基于低温等离子体辅助催化发光的乙烯传感器

将等离子体的高活化性能与催化发光的传感特性相结合,以成本低、合成简单的碱土金属纳米MgO为传感材料,构建了基于低温等离子体辅助的催化发光传感器,用于乙烯的快速检测.由于等离子体具有高活化性能,本方法的检测温度远低于传统的催化发光检测法的常用温度(300~500℃),无需加热装置,在室温下实现了对乙烯快速、灵敏的检测.室温(25℃)下,对乙烯的检出限为37 ng/mL (30 ppm),线性范围为112~4997 ng/mL (90~3998 ppm, R=0.97669),传感器具有良好的选择性和重现性.此传感器制备简单、稳定性高、低能耗、成本低,与传统的气体检测方法相比具有良好的实用性和普适性,为开发性能优异的新型催化发光传感器提供了策略.     

纳米In_2O_3催化发光传感器快速检测三氯乙烯

本文以纳米In_2O_3为传感元件,设计构建了快速检测三氯乙烯的催化发光传感器。该传感器对三氯乙烯具有灵敏度高、特异性好及响应快速等优点。在检测波长为440nm,工作温度为250℃条件下,催化发光信号强度与三氯乙烯浓度呈良好的线性关系,其线性范围为20~1 200mg/m~3(r=0.9984),检出限(S/N=3)为8.0mg/m~3。苯、甲苯、邻二甲苯、对二甲苯、间二甲苯、氨水、甲醇、乙醇、甲醛、乙醛、四氯化碳、甲酸、乙酸、乙酸乙酯、正己烷及环己烷经过此传感器时,只有乙醇产生弱的发光信号,其它物质不产生响应信号。在72h内24次测定100mg/m~3的三氯乙烯,所得相对标准偏差小于5.0%,表明传感器稳定性好,使用寿命长。将此传感器用于三氯乙烯的分析,加标回收率为93.2%~103%。     

基于CeO2-Co3O4纳米纤维的催化发光式甲醛传感器研究

采用双喷嘴静电纺丝法制备了CeO2-Co3 O4纳米纤维,将制备的CeO2-Co3 O4纳米纤维均匀涂覆于 ω型加热线圈表面形成催化发光薄膜,设计了一种新型催化发光甲醛传感器.采用X射线衍射仪、 扫描电子显微镜、 全自动程序化学吸附仪和X-射线光电子能谱仪,表征了Co3 O4-CeO2纳米纤维的相组成和微观形貌,讨论了甲醛在CeO2-Co3 O4催化剂表面的电化学特性和催化发光机理.在优化条件下,即波长500 nm、 温度550℃ 、 载气流速0.2 L/min,甲醛传感器件(Ce30)催化发光强度与甲醛浓度在1.2~50μg/m3范围内有良好的线性关系,灵敏度为40.04 a.u./(μg/m3),检出限为1.2μg/m3,动态响应和恢复时间分别为2.4和3.5 s.此传感器可用于汽车尾气中甲醛浓度检测,相对误差范围为0.4%~1.1%,相对标准偏差RSD<3%(n=6).     

基于纳米Co3O4低温催化发光的乙醚传感器

基于纳米Co3O4材料上乙醚的催化发光(CTL)现象,建立了直接测定空气中乙醚浓度的方法.研究发现,在较低温度下,乙醚在球链状的纳米Co3O4表面具有很高的发光强度和较好的选择性,以此为敏感材料就可以建立一种高效稳定的乙醚气体传感器.其最佳操作条件为:测定温度176℃,分析波长440 nm,载气流速180 mL/min.乙醚气体在4.0～1500 ppm(φ)的浓度范围内呈良好的线性关系(R=0.9993),响应时间为2 s,检出限为φ=1.67 ppm(3σ),回收率为97.3%～103.0%.考察了11种相同浓度的常见挥发性有机物的干扰情况,发现除丙酮、乙醇、四氯化碳和乙酸乙酯有轻微干扰(小于0.8%),其余7种物质均未产生明显的CTL信号.连续140 h通过150 ppm(φ)的乙醚气体,发光强度无明显降低,表明该传感器是一种长寿命的、性能稳定的传感器.     

