介孔TiO2制备及其对造纸废水的处理研究

介孔TiO2比表面积大,空隙率高,热稳定性好,在光催化、分离、水处理和空气净化等领域具有广阔的应用前景.文章综述了介孔TiO2的制备方法及其在光催化降解造纸废水方面的研究进展.     

二氧化锡掺杂二氧化钛介孔材料的合成及降解直接胡蓝5B

文章以水热法制备的纳米二氧化硅作为硬模板,将按不同质量比掺杂的锡(IV)和二氧化钛通过溶胶-凝胶法包裹在纳米二氧化硅表面,后除去二氧化硅模板得到SnO2/TiO2介孔材料。用SEM对介孔材料进行表征,其平均粒径为4um,多孔结构。光催化实验表明:合成的介孔材料在紫外光下对直接湖蓝5B有较好的光催化效果,质量比95∶5的SnO2/TiO2对染料的催化效果最好,直接湖蓝5B60min的脱色率达98%,并且锡(IV)含量的不同,会导致SnO2/TiO2介孔材料在避光阶段对染料吸附量不同。     

TiO2-SiO2介孔复合材料的合成及其在造纸上的应用

介孔材料作为一种新型的纳米结构材料,近年来已经成为跨学科的国际研究热点之一,综述了近几年介孔TiO2-SiO2复合材料的合成、表征及在造纸上的潜在应用.     

有序介孔TiO2-SiO2复合材料的制备及在造纸上的应用研究进展

介孔材料是一类孔径分布在2~50 nm之间的多孔材料,具有比表面积大、孔隙率高、孔径分布窄、孔排列有序的特点。本文综述了近几年介孔TiO2-SiO2复合材料的合成、表征及在造纸上应用的最新进展及前景展望。     

Ni掺杂介孔TiO2的制备及其光催化降解造纸废水

采用溶胶-凝胶法合成了不同Ni掺杂量的介孔TiO2材料,用X射线衍射(XRD)、透射电子显微镜(TEM)、红外(FT-IR)和N2吸附脱附等分析技术对产物结构和组成进行了表征.结果表明,介孔骨架TiO2主要以锐钛矿存在,介孔孔径由未掺杂时的8.8 nm增加到掺杂2%后的10.6 nm,BET比表面积由未掺杂时的159 m2/g降至136 m2/g.在紫外光照射、初始pH值4、连续通氧、催化剂用量1.5 g/L的反应条件下,使用不同Ni掺杂量的TiO2作为催化剂光催化降解造纸废水.实验表明,当Ni掺杂量为2%时,造纸废水的光催化降解效果最佳.以Ni掺杂量为2%的TiO2为催化剂,光催化降解造纸废水,废水的色度和CODCr去除率分别为100%和83.4%.     

新型氮铈共掺杂介孔TiO2半导体光催化剂

介孔TiO2具有极大的比表面积、规则有序的孔道结构、狭窄的孔径分布、孔径大小连续可调等特点,有利于反应物的扩散、吸附,且化学稳定性高、耐光腐蚀,有良好的光催化活性,其在水处理、空气净化、太阳能电池等方面表现出广阔的应用前景。Antonelli等首次以烷基磷酸盐阴离子表面活性剂作为模板，采用改进的溶胶凝胶法合成纯TiO2介孔材料。表面活性剂复配的目的是产生加和增效作用，也可以称为协同效应，即把不同类型的表向活性剂混合后，     

Co/TiO2的制备及其光催化降解甲基橙的研究

采用溶胶-凝胶法分别制备了二氧化钛(TiO2)和钴元素修饰的二氧化钛(Co/TiO2)光催化剂,并利用扫描电镜和X衍射分析仪等仪器对样品进行形貌和结构的表征,以甲基橙水溶液的紫外线光催化降解为探针反应,评估TiO2和Co/TiO2的光催化活性.研究结果表明,光催化剂存在钛氧化物和Co元素,具有介孔结构,且粒径分布均匀,结构规整,表面存在一定的缺陷.以甲基橙作为降解目标,发现Co/TiO2的催化活性高于未经修饰的TiO2,其在紫外光辐射下光催化降解率达到96.2％.     

氮铈共掺杂介孔TiO2的制备及在造纸废水处理中的应用

以钛酸四正丁酯为前躯体,用聚氧乙烯脂肪醇醚(Brij98)和十六烷基三甲基溴化铵(CTAB)作为复合模板剂,硝酸铈和尿素为掺杂离子给予体,通过改进的溶胶-凝胶法成功地制备了氮铈共掺杂介孔TiO2光催化剂.用X射线衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)等分析手段对所得产物的结构和光学性能进行了表征.结果表明,所制备材料为锐钛矿晶型,具有7～10 nm的均一孔径,掺杂能够阻止TiO2的相转变,提高TiO2介孔结构的热稳定性.当共掺杂催化剂含氮2％、铈2％(物质的量分数)时对造纸废水的光催化降解效果最佳,色度和CODCr的去除率分别达到100％和72％.     

