煤矿瓦斯变压吸附提纯甲烷的研究进展

因煤层赋存条件和抽采技术水平限制,导致煤矿抽采瓦斯中甲烷(CH₄)浓度偏低,而直接排空处理将造成清洁能源浪费和温室效应加剧,因此研究煤矿瓦斯中CH₄提纯利用途径将对煤炭行业节能减排具有重要意义.相比于其它气体分离提纯技术,变压吸附分离技术具有操作简单、能耗低及工业化成熟度高等诸多优势.本文将以变压吸附分离技术提纯CH₄为核心,重点论述了近些年吸附剂类型、吸附分离机制和分子动力学模拟等方面的研究进展,然后列举变压吸附提纯CH₄工艺优化及工业大规模应用实例,最后结合基础研究和工程应用总结展望了变压吸附技术在CH₄提纯领域的发展前景,并指出低浓度瓦斯(<10%CH₄)提纯及真空变压吸附技术是为进一步提升煤矿瓦斯利用率而亟需攻坚克难的主要研究方向.     

吸附分离技术在现代工业中的应用

概括介绍了吸附分离技术的发展,详细评述了吸附分离技术的最新进展和在现代工业中的应用,并预测了吸附分离技术未来的发展方向。     

扩张床吸附层析技术介质研发与应用进展

扩张床吸附层析是集固液分离、浓缩和初步纯化于一个操作单元之中的集成化生物分离技术,应用范围较广泛。本文对扩张床吸附层析介质的研究现状及该技术在生物产品分离中的应用进行了综述,以期能为该技术的进一步发展和应用提供理论基础。     

沸石中阳离子对氮/氧吸附性能影响的研究进展

基于制氧吸附剂在变压吸附空分制氧工业应用的重要性，从沸石分子筛的氮／氧吸附性能方面，介绍了低硅沸石LSX、钙沸石、锂沸石、锂银沸石等的研究进展。讨论了沸石分子筛骨架结构和其中阳离子的种类、位置、数量与其吸附特性的关系，探讨其在变压吸附空分制氧中的应用前景。     

分子筛材料在小分子吸附分离中的应用

吸附分离技术与工艺在工业上具有重要意义. 常见的吸附剂包括沸石分子筛、 金属有机框架材料、 活性炭等材料. 分子筛具有比表面积大、 稳定性高、 生产成本低等优势, 可以满足吸附分离技术中高效、 节能和环保的需求, 是一种非常有应用前景的小分子混合物分离吸附剂. 本文综合评述了吸附分离领域中常用的吸附剂材料的特点和吸附分离机理与评价方法, 总结了分子筛在空气分离、 烃类分离、 二氧化碳吸附、 芳香硫化物脱除、 一氧化碳吸附、 氮氧化物吸附、 氢气储存吸附及氢同位素分离等领域的应用, 并对基于分子筛膜的小分子混合物分离现状进行了介绍. 此外, 本文还系统分析了分子筛对不同混合物的吸附分离性能与其拓扑结构、 骨架组成及改性方法之间的关系, 并对未来的研究前景进行了展望.     

捕集高湿烟气中CO2的变压吸附技术

变压吸附法在捕集烟气中的CO₂这一领域中显示出强大的优越性,但实际电厂烟气含有少量的水蒸气,这对利用常规吸附剂捕集CO₂造成很大挑战。为解决上述瓶颈问题,改进变压吸附工艺以及开发对湿度不敏感、高效的吸附剂成为最主要的途径。本文详细介绍了两种常用的变压吸附工艺,即多层变压吸附及微波辅助真空再生法分离高湿烟气的研究进展,综述了近年来研发的适于捕集高湿烟气的高效吸附剂,系统阐述了各种吸附剂的物理化学特性及其吸附CO₂、H₂O的机制,并在此基础上讨论了变压吸附技术捕集高湿烟气时存在的问题,提出了研究展望。相信随着人们对变压吸附工艺的改进以及对新型高效吸附剂的进一步研发,必将显著降低捕集高湿烟气中CO₂的成本,这将对燃煤电厂等高湿CO₂排放源的温室气体减排具有重要意义。     

