Degradation of amoxicillin under a UV or visible light photocatalytic treatment process using Fe2O3/bentonite/TiO2: Performance, kinetic, degradation pathway, energy consumption, and toxicology studies

Abstract

The present work investigates the degradation of amoxicillin (AMX) using a Fe2O3/bentonite/ TiO2 (Fe2O3/B/TiO2) nanocomposite under visible LED light and UV irradiation. XRD, UVVisible, FTIR, EDS, VSM, EPR spectra and TEM techniques were utilized to estimate the features of the prepared photocatalyst. The saturation magnetization for Fe2O3 and Fe2O3/B/TiO2 was 57.4 and 17.4 emu/g, respectively. Factors affecting degradation rates, such as pH, catalyst dose, radiation intensity, and initial AMX concentration, were investigated. The results showed that an AMX concentration of 25 mg/L, a pH of 5, and a catalyst dosage of 0.75 gr/L are the optimal parameters suggesting a 100% degradation of the contaminant in the presence of UV light for 60 min. However, during the use of visible light the optimal contact time was 90 min, producing a removal percentage of 98.8%. The results for the reaction rate indicate the adherence of the data to pseudo-first-order kinetics, and the reaction rate constant for UV and visible radiation was 0.0181 and 0.0176 1/min, respectively. The energy consumption range for a degradation time of 10-90 min for UV and visible radiation was 9.4-14.6 and 7.61-15.4 kWh/m(3), respectively Both light sources have also been shown to convert nonbiodegradable effluent into a biodegradable form. Finally, a mere 8% reduction in catalyst efficiency was observed after 6 recycling and reuse cycles. The degradation of AMX was negatively affected by common coexisting anions in water (10-25%). Moreover, toxicity assessments indicated the usability of the studied system to remarkably diminish the toxicity of AMX solution compared to untreated controls. Hence, the studied Fe2O3/B/TiO2/UV or visible light processes could be considered an auspicious technology for providing high efficiencies in the treatment of AMX-contaminated wastewater.