TiO2纳米管的制备及光催化降解亚甲基蓝研究

以TiO2和NaOH为原料,采用水热法制备了TiO2纳米管(titania nanotube,简称TNT),通过X射线衍射(XRD)、高分辨透射电镜(HRTEM)、BET比表面积测定等手段对其结构和性质进行了表征.以亚甲基蓝(methylene blue,简称MB)为模型反应物,考察了TiO2纳米管光催化降解MB的效果.研究结果表明,TiO2纳米管是在酸交换后形成的,400℃焙烧时,TiO2纳米管中出现锐钛矿相;制备的TiO2纳米管可有效地降解MB,TiO2纳米管光催化降解MB的效率与其锐钛矿相的含量有关.     

席夫碱钴改性CoCr-LDHs材料光催化降解亚甲基蓝研究

采用共沉淀法合成席夫碱钴(SBCo)插层钴铬水滑石(CoCr-LDHs)材料。通过X射线粉末衍射(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM-EDX)、X射线光电子能谱(XPS)、比表面积(BET)分析表征CoCr-LDHs以及CoCr/SBCo-LDHs材料的结构和性质。以H₂O₂作光催化助剂, 考察了不同插层量、催化剂用量以及亚甲基蓝溶液的初始浓度对光催化活性的影响, 并探究了光催化降解过程的动力学和主要的活性基团。实验结果表明: H₂O₂有助于提高水滑石材料的光催化性能, 以氙灯模拟太阳光, 20 mg CoCr/SBCo_0.5-LDHs和H₂O₂的协同作用对初始浓度为25 mg/L的亚甲基蓝降解率高达99%。亚甲基蓝的光降解过程符合准一级动力学模型, 且起主要作用的活性基团为h ⁺和·OH。     

SiO2柱层状钛酸的制备及光催化性能

采用分步反应法制备SiO2柱层状钛酸(SiO₂-H₂Ti₄O₉)光催化材料, 研究了制备过程中烷基胺的链长、胺预撑后的洗涤方式以及与正硅酸乙酯(TEOS)水热反应时间等因素对SiO₂-H₂Ti₄O₉结构的影响. 以亚甲基蓝(Methylene Bule, MB)为探针反应物, 考察了SiO₂柱层状钛酸的光催化性能. 结果表明, 随着烷基胺链长增加, 层间距增大, 有利于在层间引入TEOS; 用1:1的乙醇水溶液洗涤正十二胺撑后的产物的结晶度显著高于用无水乙醇洗涤的产物; 胺撑后的产物与TEOS在130℃条件下水热反应两次可得到层间距为1.45nm、比表面积为148.4m²/g、结构较规整的SiO₂-H₂Ti₄O₉柱层状材料. 该柱层状材料对亚甲基蓝具有较高的光催化活性.     

SiO2柱层状钛酸的制备及光催化性能

采用分步反应法制备SiO2柱层状钛酸(SiO₂-H₂Ti₄O₉)光催化材料, 研究了制备过程中烷基胺的链长、胺预撑后的洗涤方式以及与正硅酸乙酯(TEOS)水热反应时间等因素对SiO₂-H₂Ti₄O₉结构的影响. 以亚甲基蓝(Methylene Bule, MB)为探针反应物, 考察了SiO₂柱层状钛酸的光催化性能. 结果表明, 随着烷基胺链长增加, 层间距增大, 有利于在层间引入TEOS; 用1:1的乙醇水溶液洗涤正十二胺撑后的产物的结晶度显著高于用无水乙醇洗涤的产物; 胺撑后的产物与TEOS在130℃条件下水热反应两次可得到层间距为1.45nm、比表面积为148.4m²/g、结构较规整的SiO₂-H₂Ti₄O₉柱层状材料. 该柱层状材料对亚甲基蓝具有较高的光催化活性.     

我国几种含钛物料作为光催化材料降解亚甲基蓝的实验研究

半导体光催化氧化技术是一种新型的现代化水处理技术,对多种有机物有明显的降解效果,具有广泛的前景,近年来,半导体光催化氧化已成为光化学领域和环保领域中的研究热点之一.实验研究了处理后的几种含钛物料对水溶液中染料亚甲基蓝降解的过程,讨论了其光催化活性与其TiO2含量、溶液的PH值、氧化剂加入及外加电场的关系.结果表明五种含钛物料均具有光催化活性,光催化活性与其TiO2含量有关;降解染料亚甲基蓝时与溶液PH有关,PH=10时光催化效果最好;氧化剂加入、外加电场可提高光催化反应速度.     