柱芳烃纳客在吸附和分离中的应用

非多孔自适应晶体(nonporous adaptive crystals,英文简称为"NACs",中文简称为"纳客")是本课题组首次提出和定义的一种新颖的吸附和分离材料.基于柱芳烃的纳客具有易于制备,化学、水汽、热稳定性好,溶液加工性好,重复利用性高等优点,对科学研究产生了重要影响,并在化工行业具有潜在的应用价值.本文主要介绍基于柱芳烃的纳客在吸附和分离中的应用,讨论在吸附分离过程中所伴随的晶体结构由最初的非多孔晶体状态转变为新的包裹客体晶体状态以及单晶X射线衍射、粉末X射线衍射、气相色谱和核磁等实验方法用于研究晶体在吸附和分离过程中所产生的结构变化与吸附分离性能.这些机理的研究为基于柱芳烃的纳客在工业上的可能应用奠定了理论基础.     

八十年代大孔网状吸附剂在抗生素分离纯化中的应用新进展（上）

大孔网状聚合物吸附剂是离子交换技术领域中重要发展之一,它的应用是七十年代发展起来的一项新技术。采用大孔网状吸附剂分离、纯化抗生素是抗生素工业中值得注意的动向,本文综合评述了吸附机理、吸附剂的理化特性、影响吸附的因素等。着重介绍了八十年代以来国内外在β—内酰胺类、大环内酯类、林可霉素类、糖甙类、肽类、博莱霉素类、多烯类、蒽环类、醌类、含氮杂环类、核苷类、聚醚类以及其他新抗生素和免疫抑制剂等分离、浓缩、纯化、精制上的应用。     

电厂废气中饱和水蒸气对活性炭变压吸附捕集CO2的影响

由于热电厂废气中含有高湿饱和水蒸气,选用疏水材料活性炭为吸附剂,利用真空变压吸附技术研究了活性炭分离电厂废气中水蒸气和二氧化碳的可行性和优越性,研究了水对CO₂捕集的影响。实验分析表明,水在活性炭上的“S”型等温吸附曲线有利于真空条件下被解吸。同时,圆锥模型描述了水蒸气在吸附床内的浓度分布。结果表明,即使水蒸气可以被活性炭吸附,但它的存在不影响CO₂的捕集。每个循环操作可在相对较短的解吸时间和较高的解吸压力下完成。实验中单床三步变压吸附工艺可以使CO₂回收率高达80%,CO₂纯度达43%。     

低温变压分子筛动态分离CH_4/CO_2实验研究

在低温变压条件下测量了5A和13X沸石分子筛对CH_4/CO_2混合气体的分离能力。实验研究了CH_4/CO_2气体流量、吸附压力、填料高度和吸附温度对穿透曲线和分离能力的影响。研究结果表明,增大气体流量、增加吸附压力会降低分离效果,减小混合气体的分离系数;降低吸附温度、增加填料高度有利于CH_4/CO_2分离,提高混合气体的分离系数;在相同实验条件下,13X沸石分子筛对CH_4/CO_2混合气体吸附分离能力高于5A分子筛。     

Potentiometric stripping analysis (PSA) for monitoring of antimony in samples of vegetation from a mining area

A potentiometric stripping analysis (PSA) method has been developed and checked for the fast and reliable determination of antimony in vegetation samples of Cistus ladanifer from a mining area in Badajoz, Southwest Spain. The method, modified from previous PSA methods for Sb in environmental samples, is based on dry ashing of the homogenized leaves, dissolution in hydrochloric acid, and PSA analysis on a mercury film plated on to a glassy carbon disk electrode. The influence of experimental variables such as the deposition potential, the deposition time, the signal stability and the calibration parameters, has been investigated. The method has been compared with an independent technique (instrumental neutron activation analysis) by analysis of standards and reference materials and comparison of the results. As a result of automation of the PSA equipment, the proposed method enables unattended analysis of 20 digested samples in a total time of 2 h, thus providing a useful tool for Sb monitoring of a large number of samples.     

