基于纳米CuZSM-5分子筛的传感器用于沙林检测的研究

将纳米ZSM-5或CuZSM-5分子筛作为敏感膜,结合石英晶体微天平(QCM)制备了对神经毒剂沙林(GB)敏感的传感器,研究了硅铝摩尔比和铜离子修饰对毒剂检测性能的影响.结果表明,硅铝摩尔比为25的纳米CuZSM-5分子筛对GB响应最好,并可对GB进行连续多次检测,其灵敏度为19.1 Hz/(mg·m-3),检出限达1.1 mg·m-3(S/N＝3);线性范围为1.5 ～20.0 mg·m-3,线性相关系数为0.995 8,在毒剂检测中具有较强的应用前景.     

β-环糊精调控水溶液中Cu~(2+)的辐射还原

在β-环糊精(β-CD)水溶液的安全吸收剂量范围内,利用β-CD来调控Cu2+的辐射还原.随着β-CD的加入,硝酸铜的辐射还原产物从Cu2O逐渐转变为Cu.当β-CD浓度增大至8.0mmol·L-1时,辐射还原产物主要为Cu纳米粒子.在辐照过程中,Cu2+的还原没有经历Cu2O的中间过程.这是由于β-CD对·OH的清除减少了·OH与水化电子(ea-q)的反应,增大了ea-q的产额,从而有利于Cu的生成.另外,β-CD通过羟基在Cu纳米粒子表面的吸附可增强Cu纳米粒子在水溶液中的稳定性.用紫外-可见(UV-Vis)吸收光谱、粉末X射线衍射(XRD)和选区电子衍射(SAED)对Cu2+辐射还原产物进行了表征.     

压电免疫传感器法检测蓖麻毒素

利用纳米金对石英晶体微天平(QCM)的表面修饰和质量扩增效应,建立了一种压电免疫传感器检测蓖麻毒素的新方法。首先在石英晶体的金电极上依次自组装1,6-己二硫醇和纳米金进行表面修饰,然后通过蛋白A定向固定蓖麻毒素多抗来制备敏感膜。利用纳米金的质量扩增效应设计了一种“毒素-单抗-蛋白A-纳米金”复合物,成功实现了对蓖麻毒素的检测,提高了传感器灵敏度和特异性。该传感器对蓖麻毒素响应的线性范围为0.50~10 mg/L,回归方程为△F=45.81Cric in 48.48(R=0.9986,N=10,P<0.01);检测灵敏度为45.81 Hz/(mg/L)。     

用分子筛修饰制备的NO传感器的电化学性能研究

采用层层组装方法(LBL),将纳米方钠石分子筛进一步修饰到经镍(Ⅱ)四磺酸基酞菁(NiTSPc)和全氟磺酸离子交联聚合物(NafionR)修饰的玻碳电极(GCE/NiTSPc/NafionR)表面上,制得一新型NO传感器GCE/NiTSPc/NafionR/(PDDA/Zeolite)5 (PDDA即聚二甲基二烯丙基氯化铵),并对其电化学性能进行了研究.结果表明,纳米方钠石分子筛修饰膜不仅可提高电极检测NO的灵敏度(由26 Ma/(mol·L-1)升至29 Ma/(mol·L-1)),还可提高电极抵抗共存物干扰的能力.Nafion修饰层可使电极对抗坏血酸、多巴胺、肾上腺素及亚硝酸钾的响应分别降低19%、0%、11%、33%,而进一步修饰纳米方钠石分子筛后,电极对上述干扰物质的响应分别降低了68%、51%、52%和39%.     