纳米颗粒的超临界干燥法制备及用于醋酸乙烯蒸气的催化发光检测

利用乙醇超临界流体干燥技术 (SCFD)(280 ℃× 7.0 MPa×30 min)制备了纳米MgO及Y2O3颗粒,发现其对一些有害气体的催化发光强度远高于普通干燥技术制备的纳米MgO及Y2O3.设计了一种以SCFD技术合成的纳米MgO为敏感材料,催化发光检测醋酸乙烯蒸气的传感器.此传感器具有很高的灵敏度及优异的选择性,在温度279 ℃、波长425 nm、空气流速为160 mL/min的最佳条件下,催化发光强度与醋酸乙烯蒸气浓度在1.8～1800 mg/m3内呈良好的线性关系,检出限为0.7 mg/m3.当浓度相同的丙酮、乙醛、乙酸乙酯、乙酸、甲醛、氨水、乙醇、苯和甲醇蒸气通过此传感器时,除乙醇引起3.56%的干扰外,其它气体基本不干扰醋酸乙烯的测定.应用本方法可快速测定车间空气中的醋酸乙烯.     

复合ZrO2/MgO催化发光丙烯醛气体传感器

设计了基于在纳米ZrO2中掺杂Mg0的催化发光传感器,以快速检测丙烯醛气体.与纯ZrO2相比,MgO的掺杂量为5%时,丙烯醛的催化发光强度增大了1.8倍,干扰气体乙醛的催化发光强度降为原来的约1/7.传感器在波长425 nm,温度279 ℃,流速200 mL/min条件下,对丙烯醛具有高灵敏度和选择性,发光强度与丙烯醛...     

基于纳米ZnO-ZrO2催化发光丙酮传感器的研究

研究了丙酮在纳米ZnO-ZrO2(质量比为4:1)表面催化发光行为,发现基于这种纳米催化剂的气体传感器对丙酮的检测具有高灵敏度和较强的选择性。在波长460 nm,温度219℃,载气流速25 mL/min时进行定量分析,催化发光强度与丙酮浓度在一定范围内呈良好的线性关系,线性范围为0.1～4000 mL/m3(r=0.9996,n=6);检出限为1.6 mL/m3(S/N=3)。传感器工作时间可达106h以上,可用于丙酮的实时在线检测。     

催化发光快速检测啤酒中的苯乙醛

研究了苯乙醛在纳米氧化锡(SnO_2)表面的催化发光现象,设计了一种快速检测苯乙醛的催化发光传感器。在汽化温度为193℃、反应温度为276℃、检测波长为425 nm、流速250 mL/min条件下,催化发光强度与苯乙醛质量分数在0.10～12 mg/L范围内呈良好的线性关系(r=0.9976),检出限为0.030 mg/L。质量分数均为0.60 mg/L的苯乙醇、苯、甲苯、邻二甲苯、间二甲苯、对二甲苯、正己烷、三氯甲烷、四氯甲烷、四氢呋喃、乙酸、氨气和环氧苯乙烷通过传感器时,除苯乙醇产生弱响应信号外,其它物质均不产生响应信号。将此传感器应用于啤酒样品中苯乙醛含量的测定,加标回收率为108.2%～118.5%,RSD为5.9%～12%。     

基于四氧化三钴材料催化发光的丙醛气体传感器研究

研究发现, 在一定条件下丙醛气体在四氧化三钴材料表面上具有催化发光特性,基于此建立了一种检测空气中痕量丙醛气体的催化发光传感器.在对合成的3种形貌四氧化三钴的催化发光性质进行比较的基础之上,对分析方法条件进行了优化,其结果表明:在以微球状四氧化三钴作为传感材料,检测波长490 nm, 反应温度232 ℃,载气流速400 mL/min的最优条件下,可测定的丙醛气体浓度的线性范围为0.3～171 mg/L(r=0.9977, n=13),检出限为0.1 mg/L(S/N=3),测定4.8 mg/L丙醛的相对标准偏差为1.8%(n=5).此外,考察了相同浓度的常见挥发性有机物的干扰情况,其结果表明该传感器具有很好的选择性.连续80 h通过4.8 mg/L丙醛,发光强度无明显降低,相对标准偏差小于5%,表明此传感器使用寿命长.并将该传感器成功用于人工合成样品的分析,回收率在91%～103%之间,测定浓度值与实际组成基本相符.     

季铵盐化纳米金刚石-肌红蛋白修饰电极的电化学行为

通过一系列的化学反应对纳米金刚石(ND)表面进行修饰,成功制备了季铵盐化纳米金刚石:ND-CO-NH-CH2-CH2-N(CH3)3+·I-(QAS-ND),通过FT-IR、元素分析、电化学等手段对目标产物QAS-ND进行了表征。将肌红蛋白(Mb)与QAS-ND混合液滴加在玻碳(GC)电极表面,制备QAS-ND/Mb/GC修饰电极。在0.1 mol/L磷酸盐缓冲溶液(pH 7.0)中,固定在膜内的Mb表现出良好的直接电化学性质,并显示了很好的稳定性。同时,探讨了此修饰电极表面固定的Mb对H2O2的催化还原,结果表明,此修饰电极可作为H2O2生物传感器,实现对H2O2的快速、准确检测,检出限为3.5μmol/L(S/N=3)。     

Determination of Sulfide in Spring and Wastewater by a New Kinetic Spectrophotometric Method

A simple, rapid, and sensitive method has been developed for the determination of trace amounts of sulfide based on its reaction with thionine. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of the dyestuff at 600 nm by the fixed time method. After optimization of the measuring conditions the calibration curves were found linear up to 38.0 ppm (four regions), and the theoretical limit of detection was 0.076 ppm and the relative standard deviation for determination of 1.0 ppm sulfide (n = 10) was found to be 2.7%. The proposed method was applied successfully to the determination of sulfide in spring water and wastewater samples.     

