实用型光催化氧化水处理器深度处理焦化废水

解决光催化剂与废水的即时分离问题是光催化氧化技术走向实际的关键之一。采用新型的实用型光催化水处理器——连续流即时分离型光催化反应器深度处理焦化废水,发现在适宜的反应时间、TiO2投加量、光辐照强度和初始pH值下是完全可行的。然后在此基础上选用H2O2和Fenton试剂为外加氧化剂,研究了氧化剂强化光催化深度处理焦化废水的效果。结果表明,在UV/TiO2氧化体系中投加H2O2或Fenton氧化剂,可显著提高光催化氧化对COD和色度的去除率;在最佳反应条件下,不同氧化体系对焦化废水的深度处理效果排序为:UV/TiO2/Fenton>UV/TiO2/H2O2>UV/TiO2。     

UV/Fenton光催化氧化法处理液晶显示屏清洗废水

采用UV/Fenton光催化氧化法处理难生物降解、含高浓度表面活性剂的液晶显示屏清洗废水,考察了反应时间、亚铁盐及双氧水投加量、UV光强、体系pH、有机物初始浓度等对处理效果的影响。结果表明,当初始pH值为3~7.2时,经2 h左右的反应后可将废水的COD值由1 468 mg/L降至100 mg/L以下。对COD的去除率随反应时间的延长而增大并最终趋于平稳,合适的反应时间约为2 h。当H2O2与Fe2+的物质的量之比较低时,对COD的初始去除率较高。合适的FeSO4.7H2O投加量为543.5 mg/L,双氧水投加量为2.5~3 mL/L,且一次性投加即可。增加紫外光光强、投加TiO2等对有机污染物的去除有显著促进作用。     

光助芬顿法降解印制电路板脱膜废液

研究表明,采用UV／Fenton均相光催化氧化体系降解印制电路板脱膜废液效果好。在H202用量为1倍理论药量,Fe^2＋：H2O2（摩尔比）=1：20,光照时间为80min,脱膜废液COD去除率可达80％。光助芬顿体系降解脱膜废液的诸多影响因素中,重要性次序依次为H2O2投药比〉FeSO4／H2O2的比值〉光照时间。     

UV/TiO2/Fenton光催化氧化垃圾渗滤液的研究

采用UV/TiO2与Fenton法的联合工艺处理垃圾渗滤液,考察了反应温度、pH值、TiO2投加量、H2O2用量等对COD去除率和脱色率的影响,比较了单一的Fenton法、UV/TiO2法和UV/TiO2/Fenton法处理垃圾渗滤液的效果.结果表明,反应温度越高,对垃圾渗滤液中COD的去除率和脱色率也越高;pH值为4时处理效果较好,pH值过低会抑制·OH的产生,pH值过高则水中胶体不易被去除,且Fe2+易失去催化活性;TiO2投加量需适当,TiO2过量会引起光散射,降低紫外光辐射效率;过量的H2O2会引发自由基链反应终止;UV/TiO2与Fenton试剂耦合,可促进TiO2表面羟基化,提高·OH的生成效率,加快自由基的链传递,提高对污染物的降解速率.     

光催化氧化法处理造纸废液研究

以高压汞灯作光源、锐钛矿型TiO2为催化剂，开展了光催化氧化法降解造纸废液的试验研究，考察了TiO2投量、H2O2投量、pH值、反应时间等因素对降解效果的影响。试验表明：25mL的废液在Ti02投量为0．3g、3％的H2O2投量为4mL、pH=12．5的条件下，于室温下光照2h后对COD的去除率和脱色率分别达到了60％和90％，即采用光催化氧化法处理造纸废液是有效的。     

