吸附法回收柠檬酸

用静态吸附法测定了四种大孔吸附树脂对柠檬酸的最大吸附量，用间歇法测定了不同温度下的吸附等温线，并筛选出一种最适宜的树脂进行了动态测试。用固定床吸附模型模拟了吸附动态过程。计算值与实验值基本符合。     

Theoretical and experimental SO2 adsorption onto pistachio-nut-shell activated carbon for a fixed-bed column

The adsorption and desorption behaviours of SO₂ onto activated carbons, which were prepared from pistachio-nut shells, were studied theoretically and experimentally in a fixed-bed column. A mathematical model considering non-equilibrium, non-isothermal and non-adiabatic effects for a single gas adsorbate on a fixed-bed system was derived and the model was solved by a finite-difference method. A linear driving force (LDF) approximation is used for heat and mass transfer rates. The temperature-dependent Langmuir equilibrium isotherm is used to represent gas–solid equilibrium isotherm. The theoretical study was conducted to compare the present model with the isothermal and adiabatic model. The effects of inlet concentration, flow rate and temperature were studied experimentally. These experimental data showed that the breakthrough time decreased with increasing feed concentration, increasing flow rate and increasing temperature and the trends were correctly predicted by the model calculations.     

Dynamic Adsorption of CO2 from Methane: Studies on Mass and Heat Transfer

Three‐dimensional computational fluid dynamics studies related to dynamics adsorption of CO₂ from natural gas is found to be limited. 3D analyses for dynamics adsorption are substantially crucial to give a better prediction on the adsorption process by considering the actual fluid flow behavior within the packed‐bed porous media. A kinetic adsorption model has been integrated in a commercial fluid dynamics simulator to simulate the 3D hydrodynamics and adsorption phenomenon in a zeolite‐filled packed column for a CO₂‐methane separation system. The effects of various parameters such as Reynolds number, CO₂ feed concentration, feed temperature, and column dimension on CO₂ adsorption efficiency have been investigated. A correlation for adsorption efficiency based on the CO₂ concentration profiles has been developed and validated.     

混合气组分对CO在稀土复合吸附剂上吸附的影响

采用吸附柱动态实验装置,分别考察了混合气组分H2O、CO2、CH4对稀土复合吸附剂变压吸附CO的影响。实验结果表明,原料气中微量的H2O的存在对稀土复合吸附剂的吸附性能有较大影响,当水质量浓度仅为250mg/L时,CO的变压吸附量下降约35％;与CO相比,CO2在稀土复合吸附剂上为弱吸附组分,但对CO的吸附性能有一定影响,当CO2体积分数为1％时,CO的变压吸附量可维持在12.5 ml/g左右;而CH4的存在对CO在稀土复合吸附剂上的吸附量影响不大。     

A novel slurry bubble column membrane reactor concept for Fischer–Tropsch synthesis in GTL technology

Fischer–Tropsch synthesis (FTS) plays an important role in the production of ultra-clean transportation fuels, chemicals, and other hydrocarbon products. In this work, a novel combination of fixed-bed and slurry bubble column membrane reactor for Fischer–Tropsch synthesis has been proposed. In the first catalyst bed, the synthesis gas is partially converted to hydrocarbons in a water-cooled reactor which is fixed bed. In the second bed which is a membrane assisted slurry bubble column reactor, the heat of reaction is used to preheat the feed synthesis gas to the first reactor. Due to the decrease of H₂/CO to values far from optimum reactants ratio, the membrane concept is suggested to control hydrogen addition. A one-dimensional packed-bed model has been used for modeling of fixed-bed reactor. Also a one-dimensional model with plug flow pattern for gas phase and an axial dispersion pattern for liquid-solid suspension have been developed for modeling of slurry bubble column reactor. Proficiency of a membrane FTS reactor (MR) and a conventional FTS reactor (CR) at identical process conditions has been used as a basis for comparison in terms of temperature, gasoline yield, H₂ and CO conversion as well as selectivity. Results show a favorable temperature profile along the proposed concept, an enhancement in the gasoline yield and, thus a main decrease in undesirable product formation. The results suggest that utilizing this type of reactor could be feasible and beneficial. Experimental proof of concept is needed to establish the validity and safe operation of the proposed reactor.     

