Adsorption Equilibria for Ethane and Propane Gas Mixtures on Activated Carbon

Abstract

We measured the transmission curves of binary gas mixtures of esthane and propane (and also of each gas alone) flowing through an adsorber bed at 25°C packed with (Columbia 4LXC 12/28) activated carbon. The adsorption isotherms for pure ethane and propane are described well by a modified Langmuir isotherm known as the Chakravarti-Dhar isotherm. Ethane in the binary mixtures exhibits smaller adsorption capacities than that of pure ethane; however, the presence of ethane does not significantly reduce the adsorption capacity of propane in the mixtures. The ideal adsorbed solution theory (IAST) of Myers and Prausnitz and the semiempirical method of Cook and Basmadjian (C-B) are applied to predict adsorption equilibrium properties of the binary mixtures from the known pure gas isotherms. The pure ethane isotherm data at pressures higher than 10 mmHg are obtained from a correlation formula. Good agreement between the predicted results from the IAST and C-B methods and the experimental results indicates (1) that the correlation formula can be used for estimating isotherms of related hydrocarbons with reliance and (2) that the two methods are useful in predicting the adsorption equilibrium properties for the ethane-propane mixtures on carbon.     

增强尾气回收活性炭吸附柱再生效果的措施

尾气中的吸附柱作用是将氢气净化回收,吸附柱采用活性炭进行吸附,吸附结束再生需要用氢气反吹以达到再次吸附净化的功能。吸附柱的完成一个吸附周期后进入再生周期,开始泄压/加热、吹扫/加热,需要用氢气反吹以达到再次吸附净化的功能。     

Adsorption of Binary Gas Mixtures on Strongly Heterogeneous Surfaces

The integral equation (IE) approach coupled with a rectangular adsorption energy distribution and Mean Field Approximation (MFA) is used to describe the adsorption of single gases and their binary mixture on a heterogeneous solid surface. In particular, it is important to stress that all theoretical expressions shown are the exact solution of IE approach. During the analysis of single-gas adsorption isotherms also accompanying calorimetric effects are investigated. The problem of correlations between the best-fit parameters describing energetic heterogeneity and energy of intermolecular interactions is discussed. The predictions of the theory are compared with the experimental literature data. It is shown that the new theoretical adsorption isotherms give the results that are very close to the experimental data.     

对二甲苯在活性炭固定床上的吸附动力学

研究了对二甲苯在活性炭固定床上的吸附动力学。考察了初始浓度、气体流量、床层长度等因素对吸附透过曲线的影响。同时,采用Yoon—Nelson模型对吸附透过曲线进行线性回归分析。实验结果表明,随着初始浓度的增大,透过时间缩短,吸附量增大：气体流最对透过曲线的形状影响不大：床层长度基本不影响透过曲线;Yoon-Nelson模型可以较好的模拟固定床吸附过程。     

Adsorption of Bisphenol A from Water-Ethanol Mixtures on Pulverized Activated Carbon

The effect of ethanol concentration on the removal of bisphenol A (BPA) from water-ethanol mixtures using pulverized activated carbon (PAC) was studied. Adsorption equilibria and kinetics were measured using batch uptake experiments. Equilibrium and kinetic data were correlated with the Langmuir model and the non-ideal competitive adsorption (NICA) model. Finally, BPA removal in an adsorption-microfiltration hybrid system was tested and simulated with a non-steady model. Ethanol has a strong influence on the binding capacity of BPA on PAC and the uptake from 10 mol/L (50.4 wt-%) aqueous ethanol is less than 10% of the value measured in water. The experimental adsorption isotherms were modeled using several isotherm models and by considering the effect of ethanol on solution activity coefficients. The best correlation was obtained with the NICA model assuming that part of the binding sites is inaccessible for BPA. The BPA adsorption rate was described using a pore diffusion model and reasonably good correlation with the experimental data was obtained provided that changes in solution viscosity were taken into account. Moreover, the estimated equilibrium and mass transport parameters describe reasonably well the removal of BPA in the adsorption-microfiltration hybrid system from water-ethanol mixtures.     

