Keggin型铜取代磷钨杂多阴离子可见光催化降解罗丹明B

以Keggin型铜取代杂多阴离子PW11O39Cu(Ⅱ)(H2O)5-[PW11Cu]为可见光催化剂,有机染料罗丹明B(RhB)为模型污染物,研究了在可见光照射下PW11Cu对RhB的可见光催化降解作用,提出了PW11Cu可见光催化作用的反应机理,同时考察了RhB初始浓度、PW11Cu初始浓度和溶液pH值对RhB光催化降解速率的影响。 实验结果表明,含有15.6 μmol/L PW11Cu+10 μmol/L RhB的水溶液在可见光照射下反应80 min,RhB的降解率达100%,总有机碳去除率约33%。 RhB的可见光催化降解服从准一级动力学方程,在RhB初始浓度为20、30和40 μmol/L的情况下,其表观一级速率常数分别为3.1×10-2、2.0×10-2和1.5×10-2 min-1。     

g-C3N4/rGO杂化催化剂的简易合成及其对罗丹明B的光催化降解作用

在空气中直接加热三聚氰胺和氧化石墨烯(GO)的混合物制备了g-C3N4/rGO杂化催化剂.实验结果表明,混合物中的g-C3N4保留了石墨型氮化碳原始的特征结构, g-C3N4和还原的氧化石墨烯(rGO)之间的异质结主要通过π-π作用构筑.当原料中三聚氰胺/GO的质量比是800/1时,所得催化剂对罗丹明B的催化作用最强,其一阶动力学常数是纯g-C3N4的2.6倍.这种强化作用主要是由于rGO促进了光生电子-空穴对的分离.此外, g-C3N4/rGO还表现出显著的pH值敏感特性,催化降解速率随pH的降低而增加.当pH =1.98时,其一阶动力学常数是纯g-C3N4的8.6倍.这是由于酸性条件下质子(H+)消耗掉光生电子,促进了空穴对罗丹明B的氧化作用,其中rGO充当了一个快速的光生电子转移平台.     

中孔石墨碳负载TiO2复合材料光催化降解罗丹明B和苯酚

以26nm单分散的SiO2球为模板,苯乙烯为碳源,Ni为催化剂,在950℃合成了比表面积为298.2m2/g的中孔石墨碳材料.采用粉末X射线衍射、低温N2吸附、热重分析和透射电镜等对碳材料进行了结构表征.结果发现,通过Ni的催化作用,可在较低温度下得到高度石墨化的中孔碳材料.采用溶胶-凝胶法将TiO2负载在中孔石墨碳材料上,形成TiO2/石墨碳复合材料.以罗丹明B和苯酚的光催化降解为探针反应,考察了TiO2/石墨碳复合材料的光催化降解活性.结果表明,在紫外光照射下,罗丹明B和苯酚在该复合材料上的光催化降解反应遵循一级反应动力学,复合材料对罗丹明B和苯酚的光催化降解活性明显高于相同条件下制备的纯锐钛矿型TiO2.     

铜和铝离子/UV催化臭氧降解偶氮二异丁腈废水研究

利用多相催化臭氧(O3)工艺处理偶氮二异丁腈(AIBN)废水,探讨不同催化O3体系(Cu2+、Al3+、Cu2++Al3+/UV催化O3)对AIBN废水中氰类污染物的降解特性,并对不同催化O3体系的动力学特性进行研究。结果表明,金属离子对催化O3工艺的处理效率具有明显影响,不同催化O3工艺对CN-去除作用都呈现起始去除速率较高而后减弱的特点,其中Cu2+和Al3+共同催化O3工艺的整体去除率较高,优于单独Cu2+和Al3+的催化性能。这可能是由于p H变化、金属离子与CN-配合作用、金属离子和O3作用的综合影响结果。动力学研究结果表明,不同催化O3体系降解AIBN废水中的CN-污染物的氧化反应符合准一级动力学反应,表观反应速率常数k在0.0245~0.00301 min-1之间。     

锐钛矿、金红石和板钛矿降解罗丹明B光催化活性的比较

详细考察并比较了采用低温制备的锐钛矿、金红石和板钛矿氧化钛降解罗丹明B的光催化活性.与传统高温焙烧制备的金红石相比,低温制备的金红石粒径小,比表面积大,表面羟基数目多,因此光催化效率明显增加.更重要的是,当锐钛矿和金红石具有相似粒径和比表面积时,金红石具有较高的光降解罗丹明B活性.对于板钛矿氧化钛而言,虽然其表观光催化...     

