Electrocoagulants Characteristics and Application of Electrocoagulation for Micropollutant Removal and Transformation Mechanism.

Abstract

Predominantly, the removal of dissolved contaminates via the Fe electrocoagulation (EC) process depends on the electrocoagulants stability, specific area, porosity, dissolution rate, and phase transformation kinetics. The present investigation elucidates the role of applied currents and electrolyte counteranions on the crystalline phase and surface topography of electrocoagulants generated from Fe EC. Moreover, the dissolved contaminant micropollutant removal efficiency was also evaluated by electrochemically produced coagulants. This study confirms that mixed-phase iron (oxyhydr) oxide nanostructures were consistently produced from Fe EC with predominant formation of the goethite phase. The applied current controls the morphology of the coagulants, with flake-like morphology observed with currents at and below 100 mA and spherical morphology observed with currents above 100 mA. The counteranions in the electrolyte also impacted the morphology with spherical, nanosheet, and nanorod morphologies produced by Cl- or SO42-, CO32-, and HCO3- counteranions, respectively. BET analysis revealed the formation of electrocoagulants with micro-, meso-, and macropores. Surface area was markedly reduced from 142.85 to 41.96 m2 g-1 by incident coagulation resulting from increased anodic dissolution. Applicability of the electrocoagulant was examined by different micropollutants (acetaminophen (AC), antipyrine (AT), and atenolol (AT)). Results suggest that >90% and >80% TOC reduction were achieved with Na2CO3 and NaHCO3 as electrolyte media. The lower TOC reduction was rationalized by the identified intermediate products, and possible micropollutant degradation pathways were proposed based on LC-MS/MS analysis.