氮铈共掺杂介孔TiO_2的制备及在造纸废水处理中的应用

以钛酸四正丁酯为前躯体,用聚氧乙烯脂肪醇醚(Brij98)和十六烷基三甲基溴化铵(CTAB)作为复合模板剂,硝酸铈和尿素为掺杂离子给予体,通过改进的溶胶-凝胶法成功地制备了氮铈共掺杂介孔TiO2光催化剂。用X射线衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)等分析手段对所得产物的结构和光学性能进行了表征。结果表明,所制备材料为锐钛矿晶型,具有7～10nm的均一孔径,掺杂能够阻止TiO2的相转变,提高TiO2介孔结构的热稳定性。当共掺杂催化剂含氮2%、铈2%(物质的量分数)时对造纸废水的光催化降解效果最佳,色度和CODCr的去除率分别达到100%和72%。     

可见光响应的介孔TiO2光降解罗丹明B机制及其降解途径

为获得可见光响应的高效介孔TiO₂光催化剂,利用软模板法制备了螺旋堆积的手性介孔TiO₂。对比分析了手性介孔TiO₂和非手性介孔TiO₂的差异。通过自由基捕获实验和电子自旋共振(ESR)光谱,结合福井指数(f^-)的计算探索了手性介孔TiO₂降解罗丹明B(RhB)的机制和路径。结果表明,手性介孔TiO₂的螺旋堆积结构引入了更多缺陷,从而其Ti³⁺和氧空穴的含量都高于非手性介孔TiO₂,因此具有更强的可见光响应和降解活性,其对RhB的去除率超过非手性介孔TiO₂的4倍;手性介孔TiO₂降解有机污染物分子的主要活性物种是光生空穴h⁺;越容易给出电子的原子位点(即f^-值越高)越容易受到h⁺的攻击发生降解;降解过程中中间产物分析进一步得到了可见光激发手性介孔TiO₂降解R...     

Antiperspirant compositions based on titanium salts

Antiperspirant compositions have traditionally relied upon aluminium-based active compounds to reduce sweating. Titanium is a physiologically inert metal, and titanium metal chelates appear to induce superficial physical pore blockage to provide effective antiperspirancy in a variety of product types. Titanium metal chelates can be formed from titanium alkoxides and organic acids. Conflicting opinions as to the salt structure exist and, in the case of part-neutralized ammonium titanium lactate (ATL) salt, evidence has been seen for a range of ligands bound to different strengths at different stages of hydrolysis. Aluminium is thought to work by ductal diffusion to give antiperspirancy via neutralization to a polymeric, relatively superficial gel obstruction. ATL mimics conventional alumiunium salts in that it is mainly a topical antiperspirant active, with ATL-treated skin restored to normal patterns of sweating activity after a few tape-strips. Under acidic and near-neutral pH conditions, the ATL active is relatively stable to hydrolysis and can be formulated into topical compositions as either an aqueous solution of the active or as a free-flowing powder in anhydrous systems. When judged by an in vitro efficacy technique which is thought to predict in vivo performance, ATL functions as an effective antiperspirant.     

静电纺聚四氟乙烯/二氧化钛光催化纳米纤维膜的制备及其应用

针对光催化剂二氧化钛(TiO₂)难回收、传统载体材料性能不稳定等问题,以聚四氟乙烯(PTFE)为成膜聚合物,以聚乙烯醇(PVA)为纺丝载体,引入纳米光催化剂TiO₂,采用乳液静电纺丝法制备PTFE/PVA/TiO₂初生纤维膜,然后经烧结得到负载型PTFE/TiO₂光催化纳米纤维膜。通过形貌观察、孔径、孔隙率以及疏水性能测试,考察TiO₂质量分数对纤维膜结构与性能的影响。结果表明:随着TiO₂固含量的增加,纤维膜直径均匀性有所降低,平均孔径增大;将纤维膜用于减压膜蒸馏实验,通量最高达35 L/(m²·h),截盐率稳定在99.98%以上;在光催化降解质量浓度为10 mg/L的亚甲基蓝染料水溶液过程中,经紫外线照射5 h后,染料降解率达99%;经重复使用后,PTFE/TiO₂纳米纤维膜仍能保持良好的结构与光催化性能。     

