超声、臭氧、光催化及其组合工艺处理苯酚废水

研究了在一定条件下,超声、臭氧、光催化等高级氧化技术的不同组合方法对苯酚的降解效果。结果表明,对于质量浓度为100 mg/L的苯酚溶液,反应时间为1 h时,超声、臭氧氧化、光催化三者单独降解率分别为8%、36%、35%。紫外光光催化分别与超声波或臭氧组合对苯酚降解有一定的协同作用,降解率分别为50%、78%;而声光催化技术与臭氧三者组合降解苯酚的效果尤佳,降解率达到85%。这归功于超声波的机械作用对臭氧扩散引起的积极作用以及声光催化协同产生的H2O2,从而生成的羟基自由基。     

Ag3PO4光催化-臭氧催化氧化协同降解苯酚

以Ag₃PO₄为光催化剂并通入臭氧构建了光催化-催化臭氧氧化协同体系，大幅度提高了对苯酚的降解效率。协同处理6 min后可将30 mg/L的苯酚溶液完全降解，在达到相同降解效率时，与单一氧化技术相比时间缩短了3倍。协同体系降解性能的提升源于臭氧的亲电特性，不仅加速了光生电荷的迁移，提升了光催化降解活性；同时还有效提高了臭氧利用效率，催化分解臭氧能产生更多的羟基自由基(·OH)，协同促进了苯酚的降解矿化性能。进一步通过猝灭实验验证了·OH是协同降解体系的主要活性物种，考察了臭氧浓度、催化剂投加量、苯酚浓度和酸碱性对降解效率的影响，探讨了光催化-臭氧催化氧化协同降解苯酚的降解机理。     

高压脉冲放电降解4-氯酚废水的实验研究

采用多针-板高压脉冲气液两相放电反应系统处理难降解的4-氯酚废水,并运用控制变量方法确定多种工艺参数的最佳值。考察了中间产物浓度变化情况、溶液矿化率、总有机碳浓度(TOC),并对4-氯酚的降解过程进行分析研究。实验结果表明:在脉冲电压26 kV、脉冲频率70 Hz、电极间距1.0 cm、曝气量4 L/min的情况下,150 mg/L的4-氯酚废水溶液放电处理90 min后降解率为67.25%。在放电过程中溶液导电性较高对活性粒子的生成有抑制作用导致溶液矿化率较低。整个放电过程中,溶液TOC整体呈缓慢下降趋势,中间产物浓度先增大后减小,其中峰值浓度最高的是4-氯邻苯二酚,峰值浓度最低的是对苯酚。     

光催化真空紫外-臭氧氧化一体的反应器研制

自行研制了集光催化真空紫外及臭氧氧化为一体的反应器,并采用正交实验考察其对苯酚的降解性能。结果表明,其对苯酚的矿化速率常数分别是单独真空紫外光氧化(VUV)、光催化(UV/V-N-TiO_2)的3.01和2.10倍,分别是组合真空紫外光催化(VUV/V-N-TiO_2)、真空紫外臭氧氧化(VUV/O_3)和光催化臭氧氧化(UV/V-N-TiO_2/O_3)的1.48、2.08和2.60倍,三者形成协同促进作用矿化苯酚效果好。苯酚初始质量浓度对其矿化性能影响最大,越低矿化效果越好。在初始苯酚质量浓度10 mg/L、循环体积流量0.5 L/min、p H为4、空气体积流量0.2 L/min的优化条件下,反应4 h矿化率达92.6%。一体反应器结构紧奏、工艺简单。     

臭氧法降解水中4-氟苯酚动力学研究

采用臭氧法降解4-氟苯酚模拟废水,研究4-氟苯酚降解影响因素和动力学。考察了反应液初始p H、反应物初始浓度、臭氧投量对臭氧氧化4-氟苯酚反应速率的影响。结果表明,4-氟苯酚初始浓度1 mmol/L,p H 10.0,常温常压下反应120 min后,4-氟苯酚总模拟废水的有机碳去除率为56.77%。采用幂指数方程描述反应动力学,4-氟苯酚模拟废水在臭氧氧化下的TOC去除符合表观一级动力学,并得到不同条件下的表观反应速率常数。     

