氮钒共掺杂纳米TiO2的表面改性及其对涂料中甲醛的降解

利用硅烷偶联剂(KH570)对氮钒共掺杂纳米TiO2进行表面改性,考察了偶联剂用量、反应时间、反应温度及pH等改性条件的影响,从而确定最佳用量和最佳反应条件.利用元素分析、红外光谱、透射电子显微镜和热质等表征手段及亲油化度的测定,研究了表面改性的效果及分散状况.红外光谱表明,KH570以化学键合的方式结合在纳米TiO2的表面,并形成了有机包覆层,经测量,氮钒共掺杂纳米TiO2表面包覆的KH570的质量分数约为13.36％ ～14.99％.将改性后的氮钒共掺杂纳米TiO2以一定的比例加入到成膜物质中制成一系列的涂料样品,然后测定其甲醛含量.结果表明,甲醛的降解率可达到82.2％.与普通涂料相比,加入改性后的氮钒共掺杂的纳米TiO2的涂料具有优异的物理性能.     

硅掺杂和硅钒共掺杂对TiO2光催化性能的影响

采用溶胶-凝胶法在玻璃表面制备了一定厚度(约120 nm)的掺硅TiO2薄膜,在配制原始溶液时,所用钛酸四丁酯、正硅酸乙酯、乙醇、水和硝酸的摩尔比为1∶y∶25∶1∶0.2.用扫描电子显微镜观察其表面形貌,用X射线衍射表征其结构.以甲基橙溶液为体系,考察掺杂后TiO2薄膜的光催化性能.结果表明当y≤0.3时,随硅掺入量的增加,TiO2薄膜的光催化性能提高;当y>0.3时,硅的掺入使TiO2薄膜的光催化性能降低.另外,用相同方法制备了钒硅共掺杂的TiO2薄膜,发现钒硅共掺杂可以进一步提高TiO2的光催化性能.     

钒-氮共掺杂TiO2光催化降解苯酚试验研究

采用溶胶-凝胶法制备了钒-氮共掺杂TiO2光催化剂,对苯酚溶液进行了光催化降解试验研究,考察了在模拟太阳光条件下,pH、曝气量、苯酚溶液初始和催化剂投加量对钒-氮共掺杂TiO2光催化剂降解苯酚溶液的影响。结果表明,在试验条件下,以800 W氙灯为光源,反应溶液pH=6,曝气体积流量75 mL/min,苯酚溶液初始质量浓度小于80mg/L,催化剂投加量1.5 g/L时,苯酚溶液降解率最高;钒-氮共掺杂TiO2光催化剂重复使用7次后,对苯酚的光催化活性没有明显下降,具有良好的重复使用性。可为钒-氮共掺杂TiO2的应用推广提供依据。     

氮掺杂制备锐钛矿型纳米TiO2及降解甲基橙的研究

采用溶胶凝胶法制备了氮掺杂TiO2光催化剂。考察了氮的掺杂量、热处理温度对TiO2光催化能力的影响。用XRD、 SEM和紫外-可见光分度计对样品的晶型、形貌和光催化性能进行表征。结果表明氮的掺杂有助于改善TiO2的光催化性能,在灯光照射下5％N-TiO2煅烧温度为450℃时表现出较高的光催化活性和降解甲基橙溶液的能力,在80 min内降解甲基橙溶液达到了98％。     

多种光源下氮掺杂TiO_2光催化降解染料废水的研究

以尿素为氮源,采用溶胶-凝胶法制备了氮掺杂纳米TiO2粉末,以甲基橙溶液为模拟染料废水,分别在可见光、模拟太阳光和紫外光条件下,研究了氮掺杂纳米TiO2光催化降解染料废水的性能。结果表明:氮掺杂可以提高TiO2的可见光催化活性;氮含量和煅烧温度对氮掺杂TiO2光催化活性影响较大,n(N)∶n(Ti)为10%且经500℃煅烧的氮掺杂TiO2在可见光和模拟太阳光下均具有最佳的光催化活性;然而在紫外光下,氮掺杂TiO2的光催化活性低于未掺杂的TiO2样品。     

钒掺杂纳米TiO_2的制备及光催化性能研究

采用溶胶-凝胶法制备了不同比例掺钒的TiO2粉体,研究了掺杂比例对粉体光催化降解甲基橙的影响,并对所制备的V-TiO2进行了XRD表征。结果表明:钒掺杂可以使TiO2粉体的光催化效率显著提高;钒的掺杂摩尔比例为n V∶n Ti=1.2∶100,煅烧温度为500℃时,粉体在250 W高压汞灯下对甲基橙的降解率大,达到94.7%。     

