KINETICS OF ADSORPTION OF ORGANICS FROM AN ABOVE GROUND OIL SHALE RETORT WATER

Activated carbon was used to remove organics from retort waters produced in an above ground oil shale retort. This work included batch equilibrium experiments and continuous packed bed studies. The equilibrium isotherms were nonlinear over the entire liquid concentration range (0 to 2880 mg/L). Break through curves were obtained in packed bed experiments as a function of bed length, particle size, and liquid velocity. Rates of adsorption and mass transfer coefficients were evaluated from the breakthrough curves.     

活性炭纤维填充床内多组分竞争吸附

建立了活性炭纤维填充床内多组分竞争吸附传质动力学模型 ,采用正交配置方法求解数学模型以预测突破曲线 ,从理论上探讨了竞争吸附平衡及吸附质在填充床内的轴向弥散、纤维内扩散和纤维外对流传质等因素对强、弱吸附组分突破曲线的影响。在间歇和填充床吸附器内进行了脱除水溶液中酚类化合物的实验 ,测定了活性炭纤维吸附水溶液中苯酚和氯代苯酚的吸附等温线 (间歇吸附 )以及苯酚和氯代苯酚在活性炭纤维填充床内竞争吸附时的突破曲线 ,并与模型计算值进行了比较。结果表明 ,吸附质在活性炭纤维内扩散和纤维外对流传质阻力不是填充床内吸附过程的控制步骤 ,而轴向弥散影响显著 ,不可忽略     

凝胶型强酸型阳离子交换树脂分离阿卡波糖:平衡、动力学与热力学研究(英文)

Acarbose, a potentα-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001×4 was applied to isolate acarbose from fermentation broth. It was demonstrated that cation exchanger 001×4 displayed a large adsorption capacity and quick exchange rate for acarbose. The static adsorption equilibrium data were well fitted to the Langmuir equation. Column adsorption experiments demonstrated that high dynamic adsorption capacity was reached at bed height of 104.4 mm, feed flow rate of 1.0 ml·min-1 and acarbose concentration of 4.0 mg·ml-1. Under the optimized conditions, the column chromatography packed with cation exchanger 001×4 recovered 74.3%（by mass） of acarbose from Actinoplanes utahensis ZJB-08196 fermentation broth with purity of 80.1%（by mass）, demonstrating great potential in the practical applications in acarbose separation.     

Determination of adsorption and kinetic parameters for methyl acetate esterification and hydrolysis reaction catalyzed by Amberlyst 15

In this paper, the adsorption equilibrium constants, dispersion coefficients, and kinetic parameters were obtained for the liquid phase reversible reaction of methanol with acetic acid catalyzed by Amberlyst 15. The adsorption and kinetic parameters are determined corresponding to two different mobile phases, methanol and water. Such parameters are required for three different applications of the model reaction: namely, synthesis of methyl acetate, removal of dilute acetic acid from wastewater, and hydrolysis of methyl acetate. Experiments were conducted in a packed bed reactor in the temperature range 313–323 K using a rectangular pulse input. A mathematical model for a quasi-homogeneous kinetics was developed. The adsorption and kinetic parameters together with their dependence on temperature were determined by tuning the simulation results to fit the experimentally measured breakthrough curves of acetic acid, water (or methanol) and methyl acetate using a state-of-the-art optimization technique, the genetic algorithm. The mathematical model was further validated using the tuned parameters to predict experimental results at different feed concentrations and flow rates. The kinetics reported in this study was obtained under conditions free of both external and internal mass transfer resistance. The computed parameters were found to predict experimental elution profiles for both batch and plug flow reactors reasonably well.     