光催化氧化技术在水处理中的应用及研究进展

介绍了光催化氧化的机理,就TiO2固定化制备、改性、光催化氧化在降解废水中有机污染物、无机污染物以及饮用水处理中的研究进展进行了阐述,提出了今后的发展方向。     

"表观"即时成膜型光催化反应器去除水中有机物研究

采用“表观”即时成膜型光催化反应器处理自来水和苯酚水溶液，在获得良好光催化效果的同时，成功地解决了反应完成后光催化剂与水的分离问题。当光催化剂（TiO2）投加量为1g／L时，反应3h后对自来水中CODMn、TOC和UV254的去除率分别为17．3％、29．9％和67．4％。在相同的条件下降解初始浓度为4．34mg／L的苯酚水溶液，反应3h后对苯酚和TOC的去除率分别为93．8％和47．3％。反应时间、光催化剂种类、光催化剂投加量、辐照度、外加氧化剂及有机物初始浓度对光催化效果均有不同程度的影响。     

负载型纳米TiO_2光催化降解酸性红B的研究

为解决传统纳米TiO2光催化氧化工艺催化剂不易分离和载体的比表面积较小、悬浮性差的问题,将纳米TiO2负载在聚丙烯多面球上制备了负载型TiO2光催化剂.利用XRD和氮气吸附法表征了该催化剂的结构特性,并采用其降解酸性红B,考察了初始浓度、曝气量、pH值、H2O2投加量、自由基清除剂及多面球的比表面积等对降解效果的影响.结果表明,偶联剂法制备的TiO2薄膜晶相单一(锐钛矿型),晶体粒度较小,比表面积较大;脱色率会随着酸性红B溶液初始浓度的升高和自由基清除剂(乙醇)的加入而下降,提高溶解氧浓度、增加聚丙烯多面球的比表面积以及酸性条件(pH=3.26时效果最佳)都有利于提高脱色率;投加H2O2也能提高脱色率,但当投加量增至0.5 mg/L后效果不再明显;酸性红B的光催化降解遵循一级反应动力学方程.     

TiO_2光催化降解TCAA及其动力学研究

三氯乙酸(TCAA)是饮用水中普遍存在,且难以去除的高致癌风险物.考察了通气种类、TiO2用量、溶液初始pH及共存的Fe2+浓度等因素对TiO2光催化降解TCAA效率的影响,分析了pH对TiO2光催化降解TCAA效率的影响机理,探讨了TiO2光催化降解TCAA反应动力学及Fe2+促进TiO2光催化降解TCAA反应的机理.结果表明,当通入气体为O2、TCAA初始浓度为2.0mg/L、TiO2用量为1.0g/L、溶液初始pH为5.80,共存Fe2+浓度为0.10mmol/L时,反应120min,TiO2光催化降解TCAA效率为96.18%;用Langmuir-Hinshelwood模型模拟TiO2光催化降解TCAA反应动力学,UV/TiO2、Fe2+/UV/TiO2反应体系对TCAA的降解速率常数分别为0.0131、0.0237min-1,半衰期分别为52.92和29.25min.     

H3PW12O40-TiO2/膨润土光催化降解甲基橙的催化性能

通过溶胶凝胶制得H3PW12O40Ti(OH)4凝胶,并柱撑于膨润土层间制备了复合光催化剂H3PW12O40TiO2/膨润土。由XRD、SEM、EDS对制备的复合光催化剂进行表征测试表明,固载的H3PW12O40TiO2使膨润土层状结构发生明显变化,柱撑体H3PW12O40TiO2呈弥散状态,且TiO2为锐钛结构,催化剂为颗粒粒径大小不一、分布松散的复合材料。对甲基橙的H3PW12O40TiO2/膨润土光催化降解应用表明,掺杂的杂多酸使所制备的复合催化剂光催化活性得到了极大提高,在光催化体系下有较广的pH适应范围,且制备的催化剂具有良好的催化稳定性。在表征分析及应用实验的基础上,提出了H3PW12O40TiO2/膨润土的强化催化作用原理。     

H2O2/TiO2 photocatalytic oxidation of metol. Identification of intermediates and reaction pathways