Applying Reaction Kinetics to Pseudohomogeneous Methanation Modeling in Fixed-Bed Reactors

Reactor simulations can reduce the effort when designing fixed-bed reactors for methanation processes. Several microkinetic models were developed under a variety of operating conditions. However, most production-scale fixed-bed methanation processes exceed the temperature range in which these kinetic models were obtained. In addition, heat and mass transport limitations strongly influence the reaction kinetics. In this work, microkinetic rate equations for CO and CO₂ methanation were analyzed with respect to their suitability for high-temperature, pseudohomogeneous reactor modeling. The best-suited kinetic model was fitted to the operating conditions and validated by means of CFD simulations. It is shown that the simulations match the experimental data for various operating conditions.     

动态离子交换法处理电子行业蚀刻含铝废酸工艺研究

大屏幕液晶显示器和集成电路等微电子工业的湿法蚀刻和湿法清洗工艺以电子级磷酸为原料,会产生大量含铝离子的磷酸废液。用阳离子交换树脂（Zminw-0705）对该磷酸废液在动态情况下做了处理,研究了动态情况下设备参数和操作参数对吸附效果的影响。采用傅里叶红外光谱法和X射线光电子能谱对吸附前后的树脂做了表征,验证了吸附反应的发生。用模型对动态吸附过程做了拟合,实际吸附量与理论吸附量比较接近,相关系数均在0.92以上。结果表明：在其他条件相同的情况下,150∶8为离子交换柱适宜长径比;适宜温度范围为45~55 ℃;适宜进料流速为4.67 mL/min;废酸的磷酸浓度和铝离子也在适合的操作范围内。     

Adsorption separation of raffinose from sucrose by activated carbon: Equilibrium,kinetics and dynamic breakthrough

Separation of oligosaccharides with a varied number of monosaccharides is an important issue in food chemistry. Raffinose, a functional oligosaccharide, has attracted increasing attentions due to its strong proliferative effect on bacteria. Industrially, cottonseed meal is an important resource for producing raffinose; however, raffinose extracted from the cottonseed meal contains a significant amount of sucrose that debases raffinose’s quality. In this work, an adsorptive separation of raffinose and sucrose on activated carbon was reported. Adsorption isotherms, adsorption kinetics and dynamic column adsorption–desorption were investigated. The activated carbon chosen has a significantly higher adsorption capacity of raffinose (0.60~0.65 g/g) than sucrose (0.35~0.40 g/g) at the equilibrium concentration studied (~35 g/L) and temperature from 293 K to 333 K. Adsorption isotherms and kinetics were fitted by the Freundlich isotherm model and the pseudo-second-order model, respectively. The effect of flow-rate and initial feed concentration on dynamic adsorption were investigated; meanwhile, the separation performance was further confirmed from dynamic desorption using aqueous ethanol of 20% as eluant. Remarkably, raffinose with purity over 90% and recovery of 79.2% could be obtained by the adsorption–desorption cycle using an aqueous feed solution containing 20 g/L of raffinose and 6 g/L of sucrose.     

Development of design charts for fixed-bed adsorption

A mathematical model of the dynamic behaviour of non-isothermal fixed-bed adsorbers has been developed which takes into account the various mass and heat transfer resistances. Comparison of experimental and simulated results confirms that the model can predict the adsorption and desorption breakthrough curves of an adiabatically operated column, using only equilibrium data and tortuosity factors obtained from single pellet experiments. A simplified model with a reduced number of parameters was derived by investigation of the dimensionless transfer parameters under industrial conditions. It becomes evident that the main transfer mechanisms are convective heat and mass transfer in the bulk flow and diffusion within the pores of the particle. Dimensionless effluent concentration is expresses in terms of dimensionless time, a transport parameter, a non-isothermal parameter, the adsorption equilibrium and the inlet and initial concentrations and temperatures in the simplified model. For a chosen system of adsorbate and adsorbent, design charts can be developed by computer simulation, to determine graphically the breakthrough time as a function of significant process parameters, i.e. the dimensionless transfer parameter and the feed concentration.     

