Electrochemical degradation of amoxicillin in aqueous media

• Amoxicillin removal can be performed by electrocoagulation using an iron anode.
• Ultrasound waves inhibit the amoxicillin electrocoagulation.
• Electro-oxidation of amoxicillin is achieved on a reticulated vitreous carbon anode applying a 1.25 V potential.
• Electrocoagulation and electro-oxidation of amoxicillin can be modeled with a variable order kinetics.

Removal of some contaminants present in effluent water, like pharmaceuticals, has become a major issue. Amoxicillin is a very widely used antibiotic, but its natural metabolism inside the human body, makes that its concentration in excretions reach important levels. This leads to lofty rates contaminated water, mainly in the health care facilities effluents and some domestic wastewaters. The presence of this antibiotic in water can cause serious alterations in aquatic ecosystems. In order to avoid these harmful effects, the amoxicillin should be degraded. The current methods employed in the voidance of this drug are mainly chemical oxidation by Fenton reagents, flocculation and photochemical treatments, but its efficiency are still limited. In the present work, electro-assisted process has been performed, forming flocs that can trap into its structure the amoxicillin molecules. In this process, iron anode acts as provider for the non-soluble iron oxides, which are flocs promoters. Fenton reactions are not discarded, so these tests were also carried out, using an ultrasound probe improving the micro mixing, and accelerating the Fenton reagents formation. The amoxicillin elimination amount was more than 80% in a non-optimized electrochemical cell thanks to the flocs formation. Ultrasound seems to diminish the electrocoagulation process.