纳米二氧化钛光催化降解苯酚水溶液

以P 25纳米TiO2 作为光催化剂,在环状光催化反应器中进行了苯酚水溶液的光催化降解性能研究。系统考察了溶液的pH、P 25用量、银掺杂量、苯酚的初始质量浓度等因子对苯酚溶液光催化降解过程的影响。结果表明,在pH=7时,苯酚水溶液降解率达97 4%,强酸和强碱条件均不利于苯酚的降解;质量浓度50mg/L的苯酚水溶液,P 25用量为50mg,UV辐照30min时降解率为95 6%;质量浓度100mg/L的苯酚水溶液,P 25用量为150mg,UV辐照60min时降解率为95 4%;银掺杂P 25增加了其光催化活性,用质量分数为10%的硝酸银水溶液掺杂制备的复合光催化剂,苯酚的降解率比未掺杂时增加16 5%。     

稀土元素Ce掺杂TiO_2光催化剂制备及微波强化光催化活性

在[Bmim]PF6离子液体介质中微波辅助制备稀土元素Ce掺杂改性的TiO_2光催化剂TiO_2-Ce,以甲基橙溶液和苯酚溶液为模拟污染物,在紫外光照和微波辐射-紫外光照降解条件下考察TiO_2-Ce催化剂的光催化活性。利用荧光技术以对苯二甲酸作为荧光探针检测TiO_2-Ce催化剂表面产生的羟基自由基,并对光催化降解反应进行动力学分析,以了解光催化降解反应机理。结果表明,通过优化反应条件制得的TiO_2-Ce催化剂具有较高光催化降解活性和热稳定性,在紫外光照和微波辐射-紫外光照条件下降解60 min后,甲基橙降解率分别为98.6%和99.3%,苯酚降解率分别为96.6%和97.2%。荧光光谱分析表明,TiO_2-Ce在微波辐射-紫外光照条件下产生的羟基自由基比紫外光照多,因而微波辐射-紫外光照具有强化TiO_2-Ce降解模拟污染物作用的效果。反应动力学数据表明,TiO_2-Ce光催化降解甲基橙溶液反应呈一级反应动力学规律,其表观速率常数k最大值为0.056 2 min-1。     

钛取代杂多硅钨酸盐掺杂聚苯胺的制备及光催化性能

以Keggin结构钛取代杂多硅钨酸盐α-K6[SiW11TiO40].xH2O为掺杂剂制备了α-SiW11Ti/PANI电子聚合物材料。用红外光谱和紫外光谱对此材料进行了表征。以紫外灯为光源,以α-SiW11Ti/PANI为光催化剂,探讨了光催化降解苯酚的条件。考察了催化剂的用量、光解时间对高铁酸钾氧化苯酚的影响。实验结果表明,对于浓度为10 mg/L的苯酚溶液,催化剂投加量为1.5 g/L,在300 W的紫外灯照射下,光催化降解6 h,去除率可达90.75%,TOC去除率达86.3%。     

纳米TiO2光催化降解有机物的机理及其影响因素的研究

对纳米TiO2光催化降解水中有机物的机理进行了研究，并对溴苯酚降解为目标反应，系统分析了紫外光强度、TiO2浓度、温度、溶液的pH值以及杂质等对光催化降解为溴苯酚程度的影响。优化这些因素可以提高纳米TiO2光催化降解率。     

光催化降解水中苯酚的研究

采用WL-TiO2型光催化剂,对水中的苯酚进行光催化降解：探究了该催化剂的光催化氧化机理,并考察了不同类型的TiO2、催化剂投放量、苯酚浓度、降解温度、溶液的pH值以及光源和光强等因素对降解率的影响。试验结果表明,浓度为14mg／L的苯酚溶液,用WL-TiO2光催化剂,光催化降解3h,可以将溶液中的苯酚完全降解。     

脉冲气液两相放电等离子体耦合Fe改性的TiO2催化剂降解废水中的4-氯酚

为了提高酚类废水的降解效果,本文以4-氯酚为处理对象建立了多针-板式高压脉冲气液两相放电等离子体催化体系。实验制备了系列催化剂并进行了表征分析,考察了各因素对4-氯酚降解的影响,并分析了降解过程总有机碳（TOC）、中间产物及其浓度变化。结果表明,催化剂焙烧温度及投加量对降解率有很大影响;4-氯酚浓度为150mg/L时,在电极间距10mm、脉冲电压26kV、脉冲频率70Hz、曝气量4L/min条件下,添加0.05g焙烧温度为500℃的Fe-TiO₂催化剂与放电等离子体耦合降解效果最好。中间产物对苯酚、对苯醌、4-氯邻苯二酚在放电过程中浓度随着放电时间的延长先增大后减小,最后都趋于零。催化剂表征显示脉冲放电可以改变催化剂的晶形和结构,且掺杂Fe改性的Fe-TiO₂催化性能较好,能进一步提升4-氯酚的降解率。     

