# Heterogeneous Electro-Fenton-like Designs for the Disposal of 2-Phenylphenol from Water
## 1 Introduction  
Nowadays, the need for various organic compounds to facilitate people's daily lives, such as pesticides, pharmaceuticals, cosmetics, etc., is a reality. Among these organic compounds, pesticides stand out because their use is essential to ensure the production and quality of foodstuffs demanded by the population [1, 2, 3]. In this study, the fungicide 2-phenylphenol, also called ortho-phenylphenol, has been chosen, which belongs to the hydroxybiphenyl chemical family [4]. The use of the fungicide 2-phenylphenol is mainly as disinfection, but it is also bactericide and virucide. As an example, in hospitals, shops and industries, it is generally used to disinfect surfaces and equipment, and in agriculture, it could be used to disinfect fruits, especially citrus fruits and pears, vegetables and eggs [5, 6, 7]. However, having all these advantages, the main problem is its appearance and persistence on the surface, such as food paper packages and canned soft drinks and aquaticenvironmental compartments [5]. In fact, since the early 2000s, it has been tracked down at low levels, in several environments: marine sediments and urban wastewaters [8], in sewage sludge (63-172 ug/kg), surface water (47 ng/l) and river sediments (2-69 ug/kg) from diverse streams and rivers in the state Baden-Wurttemberg (Germany) [9] or Bouregreg River (Morocco) at a concentration range of 54-257 ng/L [10]. According to the revision made, in 2003, by the World Health Organization (WHO), the permissible level in drinking-water is 0.1 mg/L, at which toxic effects can be expected, was calculated from the acceptable daily intake (ADI) for humans of 0.4 mg/kg of body weight and this data has not been updated [11]. Recently, interesting research evaluated the effects of pesticides on humans, specifically on the younger population [12]. In this study, 703 infants were selected, who are under 1-year-old, and young children, being between 1 and 3 years old. It was noted that in more than 5% of them, pesticides could be detected, and the most common pesticide detected was 2-phenylphenol (18%). Several studies have reported its acute and chronic toxicity to creatures [5; 11; 13; 14]. Indeed, the acute toxicity (LD50/LC50) in rats and mice have been determined in a range of concentration of 2880-3600 and 3152-3499 mg/kg body weight, respectively [13]. In addition, other studies determined that, when rats were fed with 2-phenylphenol level of 0.5-4% in their diet, they suffer urinary bladder carcinoma [5]. These reported drawbacks encourage progress in emerging technologies to reduce this kind of pollutants from aquatic environmental compartments. These approaches include advanced oxidation processes stand out since they are green processes and very effective in the reduction of organic pollutants [15; 16; 17; 18]. In addition, these types of processes can be performed in homogeneous and heterogeneous systems [19; 20]. Within each of these classes, multiple types can be also found, making advanced oxidation processes very versatile. Among them, electrochemical processes based on the use of electrical energy for the generation of radicals, such as hydroxyl, sulphate, etc., which have a high oxidising capacity and make it possible to break the bonds that form the molecules of these organic compounds [15; 21]. Amongst, the electro-Fenton process represents an encouraging technology able to generate in situ hydrogen peroxide via cathodic reduction of oxygen (Equation (1)) and the generation of hydroxyl radical by Fenton reaction between the ferrous ion and hydrogen peroxide (Equation (2)) and the regeneration of ferric ion to ferrous ion on cathode (Equation (3)) to maintain the catalytic cycle of [PERSON]'s reaction [15; 21].