Janus型PS/PVP/TiO_2光催化剂的制备及其催化性能研究

通过将聚苯乙烯(PS)与聚乙烯吡咯烷酮(PVP)复合,并加入二氧化钛(TiO_2)光催化剂,制备Janus型光催化薄膜,并对薄膜的润湿性能、光催化性能、耐久性能以及催化机理进行研究。结果表明:PS/PVP/TiO_2表面具有亲/疏水相间的结构,并且在光照下表现较好的催化效果,60 min内对甲基橙和刚果红的催化率达到94.2%和86.6%。此外,在不同环境中仍能表现较好的催化性能,并且具有一定的循环稳定性。     

改性纳米TiO_2/纤维素氨基甲酸酯复合薄膜的制备及性能研究

向纤维素氨基甲酸酯溶液中掺杂不同含量的改性纳米TiO_2,采用流延法制得具有光催化功能的改性纳米TiO_2/纤维素氨基甲酸酯复合薄膜。采用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、透光性能测试、热分析仪(TG)、拉伸性能测试及光催化降解性能测试等方法对复合薄膜的结构及性能进行表征。结果表明,改性纳米TiO_2成功负载到复合薄膜上,并且对复合薄膜的结构有一定的影响;随着TiO_2含量的增加,复合薄膜透光性变差,抗紫外光能力明显增强,热稳定性能降低,拉伸强度减小;当改性纳米TiO_2含量为2%时,复合薄膜对甲基橙溶液的光降解率最高,达到100%,薄膜光催化降解性能最好。     

用于高效水体净化的新型聚苯乙烯复合光催化膜的制备与表征

采用聚苯乙烯(PS)塑料废弃物与二氧化钛(TiO_2)相复合,制备了具有优异光催化性能的PS/TiO_2复合薄膜。随着TiO_2含量的增加,复合薄膜的热稳定性也随之增加。PS/TiO2-30由于TiO_2较好的分散性,表现出较好的光吸收率,并且其对甲基橙、环丙沙星以及重铬酸钾的光催化效率分别为90.2%、81.5%和71.6%,均高于其他组分的PS/TiO2薄膜。相比于粉体催化剂,PS/TiO_2-30具有较好的循环性能,6次循环后,对甲基橙的光催化效率仍保持在87.6%,可作为有效的污水处理方式。     

活性炭掺杂WO_3/ZnO复合薄膜制备及其光催化性能研究

采用溶胶-凝胶法在铝箔上制备WO3/ZnO复合薄膜,并用活性炭对其改性,以甲基橙水溶液模拟有机污染物,研究了WO3/ZnO薄膜的光催化降解性能。实验结果表明:白炽灯照射2h、WO3质量分数为2.5%时,WO3/ZnO/铝箔对甲基橙的降解率达到78.54%;紫外光照射下降解率达到99.89%。当活性炭掺杂量为10g/L时,制得的WO3/ZnO复合薄膜均匀一致且光催化性能良好,可见光照射下甲基橙降解率达到85.71%。     

PET/TiO2/石墨烯复合薄膜的制备及光催化性能研究

通过旋涂法在聚对苯二甲酸乙二醇酯(PET)塑料薄膜上涂覆具有高效可见光催化活性的TiO_2/石墨烯光催化剂,制备了PET/TiO_2/石墨烯光催化薄膜。由于PET的存在,使得TiO_2/石墨烯形成了疏松多孔的结构。对甲基橙的光催化降解实验表明:TiO_2/石墨烯和PET/TiO_2/石墨烯薄膜在可见光下表现出较高的光催化性能,远高于商品级P25催化剂。这主要是由于TiO_2/石墨烯和PET/TiO_2/石墨烯薄膜具有较好的可见光吸收能力、较低的禁带宽度值以及较高的电子空穴分离速率。循环实验表明,相较于TiO_2/石墨烯催化剂,PET/TiO_2/石墨烯薄膜具有更好的循环稳定性以及环境友好性。     

