ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

1. INTRODUCTION With the development of municipalization in China, more and more cities are challenged by the problem of how to dispose of the dramatically increased municipal waste. Generally, most of municipal solid waste is landfilled or dumped openly in the suburbs. It causes not only land waste, but also serious environment pollution. In order to solve efficiently the environment pollution caused by municipal solid waste, incineration technique was introduced in some big cities such…     

ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

Three kinds of commercial activated carbons, such as Norit RBI, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofiuran. The average pore size and specific surface area of these activated carbons were measured Temperature Programmed Desorption (‘TPD) experiments were conducted to measure the TPD curves of dibenzofuran on the activated carbons, and then the activation energy for desorption of dibenzofuran on the activated carbons was estimated. The results showed that the Chemviron and the Norit RB1 activated carbon maintained higher specific surface area and larger micropore pore volume in comparison with the Monolith activated carbon, and the activation energy for the desorption of dibencofuran on these two activated carbons was higher than that on the Monolith activated carbon. The smaller the pore of the activated carbon was, the higher the activated energy of dibenzofiuran desorption was.     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

1. INTRODUCTION In some cities of China, cancer and breath system diseases caused by the pollution of volatile organic compounds (VOCs) have been obviously increasing. The VOCs includes BTEX (benzene, toluene, ethylbenzene, and xylene), aldehydes, cresol, phenol, acetic acid, polynuclear aromatic hydrocarbons (PAHs), which have long-term human health implications. Emission of the VOCs has threatened the health of people seriously [1,2]. The pollution of the VOCs mostly hails from…     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

In this paper, six kinds of activated carbons such as Ag+-activated carbon, Cu2+-activated carbon, Fe3+- activated carbon, activated carbon, Ba2+- activated carbon and Ca2+-activated carbon were prepared. The model for estimating activated energy of desorption was established. Temperature-programmed desorption (TPD) experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons. Results showed that the activation energy for the desorption of n-hexanol on the Ag+- activated carbon, the Cu2+- activated carbon and the Fe3+- activated carbon were higher than those of n-hexanol on the activated carbon, the Ca2+- activated carbon and the Ba2+- activated carbon.     

一步法制备糖蜜基活性炭及其界面吸附行为

以糖厂废弃的糖蜜为原料,Na_2CO_3为活化剂,采用一步直接化学活化法制备了糖蜜基活性炭(AC).采用X射线衍射(XRD)、扫描电子显微镜(SEM)、N_2吸附-脱附及元素分析手段对产物进行了表征,证实其为多孔的石墨化碳材料,比表面积高达1023 m~2/g.研究了糖蜜基活性炭对溶液中的重金属离子Pb(Ⅱ)的脱除性能,结果表明:糖蜜基活性炭的吸附容量高于市售活性炭(CC),且所需吸附时间和投炭量均低于市售活性炭;其吸附动力学符合准二级动力学的Langmuir吸附,为单分子层的化学吸附;吸附Pb(Ⅱ)的糖蜜基活性炭可循环再生和重复使用.     

活性炭纤维吸附脱除NO过程中NO氧化路径分析

在小型固定床吸附实验台上开展了黏胶基活性炭纤维吸附脱除NO的实验研究。采用H₂O₂溶液浸渍以及热处理方法对活性炭纤维表面进行修饰,以获得表面孔隙结构接近而含氧官能团含量不同的样品;考察样品在惰性氮气气氛、含氧气氛下吸附脱除NO的效果,以及表面含氧含氮官能团的变化规律。探讨了含氧官能团在NO催化氧化过程中的作用及含氧气氛下O₂对于NO转化为NO₂的影响,分析了活性炭纤维表面吸附的NO向NO₂的主要转化途径。结果表明,在氮气气氛下活性炭纤维表面C-O官能团对吸附态的NO起到氧化作用,吸附态NO被C-O官能团氧化生成-NO₂官能团;在含氧气氛下活性炭纤维吸附NO后表面出现-NO₂、-NO₃官能团,通过长时间实验测定三种样品在含氧气氛下对NO吸附的效果,发现三种样品稳定时催化氧化效果一致,表明含氧官能团对初始NO的物理吸附影响较大,而对整个吸附过程影响较小。吸附在活性炭纤维表面上的NO与环境气氛中的游离态O₂发生氧化反应是NO转变为NO₂的主要途径。     

高分子热活化延迟荧光材料研究进展

高分子热活化延迟荧光材料能够利用热活化的反向系间窜越过程将三线态激子转变为单线态激子而发出荧光,理论上可以实现100%的内量子效率,突破了传统高分子荧光材料内量子效率不超过25%的极限,因而代表了未来低成本高效率高分子发光材料的发展方向。 近年来,高分子热活化延迟荧光材料在分子设计方面取得了重要进展,形成了主链型、侧链型和树枝状高分子热活化延迟荧光材料等材料体系,同时其器件性能得到了大幅提升,部分材料的器件效率达到了高分子磷光材料的水平。 本文从材料和器件两个方面,围绕高分子热活化延迟荧光材料的分子结构、光物理特性和器件性能,总结和评述了国内外研究者在该领域方向的研究进展,并分析了未来发展面临的机遇和挑战。     

