磁性碳纳米管基催化剂TiO2/CNTs光降解氨比西林抗生素水溶液的研究

以磁性多壁碳纳米管(MWCNTs)为载体,钛酸四丁酯为钛源,采用表面溶胶包覆-醇热联用法制备TiO2/CNTs复合管光催化剂。以氨比西林溶液的降解为目标反应,考察了催化剂在紫外灯下的催化活性。结果表明,二氧化钛在MWCNTs表面分布均匀,提高了对光的吸收和利用,因此TiO2/MWCNTs复合光催化剂表现出较高的光催化活性,催化剂的活性随着pH值的增大而增大,并且磁性催化剂易从降解后的溶液中分离。     

天然炭纤维负载二氧化钛颗粒的制备与光催化活性

以棉花制备的炭纤维为载体,钛酸丁酯为钛源,采用水热法制备炭纤维负载二氧化钛复合材料(CF/TiO2),利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等对CF/TiO2复合材料进行结构表征.用紫外-可见光吸收光谱(UV-vis)分析比较了TiO2、炭纤维和CF/TiO2,热处理温度以及溶液的pH值在紫外光照下对甲基蓝溶液的光催化降解性的影响,以及对CF/TiO2复合材料的失活性能研究.结果表明:炭纤维负载TiO2对甲基蓝光催化降解性较好,有效利用了炭纤维的吸附性与TiO2的催化活性;当热处理温度为220℃,pH =5时,甲基蓝溶液的吸附-光催化性能最大为85.9％;复合光催化剂使用后在紫外线照射后,其活性恢复,可以循环利用.     

碳量子点改性纳米二氧化钛的制备及其光催化降解壬基酚聚氧乙烯醚的性能研究

以柠檬酸为碳源,以1-氨丙基-3-甲基咪唑溴盐离子液体为表面修饰剂,一锅热解法制备了离子液体修饰碳量子点(L-CQDs),再通过简单的水热法将L-CQDs负载到TiO_2纳米颗粒上。以表面活性剂壬基酚聚氧乙烯醚(TX-10)溶液为模拟废水,研究了L-CQDs/TiO_2复合光催化剂的光催化性能。傅立叶变换红外光谱仪(FT-IR)和高分辨透射电子显微镜(HRTEM)表征结果证明L-CQDs负载到TiO2纳米颗粒的表面上;固体紫外-可见吸收光谱结果表明,L-GQDs/TiO_2相比于TiO_2纳米颗粒在可见光区域的吸收得到了明显增强;光催化结果表明,复合光催化剂3%L-CQDs/TiO_2在500W氙灯照射下降解0.05g/LTX-10溶液3h时,复合光催化剂对TX-10的降解率最高可达83.5%,比TiO2纳米颗粒高26.6%;重复使用5次后复合光催化剂的光催化活性保持不变。     

MWCNT/TiO2的制备及其自然光下降解甲基橙染料的性能研究

以多壁碳纳米管(MWCNT)为基核,钛酸丁酯为前驱体,采用简单的水热法制备了MWCNT/Ti O_2复合材料。利用了差热-热重(TG)、透射电子显微镜(TEM)、X-射线衍射(XRD)及紫外-可见光谱(UV-Vis)等分析手段对材料进行了表征。以甲基橙为目标降解物,考察了不同含量MWCNT/Ti O_2复合材料在自然光下的光催化活性。结果表明:MWCNT的加入可有效地防止Ti O_2粒子团聚而不会影响Ti O_2的晶型。且由于MWCNT的加入可减小Ti O_2的禁带宽度,降低光生电子和空穴的复合率,MWCNT/Ti O_2复合材料表现出比纯Ti O_2更好的可见光吸收率。光催化研究表明,MWCNT/Ti O_2复合材料的光催化性能与MWCNT含量关系密切,当MWCNT加入量为0.04 g时,MWCNT/Ti O_2的复合材料的光催化活性最强,自然光下照射反应5 h后,甲基橙降解率可达到85%。     

TiO2-GD复合光催化剂性能良好

在国家自然科学基金和国家重点实验室课题的支持下,中国科学院过程工程所王丹研究员科研团队利用水热法使TiO2与石墨炔(GD)通过Ti-O-C形成复合材料,表现出比纯TiO2、TiO2-碳纳米管以及TiO2-GR(石墨烯)复合材料更优越的光催化性能。该发现对高效光催化剂设计与开发具有重要意义。利用半导体光催化氧化处理各种污染物是环境治理的有效方法,TiO2被认为是最具应用潜力的半导体光催化剂,但其光吸收仅限于紫外区,且光照后     