Metal distribution in Clark Fork River sediments

Accurate sampling of pore waters and sediments in gravel river beds is problematic because cobbles preclude most coring techniques, while the angularity of sand grains destroys the membranes of standard pore water samplers. In the Clark Fork River, the recipient of over 100 years of mining activity, a modified single tube core-freezing device was used to profile bed sediment (approximately 65% cobbles and 35% gravel substrate), and a novel pore water sampler was developed to collect interstitial water. In the sediment, the <63 microm fraction comprised <4 wt % yet contained approximately an order of magnitude higher metal concentrations compared to the 63 microm-2 mm fraction (constituting approximately 20% of the mass). However, on a mass basis the sand fraction contained 60% of the metals, compared to 40% in the clay/silt fraction in the gravels, while in point bars the distribution was approximately 50:50. The metals occur predominantly in sulfides frequently armored with an oxide rim and other sparingly soluble phases that may explain the low pore water metal concentrations. These data demonstrate that consideration of multiple particle size cutoffs is necessary to accurately characterize fluvial bed sediment metal conditions and that the form of the metal is important in understanding metal solubility in the benthos.     

介孔材料的双功能化修饰及降低卷烟烟气中氰化氢的性能

为开发选择性吸附卷烟烟气中氰化氢的滤嘴添加剂,对水热合成法制备的有序介孔氧化硅材料MCM-41进行了碱性基团和过渡金属离子双功能化修饰,表征了功能化材料的孔结构、孔径分布、孔体积、比表面积以及元素组成等,考察了材料制备条件对吸附氰化氢性能的影响,评价了材料在卷烟滤嘴中的应用效果。结果表明:①采用N-(β-氨乙基)-γ-氨基丙基甲基二甲氧基硅烷(EPDMS)和过渡金属离子修饰后的MCM-41材料,仍保持了二维六方孔道结构以及较高的比表面积与孔体积;②EPDMS用量为4 mL/(g MCM-41)、金属离子为Zn2+时,所制备的MCM-41双功能化材料Zn2+/c-EPDMS/MCM-41的氰化氢吸附性能最好;③将上述条件下制备的Zn2+/c-EPDMS/MCM-41以二元复合滤棒的形式、20 mg/支的添加量应用于卷烟后,主流烟气HCN选择性降低31.2%,卷烟危害性指数(H)下降0.4。所制备的MCM-41双功能化材料Zn2+/c-EPDMS/MCM-41具有良好的氰化氢选择性吸附性能。      

防羽面料孔径及分布特征与透气性和防钻绒性的关系

为开发优质防羽面料,探明孔径及其分布特征对防羽面料性能的影响机制,借助多功能孔径测定仪、透气量仪和防钻绒性能测试仪获取10种不同规格防羽面料的孔径、透气率和钻绒根数,分析了孔径及其分布特征与透气性和防钻绒性之间的关系。结果表明:防羽面料的孔径分布符合正态分布的规律,且孔径均值和标准差的相关系数为0.99;在原料和组织结构相同的情况下,防羽面料透气率随着孔径均值的减小而减小;钻绒根数与孔径均值拟合方程的判定系数为0.94,当孔径均值小于8 μm时,面料的钻绒根数低于23根;提出采用透钻比(透气率和钻绒根数的比值)综合评价防羽面料的防钻绒性和透气性发现,透钻比与孔径变异系数呈显著负相关,即孔径变异系数越小,透钻比越大,面料的综合性能越好。     

Supported ionic liquid membranes for removal of dioxins from high-temperature vapor streams

Dioxins and dioxin-like chemicals are predominantly produced by thermal processes such as incineration and combustion at concentrations in the range of 10-100 ng of I-TEQ/kg (I-TEQ = international toxic equivalents). In this work, a new approach for the removal of dioxins from high-temperature vapor streams using facilitated supported ionic liquid membranes (SILMs) is proposed. The use of ceramic membranes containing specific ionic liquids, with extremely low volatility, for dioxin removal from incineration sources is proposed owing to their stability at very high temperatures. Supported liquid membranes were prepared by successfully immobilizing the ionic liquids tri-C(8)-C(10)-alkylmethylammonium dicyanamide ([Aliquat][DCA]) and 1-n-octyl-3-methylimidazolium dicyanamide ([Omim][DCA]) inside the porous structure of ceramic membranes. The porous inorganic membranes tested were made of titanium oxide (TiO(2)), with a nominal pore size of 30 nm, and aluminum oxide (Al(2)O(3)), with a nominal pore size of 100 nm. The ionic liquids were characterized, and the membrane performance was assessed for the removal of dioxins. Different materials (membrane pore size, type of ionic liquid, and dioxin) and different operating conditions (temperature and flow rate) were tested to evaluate the efficiency of SILMs for dioxin removal. All membranes prepared were stable at temperatures up to 200 °C. Experiments with model incineration gas were also carried out, and the results obtained validate the potential of using ceramic membranes with immobilized ionic liquids for the removal of dioxins from high-temperature vapor sources.     

