压缩热再生干燥器活性氧化铝固体吸附剂的除湿性能

以活性氧化铝为吸附剂材料,选取5.5～6.5 mm及4～5 mm两种粒径的活性氧化铝对压缩空气进行除湿实验研究,为活性氧化铝在压缩空气除湿系统中的运行提供依据。结果表明：在温度120℃、压力0.2 MPa、流量40 m3/h的条件下,5.5～6.5 mm活性氧化铝的再生性能优于4～5 mm活性氧化铝;在温度120 ℃、压力0.7 MPa、流量15 m3/h的条件下,前期在1200 s时间内,两者的吸附速率都很快,后期4～5 mm粒径的活性氧化铝的吸附稳定性更好。在给定的工况条件下,5.5～6.5 mm活性氧化铝再生效果比4～5 mm活性氧化铝要好,但吸附效果不如后者。     

Carbon-based oxygen selective desiccants for use in nitrogen PSA

Techniques for the production of composite oxygen selective adsorbents are disclosed. These adsorbents are comprised of a carbon molecular sieve (CMS) which is kinetically selective for the adsorption of oxygen over nitrogen and an agent for the sorption of water such as LiCl or SiO₂. The adsorption properties of the composite adsorbents and results obtained from pressure swing adsorption (PSA) process testing are presented. The composite adsorbents improve the nitrogen PSA process performance (recovery and productivity) over the use of conventional desiccants which do not exhibit oxygen selectivity. Using a standard nitrogen PSA process cycle, replacement of conventional inorganic desiccants like alumina with the current CMS-based desiccants improved air recovery 2 to 4 percentage points and increased nitrogen productivity 15 to 20% at 70°F and a nitrogen purity of 99.5%.     

Thermal regeneration of spent coal‐based activated carbon using carbon dioxide: process optimisation,Methylene Blue decolorisation isotherms and kinetics

Spent coal‐based activated carbon from the silicon industry has been used as raw material for the regeneration of activated carbon, with carbon dioxide as the regenerating agent. The regeneration process was optimised using response surface methodology and the optimum regeneration conditions were: regeneration temperature 985 °C; regeneration time 120 min; and carbon dioxide flow rate of 600 ml/min. The iodine number and yield of the activated carbon obtained under the optimum regeneration conditions were 1071 mg/g and 67%, with a Brunauer–Emmet–Teller surface area of 1270 m²/g and pore volume of 0.91 cm³/g. The regenerated carbon was tested for the removal of Methylene Blue dyes. The maximum adsorption capacity was found to be 395 mg/g and the equilibrium data fitted to the Langmuir isotherm model. The kinetic data indicated that the best fit corresponds to the pseudo‐second‐order kinetic model.     

Trennen von Gasgemischen durch Adsorption

Separation of gas mixtures by adsorption . Gas mixtures are separated primarily by absorption and rectification. Rectification requires at least (v + 1)-fold of the enthalpy of the distillate as heat energy (v is the reflux ratio). In the case of absorption, the resulting solution is frequently subjected to thermal regeneration with the energy requirement depending inter alia on the boiling point of the solvent. In view of the high energy requirements of these processes and the development of new adsorbents, possibilities of separating by adsorption with subsequent regeneration of the adsorbents, above all by change in pressure, are investigated. The separation of gas mixtures in adsorber beds (e.g. molecular sieves, silica gel, activated charcoal and coke, or alumina) depend upon various separating effects: steric effects, equilibrium effects, kinetic effects. A survey is given of proposed and practical industrial separation processes utilizing adsorption.     

Adsorptive Separation of Entrained Di-Nonyl Phenyl Phosphoric Acid from Merchant Grade Phosphoric Acid by Activated Charcoal: Kinetic and Equilibrium Studies

The separation of entrained di-nonyl phenyl phosphoric acid (DNPPA) from merchant grade phosphoric acid (MGA) by adsorption on the coconut shell based activated charcoal has been carried out. The effect of various process parameters, such as DNPPA concentration in aqueous phase of MGA, equilibrium time, amount of activated charcoal and temperature upon adsorption capacity of activated charcoal has been studied. The results showed that the adsorption equilibrium was reached after 240 minutes. The adsorption phenomenon followed pseudo-second order kinetics. Adsorption of DNPPA increased with initial concentration of DNPPA in the range of 50 to 200 mg/L. The experimental data fitted well with the Freundlich isotherm model. Decrease in adsorption with increase in temperature suggests that the adsorption process is exothermic in nature. The value of enthalpy change (ΔH = ?35.52 kJ/mol) indicated that DNPPA adsorption on activated charcoal is a physisorption phenomenon. Column operation was carried out to obtain a breakthrough curve. Desorption of DNPPA with 10% NaOH yielded near quantitative regeneration of activated charcoal in three contacts.     

