A1 Journal article (refereed), original research

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


Open Access publication

Publication Details
Authors: Zeng Huabin, Zhao Xu, Zhao Feiping, Park Yuri, Sillanpää Mika
Publisher: Elsevier
Publication year: 2020
Language: English
Related Journal or Series Information: Chemical Engineering Journal
Journal acronym: Chem Eng J
Volume number: 382
ISSN: 1385-8947
eISSN: 1873-3212
JUFO-Level of this publication: 3
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2020052939699

Abstract

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.


Last updated on 2020-05-06 at 07:56