Accelerated Fe3+/Fe2+ cycle using atomic H* on Pd/Al2O3: A novel mechanism for an electrochemical system with particle electrode for iron sludge reduction in the Fe2+/peroxydisulfate oxidation process
Zeng, Huabin; Zhao, Feiping; Park, Yuri; Sillanpää, Mika; Zhao, Xu (2019-09-27)
Post-print / Final draft
Zeng, Huabin
Zhao, Feiping
Park, Yuri
Sillanpää, Mika
Zhao, Xu
27.09.2019
Chemical Engineering Journal
382
Elsevier
School of Engineering Science
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2020052939699
https://urn.fi/URN:NBN:fi-fe2020052939699
Tiivistelmä
The high cost associated with the disposal of iron sludge in Fe2+ activated oxidation systems significantly limits their widespread use. In this study, we constructed a trace iron-based peroxydisulfate (PDS) oxidation system (Pd-EFP) using Pd/Al2O3 as the particle electrode and externally added PDS as an oxidant. At an initial solution pH of 3.0 and a current density of 3.33 mA/cm2, with the addition of 10 mM PDS, 50 mg Pd/Al2O3, and 2 mg/L Fe ions, 80.12% of 180 µM benzoic acid (BA) was degraded within 120 min. The Pd/Al2O3 catalyst provided sufficiently large surface area for atomic H* production from the adsorption of electrogenerated H2 or H+ conversion via electro-induction on the Pd/Al2O3 surface, which subsequently accelerated the transformation from Fe3+ to Fe2+. Using this method, organics could be degraded by both SO4·- and ·OH via the Fe2+-activated PDS process. In the Pd-EFP process, the optimal dosage of Fe ions was determined to be 36 μM (2 mg/L). Correspondently, the optimal current density and PDS concentration in the Pd-EFP system were 3.33 mA/cm2 and 20 mM, respectively. Furthermore, degradation of BA was efficiently promoted by the N2 atmosphere, which could steer the reaction on the surface of Pd/Al2O3 in the right direction toward Fe3+ reduction by atomic H*, by dispelling accumulated H2 above the reaction liquid and suppressing oxygen reduction. Finally, the Pd/Al2O3 catalyst was found to be durable in the Pd-EFP system according to reusability experiments and X-ray diffraction patterns of the fresh and used Pd/Al2O3 catalyst. This research provides an environmentally benign system for recycling Fe3+ in Fe2+/PDS processes and for suppressing iron sludge production.
Lähdeviite
Zeng, H., Zhao, X., Zhao, F., Park, Y., Sillanpää, M. (2020). Accelerated Fe3+/Fe2+ cycle using atomic H* on Pd/Al2O3: A novel mechanism for an electrochemical system with particle electrode for iron sludge reduction in the Fe2+/peroxydisulfate oxidation process. Chemical Engineering Journal, vol. 382. DOI: 10.1016/j.cej.2019.122972
Kokoelmat
- Tieteelliset julkaisut [1523]