掺氮TiO_2的制备与光谱分析

用硫酸钛与氨水反应得到TiO2前体,煅烧后制得掺氮TiO2粉体,研究了不同温度和加热时间下掺氮TiO2的XPS、FTIR和紫外可见光谱,结果表明,掺氮TiO2在400℃下加热1 h,所得粉体是锐钛矿相结构,与未掺杂TiO2相比,吸收边红移22 nm,对400~510 nm的可见光有一定的吸收率。氮的掺杂不仅使TiO2带隙变小,而且有助于氧空位的形成。     

N掺杂介孔TiO2的制备及光催化性能研究

以十六烷三甲基溴化铵(CTAB)为模板,通过水热法与煅烧处理结合的方法合成高度分散和尺寸均匀的纳米介孔TiO2球.通过扫描电镜(FESEM)、X射线衍射(XRD)、N2脱附吸附、紫外可见漫反射光谱(DRS)和X射线光电子能谱(XPS)等测试手段对介孔材料进行表征.结果表明,当氮掺杂浓度为2.0％时,介孔TiO2粒径较小(11.7 nm),孔径较大(9.0 nm),比表面积大(142.4 m2/g),禁带宽度较低(2.92 eV),氮掺杂相对含量可达到1.96at％(氮掺杂的固体TiO2仅为0.36at％),对可见光吸收能力明显增强,对罗丹明B降解效果最佳,3 h可达83％以上.     

自燃烧法合成氮、铁共掺杂TiO2及其可见光光催化活性

以硫酸钛、硝酸铁、尿素为原料,采用自燃烧法制备了氮、铁共掺杂的纳米TiO2粉体.XRD结果显示氮、铁共掺杂的纳米TiO2主要为锐钛矿相.当氮、铁共掺杂时,二氧化钛光谱吸收红移至可见区.XPS结果表明:铁进入TiO2的晶格中形成浅势,氮则取代氧原子形成了N-Ti键,它们的形成降低了二氧化钛的带隙,从而提高了可见光区的光催化能力.当氮、铁对钛的物质的量比分别为0.5%和0.6%时,其在可见光下降解亚甲基蓝的降解率分别是单掺杂和纯TiO2的1.4和3倍.     

燃烧合成Ag、La掺杂纳米TiO2及光催化性能研究

采用燃烧合成法制备了Ag、La掺杂纳米TiO2.XRD实验表明,La掺杂TiO2为单一相锐钛矿结构,Ag掺杂TiO2中出现了少量金红石相,与未掺杂纳米TiO2比较,Ag、La掺杂使TiO2晶体粒度更小,约8 nm.TEM实验表明,产物粒度分布均匀.用掺杂纳米TiO2降解罗丹明B,研究了元素掺杂量对TiO2催化性能的影响.结果表明,当Ag和TiO2摩尔比为1∶150、La和TiO2摩尔比为1∶75时,两种材料的催化能力最好,均优于未掺杂TiO2.比较Ag、La掺杂TiO2的催化性能,La掺杂TiO2的催化能力更强,在实验条件下,紫外光照射1.5 h,罗丹明B的降解率为99.0%.     

Thermal and Antistatic Properties of Polypropylene/Organo Montmorillonite Nanocomposites

Both polypropylene (PP) and PP/organo-montmorillonite (OMMT) masterbatch containing antistatic agent (3–9 wt%) were prepared by using co-rotating twin screw extruder followed by injection molding. PP/OMMT masterbatch was prepared by mixing PP, OMMT and maleated PP (PPgMAH). The PP nanocomposites were characterized by using X-ray diffractometer (XRD), differential scanning calorimeter (DSC), thermogravimetry analyzer (TGA), hardness and surface resistivity tests. XRD results indicated that AA could promote the intercalation in PP/OMMT nanocomposites. The decomposition temperature of PP/OMMT/AA nanocomposites is higher than that of PP/OMMT. The hardness, degree of crystallinity and surface resistivity of PP nanocomposites was influenced by the addition of antistatic agent.     

Microencapsulated ammonium polyphosphate by polyurethane with segment of dipentaerythritol and its application in flame retardant polypropylene

Dipentaerythritol (DPER), 4, 40-diphenylmethanediisocyanate (MDI) and melamine (MEL) are used as raw materials to microencapsulate ammonium polyphosphate (MAPP) in situ polymerization. The MAPP is characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). The results show that the coating operation can effectively improve water resistance of ammonium polyphosphate (APP), and MAPP has higher residual rate than that of APP after combustion. The flame retardant action of MAPP and APP in polypropylene (PP) is investigated by the limited oxygen index (LOI), vertical burning test (UL-94), TGA, SEM, and cone calorimeter test (CCT). The LOI value of the PP/MAPP composite at the same loading is higher than that of PP/APP composite. UL 94 ratings of PP/MAPP composites are raised to V-0 at 20 wt% loading. The results of CCT also show that MAPP is more efficient than APP. The morphological structures observed by digital photos and SEM demonstrated that MAPP could be promoted to form the continuous and compact intumescent char layer. The flame retardant mechanism of PP/MAPP is also discussed.     

