Oxidation of chloramphenicol compound by heterogenous electro-fenton method using layered double hydroxide catalysts

Chloramphenicol is a broad-spectrum antibiotic and is widely used due to its low cost. Since the majority of pharmaceutical drugs such as chloramphenicol are non-biodegradable, they exist the surface waters unchanged form after conventional treatment methods. These types of compounds have negative effects on aquatic organisms and human beings depending on the food chain. At the same time, human treatment becomes more difficult due to antibiotic resistance developed by bacteria. Therefore, more effective oxidation methods are needed for the contaminants such as pharmaceuticals. Electro-Fenton method is one of the electrochemical advanced oxidation methods based on the production of reactive oxygen radicals. In this study, oxidation of chloramphenicol compound was carried out by electro-Fenton method using synthesized FeIIFeIII, NiIIFeIII and CoIIFeIII layered double hydroxide catalysts. All three heterogeneous catalysts were shown to be more efficient at pH 3, while at pH 5 the oxidation efficencies declined. After the homogenous Fenton-type reactions of the metal ions that entered the solution due to some dissolution at pH 3, the oxidation efficiency rose. The GO-FeIIFeIII catalyst, which was created by layering double hydroxide FeIIFeIII catalyst over the graphene oxide surface at a loading rate of 10% by mass, was found to be more effective in promoting mineralization and degradation at pH 5 than the FeIIFeIII catalyst. While GO-FeIIFeIII catalyst dosage was 1 g/L, 100% degradation of chloramphenicol was achieved at a initial concentration of 40 mg/L after 60 minutes of Electro-Fenton treatment at pH 5 and 300 mA current. When the chloramphenicol concentration was 10, 20, 40 mg/L, the mineralization yields obtained under the same treatment conditions were 78%, 58%, and 54%, respectively.