NH4+交换度对 CuY催化剂上甲醇氧化羰基化反应性能的影响

碳酸二甲酯(DMC)是一种应用极其广泛的绿色化工产品,其中经济、绿色的甲醇氧化羰基化合成 DMC工艺极具工业前景,而 Y分子筛负载铜(CuY)是有效催化剂之一.众所周知, CuY催化剂上的 Cu+是催化活性中心. Cu+催化活性中心的引入方式用两种：(1) CuCl直接与 HY分子筛固相离子交换;(2) Cu2+与 NaY分子筛溶液离子交换,然后 Cu2+自还原生成活性中心 Cu+.在无溶剂条件下制备 CuY催化剂时,载体 HY分子筛中的可交换位 H+量是决定催化剂 CuY氧化羰基化催化性能的关键因素.文献通过以不同硅铝比的 HY分子筛为载体制备的催化剂 CuY,研究铜离子可交换位 H+量对氧化羰基化的影响,然而,硅铝比的不同也直接影响了分子筛骨架的组成、Si–O–Al的键角、甚至影响了 Al3+的分散度,这些因素都直接影响了 CuY催化剂活性.因此,研究 NaNH4Y分子筛载体中的可交换位(NH4+)的量与 CuY催化剂活性间的关系具有非常重要的意义.本文将 NaY分子筛与不同浓度的 NH4NO3溶液进行离子交换,制得具有不同 NH4+交换度的 NaNH4Y分子筛,以其为载体,以具有易升华、易分解性质的乙酰丙酮铜 Cu(acac)2为铜源,在无溶剂条件下,高温热处理二者固相混合物, NaNH4Y 分子筛中的 NH4+与 Cu(acac)2中的 Cu2+发生了离子交换, Cu2+进一步发生自还原生成活性中心 Cu+,成功地制备了完全无氯的 CuY催化剂,应用于催化常压甲醇氧化羰基化合成 DMC过程,研究 NaNH4Y分子筛中的铜离子可交换位 NH4+与催化剂 CuY催化性能间的关系.通过各种表征及对 CuY催化剂在甲醇氧化羰基化过程中催化活性分析发现, Y分子筛经过 NH4NO3溶液离子交换及催化剂的制备过程,其八面沸石结构和孔道保持良好.以未经过离子交换的 NaY负载的 CuY催化剂上的铜物种完全以 CuO形式存在,且没有催化活性.随着 NH4+交换度增加, CuY催化剂表面 CuO含量逐渐降低,而活性中心 Cu+含量逐渐增加,且其催化活性也随之增加.当 NH4+交换度趋于极限值时, CuY催化剂中 Cu+含量达最大,其催化活性也达最佳, DMC的时空收率和选择性分别为267.3 mg/(g·h)和68.5%,甲醇转化率为6.9%.因此,无溶剂条件下,以 NaNH4Y分子筛为载体, Cu(acac)2为铜源,制备完全无氯 CuY催化剂时, NH4+是形成 Cu+活性中心的必须条件,且 NH4+交换度直接影响催化剂 CuY的催化活性.     

纳米薄层HZSM-5分子筛催化甲醇制丙烯

在合成系列硅铝比纳米薄层HZSM-5分子筛的基础上,研究了纳米薄层HZSM-5分子筛催化甲醇制丙烯(MTP)的反应性能.在固定床微反装置上详细考察了工艺条件对纳米薄层HZSM-5分子筛催化性能的影响,同时与纳米HZSM-5分子筛对MTP反应的催化性能进行了比较.结果表明,纳米薄层HZSM-5分子筛具有较高的目的产物选择性和较长的催化寿命.在适宜硅铝比(n(SiO2)/n(Al2O3)=213)和反应条件下(温度470°C,甲醇质量空速为3 h-1),丙烯的选择性达到46.7%,三烯(乙烯、丙烯和C4烯烃)选择性达到78.7%.其中,丙烯/乙烯的质量比可达到6.5,是纳米HZSM-5分子筛的2倍,而芳烃的选择性比纳米分子筛明显降低.这是因为纳米薄层HZSM-5分子筛比纳米HZSM-5分子筛具有较宽的(010)晶面、较大的外比表面积和介孔孔容.     

孔道型微孔和介孔分子筛的改性及超级绝热性能

在水热体系中合成了具有规则孔道结构的微孔分子筛ZSM-5和介孔分子筛MCM-41,SBA-15,MAS-5,通过改变材料表面的电性对介孔材料进行了化学修饰.采用X射线衍射(XRD)和扫描电子显微镜(SEM)对样品的结构、形貌进行了表征;通过氮气吸附-脱附测试了产物的比表面积,采用BJH法计算孔分布和孔容;将制得的样品压制成绝热材料后,进行导热性质测定.常温(25℃)常压下,有序介孔分子筛MCM-41的导热系数为0.038 W·m-1·K-1,具有少量微孔结构的MAS-5的导热系数为0.035W·m-1·K-1,二者均为超级绝热材料.材料经改性后,绝热性能有所提高:MCM-41的导热系数降至0.028 W·m-1·K-1,MAS-5的导热系数降至0.017 W·m-1·K-1.结合纳米介孔材料导热理论模型进行分析,发现纳米孔绝热材料的孔径越小,孔隙率越大,绝热性能好;介孔分子筛的导热系数与其孔壁厚度、孔径大小以及孔隙率有关.     

