Electrochemical degradation of sulfonated amines on SI/BDD electrodes

The electrochemical oxidation of aniline (AN) and ortanilic (OA), metanilic (MA) and sulfanilic (SA) acids was performed using as anode a boron-doped diamond (BDD) electrode. Tests were performed with model solutions of the different amines, with concentrations of 200mg L(-1), using as electrolyte 0.035 M Na2SO4, in a batch cell, with re-circulation, at different current densities (200 and 300 A m(-2)). Samples were collected at pre-selected intervals and absorbance measurements, Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Total Kjeldahl Nitrogen, Ammonia Nitrogen, Nitrates and Nitrites and HPLC analysis were performed. Results have shown a good elimination of the persistent pollutant, with COD and TOC removals always higher than, respectively: AN--91% and 90%; OA--75% and 82%; MA--88% and 87%; and SA--85% and 79%. The combustion efficiencies, calculated for the first hour of the runs, for the 300 A m(-2) assays, were the following: AN--0.93; OA--0.28; MA--0.82; and SA--0.83. For all the amines studied, after 6h degradation only oxalic and maleic acids were identified by HPLC.