非均相催化Oxone高级氧化技术处理含酚废水的实验研究
发布时间：2018-07-13 15:00
【摘要】：基于硫酸根自由基(SO_4~·)的高级氧化技术是近些年发展起来的、具有发展潜力的、降解难降解有机污染物的新技术。常用钻活化过硫酸盐产生硫酸根自由基,但由于钻离子有毒,均相催化虽然效率高但不宜采用,必须将钴负载在载体上构成非均相催化氧化体系降解有机废水。本研究以Co(NO_3)_2·6H_2O和Fe(NO_3)_3·9H_2O作为前驱物,利用浸渍沉淀法将过渡金属钴和铁固定到TiO_2载体上,制备出新型复合催化剂CoFe/TiO_2,催化活化过硫酸氢钾复合盐(Oxone),产生强氧化性的自由基SO_4~·和·OH降解苯酚废水。本文探讨了催化剂CoFe/TiO_2的钴铁负载量、焙烧温度等制备条件对降解效果的影响并进行了表征分析和稳定性测试。考察了初始pH值、催化剂投加量、氧化剂投加量、反应温度和光照条件等因素对CoFe/TiO_2非均相催化氧化Oxone体系降解苯酚废水的影响。对CoFe/TiO_2活化Oxone产生的SO_4~·和·OH自由基及其降解苯酚的反应过程进行了探讨。得出以下结论:(1)以TiO_2为载体,利用浸渍沉淀法制备出复合催化剂CoFe/TiO_2。确定了最佳制备工艺:Co、Fe负载比例为1:1时,总负载量为70%,最佳焙烧温度为500℃。采用SEM、BET、XRD、XPS等手段对制得的CoFe/TiO_2进行测试。结果表明,钻和铁已成功地负载到了载体TiO_2上,且钴和铁的负载对TiO_2的结构产生了影响,使载体的比表面积和孔容减小;TiO上负载的钴和铁主要以CoFe_2O_4的形式存在,还有一部分Fe2O3。经过3次循环CoFe/TiO_2仍保持较高催化活性,且只有微量的钴离子和铁离子溶出,可安全使用。(2)对非均相CoFe/TiO_2/Oxone催化氧化体系降解苯酚废水的影响因素的研究表明:中性条件下催化剂CoFe/TiO_2催化氧化Oxone降解苯酚的去除效果最佳;最终确定的最佳反应条件为:在UVB光照条件下,反应温度35℃,不调节初始pH,催化剂CoFe/TiO_2的最佳投加量为1.5 g/L,氧化剂Oxone的最佳投加量为3 g/L。此时,苯酚的去除率能达到93.1%。(3)对CoFe/TiO_2反应前后的物理化学结构研究表明,UVB光照下催化剂结构的破坏程度比无光照下的更大,且反应前后其基本组成成分没有变化,说明催化剂不参与降解反应,只是通过催化作用促进苯酚的降解;UVB光照下的CoFe/TiO_2/Oxone系统对苯酚的降解动力学符合拟一级动力学模型;对自由基变化量的研究表明,本实验体系中起主要氧化作用的是SO_4~·自由基;苯酚的芳香环在SO_4~·自由基的攻击下,利用电子转移生成以碳为中心的自由基,进一步作用生成中间体,SO_4~·将其氧化为小分子有机酸,最终被矿化为CO_2和H_2O。
[Abstract]:Advanced oxidation technology based on sulphate radical (SO4 ~) has been developed in recent years and has the potential to degrade refractory organic pollutants. Persulfate is commonly used to activate persulfate to produce sulfate radical, but because drilling ions are toxic, homogeneous catalysis is not suitable, so it is necessary to form heterogeneous catalytic oxidation system to degrade organic wastewater by loading cobalt on the carrier. In this study, Co (no _ 3) _ s _ (26) H _ 2O and Fe (no _ 3) _ (39) H _ 2O were used as precursors, and cobalt and iron transition metal were immobilized on TiO2 carrier by impregnation precipitation method. A new type of composite catalyst CoFe- / TiO-2 was prepared to activate potassium persulfate complex salt (Oxone) and produce strong oxidizing free radicals SO4- and OH to degrade phenol wastewater. In this paper, the effects of preparation conditions such as the loading amount of cobalt and iron and calcination temperature on the degradation efficiency of CoFe- / TiO-2 catalyst were investigated, and the results of characterization and stability tests were carried out. The effects of initial pH value, catalyst dosage, oxidant dosage, reaction temperature and illumination conditions on the degradation of phenol wastewater by heterogeneous catalytic oxidation of CoFe- / TiO2-Oxone system were investigated. The reaction process of SO4- and OH radicals produced by CoFe- / TiO-2 activated Oxone and its degradation of phenol were discussed. The main conclusions are as follows: (1) CoFe- / TiO-2 was prepared by impregnation precipitation with TiO-2 as carrier. The optimum preparation technology was determined as follows: when the loading ratio was 1:1, the total load was 70 and the optimum calcination temperature was 500 鈩，
本文编号：2119793
[Abstract]:Advanced oxidation technology based on sulphate radical (SO4 ~) has been developed in recent years and has the potential to degrade refractory organic pollutants. Persulfate is commonly used to activate persulfate to produce sulfate radical, but because drilling ions are toxic, homogeneous catalysis is not suitable, so it is necessary to form heterogeneous catalytic oxidation system to degrade organic wastewater by loading cobalt on the carrier. In this study, Co (no _ 3) _ s _ (26) H _ 2O and Fe (no _ 3) _ (39) H _ 2O were used as precursors, and cobalt and iron transition metal were immobilized on TiO2 carrier by impregnation precipitation method. A new type of composite catalyst CoFe- / TiO-2 was prepared to activate potassium persulfate complex salt (Oxone) and produce strong oxidizing free radicals SO4- and OH to degrade phenol wastewater. In this paper, the effects of preparation conditions such as the loading amount of cobalt and iron and calcination temperature on the degradation efficiency of CoFe- / TiO-2 catalyst were investigated, and the results of characterization and stability tests were carried out. The effects of initial pH value, catalyst dosage, oxidant dosage, reaction temperature and illumination conditions on the degradation of phenol wastewater by heterogeneous catalytic oxidation of CoFe- / TiO2-Oxone system were investigated. The reaction process of SO4- and OH radicals produced by CoFe- / TiO-2 activated Oxone and its degradation of phenol were discussed. The main conclusions are as follows: (1) CoFe- / TiO-2 was prepared by impregnation precipitation with TiO-2 as carrier. The optimum preparation technology was determined as follows: when the loading ratio was 1:1, the total load was 70 and the optimum calcination temperature was 500 鈩，
本文编号：2119793
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