蛋白质的膨胀床吸附过程穿透模型分析

引　言膨胀床吸附技术是近十几年来出现的一种新型生物分离模式 .该技术集细胞碎片清除、料液浓缩和蛋白质纯化等步骤于一身 ,大大提高了目标产物收率 ,降低了纯化时间和费用 .自 1993年Streamline系列膨胀床吸附介质和装置问世以来 ,国外已有不少利用膨胀床吸附技术提取蛋白质的报道[1,2 ] .已有研究表明 ,料液特性、吸附剂粒径等对膨胀床的流体力学特性和蛋白质在膨胀床内的吸附行为有着不同程度的影响[3～ 5] .考察这些影响因素有助于加深对膨胀床层析行为的理解 ,指导膨胀床层析的优化设计 .然而 ,由于膨胀床层析过程的复杂性 ,众多因素相互作用 ,某一参数的改变往往引起操作参数的系统性变化 ,因此实验条件下考察单一参数的改变对膨胀床层析过程的影响是不现实的[5,6 ] .　　　前期研究表明 ,对不同黏度的缓冲液 ,穿透模型能够较准确的预测蛋白质的穿透行为 .因此 ,本研究在前期研究的基础上[4 ,7] ,利用穿透模型分析了膨胀床吸附过程的质量传递和流体力学特1　穿透模型该模型假设[4 ,5] :①吸附剂颗粒为球形 ,有均一的尺寸和密度 ,离子交换基团均匀地分布在颗粒内部 ;②床内径向不存在浓度梯度 ;...     

Effect of Temperature on Chiral Separation of Ketamine Enantiomers by High‐Performance Liquid Chromatography

Abstract

A semipreparative column packed with microcrystalline cellulose triacetate (MCTA) was used to separate ketamine enantiomers by high‐performance liquid chromatography (HPLC). The effect of temperature on the kinetics of mass transfer and equilibrium constants were evaluated by the moment analysis at 303, 313, and 323 K. Total porosity, bed porosity, and equilibrium constants were measured by the first moment. Pore diffusion and axial dispersion coefficients were evaluated by the second moment. It was observed that band broadening decreased with increasing temperature. The equilibrium constants were found to be greater than unity and decreasing with increasing temperature. The pore diffusion coefficients increased with increasing temperature and the main contribution to the band broadening was attributed to low mass transfer kinetics. The pore diffusion coefficients controlled the mass‐transfer process in MCTA column. These results may be used to the determination of operating conditions and computational simulation of a chromatographic separation in simulated moving bed unity.     

ADSORPTION OF ORGANICS FROM A TRUE IN-SITU OIL SHALE RETORT WATER ON ACTIVATED CARBON IN PACKED BEDS

The adsorption of a true in-situ oil shale retort water on activated carbon at 278 and 298 K was studied in batch experiments and in packed beds with continuous liquid flow. The isotherms were nonlinear over the liquid concentration 0 to 875 mg/1. Breakthrough curves were obtained in packed bed experiments as a function of bed length, particle size, and liquid velocity. A differential approach was used to calculate the mass transfer coefficients and the rates of adsorption. Also the breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.     

ADSORPTION OF ORGANICS FROM A TRUE IN-SITU OIL SHALE RETORT WATER ON ACTIVATED CARBON IN PACKED BEDS

The adsorption of a true in-situ oil shale retort water on activated carbon at 278 and 298 K was studied in batch experiments and in packed beds with continuous liquid flow. The isotherms were nonlinear over the liquid concentration 0 to 875 mg/1. Breakthrough curves were obtained in packed bed experiments as a function of bed length, particle size, and liquid velocity. A differential approach was used to calculate the mass transfer coefficients and the rates of adsorption. Also the breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.     

Optimal separation of n-paraffins from Kuwait kerosene using a molecular sieve adsorbent

A study has been made of the vapour-phase adsorptive separation of n-alkanes from Kuwait kerosene using zeolite molecular sieves (LMS-5A). The object was to identify the optimum operating conditions, in terms of flow rate, adsorption temperature and zeolite particle size for the separation of n-alkanes from kerosene, so that the remaining stock would also be of marketable quality. The effect of these conditions on the height of the mass transfer zone (HMTZ) and the dynamic capacity (Ad) of zeolite was also investigated. The adsorptive separation process comprised one cycle of adsorption using a fixed bed of zeolite type-5A. The bed was fed with kerosene vapour until equilibrium had been achieved, whereby the n-paraffins were adsorbed and the denormalized material excluded. The processes were carried out isobarically at one atmosphere. The optimum operating conditions were found to be a feed flow rate of 33.33 × 10^?9 m³ s^?1, an adsorption temperature of 643 K and a zeolite pellet fraction size of 1.0–2.0 × 10^?3m. This yielded an HMTZ value of 0.206 m and an Ad of 9.653 × 10^?2 kg n-paraffins kg^?1 zeolite. The data will serve as a basis for the design of commercial plant.     

