Strong promoted catalytic ozonation of atrazine at low temperature using tourmaline as catalyst: Influencing factors, reaction mechanisms and pathways

Tourmaline, an economical and eco-friendly natural mineral, has been widely used during the water treatment processes. In this investigation, the raw tourmaline has been found to be effective as a catalyst for ozonation in the degradation of atrazine (ATZ) under low temperature (278 K). Within typical experimental conditions (tourmaline dosage = 1 g L −1 , [ATZ] 0  = 5 μM, [O 3 ] 0  = 3 mg L −1 , at pH 7.0 and 278 K), the removal efficiency of ATZ in catalytic ozonation was 98% after 10 min, compared with only 27% ATZ removal in the absence of catalyst. Surface properties and components of tourmaline were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), pyridine-FTIR and energy dispersive X-ray (EDX). The characterization studies showed that metal attached hydroxyl groups (M OH, M = Fe, Al and Si) were the main active sites for ozone adsorption and decomposition. The formation of hydroxyl radicals ( OH) as well as hydrogen peroxide (H 2 O 2 ) led to fast ATZ degradation and 31 kinds of intermediates; meanwhile, possible degradation pathways of ATZ were detected and proposed. The mechanisms of reaction were proposed for tourmaline-catalyzed ozonation based on all the experimental results and material characterizations.