Electrochemical Immunoassay for Free Prostate Specific Antigen (f‐PSA) Using Magnetic Beads

Prostate specific antigen (PSA) is a prominent marker for the prostate carcinoma. It is found in human blood in free (f‐PSA) and complex forms. These two forms together are called total PSA (t‐PSA). Estimation of both forms is essential to predict malignancy. In this study we report a unique and effective technique of electrochemical detection of f‐PSA using magnetic beads on a three‐electrode screen‐printed sensor. A magnetic bead enzyme linked immunosorbent assay (ELISA) was performed in a cuvette. Following the immunoassay, magnetic beads were recovered by a magnetic concentrator and transferred on the working electrode of the 3‐electrode assembly. The amperometric response, a measure of the amount of residual enzyme activity on the beads and hence the concentration of analyte in solution, was determined by addition of enzyme substrate. The device has a detection limit of <0.1 ng mL^?1 f‐PSA and a linear range of 0 to 1 ng mL^?1 f‐PSA.     

Potentiometric stripping analysis (PSA) for monitoring of antimony in samples of vegetation from a mining area

A potentiometric stripping analysis (PSA) method has been developed and checked for the fast and reliable determination of antimony in vegetation samples of Cistus ladanifer from a mining area in Badajoz, Southwest Spain. The method, modified from previous PSA methods for Sb in environmental samples, is based on dry ashing of the homogenized leaves, dissolution in hydrochloric acid, and PSA analysis on a mercury film plated on to a glassy carbon disk electrode. The influence of experimental variables such as the deposition potential, the deposition time, the signal stability and the calibration parameters, has been investigated. The method has been compared with an independent technique (instrumental neutron activation analysis) by analysis of standards and reference materials and comparison of the results. As a result of automation of the PSA equipment, the proposed method enables unattended analysis of 20 digested samples in a total time of 2 h, thus providing a useful tool for Sb monitoring of a large number of samples. Received: 13 December 2000 / 14 February 2001 / Accepted: 26 February 2001     

Trash GGBFS-based geopolymer as a novel sunlight-responsive photocatalyst for dye discolouration

In this study, we report a waste material-ground granulated blast furnace slag (GGBFS) as a low cost geopolymer, hybridised with ZnO to form a novel and efficient photocatalyst capable of discolouring textile wastewater. GGBFS is a waste material in an iron industry. Methylene blue was used as the probe dye and natural sunlight was used for activation of the photocatalyst. It was observed that under the experimental conditions, ZnGP-40 exhibited twice the discoloration efficiency than conventionally used ZnO or TiO₂. This enhanced performance is majorly attributed to increased surface area of ZnO when strewn in the GGBFS matrix. The photocatalysts were characterized by SEM, TEM, PSA, TGA, BET and UV–Vis/NIR. The effect of photocatalyst loading, speed of agitation and solar insolation has also been studied. Since this study has been performed in direct sunlight, it exhibits a realizable application of solar energy in the treatment of wastewater.     

Tuning of Pressure Swing Adsorption Systems Based on Differential Pressure Profile

A method for tuning a Pressure Swing Adsorption (PSA) system aimed to achieve symmetrical operating conditions based on pressure differential in the adsorption vessels is developed in this study. Simulation of an oxygen Pressure-Vacuum Swing Adsorption (PVSA) process indicates that the pressure drop inside the adsorption vessel is closely related to the nitrogen concentration and gas velocity. The technique is applied to the tuning of an oxygen PVSA process. Adsorbent vessels of the PSA system are monitored and tuned by making corrective adjustments in each of the steps in a PSA cycle in response to imbalances in the differential pressure profiles in each of the adsorbent vessels. The method developed in this study provides a faster, easier, and more effective way to bring a PSA plant to its symmetrical, optimal state than those based on other parameters such as concentration, temperature, and pressure profile. This paper is dedicated to the memory of Professor Wolfgang Schirmer.     

