Abstract:
Contamination of waterways with micropollutant chemicals is a growing worldwide
environmental problem. Micropollutants are a broad array of compounds including
pharmaceutical actives, pesticides, industrial chemicals, PCBs and many others which are
united by the property of causing numerous severe health and developmental issues in both
humans and animals at parts per billion or even parts per trillion concentrations. The largest
point sources of micropollutant contamination of surface waters are the effluents from
industrial and municipal wastewater treatment plants. Current water treatment processes fail
to adequately remove the majority of micropollutants, with some passing through completely
unabated. The aim of this work was to develop a novel catalytic micropollutant removal film,
incorporating electrochemistry as one component.
Previous work in this area indicated that a film of tertiary amine-functionalised
polychloromethylstyrene deposited on a porous backing material was capable of retaining the
Fe-TAML oxidation catalyst, FeB*, which is converted into a powerful oxidant in the
presence of aqueous hydrogen peroxide. It has been demonstrated that such films are capable
of removing micropollutants from aqueous solutions. The main aims of this study were to
extend the previous work by further developing the films’ compositions and by employing
electrochemistry to obviate the need to independently supply a solution of hydrogen peroxide
to the film. Three different approaches were undertaken to achieve these aims. In the first
approach, the conducting polymer polyaniline was employed to make electrically conductive
films. After impregnation with the FeB* catalyst, a potential was applied to the film in an
attempt to directly oxidise FeB* to its active form. The second approach involved generating
hydrogen peroxide by electrochemical reduction of oxygen gas at the surface of a graphite based electrode. This alternative source of hydrogen peroxide was used in conjunction with
an FeB*-impregnated film of triethanolamine-functionalised polychloromethylstyrene for
substrate oxidation tests. In the third approach, a flexible graphite-based electrode material
was applied directly to the surface of a triethanolamine-functionalised
polychloromethylstyrene film containing FeB*. Hydrogen peroxide was generated by
electrolytic reduction of a stream of oxygen gas in close proximity to its point of use within
the film.