DSA electrochemical treatment of olive mill wastewater on Ti/RuO2 anode

Abstract

The electrochemical oxidation of olive mill wastewater (OMW) over a Ti/RuO 2 anode was studied by means of cyclic voltammetry and bulk electrolysis and compared with previous results over a Ti/IrO 2 anode. Experiments were conducted at 300-1,220 mg L -1 initial chemical oxygen demand (COD) concentrations, 0.05-1.35 V versus SHE and 1.39-1.48 V versus SHE potential windows, 15-50 mA cm -2 current densities, 0-20 mM NaCl, Na 2 SO 4 , or FeCl 3 concentrations, 80°C temperature, and acidic conditions. Partial and total oxidation reactions occur with the overall rate being near first-order kinetics with respect to COD. Oxidation at 28 Ah L -1 and 50 mA cm -2 leads to quite high color and phenols removal (86 and 84%, respectively), elimination of ecotoxicity, and a satisfactory COD and total organic carbon reduction (52 and 38%, respectively). Similar performance can be achieved at the same charge (28 Ah L -1 ) using lower current densities (15 mA cm -2 ) but in the presence of various salts. For example, COD removal is less than 7% at 28 Ah L -1 in a salt-free sample, while addition of 20 mM NaCl results in 54% COD reduction. Decolorization of OMW using Ti/RuO 2 anode seems to be independent of the presence of salts in contrast with Ti/IrO 2 where addition of NaCl has a beneficial effect on decolorization.

Electrochemical oxidation of trace organic contaminants in reverse osmosis concentrate using RuO2/IrO2-coated titanium anodes

“…The largely incomplete oxidation by FAC for some of the compounds and unexpectedly rapid disappearance of others known to react slowly with chlorine suggest that other oxidants in the bulk and/or surface reactions may play an important role. Besides reacting in the bulk, chlorine can react electrochemically at the anode forming adsorbed chloro-and oxychloro-radicals, which mediate the degradation of adsorbed organics (Bergmann and Koparal, 2005a;Papastefanakis et al, 2010). Moreover, electrogenerated O 2 can indirectly oxidize the bulk organics and form organic radicals via the hydrogen abstraction mechanism (Carlesi Jara et al, 2007).…”

Electrochemical degradation of Reactive Red 120 using DSA and BDD anodes

“…The RuCl 3 precursor, before the dilution in isopropanol, was stirred and heated at 80°C for 24 h in a 10% HCl solution. Procedures for the titanium substrate pretreatment and anode deposition are described in previous works [43,44]. The final IrO 2 -RuO 2 loading was 0.5 mg cm -2 while the geometrical surface area was 12.5 cm 2 .…”

Research Trends in Doping Methods on TiO₂ Nanotube Arrays Prepared by Electrochemical Anodization

“…For example, Wei and co-workers prepared (Ru0.3Ti0.34Sn0.3Sb0.06)O2 catalyst based on RuO2 on TiO2 nanotubes for achieving ion selectivity of CER(Chlorine Evolution Reaction) [47,48]. As a precursor, RuCl3, C16H36O4Ti, SnCl4 and SbCl3 were dissolved in iso-propanol with a proper ratio and subsequently it was brushed on as-prepared TiO2 nanotube electrodes evenly.…”