Ag_3PO_4/Palygorskite的静电调控合成及可见光催化降解罗丹明B和气相异丙醇

以大比表面的廉价易得的凹凸棒(palygorskite)为载体,借助带电荷界面的静电调控作用,采用吸附-沉积沉淀方法制备磷酸银/凹凸棒(Ag3PO4/palygorskite)复合催化剂.利用X-射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、原子吸收光谱(AAS)、紫外可见漫反射光谱(UV-Vis DRS)等技术系统地表征催化剂.之所以能够制备高分散性的凹凸棒负载的磷酸银催化剂,主要是因为凹凸棒具有较大的比表面积、带负电荷界面以及适宜的磷酸根前驱体.以可见光催化脱色降解罗丹明B和氧化降解异丙醇为探针反应,考察复合材料的催化性能.研究表明,与纯磷酸银相比,磷酸银/凹凸棒催化脱色降解罗丹明B和氧化降解异丙醇速率分别提高了2和2.5倍.     

铁基金属有机凝胶衍生的三氧化二铁纳米片用于光芬顿降解罗丹明B

光催化剂在工业废水处理中发挥着重要作用. 本工作以室温下一步合成的片状铁基金属有机凝胶(Fe-based Metal-organic gel, Fe-MOG)为前驱体, 在不同温度下煅烧得到了片状(300-Fe₂O₃和400-Fe₂O₃)和球形(500-Fe₂O₃和600-Fe₂O₃)两种形貌的衍生三氧化二铁(Fe₂O₃). 通过一系列测试手段对衍生Fe₂O₃的晶体结构和光电性能进行了表征. 其中, 具有碳骨架结构的400-Fe₂O₃因其优良的电子传输性能和较高的光生电荷分离效率表现出优异的光催化活性, 可在中性条件下60 min内光降解97.5%的罗丹明B (Rh B), 并且在连续五次循环实验后其降解效率仍能达到85.3%. 本工作为开发和设计具有优异催化活性的半导体光催化剂提供了新的思路.     

有机膨润土吸附水中重金属和有机污染物的性能及机理研究

螯合剂柱撑有机膨润土IMB-TMA-Am能有效吸附水中有机物对硝基苯酚(PNP)和重金属离子Cu2 ,其中IMB为内蒙膨润土;CTMA为溴化十六烷基三甲基季铵盐阳离子;Am分别为有机螯合剂乙二胺(En)、三乙烯四胺(TETA)和四乙烯五胺(TEPA)。实验结果表明:螯合剂柱撑有机膨润土对有机污染物的吸附主要表现为有机物在长碳链疏水介质中的分配,其吸附能力和膨润土内有机碳、氮含量一致;对水中重金属离子的吸附机理是Cu2 和进入膨润土层间的有机螫合剂Am形成了配合物,其吸附能力和所形成配合物的稳定性一致。     

g-C3N4/Fe-Cu的制备以及对4-硝基苯酚光催化降解性能研究

采用高温缩聚尿素和原位沉淀法制备磁性复合g-C_3N_4/Fe-Cu纳米材料,通过X-射线衍射谱(XRD)、高分辨率JEM 1200EX型透射电镜(TEM)和振动样品磁强计(VSM)对材料表面形貌、颗粒形态和结构性质进行表征。考察g-C_3N_4与Fe-Cu不同复合比1∶10、1∶5和1∶1的g-C_3N_4/Fe-Cu对4-硝基苯酚催化降解性能的影响,分析研究催化剂磁性及循环利用性,并初步探讨了降解热力学、动力学过程和降解机理。实验结果表明,此方法合成的g-C_3N_4/Fe-Cu复合材料反应活性位点丰富且分散均匀,表现出较强的催化和可循环性能。当Fe-Cu摩尔比为1∶1,g-C_3N_4与Fe-Cu质量比为1∶5时,表现出最优的活性,对4-硝基苯酚的催化性能最佳,在120 min内降解效率超过82.3%,重复循环利用3次后,降解效率仍能保持在70%以上。降解过程符合准一级动力学模型,反应活化能E_a=17.32 k J·mol~(-1),熵变ΔS0,ΔG0表明降解是个熵驱动的过程,降解反应是自发进行的。     

Keggin型铬取代杂多阴离子/阴离子交换树脂的可见光催化性能

将Keggin型铬取代磷钨杂多阴离子PW11O39Cr(Ⅲ)(H2O)4-(PW11Cr)负载于弱碱性阴离子交换树脂D301R表面,制备了固体光催化剂PW11Cr/D301R,并以模型污染物罗丹明B(RhB)的降解为探针评估了该催化剂的可见光催化活性,讨论了光催化反应机理,同时考察了催化剂剂量、溶液pH值和溶液中常见离子对RhB可见光催化降解反应的影响以及催化剂的稳定性。实验结果表明,当PW11Cr/D301R的剂量为100 mg时,10μmol/L RhB水溶液暴露在200 W金卤灯下进行照射,RhB完全降解所需的时间仅为30 min,比PW11Cr均相体系缩短了3倍;反应180 min总有机碳(TOC)去除率约为84%。催化剂剂量、溶液pH值和溶液中存在的Cl-、SO2-4和PO3-4对RhB光催化降解反应的速率均有一定影响。催化剂循环实验显示经循环使用7次后催化剂的活性几乎没有损失。     

