Study of degradation of trimethoprim and sulfamethoxazole using hydrogen peroxide (H2O2) eletrogenerated by gas diffusion electrodes

Author(s)

Fernando Lindo Silva

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
• Defense date: 2013-02-25

Examining board members

Marcos Roberto de Vasconcelos Lanza; Eder Tadeu Gomes Cavalheiro; Christiane de Arruda Rodrigues

• Advisor: Marcos Roberto de Vasconcelos Lanza

Abstract

Currently the class of antibiotics is notable for the large consumption and also the risk to health when administered in error, this increase is due to the growing prominence of the pharmaceutical industry. Another issue to be addressed is the environmental contamination by substances that class, because after use by humans part of the concentration administered is naturally eliminated, thus being released into sewers and subsequently contaminating water bodies, the local fauna and flora. Thus, different methods has been proposed for the degradation of these compounds, using gas diffusion electrodes (GDE) capable of generating hydrogen peroxide in situ and in acid medium, precursors of hydroxyl radicals, responsible for degradation. We studied GDE\'s not catalyzed and catalyzed with different percentages of iron phthalocyanine II, with respect to the amount of peroxide produced better yield potential and kinetic process. The results revealed that the incorporation of 0.5% of Ft-Fe in the electrode showed the best results. This electrode was then chosen to perform the degradation of the antibiotic sulfamethoxazole and trimethoprim. In the electrochemical cell used in the Fenton process, the reactions occurred in a potential range (-0.4 V ≤ E ≤ -1.4 V) and in the reactor was used a fixed potential (-1.75 V) but using Fenton and photo-Fenton processes. Degraded samples were analyzed by analytical techniques, ultraviolet spectroscopy (UV), high performance liquid chromatography (HPLC) and total organic carbon content (TOC). The results showed that in the electrochemical cell, the best degradation potential was -1.1 V, with a reduction rate of 25.5% for trimethoprim and 96.0% for sulfamethoxazole and a decreased carbon content total of 10.4%. For the reactor the best result was obtained for the photo-Fenton process where there was a reduction of 16.9% of the total organic carbon content and a reduction of 99.7% of sulfamethoxazole and 11.3% of trimethoprim, in a potential of -1.75 V. Considering the formation of byproducts was drafted a route with the possible degradation compounds formed. (AU)

• FAPESP's process: 10/14025-7 - Electrochemical treatment of wastewater containing antibiotics: study of degradation of the trimethoprim and sulfamethoxazole
• Grantee: Fernando Lindo Silva
• Support Opportunities: Scholarships in Brazil - Master