活性炭纤维吸附的研究：Ⅰ—不同工艺制备的活性炭纤维的性能比较

本文比较研究了五种不同工艺制备的活性炭纤维的产率，比表面积，孔结构，对有机溶剂蒸汽的吸附和脱附性能，对水溶液中亚甲基兰，苯酚和碘的吸附性能以及它们的热稳定性。实验结果表明，水蒸气活化的ＡＣＦ比化学活化的ＡＣＦ有更大的比表面积，但前者产品产率较低而后者很高；不论水蒸气活化还是化学活化的ＡＣＦ，它们对有机溶剂饱和蒸汽的吸附量都较高，脱附和再吸附的性能也都较好，对水溶液中的苯酚都有较好的吸附能力，但化学     

热重分析技术测定二苯并呋喃在活性炭上的吸附相平衡

以吸附动力学为基础,建立了热重分析技术测定难挥发性有机物吸附等温线的方法.通过热重分析实验测定了不同升温速率下二苯并呋喃从Norit RB1和Chemviton BPL活性炭上脱附速率曲线,及对应的脱附峰温度.运用所提出的方法,对二苯并呋喃在Norit RB1和ChemvironBPL活性炭上的Langmuir吸附等温线方程进行了估算.估算结果与静态吸附实验测定结果相比,误差不超过10%.     

乙酸丁酯废气在活性炭上的吸附和脱附行为研究

对4种商品化活性炭进行了SEM、N_2低温物理吸附等分析表征,结合吸附穿透曲线、饱和吸附量等筛选出适用于乙酸丁酯废气吸附的活性炭(编号为AC4)。分别研究了空塔气速、废气湿度等对吸附过程的影响,同时测定了25℃、40℃和60℃下不同进气浓度的饱和吸附量,并采用Langmuir和Freundlish等温吸附方程对实验数据进行拟合,结果表明,langmuir等温吸附方程能更好地描述乙酸丁酯废气在活性炭上的吸附。采用热空气脱附法对活性炭进行再生并回收乙酸丁酯,设计出在空气流速为0.2m/s时,先在140℃下脱附1.5h,然后在170℃下脱附1.5h的脱附再生工艺。在此条件下,乙酸丁酯脱附率达97.99%,回收率达89.51%。     

活性炭纤维对CS2蒸气的动态吸附研究

本文选用国产聚丙烯腈基活性炭纤维(CPANACF)作吸附剂,过热水蒸气作脱附剂,研究了CS_2蒸气的吸附与脱附的动态行为,分析了动态吸附影响因素。结果表明,该吸附体系是以气相界膜外扩散控制为主的,其吸附波遵循恒定模式规则,低温、低浓度、高流速等对吸附有利。     

活性炭催化氧化脱除单质汞的研究

模拟煤气的气氛,在硫化氢（H₂S）和氧气（O₂）存在条件下,对活性炭催化氧化吸附单质汞（Hg⁰）的性能进行了研究。结果表明,H₂S和O₂存在条件下,活性炭对Hg⁰的吸附能力明显提高。在180min内,H₂S和O₂共存气氛下,脱汞效率约为78%;只有H₂S存在下,脱汞效率约为69%;没有H₂S和O₂气氛下活性炭脱汞效率快速下降为28%。随着吸附温度的升高,入口汞浓度的提高和吸附剂粒径的增大,活性炭的脱汞效率会随着下降。通过XRD表征表明,Hg⁰的吸附反应机理是Hg⁰在活性炭催化氧化下与H₂S形成硫化汞（HgS）,从而实现了Hg⁰的稳定化脱除。     

硝酸改性活性炭上氧/氮官能团对脱汞性能的促进作用

采用硝酸氧化手段对活性炭进行了表面处理, 并在固定床反应器上测试了其脱除单质汞的性能. 研究表明, 在模拟烟气中硝酸改性活性炭能有效脱除单质汞. 采用元素分析、Brunauer-Emmett-Teller (BET)比表面积、扫描电子显微镜(SEM)、拉曼(Raman)光谱、Boehm滴定、程序升温脱附(TPD)和X射线光电子能谱(XPS)等手段研究了活性炭表面官能团对其脱汞性能的影响. 结果表明: 硝酸氧化处理能同时增加活性炭表面含氧官能团和含氮官能团的含量. 与改性活性炭的物理性质相比, 其化学性质对脱汞性能的影响更大, 单质汞主要被改性活性炭氧化为HgO而去除. 在脱汞反应中, 羰基、酯基和酸酐等含氧官能团可能是活性吸附位点, 反应后这些官能团被还原为羟基或者醚基; 而吡咯等含氮官能团可能是活性催化位点. 此外, 基于上述表征结果提出了硝酸改性活性炭表面官能团的脱汞机制.     