纳米分子筛的合成及硫化氢吸附性能

利用无模板水热法合成纳米尺寸的小孔SOD型和大孔X型分子筛, 并考察了其硫化氢脱除性能. 通过对比两种分子筛的硫化氢吸附性能, 证实分子筛对硫化氢的吸附主要集中于孔道内和可及的活性位. 考察了晶粒尺寸、 体积空速和吸附温度等因素对硫化氢吸附的影响, 发现纳米尺寸X型分子筛具有更大的硫容, 并且在低温和低空速下分子筛中的硫化氢分子易于脱除. 随后对纳米X型分子筛进行了金属离子交换改性, 发现Cu改性的分子筛硫容优于其它离子改性的吸附剂, 能达到20.6 mg/g. NaX-N和Cu-NaX-N再生后的硫容分别为新鲜分子筛的62.4%和78.5%.     

铜离子在CuLaHY分子筛中的分布与吸附脱硫性能

在空气气氛中采用等体积浸渍法制备了具有不同Cu担载量的CuLaHY分子筛吸附剂, 并用X射线衍射(XRD)、比表面积(BET)、X射线光电子能谱(XPS)技术对分子筛吸附剂进行了表征. 通过多晶XRD确定了Cu2+及La3+离子在Y型分子筛笼内的结构与分布, 并测定了分子筛吸附剂在含二苯并噻吩(DBT)的模拟柴油中的吸附脱硫性能. 结果表明, 前驱体CuCl2中的大部分Cu物种与LaHY分子筛进行了离子交换, 进入分子筛笼内, 极少部分Cu物种以CuCl形式高度分散在Y型分子筛的笼中. La3+离子及进入Y型分子筛笼中的部分Cu2+离子处于茁笼的SI'位, 而另一部分Cu2+离子与骨架氧和水分子配位, 并牢固地定位于Y型分子筛超笼中的SII及SIII位上. 处于超笼中SII及SIII位上的Cu2+离子对模拟柴油中的DBT分子具有吸附作用, 成为吸附脱硫的中心. 当模拟柴油中有萘存在时, 与DBT分子会产生竞争吸附.     

以Au/Cu纳米棒为基底的肺腺癌组织的特征表面增强拉曼光谱研究

通过金铜共混法制备了Au/Cu合金纳米棒,研究了铜掺杂对金纳米棒等离子体共振吸收和结构的影响,探究了Au/Cu合金纳米棒的等离子体共振拉曼增强效应.以Au/Cu合金纳米棒为基底对肺腺癌组织和癌旁正常组织进行了表面增强拉曼光谱检测.结果显示,癌变组织具有比癌旁正常组织更强的拉曼信号峰,位于1250,1344,1408,1568,1608和2560 cm~(-1)附近的拉曼峰分别与蛋白质的AmideⅡ氨基化合物、C—H弯曲振动、核酸中CH_3的对称变角振动、蛋白质色氨酸惰性环振动、蛋白质酰胺I谱带分子间反平行β-折叠的C—O健伸缩振动和蛋白质的巯基(S—H)伸缩振动有关,2936 cm~(-1)附近的拉曼峰为蛋白质CH_2的对称伸缩振动和CH_3的反对称伸缩振动共同作用产生.以铜掺杂的金纳米棒为基底的表面增强拉曼光谱法有望成为检测肺癌组织的有效手段.     

A quartz crystal microbalance sensor for the detection of formic acid vapors

A new quartz crystal microbalance sensor is developed to determine formic acid at low concentrations. Four previously selected polymers with acid-base characteristics were tested as possible coatings. Polyoxyethylene bis [amine] presented the best results. The sensor is rapid, sensitive [0.67 Hz/(mg/m3)], and reversible at low concentrations. The detection limit for formic acid (7.2 mg/m3) is comparable with the short term exposure limit and the threshold limit values. It presents a fast mechanical response to pressure changes, so that it can be quickly used in different environments and situations. The sensor also shows a good stability in a temperature range typical of work atmospheres (16-36 degrees C). It has a wide linear range (7.2-911.2 mg/m3) and a long useful time. It is also applicable to other low molecular mass carboxylic acids such as acetic acid.     