Fabricating protein immunoassay arrays on nitrocellulose using dip-pen lithography techniques

Advancements in lithography methods for printing biomolecules on surfaces are proving to be potentially beneficial for disease screening and biological research. Dip-pen nanolithography (DPN) is a versatile micro and nanofabrication technique that has the ability to produce functional biomolecule arrays. The greatest advantage, with respect to the printing mechanism, is that DPN adheres to the sensitive mild conditions required for biomolecules such as proteins. We have developed an optimised, high-throughput printing technique for fabricating protein arrays using DPN. This study highlights the fabrication of a prostate specific antigen (PSA) immunoassay detectable by fluorescence. Spot sizes are typically no larger than 8 μm in diameter and limits of detection for PSA are comparable with a commercially available ELISA kit. Furthermore, atomic force microscopy (AFM) analysis of the array surface gives great insight into how the nitrocellulose substrate functions to retain protein integrity. This is the first report of protein arrays being printed on nitrocellulose using the DPN technique and the smallest feature size yet to be achieved on this type of surface. This method offers a significant advance in the ability to produce dense protein arrays on nitrocellulose which are suitable for disease screening using standard fluorescence detection.     

Hydrogen PSA process product purity control method and controller

It is well known in the industry that a primary means for controlling the pressure swing adsorption (PSA) process product gas purity is the adjustment of PSA feed time or adsorption time. If the product impurity is too high, the feed time is shortened and if the impurity level is below the target the feed time is increased. Conventionally, the plant operator monitors the product purity and manually adjusts the feed time. Several control methodologies such as classical feedback and feedforward systems were suggested to automate this task with limited success. A novel control methodology based on the measurement of impurity fronts within the adsorber bed was developed by the Praxair Adsorption R&D team. The response of the concentration measurements inside the adsorber vessel to the process upsets and changes in feed time is more rapid than in the product stream. Consequently, closed loop control performance can be made much more effective and the operating impurity set points for product gas can be more aggressive resulting in longer PSA feed times, higher bed utilization and thus higher hydrogen recovery. The control methodology will be discussed in greater detail along with the advantages it has to offer such as improved process performance, disturbance rejection capability and improved process robustness. The control methodology will be illustrated using the hydrogen PSA process as an example.     

In-situ quantitative analysis of a prostate-specific antigen (PSA) using a nanomechanical PZT cantilever

We report on a novel technique of resonant frequency shift measurement based on a nanomechanical cantilever with a PZT actuating layer for label-free detection of a prostate-specific antigen (PSA) in a liquid environment. The nanomechanical PZT thin film cantilever is composed of SiO(2)/Ta/Pt/PZT/Pt/SiO(2) on a SiN(x) supporting layer for simultaneous self-exciting and sensing; it was fabricated using a standard MEMS (micro electromechanical system) process. The specific binding characteristics of the PSA antigen to its antibody, which is immobilized with Calixcrown self-assembled monolayers (SAMs) on a gold surface deposited on a cantilever, are determined to a high sensitivity. For the bioassay in a liquid environment, a liquid test cell with a 20 microl volume reaction chamber has been fabricated, using a bonding technique between poly(dimethyl siloxane) (PDMS) bilayers. An observed trend of resonant frequency change with respect to time could be explained by the binding kinetics due to the Langmuir isotherm and diffusion and by the effects of a small volume reaction chamber. In the saturated regimes, the resonant frequency of the cantilever increased with increase of the PSA concentration in the reaction chamber, showing that the trend of the resonance frequency change was similar to that of the fluorescence results. The saturated resonance frequency shift of the cantilever was proportional to the PSA antigen concentration of analyte solution.     

Comparative analysis of prostate‐specific antigen by two‐dimensional gel electrophoresis and capillary electrophoresis

Serum levels of Prostate‐Specific Antigen (PSA) are not fully specific for prostate cancer (PCa) diagnosis and several efforts are focused on searching to improve PCa markers through the study of PSA subforms that could be cancer associated. We have previously reported by 2DE a decrease in the sialic acid content of PSA from PCa compared to benign prostatic hyperplasia patients based on the different proportion of the PSA spots. However, faster and more quantitative techniques, easier to automate than 2DE, are desirable. In this study, we examined the potential of CE for resolving PSA subforms in different samples and compared the results with those obtained by 2DE. We first fractionated by OFFGEL the subforms of PSA from seminal plasma according to their pI s and analyzed each separated fraction by 2DE and CE. We also analyzed PSA and high pI PSA, both from seminal plasma, and PSA from urine of a PCa patient. These samples with different PSA spots proportions by 2DE, due to different posttranslational modifications, also presented different CE profiles. This study shows that CE is a useful and complementary technique to 2DE for analyzing samples with different PSA subforms, which is of high clinical interest.