Electrochemical degradation of triclosan in aqueous solution. A study of the performance of an electro-Fenton reactor

Abstract

Graphical abstract

Study of polarized activated carbon filters as simultaneous adsorbent and 3D-type electrode materials for electro-Fenton reactors

“…Using the reactor shown in Fig. 1 and the information reported by Fernández et al (2018), García-Espinoza et al (2019) and Robles et al (2020), a potential difference of 8 V (corresponding to 0.5 A), a concentration of Fe(II) of 2 mM and a flow rate of 30 mL min −1 , were selected to find out the polarization period of time that maximized the concentration of • OH produced from the Fenton mixture (Fe(II) and H 2 O 2 that results from O 2 reduction at the cathodic surface) [ [21] , [22] , [23] ]. Since the • OH lifetime is rather short (approximately 40 μs [ 30 ]), indirect methods based on scavengers have been developed for its quantification.…”

“…1 a). As described by Fernández et al (2018) and García Espinoza et al (2019) [ 21 , 22 ], the reactor consists of three cylindrical pieces interconnected in series using stainless steel screws (see Fig. 1 b).…”

“…While the central compartment (C 2 ) contains a packed bed of polarized AC (of either vegetal or mineral origin) positioned between two graphite clothes that worked as electrical contacts for polarization purposes (e 1 and e 2 with a geometric surface area of 4.91 cm 2 and an inter-electrode distance of 6.5 cm), compartments C 1 and C 3 were filled up with cation exchange resins. While the compartment adjacent to the cathodic side of C 2 was loaded with Fe(II) and acid as has been previously described [ 21 , 22 ], the other compartment, positioned on the anodic side, contained resin previously exchanged with Na + cations. The volume of solution treated in electrochemical experiments using this reactor was 250 mL which were pumped in continuous recirculation mode at a flow rate of 30 mL min −1 under a cyclic scheme (see Table 1 ) in which adsorption and polarization sequential stages take place [ 21 , 22 ].…”

“…While the compartment adjacent to the cathodic side of C 2 was loaded with Fe(II) and acid as has been previously described [ 21 , 22 ], the other compartment, positioned on the anodic side, contained resin previously exchanged with Na + cations. The volume of solution treated in electrochemical experiments using this reactor was 250 mL which were pumped in continuous recirculation mode at a flow rate of 30 mL min −1 under a cyclic scheme (see Table 1 ) in which adsorption and polarization sequential stages take place [ 21 , 22 ]. During the polarization stage, 0.5 A (corresponding to about 8 V) were applied between e 1 and e 2 using a power source.…”

“…From EF studies using this arrangement, we have showed that it is possible to effectively treat aqueous effluents contaminated with dyes [ 21 ], recalcitrant contaminants [ 22 ] and the full inactivation of pathogens such as E. Coli and Helminth Ova [ 23 ]. We have also reported some important aspects of the characteristics that define the performance of the AC in this reactor and although we have explored the adsorption regeneration properties, the cathodic protection [ 24 , 25 ] and the influence of the carbon particle density on the electrical conductivity of the AC packed bed compartment [ [21] , [22] , [23] , 26 ], there are still some important questions such as the influence of the AC source, size and pre-treatment process before the AC material is used in the EF treatment reactor. It is in this context that we present a report on the results of a study in which we assess the effect that some of these AC related variables exert on the performance of the EF reactor shown in Fig.…”