Abstract:

Diatomite supported nano zero valent iron (nZVI) catalyst (NDA) with complex network structure was prepared via a mild reduction precipitation method in this work. The pore structure and pore distribution of NDA can be regulated and controlled through adjusting the loading amount of nZVI. In general, the nano three-dimensional network formed by nZVI and diatomite channels greatly increase the specific surface area and pore volume of NDA, and further formed more active sites, which made NDA have better performance in activating PMS to degrade BPA than pure nZVI. The pseudo-first-order reaction rate constant of 50-NDA (50%-nZVI/diatomite) is almost 3 times higher than that of pure nZVI. Besides, the electron paramagnetic resonance (EPR) and radical quenching experiments showed that the activation process was dominated by the sulfate radical (SO₄^•-) and hydroxyl radical (^•OH) produced by Fe⁰ oxidation. The generated electrons promote the self-decomposition of PMS to produce singlet oxygen (¹O₂), and then the valence state of iron changes to produce free radicals. In addition, the possible degradation pathway of BPA was inferred from the intermediate products identified by liquid chromatograph-mass spectrometer (LC-MS). This study provides a novel strategy for the design and preparation of three-dimensional composite catalysts derived from natural mineral.

Key words: nZVI, Diatomite, Peroxymonosulfate, Sulfate radical, Bisphenol A