Iron (III) doped titanium dioxide coated dimensionally stable graphite anode electrode for electro-chemical treatment of domestic wastewater

Abstract

Availability of clean water is of concern due to pollution and diminishing supply pollution. However, purification is possible depending on the incorporated contaminants. Domestic wastewater contains dissolved organic matter and its remediation can be done by oxidation. The best oxidation can be achieved by electron transfer the same way metabolic processes occur. This study exploited the use of a film of iron (III) doped titanium dioxide applied on an electrode which was found to be effective. Natural light conditions generated electrons that migrated through the electrode leaving behind holes which oxidized the contaminants as the excess electrons were discharged at the cathode after passing through the casted proton exchange membrane (PEM) separating the two half cells of the prepared reactor. This electrochemical method has the advantage in that the organic pollutants are oxidized to carbon dioxide with no secondary pollutants and the inorganic pollutants into insoluble matter. The assembled cell was applied to purify both synthetic and real water samples of green leafy vegetable solution from the kitchen by clarification. The clarification process was monitored by UV-Vis using distilled water as a reference to compare the light that transmitted through a sample. It was observed that the electro-oxidation process took place showing a high potential 105 mV within the first 150 min followed by degradation at a high rate. The oxidation of the organic matter was confirmed by UV-Vis analysis as well as by cyclic voltametric analysis of iron released into the solution of the synthetic samples. The electro chemical treatment of the water was then applied to purify real water samples made from a sample of 4.5 g minced of green vegetables dispersed in one liter of water (4.5 g/l). The green leafy coloured solution was clarified after 154 h of continuous oxidation. The degradation process was confirmed to be independent of intermediates or other species present in solution as it was of first order reaction kinetics. The electrochemical oxidation of organic matter in water using iron (III) doped titanium dioxide coated graphite electrode has potential application on the purification of water.

Keywords: Domestic; Electrochemical cell; Oxidation; Pollution; Proton exchange membrane; Wastewater.

Figure 1

The experimental working of the electrochemical cell setup assembled.

Figure 2

UV–Vis characterization of A and B pure and Fe (III)-doped TiO₂ respectively POTENTIAL/mv.

Figure 3

The variation of potential difference of the electrochemical H⁺ H⁺.

Figure 4

The results of electro-oxidation of dissolved organic matter with time.

Figure 5

The results of UV-Vis absorbance data plotted against time-(A) Degradation kinetics and (B) Time dependent clarification of the wastewater.

Figure 6

First and second order degradation kinetics.

Figure 7

Results of starch iodine complex of the dissolved organic matter.

Figure 8

The cyclic voltamograms of the wastewater under oxidation in the electrochemical treatment.