一种光催化体系光催化降解苯胺的研究

以钛酸丁酯为原料．以膨润土为载体,用酸性溶胶法合成TiO2纳米复合物,并利用该复合物作催化剂,在H2O2存在下进行光催化降解苯胺溶液。结果表明,该催化剂在UV／H2O2系统中对苯胺溶液有很好的光催化降解效果,其效果优于纯TiO2;H2O2的存在提高了苯胺光催化降解速率,在本实验条件下其最佳摩尔浓度是5mmol／L;溶液pH是影响反应速率的重要因素．pH在中性范围内具有更强的光催化活性;该体系中苯胺能够有效地被降解,其光催化反应遵循一级反应动力学规律。     

Photocatalytic degradation of AZO dyes by supported TiO2 + UV in aqueous solution

The photocatalytic degradation performance of photocatalysts TiO2 supported on 13-X, Na-Y, 4A zeolites with different loading content was evaluated using the photocatalytic oxidation of dyes direct fast scarlet 4BS and acid red 3B in aqueous medium. The results showed that the best reaction dosage of TiO2-zeolite catalysts is about 2 g/l and the photocatalytic kinetics follows first order for all supported catalysts. The photocatalytic activity order of the three series catalysts is 13X type >Y type >4A type. The physical state of titanium dioxide on the supports is evaluated by X-ray photoelectron spectra (XPS), powder X-ray diffraction (XRD), BET, and FTIR.     

Photocatalytic degradation of imazethapyr herbicide at TiO2/H2O interface

The photocatalytic degradation of imazethapyr, a herbicide of the imidazolinone family, was investigated in an aqueous suspension of titanium dioxide used as a catalyst. A pseudo-first order kinetic model was employed to discuss the results. The effect of catalyst loading, initial concentration of imazethapyr, hydrogen peroxide, pH value, and temperature were investigated. Imazethapyr disappearance as a function of irradiation time was analyzed by HPLC. The ammonium ion formation was determined spectrophotometrically at 694 nm. The degradation was observed to proceed more favorably at natural pH (ca. 4.4) when the pH was varied in the range from 2 to 11. The addition of hydrogen peroxide to the TiO2 suspension enhanced the degradation rate constant up to 5.0x10(-3) mol l-1, but decreased it at higher concentrations. The degradation rate constants decreased by 19% with a temperature increase from 20 to 40 degrees C in the TiO2 suspension, whereas a 16% increase in imazethapyr direct photolysis was observed for the same temperature range. This behavior indicates the occurrence of physisorption between TiO2 and imazethapyr molecules.     

臭氧/双氧水/紫外光联用降解饮用水中溴氯乙腈的试验研究

为减少饮用水氯化消毒过程中产生的含氮消毒副产物溴氯乙腈(BCAN),降低其潜在的致癌风险,分别采用臭氧(O3)、双氧水(H2O2)和紫外光(UV)及其联合工艺,考察了不同试验条件下BCAN的降解效果及影响因素,并探讨了其降解机制和动力学规律。结果表明,O3、H2O2和UV工艺对BCAN降解效果都不理想,UV/H2O2和UV/H2O2/O3联合工艺可以较有效地降解水中的BCAN。在BCAN初始质量浓度为20μg/L、紫外光强为31μW/cm2、H2O2质量浓度为40 mg/L、O3质量浓度为7.9mg/L条件下,反应进行120min后,UV/H2O2联合工艺与UV/H2O2/O3联合工艺对BCAN的降解率分别为77.50%、94.05%。UV/H2O2/O3联合工艺对BCAN的降解效果比UV/H2O2联合工艺更好,UV/H2O2和UV/H2O2/O3联合工艺降解BCAN均符合一级反应动力学规律。     

La2O3/ZnO/TiO2光催化降解活性艳红K-2BP的研究

采用溶胶-凝胶法制备了La2O3/ZnO/TiO2复合光催化剂,以紫外灯为光源,活性艳红K-2BP为模型降解物,研究了La2O3/ZnO/TiO2的光催化性能。结果表明：当锌和镧的掺杂量w(ZnO)=20%, w(La2O3)=0.5%, 煅烧温度为500℃时,La2O3/ZnO/TiO2复合光催化剂的光催化活性最高;当催化剂投加量4 g/L,通气量800 mL/min,初始pH值3.12时,La2O3/ZnO/TiO2对活性艳红K-2BP的降解效果最好。实验证明,La2O3/ZnO/TiO2对活性艳红K-2BP的降解遵从Langmuir-Hinshelwood动力学模型,测得其反应速率常数k＝11.5 mg/(L·min);吸附常数K＝2.88×10-2 L/mg。     