Protein adsorption in two-dimensional electrochromatography packed with superporous and microporous cellulose beads

Anion-exchange superporous cellulose (DEAE-SC) and microporous cellulose (DEAE-MC) adsorbents were packed in an electrochromatographic column, and the effect of external electric field (eEF) on the dynamic adsorption was investigated. The column was designed to provide longitudinal, transverse or 2-dimensional (2D) eEF. It was found that the electro-kinetic effect caused by the introduction of an electric field played an important role in the dynamic adsorption of bovine serum albumin to the adsorbents. The dynamic binding capacity (DBC) in the presence of 2D eEF was higher than in the presence of a one-dimensional eEF. The effect of flow velocity on the DBC of the two adsorbents was also demonstrated. It was found that the effect of electric field on the DEAE-MC column was more remarkable than that on the DEAE-SC column at the same flow rate, whereas the DEAE-SC column showed higher DBC and adsorption efficiency (AE) than the DEAE-MC column. With increasing flow rate, the DEAE-SC column could still offer high DBC and AE in the presence of the 2D eEF. For example, a DBC of 21.4 mg/mL and an AE of 57.7% were obtained even at a flow rate as high as 900 cm/h. The results indicate that the 2D electrochromatography packed with the superporous cellulose adsorbent is promising for high-speed protein chromatography.     

Batch and continuous (fixed-bed column) biosorption of Cu(II) by Tamarindus indica fruit shell

The feasibility of employing Tamarindus indica (tamarind) fruit shell (TFS) as low-cost biosorbent for removal of Cu(II) from aqueous solutions was investigated. Batch experiments were carried out as function of initial solution pH (2–7), contact time (10–240 min), initial Cu(II) concentration (20–100 mg L^?1), biosorbent dose (0.5–5 g) and temperature (293–313 K). Biosorption equilibrium data were well described by the Langmuir isotherm model with maximum biosorption capacity of 80.01 mg g^?1 at 313 K. Biosorption of Cu(II) followed pseudo-second-order kinetics. Gibbs free energy (ΔG⁰) was spontaneous for all interactions, and the biosorption process exhibited endothermic enthalpy values. To ascertain the practical applicability of the biosorbent, fixed-bed column studies were also performed. The breakthrough time increased with increasing bed height and decreased with increasing flow rate. The Thomas model as well as the Bed Depth Service Time (BDST) model was fitted to the dynamic flow experimental data to determine the column kinetic parameters useful for designing large-scale column studies. The Thomas model showed good agreement with the experimental results at all the process parameters studied. It could be concluded that TFS may be used as an inexpensive and effective biosorbent without any treatment or any other modification for the removal of Cu(II) ions from aqueous solutions.     

Experimental study and modelling of an azo colourant dynamic adsorption onto functional cross-linked chitosan/ceramic particles in a fixed bed column

