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制备了Ce掺杂的TiO2复合SiO2光催化剂(Ce-TiO2/SiO2),使用该光催化剂在模拟太阳光下催化降解亚甲基蓝水溶液,研究了催化剂用量、亚甲基蓝初始质量浓度、溶液pH、无机阴离子对光催化降解效果的影响。结果表明:n(Ce)∶n(Ti)∶n(Si)=0.002∶1∶1时所制催化剂的光催化活性最好;对于2.5 mg/L、pH为11的亚甲基蓝溶液,投加100 mg/L的光催化剂反应2 h可达到最高降解率(92.6%);NO3-、SO42-、Cl-的存在对光催化降解具有抑制作用。 相似文献
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以膨胀珍珠岩为载体,钛酸四丁酯为原料,用溶胶-凝胶法制备漂浮型纳米TiO2光催化剂,并用该光催化剂在太阳光下对亚甲基蓝进行光催化降解实验.结果表明,在450℃焙烧2h,负载3次的条件下制备的漂浮型催化剂光催化活性较好.150 mg漂浮型纳米TiO2/EP在30 mL亚甲基蓝溶液(4 mg/L)液面平铺,经120 min太阳光照射,亚甲基蓝的降解率为97.6%.XRD和SEM分析结果表明,二氧化钛为结晶良好的锐钛矿型,粒径大约为8nm.漂浮型纳米TiO2/EP有较广阔的工程应用前景. 相似文献
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采用溶胶-凝胶法制备了Ce3 /TiO2光催化剂,研究了该催化剂对亚甲基蓝的光催化降解效果.结果表明掺杂量w(Ce3 )3.7%,催化剂用量0.12 g·L-1,体系pH值为10,12 mg·L-1亚甲基蓝溶液经2 h光催化降解,其降解率可达98.87%,与纯TiO2相比,Ce3 /TiO2光催化剂显示出良好的光催化活性. 相似文献
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以PW12/PANI/ZnO为光催化剂。在紫外灯辐射下,研究了模拟染料废水亚甲基蓝溶液的光催化降解的反应,讨论了催化剂投加量、染料浓度、溶液的pH值对亚甲基蓝降解率的影响。结果表明,亚甲基蓝溶液光催化降解的最佳条件为:pH=3,催化剂投加量为0.012 5 g,染料浓度为5 mg/L,经30 W紫外灯照射90 min后,其降解率为85.84%。 相似文献
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纳米CdS/TiO2对亚甲基蓝废水溶液的光催化降解研究 总被引:1,自引:0,他引:1
利用纳米TiO2光催化氧化技术对亚甲基蓝废水溶液进行了光催化净化研究,考察了CdS催化剂复合量、光催化剂焙烧温度对亚甲基蓝废水溶液光催化氧化的影响。研究表明:染料浓度在7.5mg,L,3%CdS/TiO2复合半导体光催化剂2.5g/L,三支8W主波长为365nm紫外灯作光源,配以适量的氧气,可达到较好的光催化降解率。适量CdS改性增强了复合半导体材料的电子和空穴分离效率,有效地提高了CdS/TiO2光催化剂的光催化活性。 相似文献
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采用溶胶-凝胶法制备了La^3+/TiO2光催化剂,研究了该催化剂对亚甲基蓝的光催化降解效果。结果表明,La^3+掺杂量(摩尔分数)2.8%、催化剂用量1.2g/L、体系pH值为11时,12mg/L亚甲基蓝溶液经2h光催化降解,其降解率可达99.1%。与纯TiO2相比,La^3+/TiO2光催化剂显示出良好的光催化活性。 相似文献
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采用浸渍法制备了H4SiW12O40/TiO2-ZrO2光催化剂,以光催化降解染料废水甲基橙为探针反应,探讨了催化剂投加量、溶液pH值对光催化降解效果的影响以及催化剂的重复使用性。结果表明,H4SiW12O40/TiO2-ZrO2催化剂具有更优越的光催化性能,当催化剂的用量为1.8 g/L,甲基橙溶液初始浓度为10 mg/L,pH=4时,反应4 h后甲基橙的降解率可达90%以上。 相似文献
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以葡萄糖为还原剂、采用液相法首先制备了八面体Cu_2O光催化剂,然后以其为基体,通过原位氧化Cu_2O的方式构筑Cu_2O/CuO复合光催化剂。通过XRD、拉曼、XPS对其成分进行检测,TEM、SEM观察其粒径和形貌;研究了亚甲基蓝降解工艺条件,实验结果表明,ρ(亚甲基蓝)=5 mg/L的溶液100 mL、Cu_2O/CuO复合光催化剂的最佳添加量为10 mg、体系pH=11时亚甲基蓝的降解效果最好。通过对最佳条件下循环降解实验表明,Cu_2O/CuO复合光催化剂有着良好的循环稳定性能。 相似文献
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A new ampholytic homopolypeptide, , 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 () 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. 相似文献
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Silvia Schicker Daniel E. García Igor Gorlov Rolf Janssen Nils Claussen 《Journal of the American Ceramic Society》1999,82(10):2607-2612
Wet milling of Al2 O3 -aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al2 O3 and Fe2 O3 /Al/Al2 O3 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 Fe2 O3 /Al/Al2 O3 powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al2 O3 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. 相似文献
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Akira Akimoto 《Polymer》1974,15(4):216-218
The polymerization of vinyl chloride has been investigated using an 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. 相似文献
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Sintering kinetics of the system Si3 N4-Y2O3 -Al2 O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si3 N4 were studied with additions of 4 to 17 wt% Y2 O3 and 4 wt% A12 O3 . 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 ' -Si3 N4 and glass or β '-Si3 N4 , α '-Si3 N4 , and glass. The compositions and amounts of the residual glassy phases are estimated. 相似文献
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Mats Carlsson Mats Johnsson Mats Nygren 《Journal of the American Ceramic Society》1999,82(8):1969-1976
Ta0.33 Ti0.33 Nb0.33 C and Ta0.33 Ti0.33 Nb0.33 C x N1− 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 , Ta2 O5 , Nb2 O5 , 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. 相似文献