Evaluation of Soil Mixing with Carpet Grasses for Polyphenol Reductive Degradation of 1,3-dinitrobenzene Contaminated Soils

The environmental contaminant 1,3-Dinitrobenzene (1,3-DNB), which contains two nitro groups (-NO₂), has a +III nitrogen atom oxidation state, and is susceptible to electron acceptance, and subsequent reductive degradation. In this study, carpet grass was investigated as a potential source of polyphenols for the reductive degradation of 1,3-DNB. A characterization of carpet grass revealed a rapid release of polyphenols from the grass in aqueous solution, and an increase in reduction capacity. The effects of the amount of grass in solution, and effects of the pH of the aqueous phase were examined. It was found that higher grass doses (e.g., 50 g L^-1) in solution resulted in complete removal of 1,3-DNB in the aqueous phase after 7 d reaction, regardless of the pH level. Kinetic analysis of 1,3-DNB degradation and its reaction intermediates, 3-nitroaniline (3-NA) and 1,3-phenylenediamine, indicated that the overall observed degradation rates (2.51-3.17 × 10^-2 h^-1) were similar across different doses of carpet grass, but found that the dose did impact the formation and degradation of 3-NA. Based on the results, a potential soil mixing treatment for 1,3-DNB contaminated soils, consisting of the blending of carpet grasses with soils was proposed. Soil slurry experiments simulating field remediation application suggested that enhanced degradation of 1,3-DNB contaminated soils can be achieved under reaction conditions with an appropriate solution volume and sufficiently high grass doses. This research offers valuable insights into the utilization of carpet grass for potential soil remediation through its incorporation into soils contaminated with 1,3-DNB.