The use of azo dyes in industrial activities generates a large volume of contaminated wastewater; these pollutants in water bodies affect aquatic biota and human health. A functional biocomposite sorbent material was synthesized using cross-linked chitosan with oxalic acid that forms a coating on alumina ceramic particles (AOCh). The removal of Reactive Red 195, a reactive azo dye, using a fixed-bed adsorption column filled with this material was tested. AOCh was physico-chemically characterized by Fourier transform infrared spectroscopy–total attenuated reflection (FTIR-ATR), scanning electron microscopy–energy dispersion spectrometry X-ray (SEM-EDS), X-ray diffraction (XDR), thermo-gravimetric analysis (TGA), and Z-potential. The dynamic adsorption performance was analyzed from experimental breakthrough curves obtained in fixed-bed columns by modifying different operating conditions (bed depth, volumetric flow rate, and dye inlet concentration). Equilibrium adsorption isotherms were determined under dynamic conditions and compared with batch results. The maximum adsorption capacity of the dynamic equilibrium isotherm obtained from the continuous assays was 331 mg/g; this value was the highest in comparison to other tested materials reported in the literature. Different dynamic adsorption models were applied to fit experimental data, including Thomas, Bohart–Admas, Yoon–Nelson, logistic general model, bed depth surface time (BDST), and modified dose response (Yan) models. A critical analysis of these equations was presented, showing the equivalences and the relationship among the coefficients. The Yan model achieved the highest level of agreement between the experimental and predicted values of the breakthrough curves. The use of this model enables scaling-up the industrial process for dye removal. The present work proposed a novel biosorbent material and contributes to the analysis of industrial dye removal under dynamic conditions.     

固定床不同床深下的米格列醇离子交换性研究

为考察米格列醇在固定床树脂不同堆积高度下的离子交换吸附行为,采用称量不同量的D001树脂装入离子交换柱中,通过固定床堆积高度的改变,在上样液流速和浓度固定前提下研究米格列醇溶液与树脂间的离子交换规律性,并结合床深服务时间(BDST)模型对此条件下固定床透过曲线进行分析评价。结果表明:固定床堆积高度的增加,提高了树脂与米格列醇溶液间的接触时间和树脂总的可交换离子数,有利于离子交换过程的进行,树脂的吸附质量和吸附率都得到了相应提高,堆积高度的增加使饱和点时间变长,吸附效率变小;对固定床透过曲线进行BDST模型拟合分析,结果表明:该模型与实验值间具有很高的相关系数,计算的相关参数间差异很小,对于该离子交换体系,表明BDST模型能很好地应用于该体系的离子交换吸附过程。     

Dynamic behaviour of an adiabatic adsorption column—I Analytic solution for irreversible adsorption

A simple theoretical model, based on the rectangular isotherm approximation, is shown to provide a good representation of the dynamic behaviour of an adiabatic adsorption column. The model provides an analytic expression for the dynamic temperature response in terms of the usual kinetic and equilibrium parameters and it is shown that within the constant pattern regime the relationship between the concentration and temperature profiles assumes a very simple form. The magnitude of the temperature rise depends on the relative velocities of thermal and concentration waves as well as the heat of adsorption and sorbate concentration. The maximum temperature rise occurs when the velocities of the temperature and concentration fronts are indentical. Under these conditions there is no temperature plateau and the magnitude of the thermal wave increases continuously as the adsorption front progresses through the bed.Experimental data for the adiabatic adsorption of moisture from an air stream are presented and discussed in relation to the theory.     

Effects of non-ideal adsorption equilibria of gas mixtures on column dynamics

A theoretical study has been made for simulating the dynamic behavior of non-ideal gas mixtures in an isothermal fixed-bed adsorber. A mathematical model was developed which takes into account the non-ideality of adsorbable species on the adsorbed phase under equilibrium. The model is based on both the real adsorbed solution theory (RAST), which incorporates the activity coefficients in the multicomponent isotherm equations to account for the deviations from ideality, and the linear driving force (LDF) model for representing diffusion resistance inside the adsorbent particles. To describe the effect of non-ideal adsorption equilibrium of gas mixtures on the breakthrough curves, we considered several model mixtures of binary and ternary components which exhibit non-ideal behavior with azeotropic crossovers in the composition domains at equilibrium. Sample calculations of a fixed-bed adsorption were done with various inlet gas compositions of binary and ternary mixtures, respectively, at a fixed total concentration. From the calculation results, it was shown that the order of breakthrough curves could be changed at a certain value of inlet gas composition ratio. This result implies that the dynamic behaviors of fixed-bed adsorption are greatly influenced by multicomponent equilibrium models. Furthermore, the reversal phenomenon of breakthrough curves could not be simulated by the ideal adsorbed solution theory (IAST).     

