Oxidative degradation of trichloroethylene, pyrene, and toluene by fenton-like reaction using nano-scale zero-valent iron and pyrite

Abstract

The research on oxidative degradation of organic contaminants in Fenton-like system has been conducted to provide basic knowledge for the development of novel technologies using bimetal and iron-bearing soil mineral to remediate soil and groundwater contaminated with chlorinated organic compounds (COCs), polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs) effectively and be applied to the operation of enhanced Fenton systems. Nano-scale zero-valent iron (nZVI) Fenton system with Cu(II) showed that trichloroethylene (TCE) can be significantly degraded (95%) in 10 min at pH 3 in a closed batch system. Aqueous Fe(II) concentration increased with increasing Cu(II) concentration. Surface analyses using X-ray spectroscopy showed that metallic Cu was formed on the nZVI surface and surface Fe(0) decreased after the addition of Cu(II) to nZVI suspension. No significant difference has been observed in the degradation kinetics of TCE by Cu/nZVI Fenton at pH 3 and pH 6, whereas the kinetics by nZVI Fenton at pH 6 were 1.6 times faster than at pH 3. An important role of Cu(II) to release Fe(II) from the nZVI surface was due to the oxidative substitution of Fe(0) by Cu(II). It was identified by change in chemical composition of Fe and Cu species with and without Cu(II). Degradation of pyrene solubilized in cetylpyridinium chloride (CPC) surfactant solution by pyrite Fenton reaction was investigated as a different recalcitrant contaminant and different case of iron source for Fenton-like reaction to produce hydroxyl radical (OHo). Pyrene in the presence of CPC was degraded gradually by 96% in 180 min at initial pH 7 in a closed batch reactor, showing pseudo-first-order reaction kinetics. However, pyrene in the absence of CPC under same experimental condition decreased abruptly by 91% in 5 min showing no significant decrease by the end of sampling time. On the other hand, 35% of pyrene in the presence of CPC was degraded in classic Fenton system at ...