RuO2/La2O3/TiO2悬浮体系中直接耐晒黑G的光催化降解

钛酸丁酯为前驱体,采用溶胶-凝胶-浸渍法制备RuO2/La2O3/TiO2复合光催化剂,以紫外灯为光源,研究了催化剂组成、煅烧温度、溶液pH值等因素对直接耐晒黑G(DFBG)光催化降解的影响.结果表明掺杂量w(La2O3)1.39%、w(RuO2)0.12%、煅烧温度500℃(2 h)、溶液pH值7.3时,光催化活性最佳.当通气量为200 mL/min,催化剂投加量为150mg时,50 mg/L的DFBG溶液经60 min降解,其降解率近100%.DFBG的光催化降解服从Langmuir-Hinshelwood动力学模型,测得相应的动力学参数k=7.42×10-3mmol/L·min,K=19.54 L/mmol.     

TiO2/H2O2/UV和TiO2/O3/UV降解对氯苯甲酸和喹啉的试验研究

主要叙述TiO2/H2O2/UV和TiO2/O3/UV体系降解对氯苯甲酸(4-CBA)和喹啉的试验研究.研究表明,(1)在TiO2/H2O2/UV体系里目标物降解速度先随过氧化氢投加量的增加而提高,但超过一定浓度之后便开始下降;(2)在TiO2/O3/UV体系中,目标降解物的反应速度都非常快,且臭氧浓度高的时候降解速度更快;(3)二氧化钛催化剂在TiO2/O3/UV体系中作为积极因素有助于提高反应速率,而在TiO2/H2O2/UV体系是消极因素,会降低反应速率.     

TiO2/H2O2/UV和TiO2/O3/UV降解对氯苯甲酸和喹啉的试验研究

主要叙述TiO2/H2O2/UV和TiO2/O3/UV体系降解对氯苯甲酸（4-CBA）和喹啉的试验研究.研究表明,（1）在TiO2/H2O2/UV体系里目标物降解速度先随过氧化氢投加量的增加而提高,但超过一定浓度之后便开始下降;（2）在TiO2/O3/UV体系中,目标降解物的反应速度都非常快,且臭氧浓度高的时候降解速度更快;（3）二氧化钛催化剂在TiO2/O3/UV体系中作为积极因素有助于提高反应速率,而在TiO2/H2O2/UV体系是消极因素,会降低反应速率.     

Photocatalytic degradation of lignin using Pt/TiO2 as the catalyst

Photocatalytic degradation of lignin was studied with the use of catalysts TiO(2) and Pt/TiO(2). The influence of several experimental parameters, i.e. pH, catalyst dosage and illumination on lignin degradation was investigated. The results showed that application of UV irradiation alone has almost no effect on the reduction of dissolved organic carbon (DOC) and American Dye Manufacture Institute value (ADMI). However, the addition of TiO(2) and Pt/TiO(2) reduced the original DOC (251 mg l(-1)) by more than 40% within 30 min of treatment and the reaction can be simulated with pseudo-first order kinetics. Rapid degradation of lignin was observed in acidic solution using either TiO(2) or Pt/TiO(2) as the catalyst compared to high pH cases. The content of Pt in the Pt/TiO(2) catalyst is 1%. In addition, too much catalyst addition has not increased the DOC and ADMI reduction proportionally. The investigation also indicated that the photocatalytic degradation rates could be enhanced 1-6 times faster after doping TiO(2) with Pt in different pH cases. A modified Nernst type model was adopted to simulate the decoloring process using TiO(2) and Pt/TiO(2) based on the profiles of oxidation reduction potential during the photocatalytic reaction. The developed equation can be used to predict the color removal efficiency of lignin wastewater by the photocatalytic process.     

