Phenol Oxidized By A Heterogeneous Fenton-like Progress Catalyzed By Ferrocene

Fenton (Fe2+/H2O2) oxidation method as one of the best effective advanced oxidation processes can produce hydroxyl radical (OH), which has a strong oxidation ability, can be used degradation of wastewater that containing refractory organic pollutants fast and efficiently. However, it is so difficult for homogeneous catalyst recovery and separate from the reaction medium, it will lose in the solution and lead to the secondary pollution. The ideal heterogeneous catalyst for Fenton reaction should have the following characteristics:(1) Can be highly efficient catalytic H2O2decomposition and produce·OH;(2) Good stability and insoluble in the water, easy to solid-liquid separation;(3) Cheap and simple preparation.Ferrocene (Fc) is easily oxidized into blue paramagbetic ferrocenium (Fc+)[η5-C5H5)2FeⅢ]+under the acid condition, and the equation Fc=Fc++e is reversible. It was used widely because of its hydrophobicity, stability, low toxity, biological activity, ferrocene used in the field of catalysis have also been reported in the literature. In our research, ferrocene was used as a substitute for catalyst of heterogeneous Fenton reaction, ferrous ion (Fe2+). Consequently, a new Fc/H2O2heterogeneous Fenton reaction system was established. The target pollutant was the phenol which concentration was100mg/L, and the specific conclusions were as follows:(i) Fc as a catalyst of heterogeneous Fenton reagent had excellent catalytic. About64%of COD can be removed by Fc/H2O2system, and the removal efficiency significantly better than the Fc alone or H2O2alone, Free radical scavenging experiment proved that it was the OH oxidation degradation of phenol.(ⅱ) The catalytic performance was stable. The COD removal rate maintained a stable rate of degradation after the Fc has reused four times under the same experimental condition.(ⅲ) Fc/H2O2system can reduce the toxicity of the simulated wastewater. The Some of aromatics intermediates such as hydroquinone, catechol and p-benzoquinone, etc. are even more toxic than phenol, our experiment have shown that these products was almost completely removed at300minutes. (iv)Some of the intermediate produced during the phenol degradation process by the Fc/H2O2system can promote the degradation of phenol. The concentration of OH produced by the system of Fc/H2O2phenol was far greater than produced by the system of Fc/H2O2. Added the respective armomatic intermidiates into Fc/H2O2-phenol system can greatly improve the efficiency of removal of phenol, which proved it were the armomatic intermidiates promoted generation of-OH.(v)The optimum conditons of degradation phenol by Fc/H2O2were as follows: concentration of hydrogen peroxide was the theoretical value which respect the concentration of hydrogen peroxide can be remove of phenol COD completely, the dosage of ferrocene was0.2g/L, the temperature was30℃and the initial pH value was4-6. The COD removal rate of phenol could achieve80%under this condition.(vi)The calcuilated kinetic parameters K1was generally less than K2, where K1respect the route turned from phenol into aromatic products, and K2respect the route of aromatic products converted to CO2and H2O or other small molecules organic acids, Proved once again that the aromatic product can promote the degradation of phenol.