MnO2/g-C3N4纳米复合材料的合成及其光催化性能

通过Na₂SO₄进行形貌调控和MnO₂掺杂对石墨类氮化碳(g-C₃N₄)改性,采用水热法制备多形貌的MnO₂/g-C₃N₄复合光催化剂(MCN),探讨最佳合成条件;研究不同形貌MCN的微观结构、光吸收能力以及对甲基橙(MO)的光催化降解性能。结果表明,MCN的最佳制备条件如下：Na₂SO₄、g-C₃N₄、KMnO₄投加量分别为 0.04、0.6、0.12 g/L,反应温度为 80 ℃,反应时间为 4 h。MnO₂掺杂可显著提高g-C₃N₄的光催化活性。MCN对MO的光催化降解率高达97.34%,而g-C₃N₄仅为54.39%;MCN具有较强的可见光响应活性,最大吸收边带为 486 nm,禁带宽度(...     

g-C3N4/TiO2复合汽车尾气光催化剂的组成设计与性能评价

随着汽车尾气对空气质量的负面影响日益严重,光催化技术在环保领域的应用逐渐受到重视。因此,基于二氧化钛(Ti O₂)和石墨相氮化碳(g-C₃N₄)的光催化性能,制备了一种g-C₃N₄/Ti O₂复合光催化剂,旨在提高汽车尾气的降解效率,即：选用三聚氰胺(C₃H₆N₆)、双氰胺(C₂H₄N₄)和尿素(CH₄N₂O)作为前驱体制备g-C₃N₄,通过质量损失和尾气降解实验分析筛选出最佳前驱体,并设计了不同质量比的g-C₃N₄/Ti O₂复合光催化剂;通过对比分析单体和复合光催化剂的光催化性能,确定了复合光催化剂的最佳质量比。实验结果表明：制备g-C₃N_...     

g-C3N4光催化混凝土对NO降解性能研究

研究了不同制备工艺及掺量的石墨相氮化碳(g-C₃N₄)对混凝土的力学性能及对NO气体光催化降解性能的影响及变化规律。通过TEM、SEM、XRD分别对材料的物相及微观结构进行了表征,利用微机控制全自动压力试验机和氮氧化物分析仪分别研究了掺g-C₃N₄后混凝土的抗压强度及对NO的降解性能。结果表明,四种不同种类的g-C₃N₄掺入后混凝土都具有对NO的降解作用,其中,少层g-C₃N₄的降解率最高,且在紫外线等照射24 h后其仍能保持较高的降解率;g-C₃N₄掺量不超过0.8%时混凝土的抗压强度不会有太大影响,在此范围内尽可能提高g-C₃N₄的掺量来提高其对NO的降解作用。     

g-C3N4基光催化剂的改性制备及在废水处理中的应用

石墨相氮化碳(g-C₃N₄)是具有二维层状结构的无金属半导体材料，以低成本富氮材料为前驱体就可制得。g-C₃N₄具有合适的禁带宽度、良好的热稳定性和化学稳定性以及绿色环保无污染等优点，被广泛应用于产氢、降解有机染料及CO₂的还原等领域，因此在光催化领域有着诱人的应用前景。但纯g-C₃N₄比表面积小、光生载流子易复合，使其光催化性能受到一定的影响，所以需要不同的制备及改性方法来提高其光催化性能。归纳了g-C₃N₄的制备及改性方法，综述了近年来g-C₃N₄在印染、抗生素、重金属和农药等生产废水处理中的应用，并对g-C₃N₄今后在合成、改性方面的研究进行了展望。     

g-C3N4/PDS光催化降解阿特拉津的效能及机理研究

为解决阿特拉津(ATZ)造成的水体污染问题，以三聚氰胺为前驱体，通过热聚合的方法成功制备了石墨相氮化碳(g-C₃N₄)，并通过X射线衍射光谱(XRD)及扫描电子显微镜(SEM)对其结构及形貌进行了表征；同时探究了在可见光条件下g-C₃N₄与过二硫酸盐(PDS)耦合体系降解ATZ的效能。动力学研究证实，在可见光下g-C₃N₄与PDS具有明显的协同效应，其对ATZ的降解明显优于g-C₃N₄/Vis、PDS/Vis及g-C₃N₄/PMS(过一硫酸盐)/Vis体系。在优化实验参数的过程中发现，适度增加PDS的浓度和g-C₃N₄的用量、降低溶液的pH能有效促进ATZ的降解；但Cl^-、CO₃^2-/HCO₃^-、NO₃     