A quartz crystal microbalance sensor for the detection of formic acid vapors

A new quartz crystal microbalance sensor is developed to determine formic acid at low concentrations. Four previously selected polymers with acid–base characteristics were tested as possible coatings. Polyoxyethylene bis [amine] presented the best results. The sensor is rapid, sensitive [0.67 Hz/(mg/m³)], and reversible at low concentrations. The detection limit for formic acid (7.2 mg/m³) is comparable with the short term exposure limit and the threshold limit values. It presents a fast mechanical response to pressure changes, so that it can be quickly used in different environments and situations. The sensor also shows a good stability in a temperature range typical of work atmospheres (16–36 °C). It has a wide linear range (7.2–911.2 mg/m³) and a long useful time. It is also applicable to other low molecular mass carboxylic acids such as acetic acid. Received: 26 September 2000 / Revised: 8 February 2001 / Accepted: 12 February 2001     

Polymer Coated Piezoelectric Quartz Crystal Protein Bio‐Sensors

A polymer coated piezoelectric crystal detection system with a home‐made computer interface for signal acquisition and data processing was prepared as a liquid chromatographic detector for various proteins. Various polymers, e.g., polyvinyl aldehhyde (polyacrolein) (PVA), polyacrylamide/glutaldehyde (PAA/GA) and bio‐gel A, were used as coating materials on quartz crystals for adsorption of various protein molecules, e.g., catalase (CA), hemoglobin (Hb), α‐chymotrypsin (Ch), albumin (Ab). The frequency responses of the polyacrlein coated piezoelectric detector for various proteins were in the order: catalase> hemoglobin> α‐chymotrypsin > albumin. In contrast, the order of the frequency responses of bio‐gel A and polyacrylamide/glutaldehyde coated piezoelectric crystals for these proteins were: hemoglobin> catalase > α‐chymotrypsin ≥ albumin and hemoglobin > albumin > catalase. The polyacrolein coated piezoelectric crystal protein detector exhibited a good linear frequency response with a high sensitivity of about 2.5×10³ Hz/(mg/mL) for catalase. In addition, bio‐gel A and polyacrylamide/glutaraldehyde coated crystals were sensitive to hemoglobin with sensitivities of about 4.5×10³ Hz/(mg/mL) and 3.0×10³ Hz/(mg/mL), respectively. Study of the interference of various organic molecules, e.g., alcohols, amines, ketones and carboxylic acids, in the detection of proteins with theses polymer coated crystals was also made. The polyacrolein coated crystal for proteins under went less interference from various organic molecules than bio‐gel A or polyacrylamide/glutaraldehyde coated crystals. Effects of coating load, concentration of proteins and flow rate of liquid chromatographic eluent were also investigated and discussed.     

基于纳米铁氰化镍修饰二氧化钛纳米管阵列电极的非酶葡萄糖传感器

以二氧化钛纳米管阵列(TNTs)为基底,利用脉冲电沉积的方法将Ni纳米粒子沉积在TNTs管内,通过循环伏安法将Ni转化为铁氰化镍(NiHCF),构造了新型的非酶型葡萄糖生物传感器(NiHCF/TNTs修饰电极)。在优化的实验条件下,传感电极的灵敏度为663μA/(mmol cm2);响应电流与葡萄糖浓度在1～23mmol/L范围内呈现良好的线性关系。在低浓度检测下,线性范围为2×10-3～1.0 mmol/L;检出限为0.5μmol/L。本传感电极具有灵敏度高、稳定性好和抗干扰能力强等特点。     

Fast, sensitive and cost-effective detection of nerve agents in the gas phase using a portable instrument and an electrochemical biosensor

The nerve agents are chemical warfare agents known to be used during terrorist attacks. An inexpensive and portable system to be used by first responders and military personnel is of interest owing to the continuing threat of possible terrorist attacks. Amperometric biosensors based on cholinesterase inhibition show such potentialities. In this work butyrylcholinesterase was immobilized onto screen-printed electrodes modified with Prussian blue and the nerve agent detection was performed by measuring the residual activity of enzyme. The optimized biosensor was tested with sarin and VX standard solutions, showing detection limits of 12 and 14 ppb (10% of inhibition), respectively. The enzymatic inhibition was also obtained by exposing the biosensors to sarin in gas phase. Two different concentrations of sarin gas (0.1 and 0.5 mg m⁻³) at different incubation times (from 30 s up to 10 min) were tested. It is possible to detect sarin at a concentration of 0.1 mg m⁻³ with 30-s incubation time, with a degree of inhibition of 34%, which match the legal limits (immediate danger to life and health).     

Analytical application of poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane} as a QCM coating for DMMP detection

A new material-poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane}(PMDFPS) sensitive to toxic organophosphate vapor was synthesized with 2,3-difluorophenol, allyl bromide and poly (methyl hydrosiloxane) as raw materials, via O-alkylation, Claisen rearrange reaction and hydrosilylation reaction. This novel material was then coated on a quartz crystal microbalance (QCM) to investigate its gas sensitive properties to the nerve agent simulant dimethyl methylphosphonate (DMMP) vapor, as well as known interfering vapors. When tested with competing vapors, the sensor was more than 10 times sensitive to DMMP than to other interfering vapors. Thus, high selectivity of poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane} to DMMP was demonstrated. The poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane}-QCM sensor responded linearly to DMMP vapor with a slope of 14 Hz/ppm in the 1-50 ppm range with a detection limit of 0.21 ppm (S/N=3).     

