浮石及其载羟基化锌催化臭氧氧化对氯硝基苯的研究

发布时间：2018-08-22 13:26

【摘要】：随工业迅猛发展和人类物质生活水平的提高，水环境污染已成为目前普遍关注的问题。水中的一些难降解有毒有害污染物，虽然浓度低，但危害大、去除难，传统给水处理工艺不能有效地去除这些有毒有害微污染物，，直接威胁城镇供水水质安全。非均相催化臭氧氧化技术，因其高效氧化性能、催化剂易分离、处理成本低、工艺简单等特点，已成为当前研究热点。本文即是从提高浮石催化活性这一关键环节入手，制备浮石基过渡金属羟基化物催化剂的基础上，研究浮石和所制备的复合催化剂催化臭氧氧化去除水中难降解有机物，获得新型催化臭氧氧化技术。探讨催化剂微观结构、表面特性与催化活性之间的内在规律。该类催化剂具有来源易得、生产成本低和制备简单等优点，具有良好市场应用前景。浮石作为催化剂催化臭氧氧化水中对氯硝基苯(pCNB)表现了较强的催化活性，与单独臭氧氧化工艺比较，浮石催化臭氧氧化工艺对水中pCNB和总有机碳(TOC)去除率明显提高，浮石与臭氧降解水中pCNB具有协同作用，浮石吸附pCNB能力很弱。实验中成功制备了浮石基羟基化锌(ZnOOH/浮石)催化剂，材料对气体具有一定的吸附能力和吸附容量，检测发现，表面含有丰富的表面羟基。ZnOOH/浮石具有明显的催化能力，催化臭氧氧化pCNB的去除率由臭氧氧化时的55.7%提高至93.4%，比浮石催化臭氧氧化pCNB去除率提高21个百分点。ZnOOH/浮石对pCNB的吸附能力比浮石有所增强。考察了ZnOOH/浮石催化臭氧氧化水中pCNB的效能和影响参数，结果表明，pCNB的去除率与臭氧浓度、催化剂投量、反应温度和pCNB初始浓度呈正相关；随着水纯净度的降低，pCNB的去除率升高；水体中Ca2+、Mg2+、Cl-、NO-3、K+和Na+对ZnOOH/浮石催化臭氧氧化pCNB的去除率影响可以忽略不计，SO2-具有一定的表面络合能力，使浮石的催化活性下降，4ZnOOH/PO3-4可以显著抑制ZnOOH/浮石的催化活性；CO2-3/HCO-3碱度对催化臭氧氧化pCNB的去除率有明显影响，高碱度明显降低了pCNB的去除率；随着反应体系中腐殖酸浓度的增加，催化臭氧化pCNB的去除率先增后降；ZnOOH/浮石随着焙烧温度的升高其催化活性降低；催化剂重复使用后，pCNB的去除率稳定，保持良好的催化活性。反应过程中体系有微量的离子溶出，但均低于国标限值。浮石和ZnOOH/浮石的引入均可明显加快臭氧的分解速度，分别使水中臭氧的分解速率常数提高了1.19和2.84倍，在2种催化反应体系中均检测到了·OH的产生。叔丁醇可以大幅度的抑制催化反应中pCNB的降解，证明催化臭氧氧化工艺中pCNB的氧化是以·OH为主、O3为辅的氧化反应。催化剂在溶液pH≈pHpzc时催化活性最强，表明-OH状态的表面可以引发臭氧分解生成·OH。催化剂表面羟基是分解水中臭氧的活性位，具有较高催化活性的催化剂通常有较大的表面羟基密度。催化剂表面活性羟基吸附水中的臭氧进而发生链式分解反应，反应过程中有高氧化性的·OH生成。
[Abstract]:With the rapid development of industry and the improvement of people's living standards, water pollution has become a widespread concern. Some refractory toxic and harmful pollutants in water, though low in concentration, are harmful and difficult to remove. Traditional water treatment processes can not effectively remove these toxic and harmful micro-pollutants, which directly threaten urban water supply. Heterogeneous catalytic ozonation has become a research hotspot because of its high efficiency, easy separation of catalysts, low cost and simple process.
Based on the preparation of pumice-based transition metal hydroxide catalysts, the removal of refractory organic compounds from water by catalytic ozonation of pumice and its composite catalysts is studied in this paper. A new catalytic ozonation technology is obtained. The microstructure, surface characteristics and catalysis of the catalysts are discussed. This kind of catalyst has the advantages of easy source, low cost and simple preparation, so it has a good market prospect.
As a catalyst, pumice exhibited strong catalytic activity for the ozonation of p-chloronitrobenzene (pCNB) in water. Compared with the ozonation process alone, the removal rate of pCNB and TOC in water by the pumice catalytic ozonation process was significantly improved. Pumice and ozone had synergistic effect on the degradation of pCNB in water, and pumice had weak adsorption capacity for pCNB.
Zinc hydroxide (ZnOOOH) / Pumice catalyst was successfully prepared in the experiment. The material has a certain adsorption capacity and adsorption capacity for gases. It was found that the surface contains abundant surface hydroxyl groups. ZnOOH / Pumice has obvious catalytic capacity. The removal rate of pCNB catalyzed ozonation increased from 55.7% to 93.4%, which is higher than that of pumice. The removal rate of pCNB by catalytic ozonation was increased by 21 percentage points. The adsorption capacity of ZnOOOH/pumice to pCNB was stronger than that of pumice.
The efficiency and influencing parameters of ZnOOH/pumice catalytic ozonation of pCNB in water were investigated. The results showed that the removal rate of pCNB was positively correlated with ozone concentration, catalyst dosage, reaction temperature and initial concentration of pCNB; the removal rate of pCNB increased with the decrease of water purity; the removal rate of Ca2+, Mg2+, Cl-, NO-3, K+ and Na+ in water was positively correlated with ZnOH/pumice catalytic ozonation. The removal rate of oxidized pCNB can be neglected, SO2 - has a certain surface complexation ability, so that the catalytic activity of pumice decreased, 4ZnOOOH / PO3 - 4 can significantly inhibit the catalytic activity of ZnOOH / pumice; CO2 - 3 / HCO - 3 basicity has a significant impact on the removal rate of catalytic ozonation of pCNB, high basicity significantly reduced the removal rate of pCNB with the reverse; With the increase of humic acid concentration, the removal rate of catalytic ozonation pCNB increased first and then decreased; the catalytic activity of ZnOOH / Pumice decreased with the increase of calcination temperature; the removal rate of pCNB was stable and maintained good catalytic activity after the catalyst was reused.
The decomposition rate constants of ozone in water were increased by 1.19 and 2.84 times, respectively. OH was detected in both catalytic systems. Tertiary butanol could significantly inhibit the degradation of pCNB in the catalytic ozonation process, which proved that the oxygen of pCNB in the catalytic ozonation process was inhibited. The catalytic activity of the catalyst is strongest at pH_pHpzc, indicating that the surface of - OH state can initiate ozone decomposition to form OH.
Catalyst surface hydroxyl group is the active site of ozone decomposition in water. Catalysts with higher catalytic activity usually have higher surface hydroxyl density. Catalyst surface active hydroxyl group adsorbs ozone in water and then produces chain decomposition reaction. OH with high oxidation is formed in the reaction process.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU991.2

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