A vinyl acetate sensor based on cataluminescence on MgO nanoparticles

A novel cataluminescence (CTL) sensor using nanosized MgO as the sensing material for determination of the trace of vinyl acetate in air was proposed in the present study. Eight catalysts were examined and the results showed that the CTL intensity on MgO nanoparticles was the strongest. Under the optimized conditions, the linear range of the CTL intensity versus the concentration of vinyl acetate vapor was 2-2000 ppm with a detection limit of 1.0 ppm (3σ) and a relative standard deviation (R.S.D.) of 1.18% for five times determination of 1000 ppm vinyl acetate. There were no CTL emissions when foreign substances, including ammonia, benzene, acetic acid, formaldehyde and ethyl acetate, passed through the sensor. CTL emissions were detected for methanol, ethanol and acetaldehyde at levels around 5.5%, 10.1% and 13.4% compared with the responsed vinyl acetate. The sensor had a long lifetime more than 100 h.     

Determination of Hydrogen Sulfide by Wavelength-modulated Diode Laser Absorption Spectroscopy

Rapid, accurate, and sensitive determination of hydrogen sulfide was provided by tunable distributed feedback diode laser absorption spectroscopy. The laser wavelength scanning range covered the strongest absorption band of hydrogen sulfide. The absorption line at 1578?nm was used for analytical measurements. A homemade digital lock-in amplifier was used to demodulate the first and the second harmonic signals. Normalization of the second harmonic by the first harmonic signal provided calibration-free measurements so that interferences from light path, circuitry, and source intensity were minimized. A mass flow controller was used to introduce 0–100?ppm hydrogen sulfide for validating the analytical performance. The results demonstrated the linearity of the normalized harmonic signals with concentration with a correlation coefficient of 0.9995. The response time was approximately 3?s. The detection limit by Allan variance was 45 ppb with an integration time of 35?s. The sensitive hydrogen sulfide sensor is suitable for environmental monitoring with real-time detection.     

催化发光法同时测定空气中的甲醛、苯和二氧化硫

基于甲醛、苯和二氧化硫在纳米Ti3CeY2O11上的催化发光有交叉敏感现象,在3个波长处分别确定甲醛、苯和二氧化硫浓度与催化发光信号强度的响应关系,再依据发光信号强度的叠加性特征即可获取甲醛、苯和二氧化硫的准确浓度,据此建立了同时测定空气中甲醛、苯和二氧化硫的新方法.3个分析波长分别为420、535和680 nm,敏感材料表面温度为280℃,载气流速为130 mL/min.本方法对甲醛、苯和二氧化硫的检出限(3σ)分别为0.04、0.05和0.10 mg/m3,线性范围分别为0.08~75.60 mg/m3、0.10~101.40 mg/m3和0.30~115.00 mg/m3, 回收率分别为96.4%~103.7%、97.8%~102.5%和97.2%~103.3%.常见共存物,如乙醛、甲苯、硫化氢、氨、甲醇、乙醇和二氧化碳等不干扰测定.连续200 h通浓度均为50 mg/m3的甲醛、苯和二氧化硫混合气体,发光强度的相对偏差≤2%,表明此纳米级复合氧化物对甲醛、苯和二氧化硫的敏感性的寿命长.本方法充分利用了交叉敏感现象,可以实现空气中甲醛、苯和二氧化硫的在线分析.     

A new cataluminescence gas sensor based on SiO2 nanotubes fabricated using carbon nanotube templates

In the present work, two morphologies of SiO₂ nanomaterials (SiO₂ nanotubes and nanoparticles) have been successfully synthesized in supercritical fluids (SCFs). The cataluminescence (CTL) features of the two SiO₂ nanomaterials to some common harmful gases were compared, and the results showed that SiO₂ nanotubes had better CTL sensing characteristic to some common harmful gases. The SiO₂ nanotubes not only had uniform size and shape with a high specific surface area, but also exhibited superior sensitivity and selectivity to ethyl acetate vapor. Using the SiO₂ nanotubes as sensing material, a CTL sensor for ethyl acetate vapor was developed. The proposed sensor showed high sensitivity and specificity to ethyl acetate at optimal temperature of 293 °C, a wavelength of 425 nm and a flow rate of 345 mL/min. With a detection limit of 0.85 ppm, the linear range of CTL intensity versus concentrations of ethyl acetate vapor was 2.0-2000 ppm. None or only very low levels of interference were observed while the foreign substances such as acetone, acetaldehyde, acetic acid, formaldehyde, ammonia, ethanol, benzene and methanol were passing through the sensor. This method allows rapid determination of gaseous ethyl acetate at workshop.     

