Heterogeneous Fenton Degradation Of Phenol-containing Wastewater With Supported Metal Catalyst

Refractory organic pollutants show a dire threat to environmental security and human health, so their efficient removal is a hotspot and difficulty in environmental field. The·OH produced from the Advanced oxidation processes has the strong oxidizing, become effective means for the removal of refractory organic pollutants. And based on the heterogeneous Fenton process, with activated carbon and ordered mesoporous carbon as catalyst support respectively, loading transition metals as the active component, catalysts for the degradation of phenol and chlorophenol was studied.The catalysts of Fe/AC, Cu/AC and Fe-Cu/AC with active carbon as supports were prepared by a wet impregnation method, and were characterized by using X-ray diffraction (XRD), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS)measurements; The degradation mechanism was discussed with analysis of intermediate products and electron spin resonance (ESR) measurement. The degradation of phenol with Fe/AC, Cu/AC and Fe-Cu/AC as catalyst in initial60min reached96.7%,77.5%and99%, respectively; the dissolution of a little active-component was found in Cu/AC and Fe-Cu/AC, but little Fe in Fe/AC was dissolved; the degradation of phenol was performed by heterogeneous Fe/AC instead of dissolved Fe, and was above93%after Fe/AC being used with three recycle runs. Under the optimum conditions of pH=3,303K, and4.38mmol/L H2O2, the removal of phenol and TOC in the Fe/AC-catalytic Fenton process could reach97%and53%, respectively. The ESR results indicated that hydroxyl radical was produced in the catalytic-decomposition of H2O2with Fe/AC as catalyst, demonstrating that the degradation of phenol mainly followed an oxidation pathway of hydroxyl radical; such intermediates as hydroquinone, p-benzenequinone and catechol were obtained, and the results showed thatortho-and para-substitution reaction by hydroxyl might be the main mechanism of phenol oxidation.The OMC was synthesized through solvent evaporation induced self-assembly method (EISA) by using amphiphilic triblock copolymers F127as template. The degradation and mineralization of4-chlorophenol (4CP) using a catalyst based on iron supported on OMC and adding H2O2through Fenton reaction have been studied. The obtained catalysts were characterized by nitrogen adsorption isotherms, X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic activity and the effect of operational parameters on degradation efficiency of4CP were evaluated. When pH=3and H2O2=3.07mM, the degradation efficiency and total organic carbon (TOC) of100ppm4CP on4.2Fe/OMC catalyst were99%and63%at40℃. Based on the degradation intermediates detected by HPLC, a possible pathway was proposed to explain the degradation of4CP:the hydroxyl radical abstracted hydrogen atom at ortho-and meta-position from4CP to form4CC and4CR could be dominated in the·OH attack of4CP, and the para dechlorination substitution reaction to generate BQ was being at the same time.