Effectiveness of AOP's on abatement of emerging pollutants and their oxidation intermediates: Nicotine removal with Fenton's Reagent

Recently more attention has been paid to emerging pollutants in water. Among the treatments proposed for abatement of these compounds Advance Oxidation Processes (AOPs) have been used. Many studies are focused on elimination of the original pollutant and TOC while less attention has been paid for generated oxidation intermediates and their associated toxicity.In this work nicotine was used as target pollutant and Fenton's Reagent (FR) as AOP. Nicotine and TOC conversion were obtained and an estimation of the toxicity of the oxidation intermediates produced was determined by using Microtox. Reactions were carried out in a batch manner, at two different temperatures (20 and 50 °C), using different amounts of hydrogen peroxide (5% to 200% of the stoichiometric dosage required for complete mineralization). Complete nicotine removal was achieved with FR at low oxidant doses even at 20 °C. However, only about 60% TOC percent removal was achieved. Moreover some toxic intermediates were generated, especially at initial oxidation stages. For example, for nicotine conversion 80% and TOC conversion 10%, toxicity obtained was fifteen times higher than the initial one. This must be taken into account in order to elucidate the time required and the effectiveness of the process.

► Complete nicotine removal was achieved with Fenton's Reagent even at low H2O2 dosages.
► About 60% of the initial TOC was removed employing the highest H2O2 dosage.
► Nicotine was not directly oxidized to CO2 but some intermediates were generated.
► Toxic intermediates were generated at initial oxidation stages.
► Not only pollutant removal but also these toxic intermediates must be considered.