浮石及其載羥基化鋅催化臭氧氧化對氯硝基苯的研究
發(fā)布時間：2018-08-22 13:26
【摘要】：隨工業(yè)迅猛發(fā)展和人類物質(zhì)生活水平的提高，水環(huán)境污染已成為目前普遍關(guān)注的問題。水中的一些難降解有毒有害污染物，雖然濃度低，但危害大、去除難，傳統(tǒng)給水處理工藝不能有效地去除這些有毒有害微污染物，，直接威脅城鎮(zhèn)供水水質(zhì)安全。非均相催化臭氧氧化技術(shù)，因其高效氧化性能、催化劑易分離、處理成本低、工藝簡單等特點，已成為當前研究熱點。 本文即是從提高浮石催化活性這一關(guān)鍵環(huán)節(jié)入手，制備浮石基過渡金屬羥基化物催化劑的基礎(chǔ)上，研究浮石和所制備的復(fù)合催化劑催化臭氧氧化去除水中難降解有機物，獲得新型催化臭氧氧化技術(shù)。探討催化劑微觀結(jié)構(gòu)、表面特性與催化活性之間的內(nèi)在規(guī)律。該類催化劑具有來源易得、生產(chǎn)成本低和制備簡單等優(yōu)點，具有良好市場應(yīng)用前景。 浮石作為催化劑催化臭氧氧化水中對氯硝基苯(pCNB)表現(xiàn)了較強的催化活性，與單獨臭氧氧化工藝比較，浮石催化臭氧氧化工藝對水中pCNB和總有機碳(TOC)去除率明顯提高，浮石與臭氧降解水中pCNB具有協(xié)同作用，浮石吸附pCNB能力很弱。 實驗中成功制備了浮石基羥基化鋅(ZnOOH/浮石)催化劑，材料對氣體具有一定的吸附能力和吸附容量，檢測發(fā)現(xiàn)，表面含有豐富的表面羥基。ZnOOH/浮石具有明顯的催化能力，催化臭氧氧化pCNB的去除率由臭氧氧化時的55.7%提高至93.4%，比浮石催化臭氧氧化pCNB去除率提高21個百分點。ZnOOH/浮石對pCNB的吸附能力比浮石有所增強。 考察了ZnOOH/浮石催化臭氧氧化水中pCNB的效能和影響參數(shù)，結(jié)果表明，pCNB的去除率與臭氧濃度、催化劑投量、反應(yīng)溫度和pCNB初始濃度呈正相關(guān)；隨著水純凈度的降低，pCNB的去除率升高；水體中Ca2+、Mg2+、Cl-、NO-3、K+和Na+對ZnOOH/浮石催化臭氧氧化pCNB的去除率影響可以忽略不計，SO2-具有一定的表面絡(luò)合能力，使浮石的催化活性下降，4ZnOOH/PO3-4可以顯著抑制ZnOOH/浮石的催化活性；CO2-3/HCO-3堿度對催化臭氧氧化pCNB的去除率有明顯影響，高堿度明顯降低了pCNB的去除率；隨著反應(yīng)體系中腐殖酸濃度的增加，催化臭氧化pCNB的去除率先增后降；ZnOOH/浮石隨著焙燒溫度的升高其催化活性降低；催化劑重復(fù)使用后，pCNB的去除率穩(wěn)定，保持良好的催化活性。反應(yīng)過程中體系有微量的離子溶出，但均低于國標限值。 浮石和ZnOOH/浮石的引入均可明顯加快臭氧的分解速度，分別使水中臭氧的分解速率常數(shù)提高了1.19和2.84倍，在2種催化反應(yīng)體系中均檢測到了·OH的產(chǎn)生。叔丁醇可以大幅度的抑制催化反應(yīng)中pCNB的降解，證明催化臭氧氧化工藝中pCNB的氧化是以·OH為主、O3為輔的氧化反應(yīng)。催化劑在溶液pH≈pHpzc時催化活性最強，表明-OH狀態(tài)的表面可以引發(fā)臭氧分解生成·OH。 催化劑表面羥基是分解水中臭氧的活性位，具有較高催化活性的催化劑通常有較大的表面羥基密度。催化劑表面活性羥基吸附水中的臭氧進而發(fā)生鏈式分解反應(yīng)，反應(yīng)過程中有高氧化性的·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.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TU991.2
本文編號：2197235
[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.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TU991.2
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