电絮凝气浮法处理分散艳蓝E-4R废水的研究

采用电絮凝气浮法处理分散艳蓝E-4R染料废水,考察了电解时间、废水初始浓度、pH值及外加电解质氯化钠和絮凝剂等不同反应条件对废水处理效果的影响。结果表明,染料废水脱色率随着电解时间的加大而逐渐增大并随初始浓度的增大而慢慢降低;pH值在2.5~10范围内电解均可获得较高的脱色率。初始浓度为400 mg/L的染料废水,电解20 min后脱色率即达87.39%,但TOC去除率只有10.49%。投加50 mg/L氯化钠后,脱色率和TOC去除率分别达到93.61%和73.49%,TOC去除率提高60%以上。在电解的条件下投加不同絮凝剂能提高染料废水的处理效果,其处理效果从大到小依次为:硫酸铝>三氯化铝>硫酸亚铁,它们的适宜用量分别为50,100,100 mg/L。     

Evaluation of Degradation Characteristics of Reactive Dyes by UV/Fenton,UV/Fenton/Activated Charcoal,and UV/Fenton/TiO2 Processes: A Comparative Study

The photochemical decolorization and mineralization of Reactive red 241 (RR241) in aqueous solution has been studied using a homogeneous photofenton process and its combination with activated charcoal and titanium dioxide. The effects of applied catalyst and adsorbent loading, dye concentrations, pH of solution, and the effect of various systems at constant UV irradiation were determined. Decolorization, COD and TOC analysis were employed to evaluate the results of the photochemical and photocatalytic degradation of RR241. The degradation of the dye was monitored by constant COD analysis and then analyzed by high performance liquid chromatography (HPLC) and IR analysis. The result shows that complete decolorization of dye with photofenton process required 240 minutes with 18.6% of maximum TOC reduction. To overcome the problem of slow decolorization and low degradation with photofenton process, it was combines with activated charcoal and Titanium dioxide. UV/Fenton/AC process gave complete decolorization in less than 80 minutes with 14.9% of TOC reduction after 240 minutes. In contrast the UV/Fenton/TiO₂ process required 120 minutes for complete decolorization but yielded maximum TOC reduction of 43.9% after 240 minutes. Therefore, according to COD and TOC reduction it could be suggested that the UV/Fenton/TiO₂ was more effective than other processes.     

Reductive/oxidative treatment with superior performance relative to oxidative treatment during the degradation of 4-chlorophenol

This study obtained information on the effectiveness of the photo-assisted Fenton oxidation of 4-chlorophenol (4-CP) combined with zero-valent pretreatment. The kinetic rate parameters of the process as well as the operating conditions were determined. Homogeneous photo-assisted Fenton enhanced processes lead to 33% mineralization of 4-chlorophenol (1.25 mM) in solutions containing Fe-ions (2–10 mg/l) and H₂O₂ (10 mM) within 2 h under visible light irradiation. When this solution was pretreated with zero-valent Fe (14 g/70 ml) in Ar atmosphere, the mineralization attained levels of >80% after the second stage photo-assisted Fenton process. Intermediates that could be effectively degraded by photo-Fenton reactions were not attained in the absence of zero-valent Fe pretreatment. The pretreatment by zero-valent Fe under light lead to about 70% of the stoichiometric amount of chloride contained in 4-CP. Partial recovery of chloride ions indicated the formation of chloro-intermediates. These intermediates were experimentally detected by high-pressure liquid chromatograph (HPLC)–MS and the most important intermediates were identified. Fenton photo-assisted processes were effective employing very low concentrations of Fe²⁺(2–5 mg/l) after the pretreatment stage that do not need to be separated after the 4-CP degradation process. This is important for the practical application of the novel combined heterogeneous–homogeneous process. Evidence for the stable catalytic performance of the coupled process to degrade 4-CP is presented. The effect on the 4-CP degradation of Fe-ion, H₂O₂, 4-CP concentration and gas atmosphere was systematically investigated. The activation energy (E_a) of 2.66 kJ/mol was found for the abatement of 4-CP.     