织物毛细孔径分布与其组织结构及组分的关系

由于织物组织结构及组分对织物毛细孔半径及其分布有影响,采用质量分级法,测定5种组织结构的棉和涤/棉机织物的毛细孔半径分布。分别考察纱线线密度、织物经纬密和组分对织物毛细孔径分布曲线的影响。结果表明：这些织物的孔径分布曲线大都由4个区段构成;随着纱线线密度的减小,整个孔径范围明显扩展,其中最小孔径略有增加,最大孔径显著增加,最大比例孔径显著减小;随着经纬密的降低,分布曲线的部分区段被压缩甚至和其他区段归并,织物孔径分布趋于简单化和均匀化;织物的组分并不影响其孔径分布曲线的特征形状,只是在不同区段曲线略有压缩和伸展变形。     

Degradation of methylene blue by three-dimensionally ordered macroporous titania

Accelerated photodegradation of methylene blue (MB) over three-dimensionally ordered macroporous (3DOM) titania (pore sizes: 0.5 and 1 microm) is demonstrated. The catalysts were synthesized by colloidal crystal templating against polystyrene spheres using a metal alkoxide precursor. The 3DOM titania walls which are predominantly anatase (> 98%) were decorated homogeneously with gold nanoparticles (5-7 nm) by pH-controlled precipitation of Au from HAuCl4 using sodium hydroxide. A combination of powder X-ray diffraction (XRD), analytical transmission electron microscopy (ATEM) and X-ray photoelectron spectroscopy (XPS) confirmed the deposition of Au(0) on the 3DOM titania macroporous walls. Photocatalytic activity was monitored by following the degradation of MB with activity benchmarked against commercial P25 (Degussa) and powdertitania prepared by hydrolysis of titanium ethoxide. Macroporous 3DOM titania with pore diameter 0.5 microm had the highest first-order rate constant of 0.042 min(-1) for decomposition of MB, compared to 0.025 min(-1) for P25 titania. Deposition of gold on the 3DOM titania surfaces decreased the reaction rate by covering the surface active sites.     

薄型非织造材料孔径和渗透率关系的探讨

本文主要介绍非织造材料的孔径与渗透率及其相互关系的理论研究。文章比较了各种孔径测试方法 ,讨论了非织造材料孔径分布的最可能规律 ,以及单层和复合的非织造材料中孔径和渗透率之间的关系     

Extracellular polymeric substances from Bacillus subtilis associated with minerals modify the extent and rate of heavy metal sorption

Extracellular polymeric substances (EPS) are an important source of organic matter in soil. Once released by microorganisms, a portion may be sorbed to mineral surfaces, thereby altering the mineral?s ability to immobilize heavy metals. EPS from Bacillus subtilis were reacted with Ca-saturated bentonite and ferrihydrite in 0.01 M KCl at pH 5.0 to follow the preferential uptake of EPS-C, -N, and -P. The sorption kinetics of Pb(2+), Cu(2+), and Zn(2+) to the resulting EPS-mineral composites was studied in single and binary metal batch experiments ([metal](total) = 50 μM, pH 5.0). Bentonite sorbed much more EPS-C (18.5 mg g(-1)) than ferrihydrite (7.9 mg g(-1)). During sorption, EPS were chemically and size fractionated with bentonite favoring the uptake of low-molecular weight components and EPS-N, and ferrihydrite selectively retaining high-molecular weight and P-rich components. Surface area and pore size measurements by N(2) gas adsorption at 77 K indicated that EPS altered the structure of mineral-EPS associations by inducing partial disaggregation of bentonite and aggregation of ferrihydrite. Whereas mineral-bound EPS increased the extent and rate of Pb(2+), Cu(2+), and Zn(2+) sorption for bentonite, either no effect or a decrease in metal uptake was observed for ferrihydrite. The extent of sorption always followed the order Pb(2+) > Cu(2+) > Zn(2+), which also prevailed in binary Pb(2+)/Cu(2+) systems. In consequence, sorption of EPS to different minerals may have contrasting consequences for the immobilization of heavy metals in natural environments by inducing mineral-specific alterations of the pore size distribution and, thus, of available sorption sites.