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

An electrochemical sensor based on Zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode was designed for the toxic diuron pesticide detection. The ZnONPs were synthesized through the hydrothermal route and their structural properties were investigated via scanning electron microscopy (SEM) and X-ray diffraction powder (XRD). The designed ZnONPs-modified carbon paste electrode (ZnONPs-CPE) was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly enhanced sensitivity on the diuron oxidation peak current, compared to the bare carbon paste electrode. Qualitative and quantitative analysis were performed using cyclic voltammetry (CV) and square wave voltammetry (SWV). Experimental parameters such as pH, amount of ZnONPs and frequency were evaluated and the optimized conditions were obtained with 0.1 M phosphate buffer solution at pH=8, a frequency of 50 Hz and a quantity of 5 mg of ZnONPs. Under these conditions, linear responses ranging from 1.3 to 7.7 μM and 8.6 to 30 μM of diuron were obtained, with correlation coefficients of R²=0.994 and 0.996 respectively. Detection and quantification limits of 0.22 μM and 0.84 μM (S/N=3) were respectively achieved based on the 3σ method. The interference of some ions on the oxidation peak of diuron on ZnONPs-CPE was also evaluated and no interference was observed, therefore demonstrating the selectivity of the sensor. The proposed sensor, designed with ecofriendly materials, is sensitive, selective and was effectively used for diuron determination in soils and water samples with recoveries ranging from 98 % to 101.5 %.     

基于硫堇掺杂的聚乙烯醇薄膜的光波导传感器检测硫化氢气体

采用旋转甩涂法将硫堇掺杂的聚乙烯醇薄膜固定在K⁺交换玻璃光波导表面,研制出一种高灵敏硫化氢气体传感器。 传感膜与硫化氢(H₂S)气体作用时,薄膜颜色从紫色变为无色,从而降低薄膜对倏逝波的吸收,使传感器的输出光强度（信号）增强。 采用流动注射法对H₂S气体进行检测。 实验结果表明,H₂S传感器对浓度在0.14~56 mg/m3范围的H₂S气体具有良好的线性响应（r=0.99667）,检出限为0.11 mg/m³(S/N=3),相对标准偏差为4.0%,响应时间（t90）＜2 s。 该传感器具有灵敏度高、响应快、可逆性和重复性好等特点。     

基于氢键作用的杯芳烃超分子识别乙醇的传感机理及分析应用

采用4种杯芳烃衍生物为吸附涂膜材料,考察了涂膜石英晶体微天平(QCM)传感器对环境大气中微量乙醇气体的识别性能,发现C-乙基杯[4]连苯三酚芳烃(3)是识别乙醇气体最有效的活性涂膜材料.制备了C-乙基杯[4]连苯三酚芳烃.2CH3CH2OH(5)单晶体并进行X射线衍射结构解析,发现其识别机制是基于超分子主体3与客体乙醇分子之间形成的C—H…π,O—H…π及O—H…O氢键作用.当涂膜质量为24.70μg时,涂膜QCM传感器对乙醇的响应最灵敏,达到10.53 Hz/(mg.L-1).分析了乙醇气体的吸附和解吸附动力学过程,得到传感器对乙醇气体吸附和解吸附的初速度分别为-0.04600 Hz/s和0.03896 Hz/s.该方法响应快,具有选择性、可逆性、重现性和稳定性好的优点,对乙醇样品测定的回收率为94.8%～105.2%,与气相色谱法的测定结果一致,表明该方法可用于生活环境中乙醇气体的检测.     

新型二氧化硫气体电化学传感器的研究

SO2 是大气的主要污染物 ,并能与环境中的 NOx,O3等协同作用 ,产生更严重的污染 .因此 ,SO2的测定在环境保护、职业健康、工业排放控制等方面起着非常重要的作用 .SO2 的测定方法包括气相色谱法 [1]、离子色谱法 [2 ]、电导测定 [3]和电解电导率 [4]、光纤传感器 [5 ,6 ]等 ,但这些方法所需仪器昂贵、操作繁琐、灵敏度较低、难以实时连续测定 .一些研究者致力于 SO2 电化学传感器的开发 [7～ 8] ,但存在着灵敏度低、需在高温下使用、稳定性差等缺点 .我们成功地研制了一种微型 SO2 气体电化学传感器 ,该传感器稳定性好、灵敏度高、价…