变压吸附空分制氮过程的研究

建立了一套中试装置 ,对以商业炭分子筛为吸附剂的变压吸附 (PSA)空分制氮循环过程进行了系统研究 .用所建立的数学模型对相应实验进行模拟并将模型预测与实验数据进行比较 ,结果表明模型是可靠的 .     

Synthesis of the Biofuel Additive 1,1‐Diethoxybutane in a Fixed‐Bed Column with Amberlyst‐15 Wet

The synthesis of 1,1‐diethoxybutane (DEB) through the acetalization reaction between ethanol and butyraldehyde was studied in a fixed‐bed adsorptive reactor packed with Amberlyst‐15 wet. The miscibilities of reactants and water were evaluated and breakthrough experiments with nonreactive pairs of ethanol‐water and ethanol‐DEB were performed. The parameters of the isotherms were fitted by a Langmuir competitive model. Synthesis of the acetal was carried out with mixtures of ethanol and butyraldehyde at different molar ratios. The dynamic behavior of the fixed‐bed adsorptive reactor was described by a mathematical model developed taking into account the reaction kinetics, adsorption mechanisms, mass transfer resistances, and velocity variations.     

色谱扰动-响应法测定C_8芳烃的吸附和传递参数

本文对固定床长吸附柱,在不考虑其轴向弥散时,简化了固定床恒温物料衡算方程,引入传递函数,导出测算吸附和传递参数的方法.此方法采用色谱-响应技术,在固定床吸附实验设备上,测定了C_3芳烃异构体各组分的吸附和传递参数,取得与工业操作相近似条件下,C_8芳烃的吸附相平衡常数和总传质系数.     

Separation of glycyrrhizic acid from licorice root extract using macroporous resin

Glycyrrhizic acid (GA) is the major active ingredient of licorice which has many pharmacological activities. In the present study, separation of GA from licorice root extract has been carried out by adsorption on five different macroporous resins. Static and dynamic adsorption of GA from crude licorice root extract is studied on ion exchange resins followed by desorption. Indion 810 shows the maximum adsorption as well as desorption capacity. The adsorption experiments indicate that equilibrium can be achieved in 360 min. The adsorption equilibrium data is well fitted in the Langmuir isotherm. The separation process is optimized by investigating the effect of pH on adsorption capacity and effect of concentration of ethanol on desorption capacity. The dynamic adsorption is carried out in a column packed with Indion 810 resin and effect of feed flow rate and initial concentration of GA in extract has been studied. The results showed that increase in feed flow rate as well as initial feed concentration of GA lowers the dynamic binding capacity and mass transfer coefficient while increases the HETP. The purity of GA is increased from 14.3% to 71.5% by the dynamic desorption with 60% ethanol. Indion 810 resin can efficiently separate GA from licorice root extract with the HPLC recovery of 63.6%. This study forms the basis for large scale preparation of GA by resin adsorption.     

大孔吸附树脂HZ816对红霉素的固定床吸附过程研究

在上柱质量浓度为2.31—6.56 mg/mL、流量为14.33—42.80 mL/h的范围内研究了固定床吸附柱中大孔吸附树脂HZ816对红霉素的动态吸附过程,考察了原料液质量浓度和进口流量等操作参数对穿透曲线的影响。并采用基于液膜及孔内扩散模型的动力学模型,同时考虑吸附树脂颗粒内外扩散阻力及轴向扩散的影响,研究了固定床上红霉素在大孔吸附树脂中的吸附动力学,并从穿透曲线回归得到液膜传质系数孔内扩散系数。结果表明,在实验范围内,该模型能较好地描述红霉素在HZ816树脂上的吸附过程,由模型拟合得到的液膜传质系数随着原料液质量浓度减小而增大,随着流量升高而增大;孔内扩散系数随着原料液质量浓度增大而减小,随着流量升高而减小。为采用大孔吸附树脂HZ816吸附技术分离纯化红霉素工艺提供了实验和理论基础。     

Modelling of heavy metal adsorption into activated carbon from apricot stones in fluidized bed

The purpose of the present study is to investigate the behaviour of activated carbon from apricot stones (ACAS) in a closed circuit fluidized bed (CCFB) for removal of Pb, Cu, Cd and Zn ions from aqueous solution. The expansion characteristics of the bed are studied. A homogeneous solid phase diffusion model was used to describe the mass transfer inside the adsorbent particles. A piston-dispersion model was applied for the liquid phase in the bed and compared to the calculations, assuming perfect mixing conditions in the whole CCFB adsorber. The close correspondence between the experimentally determined adsorption in batch and fluidized bed operation modes support the observation that the CCFB can be described by a stirred batch adsorption model. The concentration profile at the bed exit is satisfactorily predicted by the model, thus confirming the equilibrium and kinetic parameters, determined from the laboratory batch adsorption runs.     

