【摘要】：基于硫酸根自由基(SO_4~·)的高級(jí)氧化技術(shù)是近些年發(fā)展起來的、具有發(fā)展?jié)摿Φ�、降解難降解有機(jī)污染物的新技術(shù)。常用鉆活化過硫酸鹽產(chǎn)生硫酸根自由基,但由于鉆離子有毒,均相催化雖然效率高但不宜采用,必須將鈷負(fù)載在載體上構(gòu)成非均相催化氧化體系降解有機(jī)廢水。本研究以Co(NO_3)_2·6H_2O和Fe(NO_3)_3·9H_2O作為前驅(qū)物,利用浸漬沉淀法將過渡金屬鈷和鐵固定到TiO_2載體上,制備出新型復(fù)合催化劑CoFe/TiO_2,催化活化過硫酸氫鉀復(fù)合鹽(Oxone),產(chǎn)生強(qiáng)氧化性的自由基SO_4~·和·OH降解苯酚廢水。本文探討了催化劑CoFe/TiO_2的鈷鐵負(fù)載量、焙燒溫度等制備條件對(duì)降解效果的影響并進(jìn)行了表征分析和穩(wěn)定性測(cè)試�？疾炝顺跏紁H值、催化劑投加量、氧化劑投加量、反應(yīng)溫度和光照條件等因素對(duì)CoFe/TiO_2非均相催化氧化Oxone體系降解苯酚廢水的影響。對(duì)CoFe/TiO_2活化Oxone產(chǎn)生的SO_4~·和·OH自由基及其降解苯酚的反應(yīng)過程進(jìn)行了探討。得出以下結(jié)論:(1)以TiO_2為載體,利用浸漬沉淀法制備出復(fù)合催化劑CoFe/TiO_2。確定了最佳制備工藝:Co、Fe負(fù)載比例為1:1時(shí),總負(fù)載量為70%,最佳焙燒溫度為500℃。采用SEM、BET、XRD、XPS等手段對(duì)制得的CoFe/TiO_2進(jìn)行測(cè)試。結(jié)果表明,鉆和鐵已成功地負(fù)載到了載體TiO_2上,且鈷和鐵的負(fù)載對(duì)TiO_2的結(jié)構(gòu)產(chǎn)生了影響,使載體的比表面積和孔容減小;TiO上負(fù)載的鈷和鐵主要以CoFe_2O_4的形式存在,還有一部分Fe2O3。經(jīng)過3次循環(huán)CoFe/TiO_2仍保持較高催化活性,且只有微量的鈷離子和鐵離子溶出,可安全使用。(2)對(duì)非均相CoFe/TiO_2/Oxone催化氧化體系降解苯酚廢水的影響因素的研究表明:中性條件下催化劑CoFe/TiO_2催化氧化Oxone降解苯酚的去除效果最佳;最終確定的最佳反應(yīng)條件為:在UVB光照條件下,反應(yīng)溫度35℃,不調(diào)節(jié)初始pH,催化劑CoFe/TiO_2的最佳投加量為1.5 g/L,氧化劑Oxone的最佳投加量為3 g/L。此時(shí),苯酚的去除率能達(dá)到93.1%。(3)對(duì)CoFe/TiO_2反應(yīng)前后的物理化學(xué)結(jié)構(gòu)研究表明,UVB光照下催化劑結(jié)構(gòu)的破壞程度比無光照下的更大,且反應(yīng)前后其基本組成成分沒有變化,說明催化劑不參與降解反應(yīng),只是通過催化作用促進(jìn)苯酚的降解;UVB光照下的CoFe/TiO_2/Oxone系統(tǒng)對(duì)苯酚的降解動(dòng)力學(xué)符合擬一級(jí)動(dòng)力學(xué)模型;對(duì)自由基變化量的研究表明,本實(shí)驗(yàn)體系中起主要氧化作用的是SO_4~·自由基;苯酚的芳香環(huán)在SO_4~·自由基的攻擊下,利用電子轉(zhuǎn)移生成以碳為中心的自由基,進(jìn)一步作用生成中間體,SO_4~·將其氧化為小分子有機(jī)酸,最終被礦化為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，

本文編號(hào)：2119793