Degradation of p-chloronitrobenzene in drinking water by manganese silicate catalyzed ozonation

This paper describes the development of a simple method of synthesizing manganese silicate(MS) using MnCl₂ and Na₂SiO₃ as precursors. MS was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analysis, Fourier transformation infrared (FT-IR), and nitrogen adsorption-desorption. These characterization studies showed that the Mn-O-Si bond is formed on the surface of the amorphous MS which contains abundant functional groups. Here, for the first time, MS was used as an ozonation catalyst, and it showed significant activity in the decomposition of p-chloronitrobenzene (pCNB) in aqueous solution under continuous-flow conditions in both deionized and natural water. The inclusion of MS in the ozonation process enhanced pCNB decomposition by 51% and TOC removal by 21%. The adsorption of pCNB on the surface of MS had no significant effect on the degradation of pCNB. The results of a hydroxyl radical scavenger experiment confirmed that ·OH were the main active species involved in the removal of pCNB during the ozonation process catalyzed by MS. The catalytic activity of MS was related to a highly hydroxylated surface. In the continuous experiment of MS catalyzed ozonation of pCNB, the efficiency of pCNB removal was maintained around 90% for 12h continuous run.