核壳复合催化剂Fe_3O_4@PDA-Cu(Ⅱ)的制备及催化降解甲基橙的研究

Preparation of core-shell catalyst Fe_3O_4@PDA-Cu(Ⅱ) and study on its catalytic degradation of methyl orange

为了高效经济地处理染料废水,以四氧化三铁、多巴胺、醋酸铜为原料,制备核壳复合催化剂Fe_3O_4@PDA-Cu^(2+)。利用红外光谱、固体漫反射光谱、X射线光电子能谱、X射线衍射光谱对催化剂的组成和结构进行表征。考察温度、双氧水用量、催化剂用量、体系pH值和电解质对催化剂活化双氧水降解甲基橙活性的影响,研究不同浓度甲基橙降解动力学过程,并利用高锰酸钾法和高效液相色谱法测定和分析降解液的化学需氧量COD和降解产物。还采用自由基抑制实验和自由基捕获实验对机理进行验证。结果表明:温度升高、体系pH值增大、双氧水用量增加、催化剂用量增多,有利于甲基橙的降解去除;加入氯化物、硫酸盐、硝酸盐不影响甲基橙的去除效果,而加入溴化物和亚硝酸盐则会抑制甲基橙的降解。甲基橙降解产物中存在草酸、顺丁烯二酸和二氧化碳,降解完成后降解液的CODMn=1.5~7.8mg/L。制备所得催化剂与染料结合具有饱和性,甲基橙的降解过程符合米氏方程,这说明催化剂具备仿酶活性,能活化双氧水产生羟基自由基,羟基自由基进攻甲基橙分子,实现甲基橙的开环降解直至矿化。该研究结果将为实现多相催化氧化去除染料技术提供理论与实验依据。

In order to dispose dye wastewater effectively and economically,the core-shell catalyst,Fe3O4@PDA-Cu2＋ was prepared by taking ferroferric oxide,dopamine and copper ammonia acetate as raw materials.The catalyst was characterized by Fourier transform infrared spectroscopy,solid diffuse reflection spectra,X-ray photoelectron spectroscopy,and X ray diffraction spectrum.The influence of temperature,hydrogen peroxide dosage,catalyst dosage and electrolyte on methyl orange degradation by the catalyst was investigated.Meanwhile,degradation kinetics process was studied with different dosage of methyl orange.The COD of degradation liquid and degradation product were determined and analyzed by potassium permanganate method and HPLC（high performance liquid chromatography）.The mechanisms were investigated by free radical inhibition experiments and free radical capture experiments.The results show that the increase of the catalyst,temperature,pH value and the amount of hydrogen peroxide is beneficial to the degradation and removal of methyl orange.The catalytic effect is not affected in presence of chloride,sulfate and nitrate,but inhibited in presence of bromide and nitrite.The degradation products include oxalic acid,maleic acid and carbon dioxide.CODMn=1.5~7.8 mg/L after degradation.The catalyst is saturated with the dye.The catalytic degradation process of the catalyst is in accordance with the Michaelis-Menten equation.All these show that the catalyst can activate hydrogen peroxide to form hydroxy radical which attacks methyl orange molecule and achieves open-loop degradation of methyl orange until mineralization.The research results will provide theoretical and experimental basis fordy removal by heterogeneous catalysis.