H2S气体在不同催化剂表面的电化学氧化行为

1　引　　言H2 S气体能对人体产生严重伤害。在环保、生产等领域对其进行检测 ,具有重要意义。本实验通过循环伏安、线性扫描、XPS等手段 ,研究H2 S、Pd、Pt、Rh和Au电极上的电化学氧化行为。实验表明 :Au在特定条件对H2 S具有良好的电催化活性 ,以Au为工作电极并选择合适工作条件 ,可以解决催化剂中毒问题 ,传感器灵敏度可达 0 .76 μA·m3 /mg。2　实验部分2 .1　仪器设备　三电极电化学池 ;CHI6 0 2电化学系统 (美国CHI公司 ) ;恒电位仪 (长春市环保分析仪器厂 )。2 .2　样品准备与测试条件　工作电极是将Pd、Pt、Rh和Au用树…     

脱除低浓度硫化氢的改性活性炭纤维的再生研究

用改性的活性炭纤维（ACF）脱除低浓度的H2S是一种十分有效的方法,但脱硫后的改性ACF容易达到脱硫饱和而失活。用溶剂再生和气体热再生的方法可以对失活后的改性ACF进行再生。在固定床反应器上考察了再生后ACF的脱硫性能。实验结果表明,与溶剂再生相比,气体热再生是更有效的再生方法。不同再生方法的效果的不同,是由ACF脱除H2S的反应机理的不同和再生机理的不同造成的。     

汽油中气体组分含量的快速分析

采用美国HP6890炼厂气分析多维填充柱色谱仪,建立了汽油中气体组分含量快速分析方法。采用汽油直接进样,校正归一化法定量,测定汽油中CO2、H2S和各气体烃组分的含量,完成一个样品的分析仅需22min。实验表明,该方法有很好的精密度,各气体组分浓度值的相对标准偏差均小于4．5％。     

氮气中1 μmol·mol~(-1)硫化氢气体标准物质的研制

介绍了瓶装氮气中1μmol·mol-1硫化氢气体标准物质的研制过程,对称量法制备过程、均匀性、稳定性引入的不确定度进行了评定。该气体标准物质的相对扩展不确定度为Uc=2.0%,k=2,使用有效期为一年,取得了国家一级标准物质证书。     

氧化镍-铁酸锌复合薄膜/锡掺杂玻璃光波导传感元件的制备及其对硫化氢气体的气敏性

用溶胶-凝胶法制成了NiO掺杂的ZnFe2O4溶胶,并用浸渍提拉法将其固定在锡掺杂玻璃光波导表面,研制了NiO-ZnFe2O4复合薄膜/锡掺杂玻璃光波导气敏元件,并对无机有毒气体进行了检测。 实验结果表明,在室温下,该传感元件对H2S气体具有一定的选择性响应,而对相同浓度的其它无机气体的响应相对较小,能够检测到1.0×10-9（体积比）的H2S气体,其响应和恢复时间分别是6和8 s。 该元件具有灵敏度高、响应-恢复快、可逆性和重复性好、容易制备,在室温下便于操作等特点。     

硫化氢对钴改性活性焦脱除煤气中汞的影响机理

采用等体积浸渍煅烧法制备钴改性活性焦(Co-AC),并采用BET、XRD等分析手段进行表征。 利用固定床吸附实验台,研究了模拟煤气(N₂、H₂、CO、H₂S)气氛下汞的吸附特性,重点关注H₂S对汞吸附的影响。 结果表明,5%负载量的Co-AC在120 ℃和H₂S作用下具有优异的脱汞能力,2 h内平均脱汞效率高达97.8%。 此外基于密度泛函理论,首先计算了H₂S、HS及S在Co₃O₄(110)表面的吸附能及键长,通过比较H—S键键长的变化得出H₂S会逐步解离成HS与S,然后将优化后的S-Co₃O₄(110)作为Hg的吸附基底,研究其吸附特性,得出Hg与S反应生成稳定的HgS,吸附能为-3.503 eV,证明了汞的吸附遵循Eley-Rideal机制。 Co-AC吸附剂在高温下脱汞性能受到极大的抑制,因为随吸附温度升高,表面活性硫的减少及硫和汞的反应平衡常数下降显著,导致汞的脱除能力下降。 本文采用了实验加模拟的手段,探明了H₂S存在时Hg⁰在钴基吸附剂表面的反应机理,为协同脱除煤气中的H₂S和Hg⁰提供了理论指导。     

H2S对丙炔醇在Fe/H2SO4体系中缓蚀作用的影响

铁腐蚀;硫化氢;H2S对丙炔醇在Fe/H2SO4体系中缓蚀作用的影响     

2-(苯并噻唑-2-基)-5-(N,N-二乙基氨基)苯酚衍生物的合成及其对H2S的识别

以4-N,N-二乙基氨基水杨醛为原料,制备了2-(苯并噻唑-2-基)-5-(N,N-二乙基氨基)苯酚衍生物(探针L),并对其结构进行了表征。在DMSO/PBS(体积比3∶7,pH=7.4)溶液中,探针L具有高选择性并可荧光"关-开"识别H_2S,在365nm紫外灯照射下,由无荧光变成蓝色荧光。实验表明,探针L识别H_2S的检测限为2.05×10~(-6)mol/L,pH适用范围为6～9,可用于检测实际水样中的H_2S。     

