo-Fenton and semiconductor photocatalysis has been the most tested [8][9][10][11][12][13][14] However, under our knowledge, only one work has reported the treatment of water containing oxacillin [15].…”

Selecting the best AOP for isoxazolyl penicillins degradation as a function of water characteristics: Effects of pH, chemical nature of additives and pollutant concentration

“…The quantification method was used as previously reported (Villegas-Guzman et al, 2015. Dissolved iron was quantified by atomic absorbance spectroscopy.…”

“…On the contrary, at a pH above 6.8, the TiO 2 surface gets negatively charged. Therefore, at a natural pH (5.8), attractive electrostatic forces between the negatively charged molecule of DXC and the catalyst take place (Villegas-Guzman et al, 2015). As a result, DXC molecules get close to the active sites of the catalyst and degradation is favored.…”