Catalytic Degradation of Pentachlorophenol Contaminated Soil using Nano Zero-Valent Iron Catalyst

Abstract

ABSTRACT Pentachlorophenol (PCP) was widely applied in the industrial or agricultural sector in the early days. After long-term abusive use of PCP, the soil became contaminated. PCP is considered an “environmental hormone” in terms of toxicity identification; alkali-chlorine plants in Southern Taiwan are those most polluted by PCP. This study first discussed the results of functional group identification using Fourier-transform infrared spectroscopy (FT-IR) performed on three test soils. Next, it used the self-synthesized nano zero-valent iron to observe its particle size distribution with a field emission scanning electron microscope (FM-SEM). Furthermore, it conducted catalytic degradation reaction on three test soils contaminated by PCP, to which different percentages of the zero-valent iron by weight (wt%) were added, in order to explore the degradation efficiency of the zero-valent iron over PCP. Regarding the degradation efficiency of four different percentages of the zero-valent iron by weight (wt%) over PCP in soil, the experimental results suggest that there are slight differences in the degradation efficiency of different percentages of the zero-valent iron by weight over soil contaminated by PCP at room temperature; the reaction rate and degradation efficiency of the zero-valent iron over PCP in soil increase as the amount of added zero-valent iron increases. This is largely because the oxidation reaction between the zero-valent iron and PCP in soil is more significant, while more electrons are released, when the content of the zero-valent iron increases and the zero-valent iron reacts with the pollutant. Meanwhile, electrons received by test soils relatively increase the reaction between these soils and PCP in soil; they also replace the original ligands in soil, which enables the effective degradation of concentrations of PCP in soil. Currently, the zero-valent iron has been extensively applied to environmental pollution remediation, which is especially effective for remediation of soil and groundwater pollution control sites and restoration work.