A facile method for preparation of PGS@ZB‐N and gas‐sol alternating synergistic effect for fire resistance of EVA

Through the simple precipitation of palygorskite (PGS) by zinc borate (ZB) (to make PGS@ZB) and the decoration of PGS@ZB by dodecylamine (N), a novel organic‐inorganic@inorganic hybrid flame retardant of PGS@ZB‐N was prepared and was incorporated with ethylene vinyl acetate copolymer (EVA) to improve its flame retardance. The structure and morphology of PGS@ZB‐N were characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), and scanning electron microscopy (SEM), and it was confirmed that the PGS@ZB‐N hybrid had been successfully prepared. The flame retardancy and burning behavior of EVA/PGS@ZB‐N/EG (EG = expandable graphite) composite were studied through thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL‐94 (by the vertical burning test), and cone calorimeter test (CCT) characterizations. The prepared EVA/PGS@ZB‐N/EG composite obtained an LOI value of 41.2% with the addition of 30 wt% PGS@ZB‐N/EG. It was found that EVA/PGS@ZB‐N/EG was protected through a gas phase and condensed phase alternating synergistic effect mechanism.     

Synergistic effects of exfoliated LDH with some halogen‐free flame retardants in LDPE/EVA/HFMH/LDH nanocomposites

The synergistic effects of exfoliated layered double hydroxides (LDH) with some halogen‐free flame retardant (HFFR) additives, such as hyperfine magnesium hydroxide (HFMH), microencapsulated red phosphorus (MRP), and expandable graphite (EG), in the low‐density polyethylene/ethylene vinyl acetate copolymer/LDH (LDPE/EVA/LDH) nanocomposites have been studied by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermal analysis (TGA and DTG), mechanical properties, limiting oxygen index (LOI), and UL‐94 tests. The XRD results show that EVA as an excellent compatilizer can promote the exfoliation of LDH and homogeneous dispersion of HFMH in the LDPE/EVA/HFMH/LDH nanocomposites prepared by melt‐intercalation method. The TEM images demonstrate that the exfoliated LDH layers can act as synergistic compatilizer and dispersant to make the HFMH particles dispersed homogeneously in the LDPE matrix. The results from the mechanical, LOI, and UL‐94 tests show that the exfoliated LDH layers can also act as the nano‐enhanced and flame retardant synergistic agents and thus increase the tensile strength, LOI values, and UL‐94 rating of the nanocomposites. The morphological structures of charred residues observed by SEM give the positive evidence that the compact charred layers formed from the LDPE/EVA/HFMH/LDH nanocomposites with the exfoliated LDH layers play an important role in the enhancement of flame retardant and mechanical properties. The TGA and DTG data show that the exfoliated LDH layers as excellent flame retardant synergist of MRP or EG can apparently increase the thermal degradation temperature and the charred residues after burning. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

超分子前体制备g-C3N4/g-C3N4同质结及光催化性能研究

通过混合煅烧二氰二胺水热法和三聚氰胺-三聚氰酸共沉淀法制备的超分子前驱体,制备了兼具多孔纳米片和中空纳米管形貌的g-C₃N₄/g-C₃N₄同质结（CN-HP）。通过X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、紫外-可见漫反射光谱（UV-Vis DRS）、光致发光光谱（PL）等对光催化剂进行了表征。结果表明,CN-HP-1/1在75 min内对亚甲基蓝（MB）的降解率可达99.8%,伪一级动力学常数为4.02 h^-1,是块体g-C₃N₄的5倍,同时单位比表面积的反应常数提升至单体的1.8倍。PL测试表明,合适比例的三聚氰胺-三聚氰酸（MCA-H、MCA-P）超分子制备的同质结,其光生电子-空穴复合率较单体g-C₃N₄进一步降低。自由基捕获实验表明,光生空穴是光催化降解过程中的主要活性物种,并结合X射线光电子能谱价带谱测试提出了Z型电子传输机制。     