纤维素负载纳米Ag_2O复合材料对甲基橙降解性能研究

印染废水已经对环境构成严重威胁,传统吸附法对其降解性能有限,而电化学催化氧化法则需耗费许多电能,不符合当前节能环保要求,因此,无需耗能的光催化氧化在处理印染废水领域备受关注。纤维素具有较好的耐久性,价格低廉、有良好的生物降解性,是良好的载体。以纤维素负载Ag_2O/TiO_2纳米复合粒子制得具有光催化性能的净化薄膜,研究其对甲基橙的降解性能,结果发现中性环境有利于甲基橙的降解,负载型Ag_2O/TiO_2纳米复合粒子对甲基橙的降解性能均远优于Ag_2O和TiO_2各自对甲基橙的降解性能。     

磁性TiO_2/rGO-Fe_3O_4复合光催化剂的制备及性能研究

以氧化石墨烯为原料,利用共沉淀法得到rGO-Fe_3O_4磁性载体,进而采用水热法制备出TiO_2与rGO-Fe_3O_4磁基体不同配比的磁性TiO_2/rGO-Fe_3O_4复合光催化剂,紫外光下催化降解甲基橙溶液,结果表明,石墨烯的引入可以扩宽TiO_2对可见光的光谱响应范围,在紫外光照射下,m(TiO_2)∶m(磁基体)=3∶1的磁性TiO_2/rGO-Fe_3O_4复合光催化剂的催化性能最佳,经120 min光照后,甲基橙降解效率高达94. 94%,重复循环使用5次后,降解率依然能达到90. 23%。     

磁性TiO_2/rGO-Fe_3O_4复合光催化剂的制备及性能研究

以氧化石墨烯为原料,利用共沉淀法得到rGO-Fe_3O_4磁性载体,进而采用水热法制备出TiO_2与rGO-Fe_3O_4磁基体不同配比的磁性TiO_2/rGO-Fe_3O_4复合光催化剂,紫外光下催化降解甲基橙溶液,结果表明,石墨烯的引入可以扩宽TiO_2对可见光的光谱响应范围,在紫外光照射下,m(TiO_2)∶m(磁基体)=3∶1的磁性TiO_2/rGO-Fe_3O_4复合光催化剂的催化性能最佳,经120 min光照后,甲基橙降解效率高达94. 94%,重复循环使用5次后,降解率依然能达到90. 23%。     

改性二氧化钛复合体系对聚乙烯薄膜自清洁性能的影响研究

通过水热法制备了Fe掺杂改性TiO_2,并通过浸渍提拉法将改性TiO_2负载在聚乙烯(PE)薄膜上得到具有自清洁功能的改性PE薄膜。研究结果表明:改性PE薄膜热稳定性明显提高。光吸收能力表明,Fe掺杂的TiO_2相比于纯TiO_2具有更强的光吸收能力。同时,PE/Ti-2对于甲基橙的光催化降解率最高,达到96.23%(90 min)。此外,改性PE薄膜具有良好的力学性能以及耐久性,其拉伸强度以及断裂伸长率均满足标准值,分别为29.5 MPa和128%。经过100次的冲洗之后,PE/Ti-2的光催化效率、拉伸强度以及断裂伸长率均未发生明显的下降,分别为90.21%、25.2 MPa和125%。     

聚苯乙烯/铁掺杂氧化锌纳米复合膜的制备及其光催化降解性能研究

以聚苯乙烯(PS)为基体,采用溶胶-凝胶法制备了具有高效光催化性能的PS/Fe-ZnO复合薄膜,并以甲基橙和罗丹明B作为模型污染物,研究了其在可见光下的光催化活性。微观结构显示,合成的Fe-ZnO颗粒为规则的六角棱柱,并且在PS膜上分散良好。由于PS和Fe的引入,PS/Fe-ZnO复合薄膜表现出较高的可见光吸收性能。光催化性能实验表明:PS/Fe-ZnO复合薄膜具有较高的催化效果并且能够用于多种污染物的去除,70 min后对甲基橙和罗丹明B的降解率分别达到99.3%和80.2%。由于PS膜的束缚作用使得粉体流失较少,经过多次循环实验,其光催化甲基橙的效率仍保持在95%以上,具有较好的可持续性与环境友好性。机理研究证明,Fe-ZnO的催化增强是由于材料中产生的光生载流子分离效率提高导致的。     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.