Role of cupric ions in the H2O2/UV oxidation of humic acids

The purpose of this study is to reveal the role of cupric ions as a natural water contaminant in the H2O2/UV oxidation of humic acids. Humic acids are naturally occurring organic matter and exhibit a strong tendency of complexation with some transition metal ions. Chlorination of humic acids causes potential health hazards due to formation of trihalomethane (THM). The removal of THM precursors has become an issue of public concern. The H2O2/UV process is capable of mineralizing humic acids due to formation of a strong oxidant, hydroxyl radicals, in reaction solution. Experiments were conducted in a re-circulated photoreactor. Different cupric concentrations (0-3.8 mg/l) and different pH values (4-9) were controlled to determine their effects on the degradation of humic acids, UV light absorbance at 254 nm, and H2O2. The presence of cupric ions inhibits humic mineralization and decreases the rate of destruction of humic acids which absorb UV light at 254 nm. On the other hand, the higher the cupric concentration, the lower the H2O2 decomposition rate. In the studied pH range, the minimum of total organic carbon (TOC) removal occurs at pH = 6 in the presence of 2.6 mg/l of cupric ions; both acidification (pH = 4) and alkaline condition (pH = 9) lead to a better removal of TOC. It is inferred from this study that the cupric-complexed form of humic acids is more refractory than the non-complexed one.     

UV/O3降解水样中COD的动力学建模

建立动力学模型可以对UV/O3降解有机物的过程进行有效的分析和预测,帮助改进水处理工艺以提高有机物的降解效率和降低能源消耗。然而,已有的方法无法满足实际水样中未知有机物降解过程的建模需求。在化学反应机理的基础上,结合对有机物降解生成CO2浓度演化规律的分析,建立了一种可预测未知有机物降解反应的数学模型。通过改变氧化消解的条件,从理论上检验了该模型的灵敏度;同时,实验采用了含有葡萄糖、尿素和邻苯二甲酸氢钾的混合溶液作为测试水样,考察了模型的准确性,实验值与预测值的趋势一致。     

UV/TiO2光催化降解水体中的邻苯二甲酸二甲酯

酞酸酯是环境中普遍存在的有机污染物(内分泌干扰物)之一。利用UV/TiO2光催化降解水体中的邻苯二甲酸二甲酯(DMP),讨论了溶液pH、TiO2投加量及DMP初始浓度等因素对DMP降解的影响。结果表明,DMP为10mg/L左右时,TiO2投加量为0.2～0.5g/L、pH=7是比较理想的降解条件;DMP初始浓度越高,其降解率则越低。研究了Langmuir-Hinshelwood模式下DMP在TiO2表面的吸附与催化活性的关系,发现DMP主要通过吸附在催化剂的表面而非在溶液本体中发生降解。线性回归计算所得光照条件下的吸附常数远大于无光照条件下的吸附常数,可能是由于UV和TiO2体系之间产生协同效应,提高了UV/TiO2体系对DMP的降解效果。另外,初步分析了可能的降解反应机制。     

An improved UV/Fe3+ process by combination with electrocatalysis for p-nitrophenol degradation

p-nitrophenol (PNP) was investigated as a model pollutant under the improved UV/Fe3+ process by combination with electrocatalysis. In the individual UV/Fe3+ process, PNP degradation rate was dependent on Fe(III) concentration and decreased during degradation due to the depletion of ferric ion and thus it was very difficult to reach the quick mineralization of organics. These drawbacks could be significantly overcome in the modified UV/Fe3+ process, and synergetic effects for PNP and COD removal were observed at two investigated Fe(III) concentrations. The enhancements on the degree of conversion for PNP and COD in presence of 0.5 mM Fe(III) were 184% and 242%, respectively, and PNP of initial concentration of 1.0 mM could be completely removed within 1 h. Thus such a process would be very attractive to the rapid mineralization of the biorefractory compounds for wastewater treatment. The possible reasons for the synergetic effects were the electrochemical regeneration of ferric ion and the role of the oxygen that formed on the anode. Based on degradation intermediates identification and synergetic effect probe, a general reaction pathway for PNP degradation in the improved process was proposed.     

六氯苯的O3及UV/O3高级氧化降解试验研究

采用O3、UV/O3高级氧化法对水中六氯苯（HCB）的降解效果及机理进行了研究,并对结果进行了比较,结果表明,UV本身对HCB的去除率贡献不大,HCB可被O3、UV/O3快速降解,即UV＜O3＜UV/O3;O3、UV/O3作用时,提高体系的初始pH值不利于HCB的降解,在pH＝3,HCB=0.2 mg/L,反应40 min时,HCB的去除可达50%左右,酸性条件下有利于降解反应的进行;无论是O3单独作用还是UV/O3联合作用,HCB的降解基本上满足准一级反应动力学规律,如果体系的pH值基本保持恒定,这种规律就更为明显。根据离子色谱(IC)、GC对六氯苯降解中间产物进行了测定,探讨了O3、UV/O3降解六氯苯的途径和机理。     

Photocatalytic oxidation of toxic organohalides with TiO2/UV: the effects of humic substances and organic mixtures