TiO2/SiO2复合材料光催化降解甲基橙的动力学研究

以钛酸丁酯和正硅酸乙酯为主要原料,用一步溶胶-凝胶法制备了TiO2/SiO2复合材料,同时采用紫外灯为光源,考察了不同TiO2/SiO2复合光催化剂用量及不同甲基橙初始浓度对光催化降解率的影响。结果表明：TiO2/SiO2复合材料的光催化效果良好,比相同条件下纯TiO2的光催化活性有明显提高;其光催化降解甲基橙的动力学表现为Langmuir—Hinshelwood一级反应动力学规律。     

SiW12/聚苯胺/TiO2复合材料的光催化性能

以SiW12/PANI/TiO2为光催化剂。在紫外灯辐射下,研究了模拟染料废水甲基紫溶液的光催化降解的反应,考察了催化剂投加量、染料浓度、溶液的pH值对甲基紫降解率的影响。结果表明,甲基紫溶液光催化降解的最佳条件为:pH=5,SiW12/PANI/TiO2催化剂投加量为0.0125 g,浓度为5 mg/L,经30 W紫外灯照射90 min后,其降解率为90.69%。     

玻璃纤维负载纳米TiO2的制备及光催化性能

采用浸渍-提拉法在玻璃纤维(GF)表面负载纳米TiO2,制备TiO2/GF复合光催化剂.通过X射线衍射(XRD)、热重-差热分析(TG-DSC)、扫描电镜(SEM)及能谱元素分析(EDS)对TiO2/GF复合光催化剂的结构进行了表征.结果表明,经550 ℃以下热处理,TiO2的晶型为锐钛矿相,随着热处理温度的升高,TiO2的晶型逐渐转化为金红石相.以亚甲基蓝的光催化降解为探针反应,评价TiO2/GF复合材料的光催化活性.复合材料的光催化降解活性与P25相当,且经多次使用后,复合光催化剂对亚甲基蓝的降解率仍保持在80%以上.     

活性炭负载型TiO2光催化剂的制备及其光催化活性研究

采用溶胶-凝胶法制备活性炭负载型TiO2光催化剂,用XRD分析了其物相结构.以甲基橙溶液为目标降解物,以紫外灯为光源对活性炭负载型TiO2光催化剂进行了光降解性能的研究,考察了TiO2负载量、催化剂用量、热处理温度等对催化剂的光催化活性的影响.结果表明,当TiO2负载量为33.3%的活性炭负载型TiO2光催化剂用量为2～3 g·L-1、紫外光连续照射5 h时,甲基橙溶液的脱色率可达到96.1%.     

Ag-TiO_2/CNTs复合材料的制备与表征

采用溶胶—凝胶法,并后续在氮气保护下进行高温煅烧制备了负载银的TiO2/CNTs复合材料（记为Ag-TiO2/CNTs）;采用XRD、DRS对所得样品的晶体结构、光谱吸收性质进行了表征,以苯酚为模型污染物,评价了样品紫外光光催化降解苯酚的活性。结果表明：银的负载促进了锐钛矿TiO2结晶度的提高,银及碳纳米管能增强TiO2光催化剂在可见光区的吸收能力,并提高了其光催化活性。     

Electrical conductivity and oxygen permeability of polyacrylonitrile/multiwalled carbon nanotubes composites

Polyacrylonitrile (PAN)/Multiwalled carbon nanotube (MWCNT) nanocomposites were prepared by nonconventional ultrasonic‐assisted emulsifier free emulsion polymerization technique with variable percentage of functionalized carbon nanotube. PAN/MWCNT nanocomposites were characterized by ultraviolet‐visible (UV‐visible) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The result from UV‐visible suggested that the functionalized MWCNT had interfacial interaction with PAN matrices. The surface morphology of functionalized MWCNT and PAN/MWCNT nanocomposites were studied by scanning electron microscopy (SEM). Electrical properties of PAN/MWCNT nanocomposites were measured and the result indicated that the conductivity increased with increasing concentration of MWCNTs. The oxygen permeability of PAN/MWCNT nanocomposites gradually increased with increase of MWCNT concentration, the result which was in agreement with the vertical alignment ofMWCNT in SEM. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

TiO_2光催化氧化降解印染废水的研究

锐钛矿型TiO2为光催化剂,采用高压汞灯为光源对实际印染废水进行了光催化降解的研究,主要探讨了TiO2用量、光照时间、光照强度、溶液初始pH值和H2O2加入浓度等因素对印染废水CODcr去除率和脱色率的影响,找出了最佳的反应条件。结果表明:TiO2光催化氧化对印染废水CODcr和色度具有显著的去除效果,最佳的处理条件为:300W光照,TiO2用量为8g/L,光照时间为120min,初始pH值为1,H2O2加入浓度为3.0mmol/L。     