活性炭复合滤嘴吸附性能的热脱附研究

采用热脱附与气相色谱-质谱联用技术对活性炭滤嘴中活性炭和乙酸纤维脱附的组分进行了定性分析,并用峰面积归一化法测定了所含挥发性成分的质量分数,活性炭脱附组分共鉴定出芳香族化合物、醛酮类、烟碱、酸类、酯类等62种挥发性化合物.结果表明方法具有较好的重现性;为评价活性炭滤嘴的吸附性能提供了一种参考方法.     

通过氧化改性提高载银活性炭的抗菌性能

使用浓HNO3和浓H2O2对活性炭进行常温氧化改性,用FTIR和N2吸附法对活性炭进行表面分析,用AAS、SEM、XRD研究银在活性炭表面的吸附和分布特征,并研究了载银活性炭的抗茵性能.结果表明,活性炭经浓HNO3常温改性后,比表面积提高,而经浓H2O2常温改性后,比表面积略有下降,但都使活性炭表面含氧基团增加.改性后,活性炭表面增加的含氧基团为[Ag(NH3)2] 的还原吸附提供更多的活性点,使银的吸附量增大5倍多,银颗粒更加密集,大小更加均一.研究表明,载银活性炭具有明显的抗茵作用,其中对金黄色葡萄球菌的杀灭效果优于对大肠杆菌的杀灭效果,氧化改性使载银活性炭抗茵作用显著增强,其中硝酸改性现象更加明显.     

活性炭纤维吸附-蒸汽脱附回收三氯甲烷工程实例分析

采用活性炭纤维吸附-蒸汽脱附装置对江苏南通某农药厂生产工序中排放的三氯甲烷进行吸附回收。论述了该农药厂有机废气收集和处理现状、吸附剂选择、吸附装置工艺流程及操作参数、必要的安全保障等。现场运行数据表明:装置运行稳定,三氯甲烷回收率稳定在99%左右,自动化控制水平高,安全性能好,回收的三氯甲烷质量好。使用该装置后,每年可回收三氯甲烷约155 t,年净收益38万元。     

通过柠檬酸改性提高载银活性炭的抗菌性能

通过负载柠檬酸对活性炭进行改性,用N2吸附法测定活性炭的比表面积,用AAS、SEM、XRD测试技术分析了银在活性炭上的吸附和分布,并研究了载银活性炭的抗菌性能。结果表明,负载柠檬酸使活性炭的比表面积下降约24%,但载银后活性炭的比表面积增大。柠檬酸改性为[Ag(NH3)2] 的还原吸附提供更多的活性点,使银的吸附速率加快,吸附量提高约25%,表面的银颗粒变得非常密集,粒径减小,且颗粒均匀,因此抗菌性能显著增强,其中对金黄色葡萄球菌的杀灭效果明显优于对大肠杆菌的,同时对于高分散Ag/C催化剂的制备及银的回收也具有重要的价值。     

Recycling of carbon fibre reinforced polymeric waste for the production of activated carbon fibres

Composite waste composed of carbon fibres and polybenzoxazines resin has been pyrolysed in a fixed bed reactor at temperatures of 350, 400, 450, 500 and 700 °C. Solid residues of between 70 and 83.6 wt%, liquid yields 14 and 24.6 wt% and gas yields 0.7 and 3.8 wt% were obtained depending on pyrolysis temperature. The derived pyrolysis liquids contained aniline in high concentration together with oxygenated and nitrogenated aromatic compounds. The pyrolysis gases consisted mainly of CO₂, CO, CH₄, H₂ and other hydrocarbons. The carbon fibres used in the composite waste were separated from the char of the solid residue via oxidation of the char at two different temperatures and investigated for their mechanical strength properties. The carbon fibres recovered from the sample pyrolysed at 500 °C and oxidised at 500 °C exhibited mechanical properties which were 90% of that of the original virgin carbon fibres. Steam activation of the recovered carbon fibres was carried out at 850 °C at different times of activation. The effect of activation time on BET surface area, activated carbon fibres yield, porosity and the morphological structure of activated carbon fibres was evaluated. A maximum BET surface area of over 800 m² g⁻¹ was obtained for the activated carbon fibres produced at 850 °C for 5 h of activation. Nitrogen adsorption-desorption isotherms showed that the adsorption capacity increased as the activation time increased up to 5 h of activation and then after that decreased.     