钨掺杂g-C3N4薄膜电极的制备及光电性能研究

采用高温液相生长法制备了不同钨(W)掺杂量的W/g-C₃N₄薄膜电极,并通过SEM、XRD、FTIR、UV/vis DRS、XPS等手段对薄膜电极进行表征。结果表明,掺杂的W以W⁰、WO₂和WO₃等多种形态存在。将W/g-C₃N₄薄膜电极用作光阳极,进行交流阻抗测试、光电流密度测试以及降解亚甲基蓝实验,与g-C₃N₄薄膜电极相比,W/g-C₃N₄薄膜电极对可见光的响应能力明显增强,其中当Na₂WO₄与g-C₃N₄的掺杂比为1∶50时光电流密度可提高至原来的2.2倍。通过添加自由基捕获剂探究W/g-C₃N₄薄膜电极对亚甲基蓝的催化氧化机理,发现掺杂W之后,W/g-C₃N₄薄膜电...     

LaCuO3/3DOMCeO2的制备及其催化性能研究

制备了钙钛矿型LaCuO₃/3DOMCeO₂催化剂用于非均相类芬顿反应降解罗丹明B,并通过XRD、SEM和XPS等对该催化剂进行表征。结果表明,LaCuO₃/3DOMCeO₂呈现三维有序大孔结构。负载3DOMCeO₂使LaCuO₃的比表面积增大、Cu⁺含量上升。LaCuO₃/3DOMCeO₂具有比均相芬顿催化剂更宽的pH适用范围和更高的H₂O₂利用率。循环使用10次后,LaCuO₃/3DOMCeO₂仍具有较高的催化活性。LaCuO₃/3DOMCeO₂表面存在■循环,二者协同引发高效类芬顿反应,产生大量·OH和·HO₂,实现了对罗丹明B的高效降解。     

Fe/Al/C多元微电解—H2O2工艺处理农药生产废水

采用Fe/Al/C多元微电解—H₂O₂工艺处理农药生产废水。通过间歇实验考察了该工艺的运行参数,结果显示在初始p H值为4、Na₂SO₄投加量为0.03 mol/L、H₂O₂投加量为1.5 m L/L和反应时间为80 min的条件下对农药生产废水的处理效果最佳。在连续运行条件下,该工艺对农药生产废水中COD的平均去除率为88.5%,平均生物毒性削减率为63.7%,B/C值由0.126提高到0.341。Fe/Al/C多元微电解—H₂O₂工艺降解农药生产废水的过程符合一级动力学反应,速率常数k_COD=0.018 8min^-1,相关系数R²=0.989 8。农药生产废水经过Fe/Al/C多元微电解—H₂O₂工艺处理后,有机物各基团的UV-Vis光谱强度都得到了显著削减,即有机物被有效降解。     

UV/H2O2/O3工艺降解典型有机防晒剂

有机防晒剂作为一种新兴污染物引发的环境安全风险备受关注。采用紫外/双氧水/臭氧联用工艺(UV/H₂O₂/O₃)降解典型有机防晒剂2,4-二羟基二苯甲酮(UV-0),基于中心组合设计方法进行实验,考察影响因素,并探索降解机理。结果表明,在H₂O₂浓度为340μmol/L、UV-0初始浓度为5 mg/L、UV光强为170μW/cm²、O₃流量为0.38 L/min条件下,20 min内对UV-0的降解率高达99.9%,反应速率常数为0.570 7 min^-1,降解效果良好。响应面模型能较好地模拟和预测实验结果,并探索反应空间,H₂O₂浓度、UV光强、O₃流量等因素会影响降解效果。高分辨率质谱和量子化学结构分析表明,UV-0降解过程中羟基加成反应首先发生在C10位置,形成羟基和二羟基加成产物,随后通过碳碳键断裂和芳香环裂解生成草酸等小分子酸。UV/H     

