# Electrodegradation of Selected Water Contaminants: Efficacy and Transformation Products
## 1 Introduction  
### _1.1. Dibutyl Phthalate_  
Phthalate esters are dialkyl or aryl-alkyl diesters of \(o\)-phthalic acid. Their global production is estimated at approximately 8.1 million tonnes per year, while annual consumption in 2021 was approximately 3.6 million tonnes [1]. Medium and high molecular weight phthalic acid esters are mainly used in the industries as plasticizers to increase the durability, flexibility, and extensibility of polymer materials [2] and their share in theEuropean plasticizer market is around 75% [3]. Low molecular weight phthalates such as dimethyl phthalate, diethyl phthalate, and dibutyl phthalate (DBP) are also used as pesticides and in printing, cosmetics, and personal care products [4]. Given its wide range of applications, DBP can enter the environment in various ways, including through the leaching of plastic waste, through wastewater discharges from various industries and households, and through release from polymer films due to the breakdown of weak intermolecular forces [5]. DBP is classified as a Substance of Very High Concern (SVHC) due to its endocrine-disrupting properties, reproductive toxicity, very high toxicity to aquatic life, and ongoing assessment as a persistent, bioaccumulative, and toxic substance [6] and the European Commission banned it in 2020 in all products in concentrations \(\geq 0.1\%\)[7].  
The removal of DBP represents a significant environmental challenge, and various methods have been applied for its removal, such as adsorption, photocatalysis, membrane technology, electrochemical technology, and microbiological degradation [2]. Many phthalates cannot be completely removed by conventional methods, so advanced technologies or a combination of technologies are resorted to. For the removal of DBP by electrochemical oxidation, different electrode combinations were used, such as boron-doped diamond (BDD)-stainless steel [8; 9; 10; 11; 12], graphite-stainless steel [9], Ce-doped Ti/PbO\({}_{2}\), saturated calomel electrode, and platinum [10]. These processes resulted in different DBP degradation efficiencies of 74.7%, 61.75%, and 98.2%, respectively. A study [11] investigated the feasibility of using photocatalysis followed by electrocatalytic oxidation to remove DBP from an aqueous solution. This combination achieved 40% higher total organic carbon (TOC) removal compared to electrocatalytic oxidation alone, resulting in a degradation efficiency of 99.5%. Another study showed that electrocatalytic oxidation with an IrO\({}_{2}\)-Ta\({}_{2}\)O\({}_{5}\)/Ti electrode as the anode and a graphite cathode could achieve the same DBP removal efficiency (90%) as photocatalysis, but with approximately twice the treatment time and electricity consumption [12]. The electro-Fenton (EF) process with a sacrificial electrode could effectively remove DBP from wastewater with a degradation rate of 93.07% [13]. By using a bimetallic catalyst modified with aluminium in the EF process, where platinum wire was used as the anode and carbon felt as the cathode, an even higher DBP removal rate (97.1%) was achieved [14]. A more detailed overview of these research papers can be found in the Supplementary Materials (S1: Table S1a) [8; 9; 10; 11; 12; 13; 14].