臭氧预氧化/曝气生物滤池污水深度处理特性研究

研究了臭氧预氧化/曝气生物滤池联合工艺对生活污水二级出水的处理特性。结果表明当臭氧投量为10 mg/L、接触时间为4 min时,臭氧预氧化/BAF联合工艺对COD、NH3-N的去除率分别达到58%和90%;使TOC、UV254和色度分别降低了25%、75%和90%。在上述投量和接触时间条件下,臭氧化使TOC/UV254值升高1倍,使可生化溶解性有机碳(BDOC)由原来的0.8~1.1 mg/L提高到2.0~2.7 mg/L。臭氧预氧化使分子质量小于1 k的有机物比例由原来的52.9%升高到72.73%。     

Ti_3(PW_(12)O_(40))_4/TiO_2的制备及其光催化降解水中苯酚的研究

制备了标题化合物并对其进行了初步表征,在光催化反应仪中,以紫外灯为光源,以Ti3(PW12O40)4/TiO2为光催化剂,探讨了光催化降解苯酚的条件。实验结果表明,对于10 mg/L的苯酚溶液,催化剂投加量为1.5 g/L,在30 W高压汞灯照射下,光催化降解7 h,去除率可达86.5%,TOC去除率达83.2%。最后,讨论了催化剂的循环使用性。     

Removal of organic contaminants in paper pulp effluents by AOPs: an economic study

The degradation of the organic content of a bleaching Kraft mill effluent was carried out using Advanced Oxidation Processes (AOPs). The study was focused on the identification of the AOP, or combination of AOPs, that showed the highest efficiency together with the lowest cost. Direct UV photolysis (UV), TiO₂ assisted‐photocatalysis (TiO₂/UV), Fenton, Fenton‐like, and photo‐Fenton reactions (Fe(II)/H₂O/UV), UV‐assisted ozonation (O₃/UV) and addition of Fe²⁺ and/or H₂O₂ to the TiO₂/UV and the O₃/UV systems, were used for the degradation of a conventional cellulose bleaching effluent. The effluent was characterized by the general parameters TOC, COD and color, and analyzed for chlorinated low molecular weight compounds using GC–MS. The costs of the systems per unit of TOC reduction were compared. Fenton, Fenton‐like and photo‐Fenton reactions achieved better levels of TOC degradation than photocatalysis and with lower cost's than photocatalytic treatments. Ozonation is an effective but rather expensive process. The use of UVA light, however, increased the effectiveness of ozonation with a significant decrease (>25%) in the operational cost. © 2002 Society of Chemical Industry     

悬浮态纳米TiO2光催化降解喹啉的研究

采用Degussa P25 TiO2为光催化剂,在紫外光的照射下考察了有无空气、P25 TiO2催化剂用量、喹啉初始浓度、pH值及氯离子对光催化降解过程的影响。实验结果表明:空气促进喹啉和总有机碳的降解率,喹啉初始浓度越低,光催化降解过程越充分,P25 TiO2催化剂适宜浓度为0.70g/L,碱性环境下有利于喹啉的降解,pH=8.38时总有机碳的降解率达到94.47%,随着氯离子掺杂浓度的提高,总有机碳的降解率逐步下降。     

Photocatalytic degradation of phenols in aqueous solution under irradiation of 254 and 185 nm UV light

The photocatalytic decomposition and mineralization of 4-chlorophenol (4-CP), hydroquinone and 4-nitrophenol (4-NP) in aqueous solution were investigated using two kinds of low-pressure mercury lamps: one was UV (ultraviolet) lamp emitting at 254 nm and the other was VUV (vacuum ultraviolet) lamp emitting at both 254 and 185 nm. VUV irradiation led to the most efficient degradation of the organics. Different mechanisms of photocatalysis and photolysis under VUV irradiation were observed. The degradation rate was subjected to the molecular structures of the substrates. 4-CP was easy to be decomposed, while hydroquinone was easy to be mineralized. However 4-NP was difficult to be decomposed or mineralized. VUV was efficient for decomposition of refractory compounds, such as nitrophenols, and the catalyst was efficient for TOC removal.     

含磁性γ-Fe2O3核的TiO2/Al2O3催化剂的制备及光催化性能

TiO2作为光催化剂,可有效地用于水处理,但存在催化剂如何回收再利用和反应器怎样放大设计的问题。该文提出了含磁性核的TiO2催化剂的合成方法,并对典型污染物的降解作了动力学研究,力求解决此类问题。首先,采用共沉法和溶胶-凝胶法制得磁载光催化剂TiO2/A l2O3/γ-Fe2O3,并对该催化剂分别用TEM和XRD进行了形貌和晶相表征。随后,研究了该催化剂对可溶性染料中间体对硝基甲苯邻磺酸(NTS)和直接耐酸大红染料(4BS)的光催化降解性能。结果表明:该催化剂在水溶液中具有良好的分散效果和较高的催化活性,以250 W高压汞灯为光源,经1.5 h的光催化降解,染料去除率可达90%以上;在外加磁场的作用下,催化剂可与液相迅速分离。经实验数据处理,发现NTS在该催化剂上的光催化降解过程符合零级反应动力学模型。