Immobilization of flower-like ZnO on activated carbon fibre as recycled photocatalysts

Research on Chemical Intermediates - ZnO was grown on the surface of activated carbon fibre (ACF) by a hydrothermal method to form a recyclable photocatalyst. With an increase in hydrothermal time...     

Voltammetric determination of chloramphenicol in milk at electrochemically activated carbon fibre microelectrodes

Electrochemical activation of cylindrical carbon fibre microelectrodes (CFMEs) by repetitive square-wave (SW) voltammetric scans between 0.0 and +2.6 V has shown to increase dramatically the cathodic current of chloramphenicol (CAP). This is attributed to the increase of the carbon fibre surface area due to its fracture and the appearance of deep fissures along the main fibre axis. Cyclic voltammograms of CAP suggested a contribution to the total current from most likely thin-layer electrolysis. The current density:concentration ratio calculated for the reduction of CAP at an activated fibre was 6.5×10⁷ μA cm⁻² mol⁻¹ l. A method for the determination of CAP at low concentrations levels, using SW voltammetry at electrochemically activated cylindrical microelectrodes, was developed. Different chemical and electrochemical variables involved in the activation step were optimised. Calibration graphs were linear (r=0.9990) in the 1.0×10⁻⁷ to 1.0×10⁻⁵ mol l⁻¹ concentration range, with a slope of (2.69+0.03) × 10⁵ μA mol⁻¹ l. A limit of detection of 4.7×10⁻⁸ mol l⁻¹ (15 ng ml⁻¹) was found. The SWV method was applied for the determination of CAP in milk samples spiked with the antibiotic at two concentration levels: 64 and 320 ng ml⁻¹. Recoveries >97% were obtained in all cases by following a very simple experimental procedure.     

Pre-formed activated carbon matting derived from the pyrolysis of biomass natural fibre textile waste

Low grade biomass fibre produced as a by-product from the flax and hemp industry was manufactured into a non-woven, pre-formed matting material via entanglement, layering and needling. The advantage of such a structure is that textile technology is used to form a self supporting fibre matrix, utilising the ease with which fibre can be worked. The non-woven matting was then pyrolysed and gasified with steam to produce activated carbon. The influence of pyrolysis process conditions on the production of chars and activated carbon from the pre-formed, non-woven textile matting were investigated.     

Electroanalytical applications of carbon fibre electrodes

The analytical uses of carbon fibre electrodes cover such diverse areas as coulometry, potentiometry, anodic stripping voltammetry, potentiometric stripping voltammetry, spectroelectrochemistry and kinetic measurements. The electrodes have been employed in a variety of cell types and locations, including conventional two and three electrode cells, flowing streams and in-vivo. The electroanalytical applications and theory are discussed in this review, along with the structure and surface properties of carbon fibres. Specialist instrumentation is also described.     

The effect of carbonisation temperatures on nanoporous characteristics of activated carbon fibre (ACF) derived from oil palm empty fruit bunch (EFB) fibre

Activated carbon fibre (ACF) is a nanoporous material which is useful for various important applications such as safe biogas and natural gas storage as well as heavy/precious metals removal and recovery. It is commonly produced from synthetic fibres such as rayon, polyacrylnitrile and pitch mainly derived from petroleum products, which are less environmental friendly. Besides, cost of ACF production is high due to the high burnt off percentage of such expensive raw materials. As an alternative, natural fibre of oil palm empty fruit bunch was used as a raw material for ACF preparation. Thermogravimetric analysis was carried out with two different gases, i.e. nitrogen gas and oxygen gas in order to observe pyrolysis and combustion behaviours in different gases. Carbonisation temperatures were then identified from the peaks of derivative thermogravimetry results. Different carbonisation temperatures (85?C200?°C) were chosen to carbonise the EFB fibre to observe the effect of carbonisation temperatures on the nanoporous characteristics, i.e. surface area, pore size distribution and pore volume of the ACF produced. Good nanoporous characteristics such as surface area up to 2,740?m²/g of the ACF prepared were observed, suggesting EFB fibre as an excellent candidate to replace synthetic fibre for ACF production. The discussion of relationship between thermal characteristics and nanopores in ACF derived from EFB were also included in this study.     