TiO2/UV photocatalytic oxidation of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane), 1,2,3-trichlorobenzene and 4-chlorophenol were examined in aqueous solution in the presence of humic substances and organic mixtures to study if the degradation rates were affected. Both commercial and natural humic substances were observed to retard the photodegradation rates, with a greater effect from the natural humic substances. Acetonitrile and isopropanol also caused significant retardation of 4-chlorophenol photodegradation. The overall retardation can be attributed to the combination of light attenuation, inhibition and competition effects. Moreover, the TiO2/UV system favors the decomposition of compounds that have stronger adsorption onto the TiO2 surface. To engineer effective treatment facilities that use the TiO2/UV system for the treatment of toxic substances in wastewater, the methodology must allow for concerns about adventitious species which are present.     

Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni（NO3）2和Fe（NO3）3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO＋NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。     

Photocatalytic degradation of acetaminophen in modified TiO2 under visible irradiation

This study investigated the photocatalytic degradation of acetaminophen (ACT) in synthetic titanium dioxide (TiO₂) solution under a visible light (λ >440 nm). The TiO₂ photocatalyst used in this study was synthesized via sol–gel method and doped with potassium aluminum sulfate (KAl(SO₄)₂) and sodium aluminate (NaAlO₂). The influence of some parameters on the degradation of acetaminophen was examined, such as initial pH, photocatalyst dosage, and initial ACT concentration. The optimal operational conditions were also determined. Results showed that synthetic TiO₂ catalysts presented mainly as anatase phase and no rutile phase was observed. The results of photocatalytic degradation showed that LED alone degraded negligible amount of ACT but with the presence of TiO₂/KAl(SO₄)₂, 95 % removal of 0.10-mM acetaminophen in 540-min irradiation time was achieved. The synthetic TiO₂/KAl(SO₄)₂ presented better photocatalytic degradation of acetaminophen than commercially available Degussa P-25. The weak crystallinity of synthesized TiO₂/NaAlO₂ photocatalyst showed low photocatalytic degradation than TiO₂/KAl(SO₄)₂. The optimal operational conditions were obtained in pH 6.9 with a dose of 1.0 g/L TiO₂/KAl(SO₄)₂ at 30 °C. Kinetic study illustrated that photocatalytic degradation of acetaminophen fits well in the pseudo-first order model. Competitive reactions from intermediates affected the degradation rate of ACT, and were more obvious as the initial ACT concentration increased.     

O3/H2O2/UV降解1,2,4-三氯苯的研究

采用O3/H2O2/UV工艺处理1,2,4-三氯苯(TCB)模拟废水,考察了TCB初始浓度、pH、H2O2投加量及O3转化率等因素对O3/H2O2/UV降解TCB的影响,推断了TCB可能的降解途径。结果表明:(1)H2O2、O3、UV、O3/H2O2、O3/H2O2/UV 5种体系对TCB的降解效果为H2O2相似文献   

Improvement of water resistance by Fe2O3/TiO2 photoelectrocatalysts for formaldehyde removal: experimental and theoretical investigation

Environmental Science and Pollution Research - TiO2-based photocatalysts are a potential technology for removing indoor formaldehyde (CHOH) owing to their strong photooxidation ability. However,...     

H2O2/Fe0、H2O2/Fe2+、H2O2/Fe3+3种体系处理印染废水

采用H2O2/Fe0、H2O2/Fe2+、H2O2/Fe3+3种体系分别对印染废水进行处理,研究pH 值、H2O2投加量、不同价态铁元素的投加量及反应时间对印染废水的COD和色度处理效果的影响。实验最佳的处理条件:H2O2/Fe0体系在pH 为3.0,Fe0投加量为3.0 mmol/L,H2O2投加量为9.0 mL/L,反应时间为40 min时,COD去除率达到95.99%,色度去除率达到100%;H2O2/Fe3+体系在pH 为3.0,Fe3+投加量为5.0 mmol/L,H2O2投加量为12.5 mL/L,反应时间为100 min时,COD去除率达到95.89%,色度去除率达到100%;H2O2/Fe2+体系在pH 为3.0,Fe2+投加量为6.0 mmol/L,H2O2投加量为12.0 mL/L,反应时间为100 min时,COD去除率达到95.85%,色度去除率达到100%。对比分析3种体系在各因素下的处理结果,H2O2/Fe0体系和H2O2/Fe3+体系都要优于H2O2/Fe2+体系,其中H2O2/Fe0体系的处理效果最好。