Photocatalytic oxidation of aromatic aminocompounds in aqueous solutions and groundwater from abandoned military bases

Abstract

Experimental research into the photooxidation of aqueous solutions and polluted groundwater containing aromatic aminocompounds was undertaken. For the experiments with synthetic solutions, titanium dioxide under near-UV irradiation was selected as a photocatalyst, and aniline, p-toluidine and 2,4-xylidine were selected as model compounds. The photooxidative treatment of synthetic solutions was found to be more effective in acidic and strongly alkaline media. Methylated aminocompounds (p-toluidine, 2,4-xylidine) yield slightly better to photooxidation than aniline. The results obtained from experiments using model compounds were compared with the results of photooxidative purification of polluted groundwater from an abandoned military base in Estonia. Being heavily polluted, the groundwater yields better to photooxidation when diluted with potable water at a 7:3 ratio. Anatase, immobilised onto the surface of buoyant hollow glass microspheres, was less effective than when suspended in slurry. However, the immobilised photocatalyst enables water to be treated without the expense of constant stirring. This also avoids complications concerned with catalyst separation following treatment. Degussa P25 was more effective than Aldrich anatase both in stirred slurry type reactors and when attached to hollow glass microspheres.