The applicability of H2O2 to increase the efficiency of TiO2 photocatalytic degradations was investigated. The photographic developer metol [N-methyl-p-aminophenol] that does not adsorb on the surface of TiO2 particulates was used as a model for this purpose. It was proved that metol was mineralised under oxidation with H2O2/TiO2/UV through different thermal and photochemical reactions. Identification of intermediates by both HPLC-electron impact-MS and HPLC-electrospray ionisation-MS helped to elucidate the role of H2O2 and TiO2 in the degradation process and to establish degradation pathways. Intermediates yielded were partially oxygenated aromatic species and dimers, which were amenable to oxidation. The optimal degradation conditions found for mineralisation were 0.4 M H2O2, 5 mg/ml TiO2, pH 9 and irradiation centred at 360 nm (4.9 mW/cm2). The use of oxidants opens an interesting medium to the treatment of effluents containing a diversity of organics since they increase substantially the efficiency of TiO2 photocatalytic degradations.     

光氧化降解饮用水中微量有机物研究

针对饮用水进行深度处理提出紫外光激发催化化工艺,研究表明：（１）ＵＶ／ＴｉＯ２／Ｈ２Ｏ２工艺能有效去除水中的ＣＨＣｌ３;（２）ＣＨＣｌ３的光氧化降遵循一级动力学反应规律,反应速率常与Ｈ２Ｏ２投加量及紫外线辐射强度相关。     

Photocatalytic oxidation and ozonation of catechol over carbon-black-modified nano-TiO2 thin films supported on Al sheet

The photocatalytic activity of the carbon-black-modified nano-TiO2) (CB-TiO2) thin films was 1.5 times higher than that of TiO2 thin films in degrading Reactive Brilliant Red X-3B. Photocatalytic oxidation and ozonation of catechol over CB-TiO2 thin films supported on Al sheet was investigated. The experiments showed that ozone concentrations had an important effect on TOC removal. The combined photocatalysis with UV irradiation and ozonation (TiO2/UV/O3) process considerably increased TOC removal rate compared to combined photocatalysis with UV irradiation and oxygen oxidation (TiO2/UV/O2) process, ozonation alone (O3) process, combined ozonation and UV irradiation (UV/O3) process. The complete mineralization of catechol followed pseudo-zero-order kinetics dependent upon ozone (oxygen) concentration and indicated catechol concentration did not affect the kinetics during UV/O3 and TiO2/UV/O3 (O2) processes. The kinetic study showed that the rate constants in the complete mineralization of catechol with TiO2/UV/O3 are 1.32-1.80 times higher than that of UV/O3 with the same concentration of ozone. The rate constants are 2.56-5.36 times higher than the maximal rate constants of TiO2/UV/O2 and 4.68-9.8 times higher than the maximal rate constants of TiO2/UV.     

光催化氧化预处理滆湖原水试验研究

对光催化氧化预处理微污染水源水进行了研究,选择聚丙烯塑料填料作为载体,掺杂了一定量的TiO2,探讨了紫外光强、停留时间、水温对有机物去除效果的影响,以及浊度的变化情况,得出了相应的试验结果。     

铁掺杂类石墨相氮化碳类芬顿/光催化氧化作用机制

采用热聚合法制备并优化了不同铁掺杂比的铁掺杂类石墨相氮化碳(Fe-g-C₃N₄)类芬顿光催化剂,铁元素可完全掺杂进入类石墨相氮化碳(g-C₃N₄)结构中并组成Fe—N配位键,最佳的Fe掺杂比为10%(质量分数)。Fe-g-C₃N₄类芬顿/光催化氧化对罗丹明B的降解速率和降解率均远高于g-C₃N₄的,反应10 min时降解率已达到87. 9%,反应过程中起主要作用的活性基团为羟基自由基,超氧自由基和空穴电子也有一定作用。在pH值为3～9范围内,Fe-g-C₃N₄类芬顿/光催化氧化对罗丹明B的降解率均高于90%,大幅度拓宽了适用范围; H₂O₂的投加量会显著影响Fe-g-C₃N₄类芬顿/光催化氧化的降解效能,H₂O₂最佳投量范围为1. 0～1....     

