Gliding Arc Discharge (GAD) assisted catalytic degradation of bisphenol A in solution with ferrous ions

The degradation of an endocrine disruptor (ED), the bisphenol A (BPA), was studied using Gliding Arc Discharge (GAD). This kind of discharge generates a non-thermal plasma at atmospheric pressure and quasi-ambient temperature. The resulting plasma is the source of several chemical reactions that lead to the hydroxyl radical formation. Hydroxyl radicals, (OH)-O-center dot, are very powerful and non-selective oxidizing agents (E-center dot OH/H2O degrees 2.8 V vs. normal hydrogen electrode) able to degrade compounds resistant to conventional treatment. GAD belongs to the group of advanced oxidation processes (AOPs). Under different working gases such as air, argon, oxygen/argon mixture (20/80, v/v), a BPA aqueous solution (120 mu M) was submitted to GAD. The evolution of BPA concentration was followed by high performance liquid chromatography (HPLC) method. The global oxidation of the organic matter was followed by chemical oxygen demand (COD) measurement. The mineralization was determined from the total organic carbon (TOC). The GAD treatment of the aqueous solution is accompanied by a massive production of hydrogen peroxide. The addition of Fe (II) to the reaction allows a better elimination of the organic matter through the production of additional (OH)-O-center dot radicals, issued from the decomposition of hydrogen peroxide according to Fenton reaction. The optimized system - GAD with oxygen/argon (20/80) as working gas, in presence of Fe (II) - was very efficient for BPA treatment: the compound disappeared after 30 min, the abatement of the COD was total after 120 min and the TOC diminished by 70%. (C) 2008 Elsevier B.V. All rights reserved.