Resorcinol-based carbon xerogel/ZnO composite for solar-light-induced photodegradation of sulfamerazine

Recently, the release of antibiotics, such as sulfonamides, into the environment has raised significant concern due to the potential creation of antibiotic-resistant bacteria. Thus, the development of remediation technologies for effluents containing such compounds is of utmost urgency. In this context, this work evaluated the creation of a resorcinol-based carbon xerogel/zinc oxide photocatalyst (XC/ZnO) to efficiently promote the photodegradation of the antibiotic known as sulfamerazine in aqueous media. The employment of this carbonaceous structure as a co-catalyst is justified by its high surface area and electrical conductivity. The methodology used in the synthesis of the composites was a simple one-pot reaction, combining the simultaneous precipitation of zinc oxide and polycondensation of the resorcinol-based carbon gel. Regarding the composites' characterization, X-ray diffractometry confirms that the composites have the Wurtzite structure of the zinc oxide, whereas the carbon xerogel formation is evidenced by the infrared, diffuse reflectance, and X-ray photoelectron spectroscopies. Morphology-wise, the XC/ZnO is arranged as nodular particle agglomerates, with particles between 500 nm and 50 nm. The photocatalytic tests under simulated solar radiation show that the composites developed are superior to the pure oxide in the photodegradation of sulfamerazine, as all XC/ZnO materials developed achieved higher apparent reaction rate constants (kapp) than pure zinc oxide, with the XC/ZnO 0.5 material obtaining a kapp 75% higher than the one observed for the ZnO sample. Furthermore, the chronoamperometry tests confirmed that the optimized composite (XC/ZnO 0.5) has a greater capacity for photocurrent generation when compared to pure zinc oxide. Therefore, the modification proposed was successful to enhance the photodegradation of sulfamerazine in aqueous media, highlighting the viability of the composites developed for photocatalytic applications.