片状ZnO/还原氧化石墨烯复合材料的制备及其可见光降解亚甲基蓝性能研究

利用化学浴沉积法合成的ZnO为前驱体,并加入不同含量的氧化石墨烯(GO),再采用经过300℃氮气氛围煅烧法,最终得到ZnO-热还原氧化石墨烯复合物(ZnO/RGO)。对合成样品进行一系列分析测试,并测试了样品的光催化性能。结果表明:掺杂0.8%-RGO的ZnO/RGO(ZRG)复合物的光催化活性最高,可见光照4h对亚甲基蓝(MB)的降解率达到87.7%。同时,探讨了不同条件下对光催化降解亚甲基蓝(MB)的影响,通过捕获剂实验表明,光催化降解MB的活性物种主要是超氧自由基O^-₂·和空穴h⁺。     

层状双氢氧化物的制备及改性

层状双氢氧化物及其层间改性产物具有广阔的应有应用前景。综述了层状双氢氧化物及其层间嵌入纳米复合材料的制备方法和应用。     

负载型改性TiO2光降解亚甲基蓝研究进展

亚甲基蓝是印染行业常用的一种阳离子染料,每年产生的大量染料废水不仅破坏了水体环境甚至会引起人类"三致"(致畸、致癌、致突变)。TiO_2光催化技术具有低能耗、操作简单、彻底解决有机污染物等优点,但直接使用存在TiO_2与水分离难、重复利用率低等问题。而负载型改性TiO_2不仅可解决上述问题,且可借助载体比表面积大、孔隙率高的特点提高光催化速率和效率。介绍了近年来矿物材料、碳(炭)材料等负载型改性TiO_2复合光催化剂的制备及其对亚甲基蓝光催化降解的效果,指出负载型TiO_2光催化剂未来的发展方向。     

层状液晶模板法制备纳米ZnO及其光催化降解亚甲基蓝的研究

以十二烷基硫酸钠、正戊醇、水三元体系制备溶致液晶,并以此为模板,结合均匀沉淀法制备纳米ZnO,并对其在紫外光下的光催化性能进行了研究。结果表明,当水占50%(wt,质量分数),SDS∶C5H11OH为5∶5(质量比)时,溶致液晶所形成的十字花纹织构最为规整,且分布十分均匀;考察其在紫外光下的光催化性能,当纳米ZnO用量为4g/L,双氧水用量为6g/L时,光照150min即可使亚甲基蓝溶液的降解率达到89%左右。     

TiO2/膨胀石墨复合材料的制备及其对亚甲基兰的光催化降解

采用快速升温法制备出以膨胀石墨为载体的TiO2/膨胀石墨光催化剂,用SEM及XRD对其表面形貌及结构进行表征,研究了该负载型光催化剂在紫外光照射下的催化能力,探讨了在催化剂中TiO2的负载量、亚甲基兰溶液的初始浓度及其pH值对光催化剂的降解能力的影响.结果发现,负载量为10%的光催化剂对40mg/L的亚甲基兰溶液5h的光降解率达到58.8%.     

硫掺杂TiO2的制备及其光催化降解次甲基蓝研究

以TiCl4、(NH4)2SO4为原料,采用溶胶-凝胶法制备了硫掺杂纳米TiO2,利用XRD、TEM、FTIR等对样品进行了表征,并将其用于光催化降解次甲基蓝溶液.结果表明:制备的纳米TiO2为锐钛矿晶型,具有超强酸特征,平均粒径分布为10～30nm,S掺杂对TiO2的晶粒长大有抑制作用,经过硫掺杂的纳米TiO2光催化活性明显优于纯TiO2.     

手性阴离子柱撑水滑石的制备和表征

以水滑石Mg4Al2(OH)12CO3.4H2O为前体,采用返混沉淀方法进行插层组装制备了L-(-)-酒石酸、L-(-)-天冬氨酸、L-(-)-苹果酸柱撑水滑石(LDHs),用X射线衍射、红外光谱及差热分析表征了超分子结构手性层柱材料的结构,结果表明,3种手性酸根阴离子可以插入水滑石的层间完全取代CO32-,得到结晶度高、晶相单一且手性酸根阴离子在层间有序排列的超分子结构手性层柱材料。     

Ageing behaviour of unary hydroxides in trivalent metal salt solutions: Formation of layered double hydroxide (LDH)-like phases

The hydroxides of Mg, Ni, Cu and Zn transform into layered double hydroxide (LDH)-like phases on ageing in solutions of Al or Cr salts. This reaction is similar to acid leaching and proceeds by a dissolution-reprecipitation mechanism offering a simple method of LDH synthesis, with implications for the accepted theories of formation of LDH minerals in the earth’s crust.     

类水滑石的制备与改性及其在聚丙烯阻燃中的应用

采用共沉淀法制备了镁铝类水滑石（LDHs）前驱体,加入少量聚磷酸铵（APP）制得APP-LDHs,探讨了不同质量分数APP对LDHs晶体生长的影响;当APP在LDHs前驱浆液中添加量为0.8wt%时,将APP-LDHs与季戊四醇（PER）、硅烷偶联剂KH-550进行球磨混合,制备插层包覆改性的LDHs;通过XRD、FTIR、SEM和TG等对改性前后的LDHs进行了表征;采用极限氧指数（LOI）、垂直燃烧测试（UL-94）、缺口冲击和弯曲实验等方法研究了LDHs改性前后LDHs/聚丙烯（PP）复合材料的阻燃性能及力学性能的差异。研究结果表明：APP的加入,未显著影响LDHs的层板生长,但其层板堆叠受到抑制;SEM观察表明,所制备的LDHs为片状,且经插层包覆改性后的LDHs粉体形貌较为规整,颗粒粒径为100~250 nm;改性LDHs在较高温度下的热稳定性显著优于未改性的LDHs;当PP中加入质量分数为20%的LDHs及改性LDHs时,可抑制PP燃烧时产生的熔滴,并促使LDHs/PP复合材料表面形成炭层;改性LDHs/PP复合材料具有更好的阻燃性能,且其冲击强度、弯曲强度等力学性能下降不明显。     

