Electrocoagulation using stainless steel anodes: Simultaneous removal of phosphates, Orange II and zinc ions

Adelaide Dura; Carmel B Breslin

doi:10.1016/j.jhazmat.2019.04.032

Electrocoagulation using stainless steel anodes: Simultaneous removal of phosphates, Orange II and zinc ions

J Hazard Mater. 2019 Jul 15:374:152-158. doi: 10.1016/j.jhazmat.2019.04.032. Epub 2019 Apr 9.

Authors

Adelaide Dura¹, Carmel B Breslin²

Affiliations

¹ Department of Chemistry, Maynooth University, Maynooth, County Kildare, Ireland.
² Department of Chemistry, Maynooth University, Maynooth, County Kildare, Ireland. Electronic address: carmel.breslin@mu.ie.

PMID: 30999138
DOI: 10.1016/j.jhazmat.2019.04.032

Abstract

Two stainless steel anodes, AISI 420 and AISI 310, and pure iron were compared in an electrocoagulation study for the simultaneous removal of phosphates, Orange II and Zinc ions from a synthetic wastewater at a current density of 11.7 mA cm^-2 and a surface area to volume ratio of 19.4 m^-1. High removal efficiencies were observed with AISI 420 and pure iron, reaching values between 88% and 99%, while significantly lower values, approximately 30%, were obtained with AISI 310. The AISI 310 performed well in the removal of Zn²⁺ due to its removal as Zn(OH)₂. The variations in the performance of the steel anodes were attributed to the lower chromium content of the AISI 420, which gives less passive behaviour. This was supported using polarisation data, where a 10-fold increase in the corrosion current was obtained for AISI 420 compared to AISI 310. Furthermore, Cr(VI) was observed in the solution phase when AISI 310 was employed as the anode, illustrating the importance of the alloying concentrations. While rust particles were seen during the non-continuous use of the iron anode, they were not observed with the AISI 420 anode.

Keywords: Chromium content; Dyes; Electrocoagulation; Phosphates; Stainless steel; Zinc ions.

Publication types

Research Support, Non-U.S. Gov't