A reactor with a packed bed anode assembly for studying Electro-Oxidation processes.

SILVA BARNI, MARÍA F.; RODRIGUEZ, CARMEN; PROCACCINI, RAÚL A.; AYUDE, M. ALEJANDRA

Congreso; WCCE11 - 11th WORLD CONGRESS OF CHEMICAL ENGINEERING; 2023

The commercially available ceramics based on a mixture of sub-stoichiometric titanium oxides (TinO2n-1, 4≤n≤10), known as Magnéli phases (Ebonex®) have gained interest as promising working electrodes for the electrochemical degradation of diverse organic pollutants mainly due to their high electrical conductivity (~1000 S.cm-1), chemical stability in a wide range of media, high oxygen evolution potential, and relatively low manufacturing costs. . In a previous study, laminar Ti4O7 porous platforms were evaluated as anodes in the Electro-Oxidation process (EO). Enhanced EO activity and lower specific energy consumption were attained when the liquid was recirculated through the lamellar structure of the electrodes.In this work, a reactor with a packed bed anode assembly was investigated in the EO of Orange G (OG) solutions (0.23 mM). The electrochemical behavior of the system was preliminarily evaluated by a cyclic voltammetry performed between -1.5 and 2.0 V at 20 mV s-1 of scan rate, in a tree-electrode cell setup, using a saturated calomel electrode (SCE) as reference, and two Pt foils as working and auxiliary electrodes. Voltammograms for OG at pH 2.8, 3.81 and 5 showed no Faradaic peaks below 1.8 V that may interfere with the EO process studied at the reactor. Experiments were conducted in a batch recycle up-flow tubular reactor using a power supply under galvanostatic conditions at room temperature. A Ti mesh and a Pt/Ti mesh (30 × 30 mm) were employed as cathode and anode collector, respectively with a distance of 8 mm in between. The electrical contact was attained by gluing each mesh to a Ti wire.Anode and cathode potential were measured against a SCE located at the reactor entrance. About 4g of Ebonex® powder, provided by QuanVerge Inc., were packed around the anode collector with the aid of two polypropylene cloths. The inlet liquid flow rate was set to 0.2 L·h−1. The discoloration and chemical oxygen demand removal rates were notoriously improved with the addition of powder. The system exhibited very good stability along 7 cycles of 5 h reaction. Results highlighted the need of monitoring and controlling the anodic potential in a two-electrode reactor supplied by a power system to maintain electrochemical activity in successive cycles of reaction. The influence of different packed bed weights on the system performance is currently being explored.