Gas chromatographic analysis of traces of hydrogen sulfide in hydrogen

Summary A simple gas chromatographic method has been developed for analysis of hydrogen sulfide in hydrogen at the 0.5 to 100 ppm level. After enriching the traces of hydrogen sulfide by absorption in a gas loop packed with the chosen column support at 77 K it was determined by using a Chromosorb G column with silicone 550 and phthalic anhydride as liquid phases, hydrogen as carrier gas and a thermal conductivity detector. The detection limit was found to be about 0.5 ppm of hydrogen sulfide.     

A turn-on fluorescent probe for selective and sensitive detection of hydrogen sulfide

An imidazolethione based turn-on fluorescent probe was synthesized for the detection of hydrogen sulfide, a biologically relevant molecule and an important air pollutant. The probe rapidly and selectively reacted with hydrogen sulfide to produce a strongly fluorescent product, resulting in the fluorescence enhancement of the system. The detection limit was determined to be 30 nM at the probe concentration of 1.0 μM. An indicating paper for visual detection of hydrogen sulfide gas has been fabricated by immobilizing the probe on a piece of appropriate paper substrate, and the detection limit of the visual method reached as low as 0.7 ppm. Moreover, the fluorescence turn-on/off of the system showed good reversibility when exposed alternately to hydrogen sulfide and mercuric ion, which was utilized to make an INHIBIT logic circuit for the presence of the two species.     

CuS/RGO hybrid by one-pot hydrothermal method for efficient electrochemical sensing of hydrogen peroxide

In this study,a non-enzymatic hydrogen peroxide sensor was successfully fabricated on the basis of copper sulfide nanoparticles/reduced graphene oxide(CuS/RGO) electrocatalyst.Using thiourea as reducing agent and sulfur donor,CuS/RGO hybrid was synthesized through a facile one-pot hydrothermal method,where the reduction of GO and deposition of CuS nanoparticles on RGO occur simultaneously.The results confirmed that the CuS/RGO hybrid helps to prevent the aggregation of CuS nanoparticles.Electrochemical investigation showed that the as-prepared hydrogen peroxide sensor exhibited a low detection limit of 0.18μmol/L(S/N = 3),a good reproducibility(relative standard deviation(RSD) of4.21%),a wide linear range(from 3 to 1215 μmol/L) with a sensitivity of 216.9 μA L/mmol/cm~2 under the optimal conditions.Moreover,the as-prepared sensor also showed excellent selectivity and stability for hydrogen peroxide detection.The excellent performance of CuS/RGO hybrid,especially the lower detection limit than certain enzymes and noble metal nanomaterials ever reported,makes it a promising candidate for non-enzymatic H_2O_2 sensors.     

Highly sensitive and selective room temperature NH3 gas microsensor using an ionic conductor (CuBr) film

A new ammonia gas microsensor was developed, based on the large resistance change of an ionic conductor (CuBr) film when exposed to low NH₃ concentrations. The detection is based on specific interactions between ammonia molecules contained in the gas atmosphere and mobile copper ions in the copper(I) bromide layer. The sensor is operating at ambient temperature and allows highly sensitive and specific ammonia detection. The sensor works at ammonia concentrations between 1 and 500 ppm. There are no significant cross-effects to acetylene and carbon monoxide and only a weak cross-sensitivity to hydrogen sulfide gas (200 ppm). The selectivity was experimentally compared with commercial tin dioxide sensors (TGS 826). The sensor fabrication is a simple process, allowing low cost device production.     

基于稀土材料催化化学发光法检测乙腈气体传感器的研究

基于稀土粉体材料Y2O3催化乙腈气体在其表面发生氧化反应而产生化学发光现象,研制了一种基于化学发光原理检测乙腈的气体传感器。研究结果表明,该传感器具有较高灵敏度和较强的选择性。在温度175℃,波长490 nm条件下,其催化化学发光强度与乙腈浓度在一定范围内呈良好的线性关系,线性范围为2.9~290.0 mg/m3(r=0.9955);检出限为1 mg/m3。该传感器操作简便、性能稳定,实现了对乙腈气体的实时在线检测。