甲烷在石墨化热解碳黑和活性炭上的吸附

为研究影响碳基吸附剂吸附超临界温度气体的主要因素,选择石墨化热解碳黑BP280和Ajax活性炭,分析超临界温度高压甲烷在其上的吸附平衡。应用容积法,在压力0~20.5 MPa、温度253 K~313 K测定甲烷的吸附平衡数据,并由等量吸附线标绘和亨利定律常数确定等量吸附热。引入通用吸附等温方程,再由方程的Langmuir标绘确定最大吸附容量,进而通过方程的线性化计算吸附平衡态中甲烷分子的作用能。结果表明,甲烷在两种吸附剂上的最大吸附容量均随温度而变化,并都小于液态甲烷的密度;甲烷在碳黑和活性炭上的等量吸附热分别为11.9 kJ/mol~12.5 kJ/mol和17.5 kJ/mol~22.5 kJ/mol,体现了两种吸附剂不同的表面能量分布;甲烷分子间作用能随吸附量的变化特点反映了超临界温度甲烷以类似于压缩气体状态聚集的特点和吸附剂结构上的差异。碳基吸附剂的比表面积和微孔容积是影响其储存甲烷容量的重要因素。     

Low-temperature regeneration of activated carbon

Activated granular carbon samples, routinely equilibrated with synthetic aqueous solutions of o-NO₂-phenol, were regenerated by heating up to 500 °C in a dynamic N₂ atmosphere. Kinetic evaluation of five subsequent thermodesorption cycles was accomplished by two different non-isothermal computation methods. Quantitative estimation of adsorbent-adsorbate interactions was carried out by means of the thermal coefficient of the massive adsorbate release.

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Zusammenfassung Routinemäßig mit synthetischen wässrigen Lösungen von o-Nitrophenol äquilibrierte, granulierte Aktivkohle-Proben wurden durch Aufheizen auf 500 °C in einer dynamischen N₂-Atmosphäre regeneriert. Fünf aufeinanderfolgende Thermodesorptionszyklen wurden nach zwei verschiedenen nicht-isothermen Berechnungsmethoden kinetisch ausgewertet. Die quantitative Bestimmung der Adsorbent-Adsorbat-Wechselwirkungen wurde mittels der thermischen Koeffizienten der massiven Adsorbatdesorption ausgeführt.

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Potentiometric and voltammetric responses of carbon fibre electrodes

The potentiometric response of several carbon fibres to hydrogen ion concentration (ph) was investigated. The effects of electrochemical pretreatment and the presence of complexes in the sample solution were studied. In solutions free of complexing anions, the response of pristine fibres ranged from 42.0 to 58.0 mV ph^?1, with a mean of 48.5 mV ph^?1. After electrochemical pretreatment, a mean slope of 52.0 ± 2.0 mV ph^?1 was obtained. In the presence of EDTA, Tris, citrate, oxalate and tartrate, slopes of 59.0 mV ph^? were obtained with pretreated fibres compared with zero slopes or highly curved plots obtained in the absence of pretreatment. The differential pulse voltammetry of iron (III) in a peroxide-containing electrolyte and of molybdate in nitrate- and chlorate-containing electrolytes was examined. At a conventionally sized glassy carbon electrode, the effect on the peak current of increasing the concentration of these ions was broadly in line with depolarizer/electrolyte systems in which catalytic currents occur. At carbon fibre electrodes, these catalytic currents were either absent (for molybdenum/nitrate and iron (III)/peroxide) or severely diminished (for molybdenum/chlorate).     

Electropolymerisation of methyl methacrylate on carbon fibre surfaces

The electroinitiated polymerisation of methyl methacrylate containing sulphuric acid was found to be localised at the surface of a cathode of carbon fibre. The influences of various reaction parameters on the rate of polymerisation and the molecular weight have been recorded but do not agree totally with classical free radical electropolymerisations. The behaviour of molecular weight and evidence of post-polymerisation suggest the existence of living polymer radicals. It is argued that atomic hydrogen is responsible for initiation of the polymerisation.