Adsorption of SO2 on Activated Carbon for Low Gas Concentrations

Adsorption experiments of SO₂ on activated carbon has been carried out for low concentrations (about 100 ppm) at room temperature (15 to 33 °C) with varying humidity in the air. The breakthrough curves show that at high relative humidity or relative higher SO₂ concentration, the load capacity increases with respect to temperature. The humidity of the air is also of benefit to the load capacity of SO₂. When an adsorption process is interrupted and the activated carbon is kept closed for a while, the SO₂ concentration at the exit of a fixed‐bed adsorber is similar to that of the fresh activated carbon and begins at a very low value. It appears that the sorption potential has been refreshed after the storage period. Analysis of desorption experiments by simultaneous thermal analysis combined with mass spectrometry (MS) after loading, shows that the physisorbed SO₂ and H₂O are desorbed at low temperatures. At higher temperatures, the MS peak of SO₂ and H₂O occur at the same time. Compared with desorption immediately after loading, after one day, the desorption peak due to the physisorbed SO₂ disappears. From this, it can be concluded that the refreshment of the loading capacity of the activated carbon after storage is mainly due to a change in the nature of the SO₂ from a physisorbed state to a chemisorbed form. The same mechanism leads to a continuous refreshment of the sorption potential by means of a chemical reaction during the adsorption process.     

活性染料的活性炭吸附脱色研究

研究了活性炭对染料溶液色度的去除率,考察了活性炭量、温度、pH值、时间对染液脱色率的影响,并从动力学角度探讨了吸附机理。研究表明活性炭对两种活性染料的吸附过程符合伪二级吸附速率方程,以物理吸附为主,拟合的模型和吸附活化能为了解其吸附途径和吸附机理提供了依据。     

活性炭纤维对有机废气的吸附性能研究

活性炭纤维的吸附性能强、吸附量大、吸附脱附速度快,在有机废气中得到了很好的应用。深入研究活性炭纤维在物理吸附性能和化学改性后吸附性能,分析活性炭纤维在有机废气处理中的应用现状,对活性炭纤维的发展前景进行展望。     

Modeling Anomalous High-Temperature Adsorption from Binary Mixtures

The working dynamic activity of an adsorbent rises with increasing temperature owing to the equilibrium shifting toward the desorption of initial components and vacant positions being occupied by the adsorbable impurity.     

Concentration-Thermal Swing Adsorption Process for Separation of Bulk Liquid Mixtures

Abstract

A novel concentration-thermal swing adsorption process is described for separation of bulk binary liquid mixtures. The process is designed to produce essentially two pure products with high recoveries of both components. It is particularly suited for separation of azeotropic or close-boiling liquid mixtures which are difficult to separate by distillation. An example of the performance of the new process for separation of an azeotropic water-methyl acetate mixture is given. Experimental binary surface excess equilibrium isotherms, adsorptive mass transfer coefficients, and column dynamics for adsorption of water-methyl acetate mixtures on NaX zeolite are reported.     

煤质活性炭对苯酚吸附动力学研究

通过静态吸附实验研究了煤质活性炭对苯酚的吸附特性,并用两种动力学模型对实验数据进行了拟合。结果表明,准二级动力学模型能精确描述苯酚在煤质活性炭上的吸附动力学行为;颗粒内扩散模型拟合表明内扩散过程为该吸附过程的主要控制步骤,但不是唯一控制步骤,吸附同时还受外扩散过程影响。     

Separation of Methane and Carbon Dioxide Gas Mixtures by Pressure Swing Adsorption

Abstract

Two pressure swing adsorption processes for separation of methane and carbon dioxide gas mixtures are described. One process simultaneously produces a high purity CH₄ and a high purity CO₂ product with high recoveries of both components from the feed gas. The other process only produces a high purity CH₄ product with high recovery. Test data for these processes are reported and their relative advantages are discussed.     