溅射气体中氩气含量对Y1Ba2Cu3O7-δ薄膜结构和Tc的影响

采用倒筒直流磁控溅射系统在不同溅射气体组分下(氩氧比不同)原位沉积Y1Ba2Cu2O7-δ(YBCO)薄膜.样品的XRD分析发现在Ar含量过高和过低的溅射气氛下沉积的薄膜存在极少量的BaCuO2第二相, 同时显示薄膜的c轴长度, (006), (007)对(005)峰强度比随着溅射气体中Ar含量的变化而发生改变.通过薄膜超导零电阻温度检测发现, YBCO薄膜的超导零电阻温度Tc随之发生改变.这说明在磁控溅射沉积YBCO薄膜过程中, 溅射气体中Ar气含量影响薄膜各元素的化学计量比, Ar含量过高和过低导致沉积YBCO薄膜晶体结构发生畸变, 恶化超导电性.     

Optical fibre sensor for hydrogen sulphide monitoring in mouth air

A reversible optical fibre chemical sensor for hydrogen sulphide monitoring in mouth air based on reflectance measurements has been developed. The active sensing phase has been prepared by immobilising the colorimetric reagent 2,6-dichlorophenolindophenol (DCPI) in a silica gel support. The principle of the determination is based on the increase of reflectance of such solid sensing phase when hydrogen sulphide reduces the colorimetric reagent with the subsequent decolouration process. The addition of 1.26 μg of Cu(II) per gram of solid support improved the response time and reversibility of the sensing phase.The detection limit is 10 ppb (v/v) of hydrogen sulphide. The linear range using the Kubelka-Munk function extends at least up to 1000 ppb (v/v). The sensor exhibits a response time of less than 2 min for hydrogen sulphide concentrations in the linear range and the signal is reversible.The optical sensor has been successfully tested for human malodour monitoring and the results validated by comparison with those obtained for the same individuals using a commercially available electrochemical instrument.     

Nondestructive determination of crystallinity by diffuse reflectance FT-IR in composites made from polyphenylene sulphide and carbon fibres

Diffuse reflection Fourier transform infrared spectroscopy can be used for nondestructive determination of the degree of crystallinity at the surface of composite materials made from polyphenylene sulphide reinforced with carbon fibres. In particular, the ratio of the heights of the peaks at 1075 and 1093 cm^–1 can be used as a quantitative indicator of the crystallinity. This has been confirmed by annealing highly amorphous prepreg to give samples of varying degrees of crystallinity, in which case a good linear relationship is observed between the peak ratio and the enthalpy of crystallization as determined by differential scanning calorimetry.     

Improved method of sampling and determination of traces of hydrogen sulphide

A sensitive spectrophotometric method for the determination of traces of hydrogen sulphide in environmental samples, after fixation as zinc sulphide, is reported. The method is based on the reaction between iodate and sulphide in the presence of excess of chloride ions. The resulting iodine chloride complex is ion-paired with Pyronine G and the product is extracted into benzene. The colour system obeys Beer's law over the range of 0.05–0.6 g of hydrogen sulphide. The coefficient of variation is 6.3% for 10 determinations of 0.3 g of hydrogen sulphide. The suitability of the method for monitoring hydrogen sulphide in atmospheric air in the vicinity of possible sources such as a sewage treatment plant and in wastewater has been evaluated.     

Determination of hydrogen in stainless steels by spark-source mass spectrometry

A spark-source mass spectrometric (SSMS) method capable of determining traces of hydrogen in micro-volumes of metals was developed by using a pointed metal probe technique. The hydrogen background was decreased to μg g^?1 levels by the combination of a method in which the sample in the ion source is baked under vacuum at 323–343 K for more than 25 ks and a liquid nitrogen or liquid helium cryogenic pump method. This method was applied to the analysis of austenitic stainless steels at μg g^?1 hydrogen levels, and the relative standard deviation was within 20% for samples with hydrogen concentrations ranging from 2 to 4 μg g^?1. The relative sensitivity coefficent was 2.3 (Fe=1).     