Activated carbons obtained from agro-industrial waste: textural analysis and adsorption environmental pollutants

In this study, we aimed to use as a new lignocellulosic precursor in the production of activated carbon. The physicochemical characteristics of the activated carbons obtained under optimum conditions were determined by using some techniques such as thermo-gravimetric (TG/DTG) analysis, nitrogen adsorption–desorption, scanning electron microscopy (SEM) and surface functional group analysis by Fourier transform infrared spectroscopy (FT-IR), Boehm titration method and point of zero charge (pHpzc). In addition, the activated carbons were tested to remove phenols from aqueous solutions. The results indicated that activated carbon the orange peel, pine cone and yerba mate, could be employed as an alternative low-cost activated carbon for the removal the phenolic contaminants from wastewater.     

Adsorption of toluene and toluene–water vapor mixture on almond shell based activated carbons

The aim of work is to study the adsorption of a common volatile organic compound such as toluene using activated carbons prepared by chemical activation with phosphoric acid of a lignocellulosic precursor, almond shell, under different conditions. The Impregnation ratio, temperature and time of activation were modified to obtain activated carbons with different characteristics. Regarding the characteristics of the activated carbons, the effects of porous structure and surface chemistry on the toluene adsorption capacity from toluene isotherms have been analysed. Results show that the control of properties of the activated carbons, particularly porous structure, highly dependent on the preparation conditions, plays a decisive role on the toluene adsorption capacity of the activated carbons. Concerning the experiments of toluene adsorption conducted in dynamic mode, activated carbons prepared at low temperatures of activation show higher breakthrough times than those obtained for activated carbons prepared at higher activation temperatures. The amount of toluene adsorbed in presence of water vapor in the gas stream lead to a decrease ranging from 33 to 46 % except for carbons prepared at higher temperatures activated that show only a slight decrease in the amount of toluene adsorbed. Activated carbons can be regenerated with soft heat treatment showing a slight decrease in the adsorption capacity. The high toluene adsorption capacities as well as the high breakthrough times obtained in presence of water vapor make these activated carbons suitable for commercial applications.     

杂多酸在活性炭上的固载化──Ⅰ．几种国产活性炭的表面性质

本文研究了作为杂多酸载体的几种国产活性炭的表面性质，实验证明，活性炭表面的化学特性是由表面含氧基团的化学结构以及这些基因的数目决定的。为了得到适当表面化学特性的活性炭，对它们进行了不同的化学改性处理，并使用ＸＰＳ，ＩＲ，ＳＦＭ，Ｂｏｅｈｍ酸－碱滴定以及ｐＨ滴定等手段研究了活性炭的表面性质。     

用活性炭纤维同时脱除二氧化碳中COS与H_2S的研究

采用固定床动态吸附实验考察了用NaOH、KOH、Na2CO3、K2CO3和Fe3+、CO2+等对活性炭纤维(ACF)进行改性,并分别对其脱除氧硫化碳(COS)和硫化氢(H2S)的性能进行了测试。重点是以N2和CO2为稀释气,对改性离子的种类、含量、反应气氛和反应温度等的脱硫性能进行研究,还考察了在COS和H2S同时存在的情况下,ACF脱除COS和H2S的性能。结果表明,碱改性ACF比空白ACF脱除效果好,金属离子改性ACF与碱改性ACF相比可以有效地提高活性炭纤维的硫容量。其中,用CO2+改性ACF能同时提高脱除COS和H2S的效果。     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n—HEXANE ON ACTIVATED CARBONS BY PTD TECHNIQUE

In this paper,six kinds of activated carbons such as Ag^+-activated carbon,Cu^2+activated carbon,Fe^3+-activated carbon,activated carbon,Ba^2+-activated carbon and Ca^2+activated carbon were prepared.The model for estimating activated energy of desorption was established.Temperature-programmed desorption(TPD)experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons.Results showed that the activation energy for the desorption of n-hexanol on the Ag^+-activated carbon,the Cu^2+-activated carbon and the Fe^3+-activated carbon were higher than those of n-hexanol on the activated carbon,the Ca^2+-activated carbon and the Ba^2+-activated carbon.     

Textural characteristics,surface chemistry and oxidation of activated carbon

Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation.Activated carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its"Textural Characteristics"and"Surface Chemistry".These two terms,coupled with each other,are responsible for behavior of activated carbon in adsorption processes and in catalytic applications.Although as-prepared activated carbons are usually nonselective and their surfaces suffer from lack of enough reactive groups,their different aspects may be improved and developed by diverse types of modifications.Oxidation is one of the most conventional modifications used for activated carbons.It may be used as a final modification or as a pre-modification followed by further treatment.In this paper,methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.     

Textural characteristics, surface chemistry and oxidation of activated carbon

Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation. Activated carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its "Textural Characteristics" and "Surface Chemistry". These two terms, coupled with each other, are responsible for behavior of activated carbon in adsorption processes and in catalytic applications. Although as-prepared activated carbons are usually non-selective and their surfaces suffer from lack of enough reactive groups, their different aspects may be improved and developed by diverse types of modifications. Oxidation is one of the most conventional modifications used for activated carbons. It may be used as a final modification or as a pre-modification followed by further treatment. In this paper, methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.     