改性活性炭对含汞废气吸附机理及性能研究

汞具有高挥发性,含汞废物处理过程中产生的气态汞如未及时处理,会对人体健康及周边环境存在极大风险.为分析改性活性炭对含汞废气吸附机理及性能,采购4种市售载硫量的活性炭样品进行相关参数表征,并通过气体吸附实验装置进行汞的吸附实验.结果表明:市售载硫活性炭基本参数差距较大,4种活性炭中硫质量分数最高为11.46％,最低为0....     

Low-Temperature Adsorption of Hydrogen on Activated Carbon

Abstract

The adsorption isotherm of pure hydrogen on activated carbon (coconut shell) was determined at — 186[ddot]C over a pressure range of 1 to 772 mm Hg. A McBain balance apparatus with a modified refrigerant thermostat was used.     

用活性炭纤维吸附回收废气中环己烷

采用活性炭纤维吸附回收装置处理含环己烷废气。综述了废气处理要求、工艺流程、装置操作参数和安全保障及吸附剂的选择等。现场生产数据表明,该工艺装置处理含环己烷废气,环己烷的吸附效率大于99%,具有很好的经济前景。     

活性炭吸附工艺在工业有机废气治理中的应用

近年来,随着全球变暖等现象的出现,社会对环保问题的讨论也持续不断,国家也提高了对环境保护问题重视程度。其中,关于工业生产中所产生的各类气体污染,也成为了人们的关注对象。而对于工业企业而言,有机废气是不可避免的产物,如何处理有机废气便是工业企业针对环保问题的重点研究对象。主要从活性炭吸附工艺来研究工业有机废气治理过程,希望对有机废气的治理提供些许帮助。     

苯酚在活性炭上吸附平衡模型的研究

本文研究了苯酚在活性炭上的吸附特性,并发现在低pH,低温度下有利于活性炭吸附苯,研究表明Freundlich模型能较好描述吸附过程,并得到了在考虑温度,pH值影响情况下苯酚的Freundlich模型表达式。     

低浓度氰化氢在浸渍活性炭上的吸附净化研究

采用浸渍法改性活性炭吸附脱除低浓度氰化氢(HCN),研究了NaOH与磺化酞菁钴(CoPcS)混合浸渍改性活性炭净化HCN的性能。研究表明:改性炭在制备过程中适当增加NaOH的浓度有利于提高其吸附HCN的能力,当NaOH浸渍液浓度为10%时,CoPcS/NaOH配比0.15mg·g-1、焙烧温度350℃为最佳制备条件;吸附反应阶段较适宜的体积空速为923h-1、氧体积分数2%、吸附温度为90℃。N2吸附表征了活性炭的比表面积和孔结构性质,与原活性炭相比,CoPcS与NaOH混合浸渍改性活性炭的比表面积和孔体积有所降低,但对HCN的吸附能力却显著提高,说明HCN与浸渍剂在活性炭表面发生了化学反应;孔径分布说明HCN在改性炭的中孔或大孔上参与化学吸附造成微孔扩充,而不是微孔填充和覆盖。     

Adsorption of Pure Fluids in Activated Carbon with a Modified Lattice Gas Model

In this article we study the effects of adsorbed phase compression, lattice structure, and pore size distribution on the analysis of adsorption in microporous activated carbon. The lattice gas approach of Ono-Kondo is modified to account for the above effects. Data of nitrogen adsorption at 77 K onto a number of activated carbon samples are analyzed to investigate the pore filling pressure versus pore width, the packing effect, and the compression of the adsorbed phase. It is found that the PSDs obtained from this analysis are comparable to those obtained by the DFT method. The “discrete” nature of the PSDs derived from the modified lattice gas theory is due to the inherent assumption of discrete layers of molecules. Nevertheless, it does provide interesting information on the evolution of micropores during the activation process.