Photocatalytic Oxidative Destruction of Diclofenac in Water Using Iron-Containing Metal-Ceramic Composites under Irradiation and Ozonation

The photocatalytic activity of iron-containing metal-ceramic composites based on silicon nitride in the process of oxidative degradation of the pharmaceutical pollutant diclofenac (DCF) was investigated. The composites were obtained by nitriding ferrosilicon without additives and ferrosilicon with shungite (modifier for SiC production) in the combustion mode. The use of urea modifies the ceramic matrix of composites with semiconducting phases (Fe2O3, C3N4) capable of absorbing near-UV and visible light. The phase composition was determined, morphological features and optical properties of the composites were studied. The acid-base properties of the surface were investigated. Adsorption and catalytic activity of composites in the absence and with H2O2 addition under UV irradiation (Fenton process), under ozonation conditions under UV and visible light irradiation were studied. The highest degree of DCF degradation was found when heterogeneous photocatalysis and Fenton process were combined (84%) and under photocatalytic ozonation conditions (88%). The kinetics of photocatalytic degradation of DCF was studied using a pseudo-first-order model. The degradation products of DCF were determined by GC-MS.