Optical fiber evanescent wave absorption spectrometry of nanocrystalline tin oxide thin films for selective hydrogen sensing in high temperature gas samples

SnO₂ nanocrystalline material was prepared with a sol-gel process and thin films of the nanocrystalline SnO₂ were coated on the surface of bent optical fiber cores for gas sensing. The UV/vis absorption spectrometry of the porous SnO₂ coating on the surface of the bent optical fiber core exposed to reducing gases was investigated with a fiber optical spectrometric method. The SnO₂ film causes optical absorption signal in UV region with peak absorption wavelength at around 320 nm when contacting H₂-N₂ samples at high temperatures. This SnO₂ thin film does not respond to other reducing gases, such as CO, CH₄ and other hydrocarbons, at high temperatures within the tested temperature range from 300 °C to 800 °C. The response of the sensing probe is fast (within seconds). Replenishing of the oxygen in tin oxide was demonstrated by switching the gas flow from H₂-N₂ mixture to pure nitrogen and compressed air. It takes about 20 min for the absorption signal to decrease to the baseline after the gas sample was switched to pure nitrogen, while the absorption signal decreased quickly (in 5 min) to the baseline after switching to compressed air. The adhesion of tin oxide thin films is found to be improved by pre-coating a thin layer of silica gel on the optical fiber. Adhesion increases due to increase interaction of optical fiber surface and the coated silica gel and tin oxide film. Optical absorption spectra of SnO₂ coating doped with 5 wt% MoO₃ were observed to change and red-shifted from 320 nm to 600 nm. SnO₂ thin film promoted with 1 wt% Pt was found to be sensitive to CH₄ containing gas.     

Multiphoton dissociation/ionisation of dimethyl sulphide (CH3SCH3) at 355 and 532 nm

Multiphoton dissociation/ionization has been studied for CH₃SCH₃ at 355 and 532 nm using a time-of-flight mass spectrometer. The major ion signals observed at 355 nm are C⁺, CH₃ ⁺, HCS⁺, CH₂S⁺, CH₃S⁺ and CH₃SCH₃ ⁺. Power dependence studies at 355 nm show a (2+1) REMPI process for the formation of parent ion. Peaks atm/e = 46, 47 and 61 show two-photon laser power dependence whereasm/e = 15 and 45 peaks show four-photon dependence. However, in 532 nm photo-ionisation, no parent ion signal is observed. A peak atm/e = 35 corresponding to SH₃ ⁺ has been observed. SH₃ ⁺ has been suggested to originate from CH₃SCH₂ ⁺ via a cyclic transition state. Photoionisation results of CH₃SCH₃ have been compared with those of CH₃SSCH₃, at these two wavelengths.     

锂盐-锍镍试金-等离子质谱法测定黑色页岩中铂族元素

建立锍镍试金-等离子质谱法测定黑色页岩中铂族元素(PGEs)的方法。在不减少称样量的前提下,结合黑色页岩成分特点,调整试金配料,利用硝酸钾的氧化性,解决形成锍扣难的问题;利用四硼酸锂的助融性,使盐酸溶解锍扣后黑色沉淀量大幅度降低,用等离子质谱法测定黑色页岩中铂族元素。PGEs的线性相关系数均不小于0.9995。Pt,Pd,Rh,Ir,Ru的检出限分别为0.30,0.36,0.032,0.028,0.041 ng/g。用该方法测定实际样品,测定值与参考值一致,测定结果的相对标准偏差为1.2%~10.6%(n=10)。该方法满足地质矿产实验室测试质量管理规范(DZ/T 0130-2006)的要求,可用于黑色页岩中铂族元素的测定。     

Determination of hydrogen peroxide by photoinduced fluorogenic reactions

4-Hydroxyproline, 8-hydroxyquinoline, 4-hydroxyquinoline-2-carboxylic acid and 4-hydroxyphenylacetic acid (HPA) react with H₂O₂ when irradiated with UV light to yield fluorescent products. Sub-micromolar detection limits of H₂O₂ are possible with HPA. The fluorescent product is the same as that formed in the peroxidase enzyme-mediated H₂O₂ oxidation of HPA. Several compounds that participate in the photomediated reaction do not react in the enzyme-mediated system. A mechanism for the photomediated reaction involving an aryloxy radical derived from the substrate is suggested. Although the limits of detection for H₂O₂ do not equal the best achievable with the enzyme-mediated systems, the simplicity of a single-step reaction and an ability to “photodevelop” the product offer a range of novel analytical possibilities.     

Thermal yellowing sensitised by pre-photo-oxidation of non-deacidified paper

Characterization of oxidation products responsible for yellowing of paper through absorption and through emission is presented using independently UV-visible absorption spectrophotometry and microspectrofluorimetry to survey the thermal oxidation at 100 °C and the photo-oxidation at λ ≥ 340 nm and at 60 °C of the three types of paper containing low amount of ligneous residues (SA papers) or not (WH and C papers). It was shown that due to secondary oxidation yellowing of product is favoured in the dark. It was shown that pre-photo-oxidation largely increased the yellowing in the dark. The effect of pre-photo-oxidation on yellowing through absorption and on yellowing through emission was shown to be different.     

反射光谱法直接测定沉淀物研究

报道一种新的分析方法－反射光谱法直接测定沉物。探讨了该方法的基本原理，影响因素及测定条件。该方法直接测定沉物快速，简便。应用于污水及土壤样品中微量汞（Ⅱ）的测定，结果满意。