Electrical and mechanical properties of multi‐walled carbon nanotubes reinforced PMMA and PS composites

The use of multi‐walled carbon nanotubes (MWCNT) as reinforcing material for thermoplastic polymer matrices, polymethyl methacrylate (PMMA), and polystyrene (PS) has been studied. MWCNT were synthesized by chemical vapor deposition (CVD) technique using ferrocene‐toluene mixture. As‐prepared nanotubes were ultrasonically dispersed in toluene and subsequently dispersed in PMMA and PS. Thin polymer composite films were fabricated by solvent casting. The effect of nanotube content on the electrical and mechanical properties of the nanocomposites was investigated. An improvement in electrical conductivity from insulating to conducting with increasing MWCNT content was observed. The carbon nanotube network showed a classical percolating network behavior with a low percolation threshold. Electromagnetic interference (EMI) shielding effectiveness value of about 18 dB was obtained in the frequency range 8.0–12 GHz (X‐band), for a 10 vol% CNT loading. An improved composite fabrication process using casting followed by compression molding and use of functionalized MWCNT resulted in increased composites strength. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Properties of microinjection molding of polymer multiwalled carbon nanotube conducting composites

The effects of processing conditions on the microstructure and properties of polypropylene/multiwalled carbon nanotube (PP/MWCNT) and polycarbonate/multiwalled carbon nanotube (PC/MWCNT) composites were studied. Samples of various MWCNT loadings were prepared by diluting commercial masterbatches. Different processing conditions were then used to systematically change the degree of nanotube alignment, from random to highly aligned. The crystallinity of the PP/MWCNT nanocomposites was found to go through a maximum as a function of nanotube content while the overall rate of crystallization increased. For the highly sheared microinjected PP/MWCNT samples well oriented crystals were formed. Electrical conductivity of the nanocomposites was improved by the presence of the crystalline structure; however, the high degree of nanotube alignment in the microparts resulted in a significant increase in the electrical percolation threshold. The PP nanocomposites exhibited mechanical properties significantly enhanced by nanotube loading; this effect was small in the case of the PC nanocomposites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Solution spinning of cellulose carbon nanotube composites using room temperature ionic liquids

Multiwall carbon nanotube (MWCNT)/cellulose composite fibers were processed from solutions in ethyl methylimidazolium acetate (EMIAc). Rheological percolation in MWCNT/Cellulose/EMIAc solution was observed above 0.01 mass fraction of MWCNT, while electrical percolation in oriented fibers was observed above 0.05 mass fraction of MWCNTs with respect to the weight of the cellulose. Cellulose orientation and crystal size were significantly higher in the composite than in the control cellulose fiber. In addition, in the composite fiber, carbon nanotube orientation was higher than cellulose orientation. At 0.05 mass fraction MWCNT, fiber tensile strength increased by about 25%, strain to failure increased by 100%, and modulus essentially remained unchanged. The composite fibers showed lower thermal shrinkage than the control cellulose fiber. The axial electrical conductivity at 0.1 mass fraction MWCNTs in these oriented fibers was more than 3000 S/m.     

Crystallization behavior and mechanical strength of poly(butylene succinate‐co‐ethylene glycol)‐based nanocomposites using functionalized multiwalled carbon nanotubes

Biodegradable poly(butylene succinate‐co‐ethylene glycol) (PBSG)/multiwalled carbon nanotube (MWCNT) nanocomposites were successfully prepared through physical blending and silication between PBSG and acyl aminopropyltriethoxysilane functionalized multiwalled carbon nanotube (MWCNT‐APTES). Nuclear magnetic resonance (NMR) spectra observations revealed that the PBSG chains were covalently attached to the MWCNT‐APTES by hydrolysis. PBSG/MWCNT‐APTES nanocomposites after hydrolysis showed excellent interfacial compatibility between PBSG and MWCNT‐APTES, which was helpful for the dispersion of MWCNT in the PBSG matrix. The incorporation of MWCNT‐APTES accelerated the crystallization of PBSG in the nanocomposites for both approaches of physical blending and hydrolysis due to the heterogeneous nucleation effect of MWCNT while the crystal structure of PBSG was remained. Furthermore, the crystallization rate of PBSG in PBSG/MWCNT‐APTES nanocomposites after hydrolysis was slower than that in the nanocomposite by physical blend. The tensile strength and modulus of the nanocomposites increased about 6% and 11% with the addition of only 1 wt% MWCNT‐APTES compared with that of neat PBSG, and was larger for the PBSG/MWCNT‐APTES nanocomposites after hydrolysis. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Preparation and characterization of melt‐processed polycarbonate/multiwalled carbon nanotube composites