PERFORMANCE OF A PACKED-BED REACTOR

We examined the conversion rates in a packed bed catalytic reactor with a two phase upward flow in a wide range of operating conditions. The oxidation of ethanol to acetic acid in the liquid phase on a Pd-Alumina catalyst was chosen as the test reaction.

Global reaction rates were measured by changing gas velocities, temperature, and feed concentrations of ethanol in the liquid phase. The observed rates were compared with those calculated using two models, assuming a total external wetting of the catalyst. In the first model, a “kinetic” conversion rate was calculated by neglecting any interphase mass transfer resistance. In the second model the interphase mass transfer resistance was considered and expressed by an overall coefficient evaluated from published correlations. The results show that there is an hydrodynamic influence, probably due to the mass transfer and/or to the partial effective wetting of the catalyst. Mass transfer, on the other hand, is better than that observed in other cases. A comparison with the performances of a downflow trickle-bed reactor operating at the same tested conditions showed a much smaller influence of mass transfer and hydrodynamics on the overall conversion rate for the upflow reactor.     

沸石ZSM-5吸附回收低浓度煤层气中CH4

利用高硅疏水性沸石ZSM-5吸附回收低浓度煤层气中的甲烷,对其吸附平衡、吸附动力学以及真空变压吸附分离过程进行了理论和实验研究。通过重量法和穿透曲线法测定了CH₄/N₂单组分及双组分的竞争吸附平衡数据,并采用Multisite Langmuir吸附等温线模型对其进行拟合。结合CH₄和N₂稀释穿透曲线实验数据和等温无动量损失的双分散二级孔结构扩散模型,获得CH₄和N₂在沸石ZSM-5上的微孔扩散系数。建立并求解包含质量、动量及能量传递的固定床吸附分离模型方程,预测了CH₄和N₂在沸石ZSM-5上的竞争吸附穿透曲线。进一步采用ZSM-5吸附剂填充床单柱四步真空变压吸附实验考察了进料浓度、进料流速、进料时间以及吹扫比对分离效果的影响。结果发现沸石ZSM-5对CH₄具有较好的选择性,沸石晶粒内的微孔扩散为吸附速率控制步骤,真空变压吸附工艺可将模拟煤层气中20%的CH₄提纯至31%～41%,回收率为93%～98%。     

FLUIDIZED BED ADSORBER MODELLING AND EXPERIMENTAL STUDY

A mathematical model for adsorption in a batch fluidized bed is developed considering fluidized bed behaviour. A criterion is also developed to determine the validity of the proposed model. The unsteady state equation of the model is solved by assuming a non-linear equilibrium relationship. A simple procedure is also evolved to estimate back the parameters of the equilibrium relationship from simple batch experiments. Experiments are reported on the adsorption of moisture in air on silica gel for various air flow rates and bed mass. The best values for the parameters of the assumed equilibrium relationship are estimated. It is found that a unique set of values for these parameters predict the experimental results satisfactorily for the whole range of variables studied, thus proving the applicability of the proposed method of obtaining the equilibrium relationship and the proposed model.     

FLUIDIZED BED ADSORBER MODELLING AND EXPERIMENTAL STUDY

A mathematical model for adsorption in a batch fluidized bed is developed considering fluidized bed behaviour. A criterion is also developed to determine the validity of the proposed model. The unsteady state equation of the model is solved by assuming a non-linear equilibrium relationship. A simple procedure is also evolved to estimate back the parameters of the equilibrium relationship from simple batch experiments. Experiments are reported on the adsorption of moisture in air on silica gel for various air flow rates and bed mass. The best values for the parameters of the assumed equilibrium relationship are estimated. It is found that a unique set of values for these parameters predict the experimental results satisfactorily for the whole range of variables studied, thus proving the applicability of the proposed method of obtaining the equilibrium relationship and the proposed model.