Cross-flow microfiltration with periodical back-washing for photocatalytic degradation of pharmaceutical and diagnostic residues-evaluation of the long-term stability of the photocatalytic activity of TiO2

The combination of semiconductor photocatalysis with cross-flow microfiltration accompanied by periodical back-washing was investigated in a pilot plant. The investigation included the testing of membrane materials because the membrane must resist the abrasion and the periodical back-washing. Another objective of this investigation was to assess the potential of two different TiO(2) materials (Hombikat UV100 and P25) for continuous photocatalytic degradation of persistent organic pollutants. The study focused on the long-term stability of the photocatalytic activity of TiO(2) during its continuous application. The combination of photocatalysis and cross-flow microfiltration allowed the separation and reuse of TiO(2) after the photocatalytic degradation of clofibric acid, carbamazepine and iomeprol. The investigations showed that the photocatalytic activity of P25 and Hombikat UV100 was constant during continuous usage over several days. This study indicates the high potential of the combination of heterogeneous photocatalytic oxidation processes with cross-flow microfiltration accompanied by periodical back-washing of the membrane. Thus environmentally relevant pharmaceuticals and X-ray contrast media can be transformed and mineralized in a continuous water treatment process.     

Photocatalytic degradation of E. coliform in water

This study aims to further investigate the total mineralization of the bacteria to the extent of death and cell-mass inactivation using a TiO2-Fe2O3 membrane photocatalytic oxidation reactor. Experimental results clearly indicated that dissolved oxygen (DO), hydraulic retention time (HRT) and concentration of the model bacteria (Escherichia coliform) affected the removal efficiency. It was found that the ultimate removal efficiency was 99% at DO level of 21.34 mg/l, HRT at 60s and high concentration of E. coli at 10(9)CFU/ml. The morphologic studies also showed that E. coliform could be further mineralized into CO2 and H2O. Dissolved organic carbon, pH and gas chromatograph analysis had justified most importantly the evolution of CO2. Experimental results revealed that the photomineralization rate of E. coliform followed pseudo-first-order kinetics by the role of DO. The derived empirical models were found consistent with the proposed reaction pathways of a combined UV breakdown on mass cell and a dual-site Langmuir-Hinshelwood mechanism where the rate-controlling step is the surface interaction between the adsorbed cleavage bacterial cells and hydroxyl radicals.     

Ozone and photocatalytic processes to remove the antibiotic sulfamethoxazole from water

In this study, water containing the pharmaceutical compound sulfamethoxazole (SMT) was subjected to the various treatments of different oxidation processes involving ozonation, and photolysis and catalysis under different experimental conditions. Removal rates of SMT and total organic carbon (TOC), from experiments of simple UVA radiation, ozonation (O(3)), catalytic ozonation (O(3)/TiO(2)), ozone photolysis (O(3)/UVA), photocatalytic oxidation (O(2)/TiO(2)/UVA) and photocatalytic ozonation (O(3)/UVA/TiO(2)), have been compared. Photocatalytic ozonation leads to the highest SMT removal rate (pH 7 in buffered systems, complete removal is achieved in less than 5min) and total organic carbon (in unbuffered systems, with initial pH=4, 93% TOC removal is reached). Also, lowest ozone consumption per TOC removed and toxicity was achieved with the O(3)/UVA/TiO(2) process. Direct ozone and free radical reactions were found to be the principal mechanisms for SMT and TOC removal, respectively. In photocatalytic ozonation, with buffered (pH 7) aqueous solutions phosphates (buffering salts) and accumulation of bicarbonate scavengers inhibit the reactions completely on the TiO(2) surface. As a consequence, TOC removal diminishes. In all cases, hydrogen peroxide plays a key role in TOC mineralization. According to the results obtained in this work the use of photocatalytic ozonation is recommended to achieve a high mineralization degree of water containing SMT type compounds.