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…     

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.     

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…     

环已胺在沸石分子筛上的吸脱附行为研究

本文以程序升温脱附(TPD)为主要实验手段,对环己胺在5种不同沸石分子筛上的吸脱附行为进行了研究。结果表明,沸石分子筛对环己胺有着较强的吸附作用,不同的沸石分子筛对环己胺的吸附能力受其结构和表面酸性特征的影响而异。有效吸附部位为与沸石分子筛表面酸性有关的弱化学吸附位;环己胺从不同沸石分子筛表面脱附的动力学与晶内扩散有关,其表观脱附活化能分别为:63.6kJ/mol(5A),68.6kJ/mol(13X),20.1kJ/mol(菱沸石),46.9kJ/mol(NaY)和47.3KJ/mol(ZSM-5)。     

PREPARATION AND CHARACTERIZATION OF POLYMER-BASED SPHERICAL ACTIVATED CARBONS

A series of spherical activated carbons(SACs)with different pore structures were prepared from chloromethylated polydivinylbenzene by ZnCl_2 activation.The effects of activation temperature and retention time on the yield and textural properties of the resulting SACs were studied.All the SACs are generated with high yield of above 65% and exhibit relatively high mesopore fraction(me%)of 35.7%-43.6% compared with conventional activated carbons.The sample zlc28 prepared at 800℃for 2 h has the largest BET s...     

碱性分子筛上不同吸附物的TPD研究

借助吸附不同酸性物的程序升温方法研究了碱金属交换的Ｘ型分子筛的碱性。发现吸附物对分子筛碱性的ＴＰＤ表征有很大影响。主要与吸附物的分子体积和酸强度两种因素有关，并对这些影响因素进行了分析。结果表明；甲醇做吸附物对用ＴＰＤ表征分子筛的碱性相对比较可靠。     

INVESTIGATION OF THE INTERACTIONS BETWEEN WATER AND MODIFIED SILICA GEL BY IGC AND TPD

1. INTRODUCTIONSilica gel is an amorphous inorganic polymer composed of siloxane (Si-O-Si) groups in the inner region and silanol (Si-OH) groups distributed on the surface [1]. Silanol groups can be easily functionalized by different chemical procedures. …     

INVESTIGATION OF THE INTERACTIONS BETWEEN WATER AND MODIFIED SILICA GEL BY IGC AND TPD

In this work, the thermodynamic parameters for the adsorption of water vapor on untreated silica gel and silica gel treated with hygroscopic salts and silane coupling agent were determined by Inverse Gas Chromatography (IGC) in the infinite dilution region. The desorption activation energies of the water vapor on virgin and modified silica gels were estimated by using the Temperature Programmed Desorption (TPD) technique. The interactions between the water and the virgin and modified silica gels were discussed. Results showed that the thermodynamic parameters and desorption activation energy of water vapour on the silica gels increase with decreasing pore size and increasing the surface hydrophilic properties. The desorption activation energy of virgin and modified silica gels was found to increase with increasing the thermodynamic parameters. The larger the adsorption parameters and the desorption activation energy were, the interactions between water and virgin and modified silica gels were.     

染料在青霉菌上的解吸特性研究

比较了有机溶剂的加入及温度变化对染料高效吸附青霉菌(BX1)解吸染料效果的影响,并对解吸过程的动力学进行了研究.结果表明,染料的解吸效果与有机溶剂的极性,以及溶剂的官能团有关,丙酮和甲醇解吸效果最好.解吸过程与吸附过程类似,可分为快速解吸和缓慢解吸两个阶段,整个过程可用二级动力学方程较好的拟合,其表观活化能约为10.64kJ/mol.△H°和△G°的计算表明,在甲醇作用下RB19染料的解吸为吸热和自发的过程.     

ADSORPTION ISOTHERMS AND POTENTIAL DISTRIBUTIONS OF NITROGEN ON VARIOUS ACTIVATED CARBONS

The adsorption isotherms of four activated carbons (Norit RB1, Chemviron BPL, Monolit, and Ambersorb-572) have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculation has been proposed based on the adsorption isotherms. This distribution provides information about possible changes in the Gibbs free energy caused by the energetic and geometrical heterogeneities of an activated carbon as well as by the adsorbate-related entropic effects. The general character of the adsorption potential distribution is clearly visible by its simple relation to the micropore and mesopore distribution.     