This study describes the preparation of polycarbonate (PC)/multiwalled carbon nanotube (MWCNT) composites by melt processing the PC and PC/MWCNT master batch at 260°C. The PC/MWCNT master batch was prepared using ultrasonic mixing the carboxylic acid containing MWCNT and PC in a tetrahydrofuran (THF) solution. The HRTEM images of PC/MWCNT master batch and PC/MWCNT nanocomposites show that the MWCNT is well separated and uniformly distributed in the PC matrices. Mechanical properties of the fabricated nanocomposites measured by dynamic mechanical analysis indicate significant improvements in the storage modulus when compared with that of pure PC matrix. The conductivities of 2 and 5 wt% PC/MWCNT nanocomposites are more than four and seven orders in magnitude higher than that of PC without MWCNT, respectively. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Influence of aminosilane‐functionalized carbon nanotubes on the rheometric,mechanical, electrical and thermal degradation properties of epoxidized natural rubber nanocomposites

We describe the preparation, characterization and physical properties of multiwalled carbon nanotube (MWCNT)‐filled epoxidized natural rubber (ENR) composites. To ensure better dispersion in the elastomer matrix, the MWCNTs were initially subjected to aminopropyltriethoxysilane (APS) treatment to bind amine functional groups (?NH₂) on the nanotube surface. Successful grafting of APS on the MWCNT surface through Si–O–C linkages was confirmed using Fourier transform infrared spectroscopy. Grafting of APS on the MWCNT surface was further corroborated using elemental analysis. ENR nanocomposites with various filler loadings were prepared by melt compounding to generate pristine and APS‐modified MWCNT‐filled elastomeric systems. Furthermore, we determined the effects of various filler loadings on the rheometric, mechanical, electrical and thermal degradation properties of the resultant composite materials. Rheometric cure characterization revealed that the torque difference increased with pristine MWCNT loading compared to the gum system, and this effect was more pronounced when silane‐functionalized MWCNTs were loaded, indicating that this effect was due to an increase in polymer–carbon nanotube interactions in the MWCNT‐loaded materials. Loading of silane‐functionalized MWCNTs in the ENR matrix resulted in a significant improvement in the mechanical, electrical and thermal degradation properties of the composite materials, when compared to gum or pristine MWCNT‐loaded materials.© 2013 Society of Chemical Industry     

Effect of carbon nanoparticle type,content, and stress on piezoresistive polyethylene nanocomposites

This study examines the piezoresistive behavior of polyethylene (PE) composites containing different types of carbon nanoparticle fillers. The fillers investigated are single‐wall carbon nanotube (SWCNT), multi‐wall carbon nanotube (MWCNT), and graphene nanoplatelets (GNP), which were dispersed in PE through melt blending in concentrations ranging between 0.5 and 10 wt%. The dispersion and nanocomposite morphology were investigated using scanning electron microscopy and X‐ray diffraction with strong evidence found for shear‐induced orientation of GNP nanoparticles during the compression molding process. The conductivity and permittivity of the composite materials was investigated using impedance spectroscopy and the lowest percolation threshold and highest electrical conductivity was observed for SWCNT composites, followed by MWCNT and GNP. The compressive piezoresistance of the nanocomposites was measured and the initial, elastic, and plastic deformation regions were all identifiable by the resistance measurements. The main finding of this study is that the piezoresistance of MWCNT nanocomposites is more sensitive to the effects of varying stress and composition than SWCNT nanocomposites. This indicates an evolving filler network in the case for MWCNT, while a static network for SWCNT, which is explained by the higher aspect ratio and surface area of the latter. POLYM. ENG. SCI., 55:1643–1651, 2015. © 2014 Society of Plastics Engineers     

Increased sensitivity of multiwalled carbon nanotube network by PMMA functionalization to vapors with affine polarity

Multiwalled carbon nanotube network (MWCNT‐N)/poly(methyl methacrylate) (PMMA ) composite is prepared by solution radical polymerization. The entangled multiwall carbon nanotube network (MWCNT‐N) is obtained by vacuum filtration and functionalized by allyl isocyanate to form polymerizable vinyl groups on a nanotube surface. The solution polymerization binds PMMA covalently to these groups and yields MWCNT‐N/PMMA composite manifesting electrical conduction and selective chemical vapor sensing. The latter property is evaluated in terms of affinity of organic solvent vapor and PMMA polarities. It is found that the affinity of acetone polarity with polarity of PMMA improves significantly the sensitivity of the composite to this solvent while the sensitivity to methanol is the same and to iso‐pentane even decreased in comparison with the corresponding property of MWCNT‐N. The composite selective response is favorable for a possible composite use as a sensing element and/or vapor switch. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012