（NH_4）_2MOS_4在活性炭上浸渍过程的研究Ⅰ．浸渍参数对（NH_4）_2

（ＮＨ＿４）＿２ＭＯＳ＿４在活性炭上浸渍过程的研究Ⅰ．浸渍参数对（ＮＨ＿４）＿２ＭＯＳ＿４在活性炭上分布的影响秦慧芳，张成芳，陆岗，俞丰，朱子彬（华东理工大学无机化工研究所，上海２００２３７）关键词硫代钼酸铵，浸渍，活性炭，钼分布负载型催化剂制备一般...     

微波辐射在制备竹节活性炭中的应用研究

研究了以竹节废料为原料，采用微波辐射氯化锌法制备优质活性炭的可行性．探讨了微波功率．活化时间及氯化锌浓度对产品各项指标的影响．得到了微波辐射氯化锌法制备活性炭的最佳工艺：微波功率350W、活化时间5min、氯化锌浓度40%．用此工艺制得的活性炭碘吸附值1088．4mg／g、亚甲基蓝脱色力22．0ml/0．1g．得率39．2％．该工艺所需活化时间为传统方法的1／36，产品活性炭亚甲基蓝脱色力为国家一级标准的1．83倍(GB/T13496.10-1999)．微波辐射法所制活性炭比传统方法所制活性炭具有更加发达的孔隙结构，且孔隙的分布更加均匀．     

Effects of fiber diameter and CO2 activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers

The effects of fiber diameter and activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers are investigated. It was found that lower fiber diameters as well as higher activation temperatures lead to a higher weight loss, specific surface area and total pore volume. The nitrogen adsorption capacity of activated carbon nanofibers is almost three times that of activated carbon fiber with a diameter of 10 µm. As far as the size of pores in activated carbon nanofibers is concerned, it is basically the micropores that dominate the scene. Moreover, tailoring the pore characteristics by adjusting the activation temperature and fiber diameter is plausible. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation of activated carbon for mercury capture from chicken waste and coal

Chicken waste and chicken waste blended samples with selected high sulfur coal were used as raw materials for activated carbon preparation. Raw materials were subjected to the preparation procedures of carbonization in a nitrogen atmosphere and activation in a steam atmosphere. The basic properties of the raw materials, chars and activated carbons were investigated by components analysis, surface porosity and thermogravimetric analysis. Two activated carbon samples were selected for elemental mercury capture tests in a lab-scale drop tube reactor with air flow.

The current results show that chicken waste is not a suitable raw material for activated carbon production due to its higher contents of volatile matter and ash. Coal can be used as a carbon carrier for improving the carbon content of products. A low-cost activated carbon was prepared by a co-process of chicken waste and coal, and examining the high capture efficiency for elemental mercury. It suggests that the coal provides a carbon carrier or trap for some active species, such as chlorine released from the chicken waste. These active species would likely provide or create the adsorptive sites on the surface of activated carbon for elemental mercury.     

Preparation of activated carbon for mercury capture from chicken waste and coal

Chicken waste and chicken waste blended samples with selected high sulfur coal were used as raw materials for activated carbon preparation. Raw materials were subjected to the preparation procedures of carbonization in a nitrogen atmosphere and activation in a steam atmosphere. The basic properties of the raw materials, chars and activated carbons were investigated by components analysis, surface porosity and thermogravimetric analysis. Two activated carbon samples were selected for elemental mercury capture tests in a lab-scale drop tube reactor with air flow.The current results show that chicken waste is not a suitable raw material for activated carbon production due to its higher contents of volatile matter and ash. Coal can be used as a carbon carrier for improving the carbon content of products. A low-cost activated carbon was prepared by a co-process of chicken waste and coal, and examining the high capture efficiency for elemental mercury. It suggests that the coal provides a carbon carrier or trap for some active species, such as chlorine released from the chicken waste. These active species would likely provide or create the adsorptive sites on the surface of activated carbon for elemental mercury.     

Adsorption properties of activated carbon from waste newspaper prepared by chemical and physical activation

Adsorption properties of activated carbons prepared from waste newspaper by chemical and physical activation were investigated using water vapor, ammonia, methane, and methylene blue (MB) as adsorbents. The water vapor adsorption isotherms show type V behavior and the maximum vapor adsorption of the chemically and physically activated products is about 1050 and 450 ml/g, respectively. The higher water vapor adsorption of the chemically activated products is attributed to the higher specific surface area (S(BET)) and greater hydrophilic activity (arising from the surface oxygen-containing functional groups) than in the physically activated products. The adsorption of ammonia and methane was measured by temperature-programmed desorption (TPD). NH(3) adsorption is found to be higher in the chemically activated product than in the physically activated product while methane adsorption is slightly higher in the physically activated products even though these have lower S(BET) values. In the MB adsorption, the chemically activated products show higher adsorption (390 mg/g) than the physically activated product. These results are suggested to be related to the surface characteristics.