# Catalytic Advanced Oxidation Processes for Sulfamethoxazole Degradation
## 2 Materials and Methods
### Catalytic Tests  
All SMX degradation reactions were performed in the same photochemical glass reactor (60 mm diameter, 250 mm height). A glass reactor was chosen, since all processes studied can be performed in this kind of reactor. Therefore, it is possible to make an authentic comparison of the results. The initial SMX concentration used was 30 mg L\({}^{-1}\) at natural pH (\(\approx\)5.1). The initial SMX concentration selected for this study was 30 mg L\({}^{-1}\), to allow easier comparison between the different treatments and to study the mineralization degree by total organic carbon (TOC) measurements. The experiments were carried out at the natural pH of the initial solution (\(\approx\)5.1), avoiding adding additional chemicals for pH control. The pH and concentration used in this work were selected to clearly distinguish the different processes at the natural pH of the solution. If the experiments were carried out at lower concentrations, in the range of ng L\({}^{-1}\), the comparison between the different processes would not be accurate, especially in terms of mineralization degree. The reactor has 250 mL capacity, and the reactions were performed under a constant agitation of 400 rpm.  
In photoreactions, a Heraeus TQ150 medium pressure mercury vapor lamp was used as an irradiation source, delivering near-UV/Vis irradiation (\(\lambda>350\) nm; \(50\) mW cm\({}^{-2}\)). A recirculation glass jacket (Duran(r) 50, Mainz, Germany) placed around the lamp, with the main resulting emission lines at \(\lambda_{\rm exc}=365\), 405, 436, 546, and 578 nm. A UV-vis spectroradiometer (USB2000+, Ocean Optics, Winter Park, FL, USA) was used to measure the light intensity and photon flux. The obtained values of UV dose and photon flux were \(4.6\times 105\) mJ cm\({}^{-2}\) and \(9.7\times 1016\) photons cm\({}^{-2}\) s\({}^{-1}\), respectively.  
In all catalytic reactions, 125 mg of catalyst (optimal amount) was added. The collected samples were centrifuged for 15 min at 13.5 rpm using a VWR MicroStar 12 centrifuge to ensure the absence of suspended particles during analytic analysis.  
Ozone (O\({}_{3}\)) was generated from pure oxygen through a BMT 802X generator, and its concentration was monitored by a BMT 960 analyzer (BMT MESTECHNIK GMBH, Stahnsdorf, Germany). The O\({}_{3}\) flow rate and concentration used were of 150 cm\({}^{3}\) min\({}^{-1}\) and 50 g m\({}^{-3}\), respectively. The gas stream charging was carried out through a diffuser with 1 cm of diameter, and the O\({}_{3}\) gas, which had left the reactor, passed by washing bottles with potassium iodide (KI 20%). In all reactions where O\({}_{3}\) was not involved, O\({}_{2}\) was used to keep the same experimental conditions.  
In H\({}_{2}\)O\({}_{2}\)-based reactions, a theoretical stoichiometric amount of H\({}_{2}\)O\({}_{2}\) was added, determined by Equation (1), considering an excess of 50% (45.3 \(\mu\)L). Sodium sulfite (Na\({}_{2}\)SO\({}_{3}\)) was added to the samples collected in these reactions to ensure complete consumption of H\({}_{2}\)O\({}_{2}\) and stop the reaction, according to Equation (2).  
\[\mathrm{C_{10}H_{11}N_{3}O_{3}S+33H_{2}O_{2}\to 10 CO_{2}+36H_{2}O+H_{2}SO_{4}+3 HNO_{3}} \tag{1}\]  
\[\mathrm{Na_{2}SO_{3}+H_{2}O_{2}\to Na_{2}SO_{4}+H_{2}O} \tag{2}\]  
All individual processes were tested, in the presence and absence of catalysts, as well as all possible combinations of the three tested processes (O\({}_{3}\), light, and H\({}_{2}\)O\({}_{2}\)). The detailed information of non-catalytic runs with individual and combined processes was previously published [33].