## 1 Introduction
However, any chemical sprayed in fields will result in secondary effects on aquifers, biodiversity, and reclaimed water; this is also the case with Acetamiprid, which has been associated deleterious effects in honeybee queen production, increases in songbird mortality, or decreases in earthworm activity, and some studies even indicate toxicity in certain small mammals [33; 36; 37; 34]. Moreover, their use in large quantities due to intensive agriculture and multiple cropping cycles per year can still be detrimental due to accumulation. This is particularly relevant in Spain, which leads in the use of pesticides within the European Union [38]. In recent years, the literature has documented significant research efforts aimed at the removal of Acetamiprid from wastewater via advanced oxidation methods [39]. Therefore, the photocatalytic degradation of Acetamiprid has been studied using inorganic photosensizers, such as titanium dioxide (TiO\({}_{2}\)) [40; 41] or sulfate-doped Ag\({}_{3}\)PO\({}_{4}\) with enhanced visible light activity [42]. However, the method that has yielded the best results is the photo-Fenton method, which is currently being extensively studied [43], even innovating in the materials used for metals used to catalyze hydroxyl (OH) production, such as \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)-pillared bentonite/L-cysteine complex [44] or NH\({}_{2}\)-MIL-88B(Fe) with different monodentate ligands in order to increase the pH action range [45]. Notably, the photo-Fenton method has been applied for wastewater treatment [46] and has also been combined with other methods such as ultrasound, enhancing its performance [47]. In sum, many concur that Acetamiprid is highly resistant to direct molecular ozone attack but its reaction with hydroxyl radicals exhibits fast kinetics [48]. The stringent acidic pH limitation is the main barrier for Fenton implementation, taking into account that water and wastewaters effluents have a pH usually ranging between 6.5 and 8.5 [43]. An alternative that has not been extensively studied in the literature is the Acetamiprid oxidation via singlet oxygen (O\({}_{2}\)(\({}^{1}\Delta_{\text{g}}\))), and that furthermore can solve the problem of application at basic medium. [PERSON] determined in 2010 the reaction mechanism of Acetamiprid with O\({}_{2}\)(\({}^{1}\Delta_{\text{g}}\)) using Rose Bengal (RB) as a photosensitizer [49]. RB is a xanthene-based natural compound that displays high absorption in the 500-600 nm range, its triplet state can be completely quenched by oxygen and so RB is considered a highly efficient photosensitizer for generating O\({}_{2}\)(\({}^{1}\Delta_{\text{g}}\)) [50; 51]. RB demonstrates a high quantum yield (\(\O\Delta\)) of 0.75 for O\({}_{2}\)(\({}^{1}\Delta_{\text{g}}\)) generation in water [52]; therefore, RB is widely used as photosensizers for conducting singlet oxygen reactions in aqueous media. A notable advancement in recent years has been the application of Rose Bengal as a photosensitizer immobilized on organic polymers as heterogenous photocatalysts with highly effective approach for the treatment of contaminated effluents [53] or the degradation of EPs [54; 55; 56; 57] under visible light irradiation. In fact, heterogenous photosensitizers with RB, which operate in the visible range, can address the major limitations of traditional photocatalysts like TiO\({}_{2}\), which are only active under UV radiation [58]. In this study, hydrophilic photoactive polymeric microparticles with covalently anchored RB were used as supported photosensitizers. The synthesis of these heterogeneous photocatalysts has been previously reported by our research group [59], as had their efficiency as photosensitizers in the evaluation of the repeated chemical transformations of a substrate through a mechanism involving chemical interaction and subsequent photocatalyst regeneration [59; 60].