Diamond cylindrical anodes for electrochemical treatment of persistent compounds in aqueous solution

Abstract

Boron-doped diamond (BDD) films were deposited onto either silicon or niobium cylindrical substrates with areas up to 35 cm^2 for electrochemical applications. BDD electrodes were characterised in terms of their material and electrochemical properties by scanning electron microscopy, Raman spectroscopy and linear sweep voltammetry. These characterisation techniques indicated conductive polycrystalline BDD with low quantities of non-diamond carbon impurities. Electrochemical oxidations of pharmaceutical compounds were performed using these cylindrical electrodes and monitored by UV/Vis spectroscopy, chemical oxygen demand and total organic carbon. Mixtures of chlortetracycline, oxytetracycline and diclofenac were electrolyzed on a 9.42 cm^2 (∅ = 6 mm, h = 50 mm) cylindrical Si/BDD anode using a current density of 8.2 mA cm^−2. Ibuprofen was electrolyzed on an 18.0 cm^2 (∅ = 10 mm, h = 60 mm) cylindrical Nb/BDD anode using a current density of 25 mA cm^−2. Cylindrical-shape diamond electrodes present several advantages with respect to conventional plate-shape BDD electrodes such as handling, sealing and cell assembly. The obtained results show that BDD cylindrical anodes are promising for electrochemical wastewater treatment.