Insights into the role of nanoscale zero‐valent iron in Fenton oxidation and its application in naphthalene degradation from water and slurry systems

Abstract

Few researches have focused on the role of nanoscale zero‐valent iron (nZVI) in Fenton‐like process for polycyclic aromatic hydrocarbons (PAHs) removal. In this study, the naphthalene (NAP) degradation tests in ultrapure water showed that nZVI addition could enhance NAP degradation from 79.7% to 99.0% in hydrogen peroxide (H2O2)/Fe (II)/nZVI/NAP system at the molar ratio of 10/5/3/1, showing the excellent role of nZVI in promoting NAP removal. Multiple linear regression analysis found that the correlation coefficient between H2O2 consumption and NAP degradation was converted from −9.17 to 0.48 with nZVI and 1‐mM H2O2, indicating that nZVI could decompose H2O2 more beneficially for NAP degradation. Multiple Fe (II)‐dosing and iron leaching tests revealed that nZVI could gently liberate Fe (II) and promote Fe (II)/Fe (III) redox cycle to enhance the NAP degradation. When the H2O2/Fe (II)/nZVI/NAP molar ratios of 10/5/3/1 and 50/25/15/1 were applied in the simulated NAP contaminated actual groundwater and soil slurry, respectively, 75.0% and 82.9% of NAP removals were achieved. Based on the major degradation intermediates detected by GC/MS, such as 1,4‐naphthalenedione, cinnamaldehyde, and o‐phthalaldehyde, three possible NAP degradation pathways were proposed. This study provided the applicable potential of nZVI in Fenton process for PAHs contaminated groundwater and soil remediation. Practitioner Points nZVI enhanced the NAP degradation in Fenton‐like process. Three schemes of NAP degradation pathway were proposed. nZVI performed well in the remediation of the simulated NAP contamination.

Abatement of Naphthalene by Persulfate Activated by Goethite and Visible LED Light at Neutral pH: Effect of Common Ions and Organic Matter

“…These oxidants must be activated to produce radical species able to degrade rapidly persistent pollutants to increase their oxidising potential. The degradation of NAP has been studied in the literature using H 2 O 2 and PS activated by iron through different methods, for example, using Fe (II) (Fenton reaction) [9,10], ultraviolet and visible light (photo-Fenton) [11], power (electro Fenton) [12], and persulfate activated by iron [13][14][15] or by using both oxidants [16]. Despite the removal of NAP reported in those works often reaching 90%, there are several drawbacks, such as the need to operate at an acidic pH and the generation of iron in the solution, which must be removed in additional treatments (for example, neutralisation, separation, and management of the iron hydroxide sludge generated).…”