Preparation of Fe-Mn/K/Al2O3 Fischer-Tropsch Catalyst and Its Catalytic Kinetics for the Hydrogenation of Carbon Monoxide

A K promoted iron-manganese catalyst was prepared by sol-gel method, and subsequently was tested for hydrogenation of carbon monoxide to light olefins. The kinetic experiments on a well-characterized Fe-Mn/K/Al₂O₃ catalyst were performed in a fixed-bed micro-reactor in a temperature range of 280-380 ℃, pressure range of 0.1-1.2 MPa, H₂/CO feed molar ratio range of 1-2.1 and a space velocity range of 2000-7200 h^-1. Considering the mechanism of the process and Langmuir-Hinshelwood-Hogan-Watson (LHHW) approach, unassisted CO dissociation and H-assisted CO dissociation mechanisms were defined. The best models were obtained using non-linear regression analysis and Levenberg-Marquardt algorithm. Consequently, 4 models were considered as the preferred models based on the carbide mechanism. Finally, a model was proposed as a best model that assumed the following kinetically relevant steps in the iron-Fischer-Tropsch (FT) synthesis: (1) CO dissociation occurred without hydrogen interaction and was not a rate-limiting step; (2) the first hydrogen addition to surface carbon was the rate-determining steps. The activation energy and adsorption enthalpy were calculated 40.0 and -30.2 kJ·mol^-1, respectively.     

Dynamic Behavior of a PEM Fuel Cell During Electrochemical CO Oxidation on a PtRu Anode

The dynamic behaviour of a single PEM fuel cell (PEMFC) with a PtRu/C anode catalyst using CO containing H₂ as anode feed was investigated at ambient temperature. The autonomous oscillations of the cell potential were observed during the galvanostatic operation with hydrogen anode feed containing CO up to 1000 ppm. The oscillations were ascribed to the coupling of the adsorption of CO (the poisoning step) and the subsequent electrochemical oxidation of CO (the regeneration step) on the anode catalyst. The oscillations were dependent on the CO concentration of the feed gas and the applied current density. Furthermore, it was found that with CO containing feed gas, the time average power output was remarkably higher under potential oscillatory conditions in the galvanostatic mode than during potentiostatic operation. Accompanying these self-sustained potential oscillations, oscillation patterns of the anode outlet CO concentration were also detected at low current density (<100 mA/cm²). The online measurements of the anode outlet CO concentrations revealed that CO in the anode CO/H₂ feed was partially electrochemically removed during galvanostatic operation. More than 90% CO conversion was obtained at the current densities above 125 mA/cm² with low feed flow rates (100–200 mL/min).     

多组分吸附过程的吸附速率模型

Three adsorption rate models are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intraparticle concentration profile. Models I and Ⅱ are obtained from the parabolic concentration layer approximation. Examples are presented to demonstrate the usage and accuracy of these models. It is shown that Model I is suitable for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed adsorption processes while the LDF model should not be used in batch adsorption and may be considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.     

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.     

表面活性素集成生产过程(Ⅲ)吸附柱的模型

The study is focused on modeling of separation process and optimization.An adsorption separation process is simulated.The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption in a fixed-bed column packed with commercial active carbon is studied in laboratory.The adsorption column achieves high surfactin recovery(94%)by up-flow methanol elution at 25°C.The adsorption column is simulated with a complex one-dimensional plug flow dispersion model coupled with nonlinear adsorption equilibrium,based on the assumption that the adsorption of surfactin is monomolecular layer and no micelle is formed.The molecular diffusion coefficient of surfactin in water solution with electric neutrality is estimated to be 0.428×10 -5 cm 2 ·s -1 by molecular dynamics simulation.The model developed can describe the complex interplay of adsorption kinetics,fluid dynamics,and mass-transfer phenomena based on the assumption of no radial temperature and concentration gradients,and is of adequate precision.The work involved in this paper is valuable for the optimization of the production process of surfactin.