Comparative Effect of UV,UV/H2O2 and UV/H2O2/Fe on Terbuthylazine Degradation in Natural and Ultrapure Water

Different advanced oxidation processes (AOPs) (ultraviolet radiation, hydrogen peroxide photolysis and photo-Fenton) were applied to test the degradation of terbuthylazine in three types of water: (a) ultrapure water, (b) surface water from the Gaditana area (Los Hurones reservoir, Cádiz, Spain) and (c) groundwater from the Tempul spring in Jerez de la Frontera (Cádiz, Spain). The experiments were carried out on a laboratory scale, using two different types of reactors, batch and semi-continuous. In batch reactors, the most efficient process for the experiments carried out with both ultrapure water and underground groundwater was ultraviolet radiation, whereas for surface water from the Gaditana area, the process that obtained the best results was the photolysis of hydrogen peroxide with 2.5 mg L⁻¹ of H₂O₂. In semi-continuous reactors, the most efficient process was the photolysis of hydrogen peroxide with 2.5 mg L⁻¹ of H₂O₂ for all the matrices studied. In both types of reactors, terbuthylazine degradation percentages higher than 90% were achieved; the main difference was in the reaction time, which varied from minutes in the batch reactor to seconds in the semi-continuous reactor. In all the applied AOPs, N-terbutyl-6-hydroxy-N′ethyl-1,3,5-triazine-2,4-diamine (TBA-212) was generated as a reaction intermediate.     

Activation of Peracetic Acid with CuFe2O4 for Rhodamine B Degradation: Activation by Cu and the Contribution of Acetylperoxyl Radicals

Advanced oxidation processes (AOPs) demonstrate great micropollutant degradation efficiency. In this study, CuFe₂O₄ was successfully used to activate peracetic acid (PAA) to remove Rhodamine B. Acetyl(per)oxyl radicals were the dominant species in this novel system. The addition of 2,4-hexadiene (2,4-HD) and Methanol (MeOH) significantly inhibited the degradation efficiency of Rhodamine B. The ≡Cu²⁺/≡Cu⁺ redox cycle dominated PAA activation, thereby producing organic radicals (R-O˙) including CH₃C(O)O˙ and CH₃C(O)OO˙, which accounted for the degradation of Rhodamine B. Increasing either the concentration of CuFe₂O₄ (0–100 mg/L) or PAA (10–100 mg/L) promoted the removal efficiency of this potent system. In addition, weakly acid to weakly alkali pH conditions (6–8) were suitable for pollutant removal. The addition of Humid acid (HA), HCO₃⁻, and a small amount of Cl⁻ (10–100 mmol·L⁻¹) slightly inhibited the degradation of Rhodamine B. However, degradation was accelerated by the inclusion of high concentrations (200 mmol·L⁻¹) of Cl⁻. After four iterations of catalyst recycling, the degradation efficiency remained stable and no additional functional group characteristic peaks were observed. Taking into consideration the reaction conditions, interfering substances, system stability, and pollutant-removal efficiency, the CuFe₂O₄/PAA system demonstrated great potential for the degradation of Rhodamine B.     

A Review on the Degradation of Pollutants by Fenton-Like Systems Based on Zero-Valent Iron and Persulfate: Effects of Reduction Potentials,pH, and Anions Occurring in Waste Waters

Among the advanced oxidation processes (AOPs), the Fenton reaction has attracted much attention in recent years for the treatment of water and wastewater. This review provides insight into a particular variant of the process, where soluble Fe(II) salts are replaced by zero-valent iron (ZVI), and hydrogen peroxide (H₂O₂) is replaced by persulfate (S₂O₈²⁻). Heterogeneous Fenton with ZVI has the advantage of minimizing a major problem found with homogeneous Fenton. Indeed, the precipitation of Fe(III) at pH > 4 interferes with the recycling of Fe species and inhibits oxidation in homogeneous Fenton; in contrast, suspended ZVI as iron source is less sensitive to the increase of pH. Moreover, persulfate favors the production of sulfate radicals (SO₄^•−) that are more selective towards pollutant degradation, compared to the hydroxyl radicals (^•OH) produced in classic, H₂O₂-based Fenton. Higher selectivity means that degradation of SO₄^•−-reactive contaminants is less affected by interfering agents typically found in wastewater; however, the ability of SO₄^•− to oxidize H₂O/OH⁻ to ^•OH makes it difficult to obtain conditions where SO₄^•− is the only reactive species. Research results have shown that ZVI-Fenton with persulfate works best at acidic pH, but it is often possible to get reasonable degradation at pH values that are not too far from neutrality. Moreover, inorganic ions that are very common in water and wastewater (Cl⁻, HCO₃⁻, CO₃²⁻, NO₃⁻, NO₂⁻) can sometimes inhibit degradation by scavenging SO₄^•− and/or ^•OH, but in other cases they even enhance the process. Therefore, ZVI-Fenton with persulfate might perform unexpectedly well in some saline waters, although the possible formation of harmful by-products upon oxidation of the anions cannot be ruled out.