Sorption study of an acid dye from an aqueous solution on modified Mg-Al layered double hydroxides

In this paper, experimental methods and results are reported on the removal of the dye Green Bezanyl-F2B (an acid dye) from MgAlCO(3) (HT) and from intercalated anionic surfactant, "sodium dodecylsulfate (SDS)", into the Mg-Al layered double hydroxides by the calcination-rehydration reaction using Mg-Al oxide precursors calcined at 773 K. Dodecylsulfate hydrotalcite was prepared by the calcination-rehydration method. The surfactant intercalation in the interlayer space of hydrotalcite was investigated by XRD and FT-IR spectroscopy where the resulting materials were found to be similar to those reported in the literature and were used to remove an acid dye from an aqueous solution. Equilibrium time and rate-determining step of the dye Green Bezanyl-F2B sorption were determined. Two simplified kinetic models were tested to investigate the sorption. The adsorption capacity data were also fitted to Langmuir and Freundlich equation as well. The sorption data fitted to the Langmuir model gave good values of the determination coefficient.     

酒石酸柱撑水滑石吸附水中的Ni~(2+)的特性研究

采用离子交换法制得酒石酸插层MgAl水滑石(MgAl-TA LDHs),并进行了XRD、IR、SEM、比表面积及孔径分析表征。考察了MgAl-TA LDHs吸附剂对溶液中Ni 2+的吸附能力,探讨了水滑石吸附剂投加量、Ni 2+溶液浓度、pH值以及吸附温度对Ni 2+吸附率的影响,并进行了动力学和热力学特征的研究。结果表明,适宜的水滑石投加量为2g/L,pH值以中性为宜,对于Ni 2+浓度不超过100 mg/L的溶液室温下Ni 2+吸附率在60%以上,而高温有利于提高Ni 2+吸附率。吸附过程符合二级动力学模型,吸附等温曲线可用R-P模型来描述。吸附过程能够自发进行,为吸热过程,属于化学吸附。     

Synthesis of manganese vanadate nanobelts and their visible light photocatalytic activity for methylene blue

Manganese vanadate nanobelts have been synthesised by a simple hydrothermal process using polymer polyvinyl pyrrolidone as the surfactant by adjusting the pH value. The X-ray diffraction, selected area electron diffraction and the high-resolution transmission electron microscopy (TEM) show that the manganese vanadate nanobelts are composed of a single crystalline monoclinic Mn₂V₂O₇ phase. Scanning electron microscopy and TEM observations show that the thickness, width and length of the nanobelts are 20 nm, 350 nm–1 μm and several dozens to several hundreds of micrometres, respectively. The photocatalytic activities of the manganese vanadate nanobelts have been evaluated by the photocatalytic degradation of methylene blue (MB) in an aqueous solution as a model pollutant under the solar light irradiation. After 4 h of the irradiation by the solar light, the MB solution with the volume of 10 mL and the concentration of 10 mg·mL^?1 can be totally degraded using 10 mg manganese vanadate nanobelts.     

Sorption of an anionic dye by uncalcined and calcined layered double hydroxides: a case study

Layered double hydroxides (LDHs) with a Mg/Al molar ratio of 2:1 were synthesized by using a co-precipitation method and their calcined products (CLDHs) were obtained by heating Mg/Al-LDHs at 500 °C. Sorption of a weak acid dye, Brilliant Blue R (BBR), by LDHs and CLDHs indicated equilibrium time required for BBR sorption by CLDHs was less than 12 h, regardless of initial concentration of BBR, whereas BBR sorption by LDHs was longer than 20 h. Sorption capacity of CLDHs was much larger than that of LDHs. Therefore, CLDHs could be used to remove anionic dyes of relatively high concentrations while LDHs may only be used to remove anionic dyes of low concentrations. Isotherms for BBR sorption by CLDHs and LDHs were well described using the Freundlich and Langmuir equations, respectively. When the initial pH of BBR solutions was lower than 8.0, the final pH of the solution after sorption was enhanced and stabilized at 10.6–10.8. The effect of initial pH (<8.0) on BBR removal was negligible, which would be environmentally important for precipitation/co-precipitation of co-existing metal cations. The effects of both Cl⁻ and SO₄²⁻ on BBR sorption by CLDHs were minimal; but the presence of CO₃²⁻ markedly reduced BBR removal. Thermal regeneration for re-use of LDHs and CLDHs after BBR sorption was feasible only within the first two cycles, after which the regenerated materials suffered from a large loss in their sorption capacities.