Electrochemical treatment of shrimp farming effluent: role of electrocatalytic material.

This study investigated the electrochemical oxidation of organic matter present in shrimp farming effluent using three types of electrocatalytic materials: Ti/Ru0.34Ti0.66O2, Ti/Pt, and boron-doped diamond (BDD). An electrochemical cell with 300 mL under stirring agitation was used by applying 20, 40, and 60 mA cm-2. A Ti/Ru0.34Ti0.66O2 anode showed a reduction of chemical oxygen demand (COD) about 84 % after 1 h of electrolysis, while at the same time, 71 % of COD decay was achieved at Ti/Pt. Conversely, only 71 % of COD was removed after 2 h with a BDD anode. Regarding the temperature effect, BDD showed better performances than those achieved for Ti/Ru0.34Ti0.66O2 and Ti/Pt anodes during an electrochemical treatment of a shrimp farming effluent, obtaining 72 % of COD removal by applying 20 mA cm-2 at 40 °C after 15 min. Energy consumption and cost were estimated in order to established the engineering applicability of this alternative process.

Electrochemical removal of synthetic textile dyes from aqueous solutions using Ti/Pt anode: role of dye structure.

In this work, the efficiency of electrochemical oxidation (EO) was investigated for removing a dye mixture containing Novacron Yellow (NY) and Remazol Red (RR) in aqueous solutions using platinum supported on titanium (Ti/Pt) as anode. Different current densities (20, 40 and 60 mA cm(-2)) and temperatures (25, 40 and 60 °C) were studied during electrochemical treatment. After that, the EO of each of these dyes was separately investigated. The EO of each of these dyes was performed, varying only the current density and keeping the same temperature (25 °C). The elimination of colour was monitored by UV-visible spectroscopy, and the degradation of organic compounds was analysed by means of chemical oxygen demand (COD). Data obtained from the analysis of the dye mixture showed that the EO process was effective in colour removal, in which more than 90% was removed. In the case of COD removal, the application of a current density greater than 40 mA cm(-2) favoured the oxygen evolution reaction, and no complete oxidation was achieved. Regarding the analysis of individual anodic oxidation dyes, it was appreciated that the data for the NY were very close to the results obtained for the oxidation of the dye mixture while the RR dye achieved higher colour removal but lower COD elimination. These results suggest that the oxidation efficiency is dependent on the nature of the organic molecule, and it was confirmed by the intermediates identified.