铁酸铋催化类芬顿及光芬顿体系降解诺氟沙星

通过水热法制备铁酸铋催化剂,采用XRD、SEM等方法对样品进行表征,并以类芬顿体系和光芬顿体系分别降解诺氟沙星,考察相关反应参数对诺氟沙星降解效果的影响。试验结果表明,类芬顿体系降解诺氟沙星过程符合伪一级反应动力学模型,在诺氟沙星初始浓度为10mg/L、pH值为3、H_2O_2投加量为1 mmol/L、铁酸铋催化剂投加量为1. 0 g/L、反应时间为2 h条件下,体系对诺氟沙星的降解率达到100%,表观速率常数K_(app)为0. 018 7 min~(-1)。比较铁酸铋催化类芬顿及光芬顿体系分别降解诺氟沙星的效果,发现光照对类芬顿体系降解诺氟沙星具有显著的促进作用,且能够扩宽体系pH值的适用范围。重复使用性试验和相关检测结果表明,制备的铁酸铋催化剂性质稳定,无金属离子溶出,具有较好的重复使用性。     

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。     

Bi2MoO6/AgBr的制备及其光催化活性增强机制

采用水热法合成了Z型异质结Bi₂MoO₆/Ag Br光催化剂,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、比表面积测试仪(BET)、稳态/瞬态荧光光谱仪等对其微观形貌、物相组成以及光电性能等特性进行表征;通过对目标污染物罗丹明B(Rh B)的降解分析该催化剂的活性和降解机理。结果表明,该催化剂由立方相的Bi₂Mo O₆纳米片堆叠而成的纳米微球和负载在其表面的Ag Br纳米花簇构成,异质结的形成使得比表面积增加了7.2 m²/g,光生电子对寿命延长。Bi₂Mo O₆与Ag Br复合后光催化活性明显提高,当Ag Br复合量为10%时效果最佳,光催化反应速率常数是Bi₂Mo O₆的1.6倍。当Rh B浓度为0.5×10^-5mol/L、Bi₂Mo O₆/Ag Br投加量为250 mg/L、p H值=7时,反应20 min后对Rh B的降解率可达到95.9%,且Bi₂Mo O₆/Ag Br经过5次循环实验后仍具有较高的光催化活性。自由基捕获实验结果表明,Bi₂MoO₆的主要活性基为·O₂^-,Bi₂Mo O₆/Ag Br的主要活性基团为·O₂^-和h⁺。根据以上实验结果,提出了一种由Ag⁰粒子为通道的Z型电荷转移机理。     

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.     

净化空气多功能内墙涂料的制备及其性质研究

加入纳米TiO2作为光催化粉体,对传统建筑内墙涂料进行改性,使之具有较强的净化空气、杀菌抑菌的功能。从分散剂用量的确定、纳米TiO2用量的确定、PVC的确定三个方面来提高涂料本身的性能。对其光催化氧化降解甲醛进行了初步测试表明,对室内有害气体污染有较大的改善作用。     

Photocatalytic degradation of methyl orange by TiO2-coated activated carbon and kinetic study

TiO2-coated activated carbon (AC) grain (TiO2/AC) was prepared through hydrolytic precipitation of TiO2 from Tetrabutylorthotitanate and following heat treatment. The TiO2/AC was characterized by BET, SEM, XRD and optical absorption spectroscopy. The samples were employed as catalysts for methyl orange photocatalytic oxidation degradation in aqueous suspension, used as probe reaction. The kinetics of methyl orange photodegradation was analyzed. The results indicate that BET surface area of TiO2-coated ACs decreased drastically in comparison with the original AC with increasing TiO2 coatings by more than 1 doped cycle. Nano-TiO2 particles were dispersed on the AC with the size of 20-40 nm. Crystalline TiO2 doped onto AC was from anatase to rutile with increase of heat-treatment temperature. The TiO2/AC was shown high photoactivity for the photodegradation of methyl orange (MO) dyestuff in aqueous solution under UV irradiation. The kinetics of photocatalytic MO dyestuff degradation was found to follow a pseudo-first-order rate law. It was observed that the presence of the AC enhanced the photoefficiency of the titanium dioxide catalyst. Different amount of TiO2 coatings induced different increases in the apparent first-order rate constant of the process. The kinetic behavior could be described in terms of a modified Langmuir-Hinshelwood model. The values of the adsorption equilibrium constants for the organic molecules, KC, and for the rate constants, kc, were certainly dependent on TiO2 content. At 47wt% TiO2 coatings with the highest rate constant, the KC and kc was 0.1116l mmol(-1) and 0.1872 mmol l(-1) min(-1), respectively. The mechanism of methyl orange degradation was discussed in terms of the titanium dioxide photosensitization by the AC.     