载体二氧化钛的晶型对对硝基苯酚加氢催化剂Ni/TiO2的影响

The catalytic hydrogenation ofp-nitrophenol to p-aminophenol was investigated over Ni/TiO2 catalysts prepared by a liquid-phase chemical reduction method. The catalysts were characterized by inductively coupled plasma （ICP）, X-ray powder diffraction （XRD）, transmission electron microscopy （TEM）, X-ray photoelectron spectra （XPS） and temperature-programmed reduction （TPR）. Results show that the titania structure has favorable influence on physio-chemical and catalytic properties of Ni/TiO2 catalysts. Compared to commercial Raney nickel, the catalytic activity of Ni/TiO2 catalyst is much superior, irrespective of the titania structure. The catalytic activity of anatase titania supported nickel catalyst Ni/TiO2（A） is higher than that of rutile titania supported nickel catalyst Ni/TiO2（R）, possibly because the reduction of nickel oxide to metallic nickel for Ni/TiO2（A） is easier than that for Ni/TiO2（R） at similar reaction conditions.     

Optimization of cellulase production using Trichoderma reesei by RSM and comparison with genetic algorithm

The potential of Trichoderma reesei for cellulase production using pineapple waste as substrate has been investigated. A maximum cellulase activity of 9.23 U/mL is obtained under the optimum experimental conditions: pH (5.5), temperature (37.5°C), initial substrate concentration (3%), inoculum concentration (6.6 × 10⁸?CFU/mL), and culture time (6 days). Box-Behnken design (BBD) statistical tool and genetic algorithm (GA) are used to optimize the process parameters. The BBD study of linear and quadratic interactive effects of experimental variables on the desired response of cellulase activity showed that the second order polynomial is significant (R² = 0.9414). The experimental cellulase activity under the optimal conditions identified by the BBD is 9.23 U/mL and that by GA is 6.98 U/mL. This result indicates that the BBD model gives better result than GA in the present case.     

香叶天竺葵鲜叶挥发油的镇咳活性成分分析

采用水蒸气蒸馏香叶天竺葵鲜叶,提取香叶油,并用GC-MS法对从香叶油中分离出的40多种组分做了分析,鉴定了其中24个化学组分,其GC含量占挥发油总量的95.45%含量最高的是香茅醇(30.69%),其它依次为甲酸香茅酯(11.89%)、异薄荷酮(9.73%)、β-古芸烯(6.89%)、芳樟醇(3.52%)、顺-玫瑰醚(3.38%)、大牛儿烯(3.13%)、香叶醇(3.05%)、α-石竹烯(2.55%)、α-蒎烯(2.43%)、β-石竹烯(2.31%)、α-二去氢菖蒲烯(2.21%)、β-榄香烯(2.19%)、丙酸香茅酯(2.08%)等。研究结果还表明,香叶油含有13.89%镇咳平喘药用功效的成分,如香叶醇、石竹烯、α-蒎烯、α-水芹烯、愈创木醇、β-月桂烯、柠檬烯等。本研究为香叶油的利用开拓了思路,也为其药用价值提供了初步的实验依据。     

HMX/ANPZO共晶炸药的制备及表征

运用分子动力学方法,计算了1,3,5,7-四硝基-1,3,5,7-四氮环杂辛烷(HMX)分子、2,6-二氨基-3,5-二硝基-吡嗪-1-氧(ANPZO)分子以及HMX/ANPZO共晶分子的分子间作用力、结合能和内聚能密度。通过气相扩散法制备了HMX/ANPZO共晶炸药,用红外光谱(IR)、差示扫描量热(DSC)和X射线衍射(XRD)表征了其结构,并测试了其机械感度。结果表明,HMX/ANPZO共晶分子间的相互作用力大于HMX分子间以及ANPZO分子间的相互作用力。与HMX和ANPZO相比,HMX/ANPZO共晶炸药的晶体结构和热分解特性变化较大,特性落高为59cm,与HMX相比提高了96.7%;理论爆速达9 060m/s。     

超高相对分子质量PA6冻胶体系的结构与性能

以三氯化镓(GaCl_3)、氯化锂(LiCl)、苯甲醇、氯化钙(CaCl_2)作为络合剂或溶剂,分别配制PA6/GaCl_3/硝基甲烷(CH_3NO_2)、PA6/LiCl/甲酸、PA6/苯甲醇和PA6/CaCl_2/甲酸等体系,制得冻胶试样,采用差示扫描量热法、红外光谱分析、X射线衍射和扫描电子显微镜等方法对冻胶试样的结构与性能进行了分析对比。结果表明:各个PA6冻胶体系的形成机理不同,各体系冻胶结构和性能差异较大。GaCl_3,LiCl,CaCl_2主要是通过破坏PA6的内部氢键,对其进行络合成冻胶,但三者的络合能力又有所区别。苯甲醇主要是通过溶剂效应而形成冻胶。