The rate and efficiency of iron generation in an electrocoagulation system

Abstract

The rate and efficiency of iron generation in a bench-scale electrocoagulation (EC) system was investigated when variations were made to operating voltage, cathode material and electrolyte composition. Two electrolytes were tested, one with organic compounds (naphthalene, acenaphthene and 4-nonylphenol) and one without. While aromatic structures often make good corrosion inhibitors, in this case they had no discernible effect. This is a positive indicator that EC systems will not have adverse effects when treating wastewaters associated with oil and gas production. Using a stainless steel cathode rather than an aluminium one resulted in 35% more production of iron at the anode per volt per minute; it also resulted in greater iron production given equivalent quantities of power. This occurred because the rate-limiting hydrogen evolution reaction at the cathode occurs more quickly on iron than on aluminium. It was also observed that the EC system (using either cathode) produced more iron per unit power when operated at lower voltages. At lower voltages, the corrosion that occurred spontaneously in the absence of an applied current contributed more significantly to the total amount of iron released. This research suggests that it is more efficient to design EC systems using iron-based cathodes rather than aluminium ones. It also indicates that it is more energy efficient to use more electrodes at low power, rather than fewer electrodes at high power.

Regeneration of As(V)‐loaded granular activated carbon through electrocoagulation

“…It is demonstrated that regeneration efficiency increases both with electrocoagulation time and current density. This is explained by Faraday's law, as generation of the adsorbent is affected linearly by both the applied current and the electrocoagulation time (Lee & Gagnon, 2015). At higher current densities and reaction times, it becomes apparent that both lead to diminishing returns, with a maximum regeneration of 85.3% under these parameters.…”

“…It is demonstrated that, within the tested range, a higher current density leads to a faster removal. Higher current densities lead to an increased generation of both iron and hydroxyl ions, as explained by Faraday's law (Lee & Gagnon, 2015). The Fe concentration during electrocoagulation was measured, also featured in Figure 4.…”

Power Electronic Pulse Generators for Water Treatment Application: A Review

“…Nowadays, as a relatively mature technique for water treatment, electrolysis is common used to deal with the wastewater containing cyanide and chromium. The typical application is the treatment of printing and dyeing wastewater, tannery wastewater, papermaking wastewater and so on [7,8].…”