Feasibility of a two-stage reduction/subsequent oxidation for treating Tetrabromobisphenol A in aqueous solutions

A “two-stage reduction/subsequent oxidation” (T-SRO) process consists of Fe-Ag reduction and Fenton-like oxidation under ultrasound (US) radiation. Due to the refractory oxidation of brominated flame retardant, T-SRO was employed to remove Tetrabromobisphenol A (TBBPA) by the combination of first debromination and succeeding oxidation. It indicated that the T-SRO process resulted in a complete decrease in TBBPA concentration and a 99.2% decrease in BPA concentration. The T-SRO process for the removal of TBBPA is much effective than Fenton-like oxidation of TBBPA alone. The result showed that US radiation improved the Fenton-like oxidation rate of BPA solutions. The addition of dissolved iron into the Fenton-like oxidation system could accelerate the first 2 min reaction, but had little effect on the following process. The main intermediate products resulting from TBBPA reduction and BPA oxidation were identified by GC-MS and LC-MS/MS. On the basis of this analysis, reactions with •OH radical were identified as the major chemical pathways during BPA oxidation.     

Treatment of textile dyehouse wastewater by TiO2 photocatalysis

The oxidative degradation of an actual textile dyehouse wastewater was investigated by means of photocatalysis in the presence of TiO2. The UV-A-induced photocatalytic oxidation over TiO2 suspensions was capable of decolorizing the effluent completely, as well as reducing chemical oxygen demand (COD) sufficiently (COD reduction generally varied between about 40% and 90% depending on the operating conditions) after 4 h of treatment. Two crystalline forms of TiO2, viz. anatase and rutile, were tested for their photocatalytic activity and anatase was found to be more active than rutile. The extent of photocatalytic degradation was found to increase with increasing TiO2 concentration up to 0.5 g/L TiO2, above which degradation remained practically constant, reaching a plateau. Furthermore, textile effluent degradation was enhanced at acidic conditions (i.e. pH = 3) and in the presence of hydrogen peroxide. To assess catalyst activity on repeated use, experiments were performed where the catalyst was recovered and reused; after three successive uses, TiO2 had sufficiently retained its photocatalytic activity. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute ecotoxicity of samples prior to and after the photocatalytic treatment and it was found that ecotoxicity was fully eliminated following photocatalytic oxidation.     

Carbon isotope effects associated with Fenton-like degradation of toluene: potential for differentiation of abiotic and biotic degradation

Hydrogen peroxide (H(2)O(2))-mediated oxygenation to enhance subsurface aerobic biodegradation is a frequently employed remediation technique. However, it may be unclear whether observed organic contaminant mass loss is caused by biodegradation or chemical oxidation via hydroxyl radicals generated during catalyzed Fenton-like reactions. Compound-specific carbon isotope analysis has the potential to discriminate between these processes. Here we report laboratory experiments demonstrating no significant carbon isotope fractionation during Fenton-like hydroxyl radical oxidation of toluene. This implies that observation of significant isotopic fractionation of toluene at a site undergoing H(2)O(2)-mediated remediation would provide direct evidence of biodegradation. We applied this approach at a field site that had undergone 27 months of H(2)O(2)-mediated subsurface oxygenation. Despite substantial decreases (>68%) in groundwater toluene concentrations carbon isotope signatures of toluene (delta(13)C(tol)) showed no significant variation (mean=-27.5+/-0.3 per thousand, n=13) over a range of concentrations from 11.1 to 669.0 mg L(-1). Given that aerobic degradation by ring attack has also been shown to result in no significant isotopic fractionation during degradation, at this site we were unable to discern the mechanism of degradation. However, such differentiation is possible at sites where aerobic degradation by methyl group attack results in significant isotopic fractionation.