Removal of polycyclic aromatic hydrocarbons from sediments using sodium persulfate activated by temperature and nanoscale zero-valent iron

J Air Waste Manag Assoc. 2015 Apr;65(4):375-83. doi: 10.1080/10962247.2014.996266.

Abstract

The oxidation of 16 polycyclic aromatic hydrocarbons (PAHs) compounds in sediments by sodium persulfate (Na2S2O8) simultaneously activated by temperature and nano zero-valent iron (nZVI) as the source of catalytic ferrous iron was investigated. The effect of various controlling factors, including S2O8(2-) (0.017-170 g/L), nZVI (0.01-1 g/L), and temperature (50-70 °C) were performed. The efficiency to remove PAHs was 10.7-39.1% for unactivated persulfate. The treated sample had over 50% of the persulfate still remaining from an initial persulfate dose of 170 g/L, whereas less than 1% of the persulfate remained from an initial persulfate dose of 0.017, 0.17, and 1.7 g/L. Adequate persulfate (170 g/L) must be present because it is the source of the sulfate radicals responsible for the degradation of PAHs. Results indicated that increasing temperature and the addition of nZVI into a persulfate-slurry system could enhance the persulfate oxidation process. The best removal efficiency (90%) was achieved after 24 hr while adding nZVI (0.01 g/L) to persulfate (170 g/L) at temperature of 70 °C. The results suggested that nZVI assisted persulfate oxidation without elevating temperature may be a suitable and economic alternative for the ex situ treatment of PAH-contaminated sediments.

Implications: Nano zero-valent iron (nZVI) has been successfully applied to transform/degrade contaminants in soils and water. Additionally, nZVI has been used as a catalyst to activate persulfate for the treatment of various contaminants. In this study, with the support of temperature, nZVI-persulfate oxidation system for treatment of PAH-contaminated sediments was improved significantly and the treated sediment could meet remediation goals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Geologic Sediments / chemistry*
  • Iron / chemistry*
  • Metal Nanoparticles / chemistry*
  • Oxidation-Reduction
  • Polycyclic Aromatic Hydrocarbons / chemistry*
  • Sodium Compounds / chemistry*
  • Sulfates / chemistry*
  • Temperature
  • Time Factors
  • Water Pollutants, Chemical / chemistry

Substances

  • Polycyclic Aromatic Hydrocarbons
  • Sodium Compounds
  • Sulfates
  • Water Pollutants, Chemical
  • Iron
  • sodium persulfate