ADSORPTION ISOTHERMS AND POTENTIAL DISTRIBUTIONS OF NITROGEN ON VARIOUS ACTIVATED CARBONS

1. INTRODUCTION Activated carbon, a kind of microporous materials, is widely used as adsorbents and catalytic supports. The knowledge of their basic sorption and structural characteristics is an important factor that determines or limits their applications. Various modern techniques, such as electron microscopy, small angle X-ray scattering, NMR, and some classical measurements, such as calorimetric measurements, adsorption-desorption of vapors and liquids, have been applied. Classical a…     

运用等键反应能估算自由基和正碳离子的相对稳定性

自由基和正碳离子是化学反应中的活性中间体 ,它们的相对稳定性与其结构有密切关系。例如 ,烷基自由基、烷基正碳离子的稳定性顺序为3°>2°>1°。对于前者 ,一般是从 R- H键的离解能( D值 )进行推断的结果 ,D值越高 ,自由基越不稳定。而正碳离子的稳定性则与其生成热有关。生成热越大 ,正碳离子越不稳定。这就是人们判断上述活性中间体相对稳定性的一般方法 [1] 。那么 ,我们能否用一种统一的方法来评价自由基和正碳离子的相对稳定性呢 ?近年来 ,在物质的结构和性能关系研究方面 ,出现了一个很有应用价值的新概念——“等键反应能”( Iso…     

一种测量超临界条件下苯酚吸附等温线方法

超临界吸附相平衡是超临界吸附／色谱分离过程设计的基础,通常,研究超临界吸附相平衡的实验不仅需要在高压下操作,而且需使用耐高压的检测器,本文提出一种测量超临界条件下吸附相平衡关系的“扩容减压吸收法”方法,它不需要耐高压检测器,以“苯酚－活性炭－超临界二氧化碳流体”为体系,测定了苯酚在活性炭－超临界二氧化碳流体之间的吸附相平衡关系,测定了苯酚在两种活性炭上的超临界吸附等温线,比较了苯酚在超临界条件和常     

ZrO2催化剂上吸附甲酸的TPD和IR研究

众多的研究表明甲酸在氧化物催化剂上的吸附分解与催化剂的表面酸碱性质有关。研究吸附相甲酸物种的变化表明甲酸分解反应的选择性除受温度影响外,还与甲酸的表面覆盖度有关。Z_rO_2表现为较典型的弱酸弱碱双功能性催化剂。最近我们的研究表明Z_rO_2表面存在表面键诱导酸-碱相互作用,它的酸-碱双功能催化作用在烷基胺分解转化为腈的反应中得到了较好地体现。本文报导Z_rO_2催化剂上吸附甲酸的程序升温脱附(TPD)和红外光谱(IR)研究结果。     

A NEW MODEL FOR ESTIMATION OF DIFFUSION COEFFICIENT OF PHENOL DESORPTION WITHIN POLYMERIC RESIN UNDER ULTRASOUND

4 new model, phase equilibrium-kinetics model (PEKM), for estimation of diffusioncoefficient was proposed in this paper. Kinetic experiments of phenol desorption on NKAII resin inthe presence and the absence of ultrasound were separately conducted, and diffusion coefficients ofphenol within an adsorbent particle were estimated by means of proposed PEKM and classicsimplified model. Results show that the use of ultrasound not only changes the phase equilibriumstate of NKAll resin/phenol/water system which had been equilibrium at normal condition, but alsoenhances diffusion of phenol within the resin. The diffusion coefficient of phenol in the resin in thefield of ultrasound increases in an order of magnitude in comparison with the diffusion coefficientdetermined under no ultrasound Experimental results also indicated that the diffusion coefficientsestimated by PEKM were more accurate than that estimated by the classic simplified model.     

A NEW MODEL FOR ESTIMATION OF DIFFUSION COEFFICIENT OF PHENOL DESORPTION WITHIN POLYMERIC RESIN UNDER ULTRASOUND

1. INTRODUCTION Ultrasound is a kind of mechanical wave whose frequency is more than 20 kilohertz. It can enhance the mass transfer, increase the rate and conversion of chemical reaction, change the reaction pathway [1,2] and accelerate the conversion of…     

大孔吸附树脂对氢化可的松的吸附与洗脱性能研究

本文系统研究了大孔附树脂对水溶液中氢化可的松的吸附与洗脱性能,包括树脂的筛选,氢化可的松的渡,解吸剂的选择。结果表明,用AB-8树脂比其它的树脂有更优的性能,其静态吸附容量比试剂级微球硅胶大一个数量级以上,且吸附速度快,易于洗脱再生,是一种具体工业化应用前景的优良吸附剂。     

D406螯合树脂对硫酸锌溶液中氟的吸附和解吸性能及动力学研究

研究了D406螯合树脂对硫酸锌溶液中氟的吸附和解吸性能,考察了影响氟吸附和解吸的因素以及该树脂吸附和解吸氟的动力学参数。结果表明,在25℃、pH=2、硫酸锌浓度为1.50mol/L、氟离子浓度为200mg/L条件下,D406螯合树脂对氟的吸附量为5.55mg/g。D406螯合树脂对氟的吸附符合Freundlich吸附模型。吸附和解吸的动力学符合Boyd液膜扩散方程,吸附反应活化能Ea=12.14kJ/mol,解吸反应活化能Ea=19.54kJ/mol。     

PYR树脂对甜菊糖的吸附与洗脱性能研究

系统研究了PYR型树脂对甜菊糖的吸附与洗脱性能，并与目前国内应用于甜菊糖提取分离的某些商品化吸附树脂进行了比较。结果表明，PYR树脂比其它树脂具有更优的性能，其静态吸附容量比AB—8树脂提高25％，且吸附速度快，易于洗脱再生，是一种具有工业化应用前景的新型吸附剂。