A comparative study of the degradation efficiency of chlorinated organic compounds by bimetallic zero-valent iron nanoparticles

Abstract

The efficacy of zero-valent iron nanoparticles (nZVI) in degrading aquatic pollutants could be enhanced by the deposition of other metals on their surface. This article describes the synthesis of bimetallic nZVI with palladium (nZVI/Pd), nickel (nZVI/Ni), silver (nZVI/Ag), and copper (nZVI/Cu). The obtained bimetallic nZVIs were used in the degradation of chlorinated volatile organic compounds (CVOC) such as vinyl chloride (VC), 1,2-dichloroethylene (DCE), trichloroethylene (TCE), and perchloroethylene (PCE) in spiked water and real groundwater. Bimetallic nZVIs demonstrated superior degradation efficiencies compared to pristine nanoparticles. While pristine nZVI degraded ∼6%, ∼57%, and ∼26% of DCE, TCE, and PCE (25 mg L⁻¹, spiked water), respectively, nZVI/Pd and nZVI/Ni degraded all the contaminants completely within 24 h. In addition, nZVI/Pd and nZVI/Ni demonstrated better degradation efficiencies as compared to nZVI/Ag and nZVI/Cu. This efficiency of nZVI/Pd and nZVI/Ni was further observed in the contaminant mixture (total CVOC concentration 25 mg L⁻¹, 24 h of degradation time frame) as well as real groundwater (taken from Novy Bydzov locality). These bimetallic nZVIs demonstrated a significant increase in the degradation efficiency (from ∼10% using pristine nZVI to 99.9% using nZVI/Pd or nZVI/Ni). Even in groundwater, which contains numerous interferants such as organic acids and sulfate anions, bimetallic nZVI/Pd, and nZVI/Ni showed excellent degradation efficiency towards PCE [complete degradation when using nZVI/Pd or nZVI/Ni (24 h)]. Both nZVI/Ag and nZVI/Cu showed only a minor improvement in degradation efficiency.