Peracetic acid (PAA) has been used as an alternative bleaching agent and disinfectant to chlorine-based oxidants owing to less generation of toxic by-products and high oxidation potential value. In recent years, the application of PAA in wastewater treatment has gained growing interests. Generally, PAA alone does not degrade organic contaminants easily due to structural selectivity; however, highly oxidizing radicals which are generated from PAA activation can easily attack recalcitrant contaminants. Iron(II), which is ubiquitous in the environment, can be a good activator for PAA. Compared to the well-known Fe(II)/H2O2 Fenton reaction, a fundamental mechanism of reaction between PAA and Fe(II) has not been clearly elucidated. This study focuses on PAA activation by Fe(II) and contaminant degradation by radicals generated from the Fe(II)/PAA process. The fast reaction between PAA and Fe(II) was evaluated under various conditions (e.g., different solution pH and concentrations of PAA/Fe(II)/H2O2). Our study revealed, for the first time, that the reaction of PAA with Fe(II) is more than three orders of magnitude faster than that of H2O2 and Fe(II), and is operative in a wider pH range (3-7). The redox cycle of Fe(II)/Fe(III) was investigated and the dominant radical species were confirmed by radical scavenger tests and electron paramagnetic resonance analyses. Degradation of target organic compounds was also evaluated in the Fe(II)/PAA process, and reaction products and their toxicities were evaluated. The main results include: (1) Fe(II) rapidly reacted with PAA and was gradually re-generated by Fe(II)/Fe(III) redox cycle; (2) dominant radical species in the Fe(II)/PAA process were carbon-centered radicals and these radicals contributed more to organic compound degradation than hydroxyl radical; (3) a 1:1 molar ratio of Fe(II) to PAA showed the highest efficiency for compound degradation; and (4) the Fe(II)/PAA process generated oxidation products of lower toxicity compared to the parent compounds. This study significantly advances the fundamental understanding of PAA and Fe(II) reaction, and also demonstrates the Fe(II)/PAA process to be a promising novel advanced oxidation technology for water treatment.

Novel advanced oxidation process by peracetic acid and Fe(II)

2019 Fall National Meeting

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