The Preparation Of Modified Coal Fly Ash As A Composite Catalyst And Degradation Of 2-chlorophenol

Coal fly ash, is a by-product of coal combustion has been regarded as a recalcitrant solid waste. The fly ash of the Inner Mongolia region as a raw material, by EDTA hydrothermal modification after the transition metal ions adsorption Fe for preparation of iron catalysts of fly ash, The obtained catalyst was characterized mainly by scanning electron microscopy (SEM), a specific surface area (BET), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), X-ray photoelectron spectroscopy (XPS). The morphology of the catalyst, surface properties of and other means and thermal stability were characterized. The study use 2-chlorophenol simulated wastewater of BTEX contaminants to build ozone catalytic oxidation system for oxidative degradation of waste water. Pilot test applied to the coal chemical MTO sewage water and the main conclusions are as follows:(1) Respectively, using 0.05 mol/L EDTA to modify the surface of fly ash by the thermal activation modification, Al、Si content increased. The composite catalyst was directly prepared by modification of fly ash and Fe(NO3)3 solution by the co-precipitation method. The catalyst after calcination to synthesize iron based fly ash composite catalyst. Scanning electron microscopy analysis FA-A based composite catalyst, it has an irregular, porous surface, BET increased to 200.3 m2/g; thermogravimetric analysis at about 600 ℃, it has good thermal stability; FTIR analysis it has no significant change in the composite catalyst group;XPS spectra show the catalyst which included iron oxide.(2) The ozone catalytic degradation mechanism of using iron-based catalyst to degrade 2-chlorophenol:① with a 5:1 liquid-solid ratio, the catalytic ozonation removal efficiency of 2-chlorophenol was improved 40.57-57.21%　compared with O3 alone at pH 9.0 with different reaction time. ② The ozonation degradation of 2-chlorophenol versus time curves with different liquid-solid 2:1、 5:1、 10:1 (mL/g), the removal efficiency of 2-chlorophenol is improved gradually with the decrease of liquid-solid ratio. ③ Liquid to solid ratio of 10:1 (mL/g), to explore 100mg/L,200 mg/L,500 mg/L,1000 mg/L 2-chlorophenol solution catalytic degradation,100 mg/L of 2-chlorophenol removal efficiency is high, but the amount of degradation of 2-chlorophenol is gradually decreasing. ④ 2-chlorophenol initial concentration of 200 mg/L, liquid to solid ratio of 10:1 (mL/g), added in an amount of t-butanol was 5 mmol/L, t-butanol is added more significantly inhibited during ozone alone, and the influence of catalytic ozonation is reduced. ⑤ The ozonation degradation of 2-chlorophenol well followed the first order kinetic model, the reaction rate constants were 0.03,0.05, and 0.1 min-1 for ozone only, ozone with fly ash, and ozone with the catalyst, respectively. The catalytic ozonation of 2-chlorophenol first converted to o-benzoquionone; then phthaldialdehyde quinone intermediate oxidized ring opening into a muconic acid, maleic acid, oxalic acid et al; finally mineralization of the organic acid intermediate product carbon dioxide.(3) MTO stripper outside the sewage water pilot test and mechanism of using iron-based catalyst:the use of catalytic ozonation oxidation and membrane coupling technology on MTO stripper outside the sewage water treatment, effluent index consistent with meter rinse water indicators. The load FA-A based composite catalyst to produce more hydroxyl radicals, organic matter which is adsorbed on the catalyst surface can directly occurred ozone oxidation, or indirectly with the hydroxyl radical oxidation occurs.