In this study, the effectiveness of a rhodamine B (RhB) dye degradation process at a concentration of 20 mg/L in different advanced oxidation processes—H2O2/UV, O3/UV and PDS/UV—has been studied. The use of UV in a photo-assisted ozonation process (O3/UV) proved to be the most effective method of RhB decolorization (90% after 30 min at dye concentration of 100 mg/L). The addition of sulfate radical precursors (sodium persulfate, PDS) to the reaction environment did not give satisfactory effects (17% after 30 min), compared to the PDS/UV system (70% after 30 min). No rhodamine B decolorization was observed using hydrogen peroxide as a sole reagent, whereas an effect on the degree of RhB degradation was observed when UV rays strike the sample with H2O2 (33% after 30 min). The rhodamine B degradation process followed the pseudo-first-order kinetics model. The combined PDS/O3/UV process has shown 60% color removal after 30 min of reaction time at an initial dye concentration of 100 mg/L. A similar effectiveness was obtained by only applying ozone or UV-activated persulfate, but at a concentration 2–5 times lower (20 mg/L). The results indicated that the combined PDS/O3/UV process is a promising method for high RhB concentrations (50–100 mg/L) comparing to other alternative advanced oxidation processes.

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The scientific data review shows that advanced oxidation processes based on the hydroxyl or sulfate radicals are of great interest among the currently conventional water and wastewater treatment methods. Different advanced treatment processes such as photocatalysis, Fenton’s reagent, ozonation, and persulfate-based processes were investigated to degrade contaminants of emerging concern (CECs) such as pesticides, personal care products, pharmaceuticals, disinfectants, dyes, and estrogenic substances. This article presents a general overview of visible light–driven advanced oxidation processes for the removal of chlorfenvinphos (organophosphorus insecticide), methylene blue (azo dye), and diclofenac (non-steroidal anti-inflammatory drug). The following visible light–driven treatment methods were reviewed: photocatalysis, sulfate radical oxidation, and photoelectrocatalysis. Visible light, among other sources of energy, is a renewable energy source and an excellent substitute for ultraviolet radiation used in advanced oxidation processes. It creates a high application potential for solar-assisted advanced oxidation processes in water and wastewater technology. Despite numerous publications of advanced oxidation processes (AOPs), more extensive research is needed to investigate the mechanisms of contaminant degradation in the presence of visible light. Therefore, this paper provides an important source of information on the degradation mechanism of emerging contaminants. An important aspect in the work is the analysis of process parameters affecting the degradation process. The initial concentration of CECs, pH, reaction time, and catalyst dosage are discussed and analyzed. Based on a comprehensive survey of previous studies, opportunities for applications of AOPs are presented, highlighting the need for further efforts to address dominant barriers to knowledge acquisition.

This paper presents the evaluation of the photocatalytic kinetics of bisphenol A decomposition in the presence of commercial titanium(IV) oxide and modified photocatalysts (composites). The following modification methods were used: mechanical mixing, calcination and impregnation. The decomposition process was carried out with the addition of photocatalysts and activated carbon at doses of 100 mg/dm 3 and 25 mg/dm 3 , respectively. The photocatalytic process was performed in a reactor from the Heraeus Company (Warsaw, Poland) with a volume of 0.7 dm 3. The reactor was equipped with an immersed medium-pressure mercury lamp with a power of 150 W (λ = 200-580 nm). The degree of bisphenol A decomposition was determined by chromatographic analysis preceded by solid-phase extraction SPE. The qualitative-quantitative analysis was performed using a high-performance liquid chromatograph HPLC (UV detector, λ = 218 nm) from Varian (Warsaw, Poland). The dependence of the BPA decomposition on the duration of irradiation was found, wherein the modified photocatalysts were the most effective (from 75 to 90% after 15 minutes). The order of photocatalyst efficiency has been proposed as follows: TiO 2 < TiO 2 /AC < C dextran-TiO 2 /AC < C methanol-TiO 2 /AC< C ethanol-TiO 2 /AC < TiO 2-AC. The highest degree of decomposition was observed in the presence of TiO 2 /AC (99%). Numerous studies suggest that the results of the TiO 2 photocatalytic oxidation of organic substances fit well with the Langmuir-Hinshelwood (L-H) kinetic model. The kinetic parameters of the photocatalysis process were carried out according to the L-H model. According to the pseudo-first-order parameters, the results showed that the decomposition of bisphenol A was most intensive in the first 15 minutes of the process.

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