A weak aspect of the electro-Fenton (EF) oxidation of contaminants is the dependence of the Fenton reaction on acidic pH values. Therefore, the rationale of this work was to develop a novel catalyst capable of promoting the EF oxidation process at near-neutral and basic pH values. In this framework, rhombohedral FeCO₃ was synthesized hydrothermally and used as a catalyst in the EF oxidation of p-benzoquinone (BQ). The catalyst was characterized using various surface and spectroscopic methods. Moreover, the effects of applied current (100–500 mA), time (1–9 h), catalyst dosage (0.25–1.00 g L⁻¹), and initial concentration of BQ (0.50–1.00 mM) on the total organic carbon removal efficiency were determined. The results indicated that a 400 mA current was sufficient for a 95% total organic carbon removal and that the increase in catalyst dosage had a positive effect on the mineralization of BQ. It was determined that at pH 3, FeCO₃ behaved like a homogeneous catalyst by releasing Fe³⁺ ions; whereas, at the pH range of 5–7, it shifted to a homogeneous/heterogeneous catalyst. At pH 9, it worked solely as a heterogeneous catalyst due to the decrease of Fe ions passing into the solution. Finally, the spent catalyst did not undergo structural deformations after the EF treatment at higher pH values and could be regenerated and used several times

Pharmaceuticals are frequently detected in natural and wastewater bodies, and are very important in environmental toxicology because of their stable nature. Advanced oxidation methods used to remove contaminants are of great benefit, especially removing pharmaceuticals unsuitable for biodegradation. In this study, imipramine was degraded by anodic oxidation and subcritical water oxidation, which are advanced oxidation methods. The determination of degradation products was performed by Q-TOF LC/MS analysis. The genotoxicity and cytotoxicity of the degradation samples were determined by the in vivo Allium Cepa method. Among the anodic oxidation samples, the lowest cytotoxicity was obtained after using 400 mA current, and 420 min of degradation time. No cytotoxic effect was observed in any subcritical water oxidation sample. However, when 10 mM hydrogen peroxide as an oxidant was used at 150 °C and the reaction time was 90 min, the subcritical water oxidation sample showed a genotoxic effect. The results of the study showed that it is crucial to evaluate the toxicity levels of the degradation products and which advanced oxidation methods are preferred for removing imipramine. The optimum conditions determined for both oxidation methods can be used as a preliminary step for biological oxidation methods in the degradation of imipramine.