Removal of Lead (II) Ions from Aqueous Solution Using Eggplant Peels Activated Charcoal

The eggplant peel activated charcoal (EPPAC) was investigated as an adsorbent for the removal of lead II ions from aqueous solution. Three methods were tested for the production of eggplant peel activated charcoal (EPPAC) from eggplant peel charcoal (EPPC), yielding three different products; EPPAC-1, EPPAC-2, and EPPAC-3. The difference among the three methods lies in the primary physical mixing of the EPPC with the activating agent (potassium hydroxide) before heating the mixture in a furnace for activation. The removal efficiency of lead II ions by the three adsorbents was 57.7%, 70.0%, and 60.0% for EPPAC-1, EPPAC-2, and EPPPAC-3, respectively. The optimized activation parameters for EPPAC-2 were: activation time 2 hours, activation temperature 700°C, and activation ratio 1:2 (EPPAC: KOH). Scanning electron microscopy (SEM) revealed that EPPAC-2 has the most porous structure. The surface area of EPPAC-2 was measured to be 739 m²/g. Adsorption kinetics of lead (II) is best described by the pseudo-second-order kinetic model with second order rate constant of 1.70 × 10^?3 g/mg.h at room temperature. The adsorption of lead on EPPAC-2 is found to follow the Langmuir isotherm with a maximum adsorption capacity of 1.4 × 10² mg/g.     

Kinetics of zinc adsorption on charcoal

The kinetics of zinc adsorption on charcoal was carried out. In order to study the kinetics of adsorption various parameters were studied such as pH, particle size of charcoal, temperature, amount of charcoal as well as initial Zn²⁺ ion concentration. The adsorption kinetics followed a Freundlich adsorption isotherm. Good correlation of the theoretical and experimental equilibrium concentrations of Zn²⁺ ions was observed for the isotherm model. A mathematical model was developed to explain the kinetic data. The rate determining step for adsorption was found to be diffusion controlled.     

Effects of capillary condensation on adsorption and thermal desorption dynamics of water in zeolite 13X and layered beds

The effects of capillary condensation on the adsorption and thermal desorption dynamics of water in zeolite 13X beds and layered beds with zeolite 13X/silica gel or zeolite 13X/alumina were experimentally and theoretically studied. As the equilibrium isotherm of water on zeolite 13X pellet was found to be most favorable at a low relative humidity and indicated capillary condensation at a high relative humidity, it was possible to construct a non-isothermal model that included capillary condensation and that could successfully predict plateaus of temperature and concentration profiles in thermal regeneration. In adsorption breakthrough, by using a feed in the capillary condensation range of the isotherm on zeolite 13X, the breakthrough curve showed a shock wave in the low concentration and a proportionate pattern in the high concentration. In thermal desorption breakthrough, the desorbed water at the upper part of the bed was re-adsorbed at the lower part of the bed, and that re-adsorption mainly occurred in the capillary condensation range of the isotherm. Therefore, even though an adsorption was performed at a feed in the favorable range of the isotherm, and could be well predicted with type I isotherm, its desorption dynamics should be predicted by using the isotherm model with its consideration of capillary condensation. The layered bed with silica gel or alumina did not have any advantage over the zeolite 13X bed with respect to adsorption breakthrough performance. However, compared to the zeolite 13X bed, the complete regeneration time in the layered bed was drastically shortened due to a greater variation of the amount of equilibrium adsorption of water under temperature on both silica gel and alumina. In addition, since an increase in temperature led to a greater decrease of the amount of equilibrium adsorption of water on silica gel than on alumina, a layered bed with silica gel obviously could be regenerated more efficiently than a layered bed with alumina.     

快速,大量提纯C60的方法

介绍两种速，大量提纯Ｃ６０的方法：（１）采用复结晶及活性炭吸附、吸滤相结合的方法，得到纯Ｃ６０及Ｃ７０富集物；（２）采用中性氧化铝－活性炭／硅胶层吸滤法制备纯Ｃ６０。     

水蒸气活化再生乙酸乙烯合成触媒载体活性炭

探讨了活化温度、活化时间、水蒸气流量对再生后活性炭吸附性能和得率的影响,得到了最佳工艺条件:活化温度1 000℃,活化时间60 min,水蒸气流量2.23 g/min。该工艺条件下再生活性炭的碘吸附值1 174.37 mg/g,亚甲基蓝吸附值200 mL/g,得率为62.87%。再生后活性炭的吸附指标达到国家一级品的标准,其中亚甲基蓝吸附值是国家一级品标准的2.22倍。同时,测定了该活性炭氮吸附,通过BET计算了活性炭的比表面积,通过密度函数理论(DFT)表征了活性炭的孔结构。结果表明:该活性炭为微孔型,BET比表面积为1 254.51 m2/g,总孔容为0.592 6 mL/g。     

Influence of regeneration conditions on the cyclic performance of amine-grafted mesoporous silica for CO2 capture: An experimental and statistical study

This work deals with the behavior of amine-grafted mesoporous silica (referred to as TRI-PE-MCM-41) throughout adsorption–desorption cycles in the presence of 5% CO₂/N₂ using various regeneration conditions in batch experiments. The criteria proposed to determine the optimum regeneration conditions are the working adsorption capacity, the rate of desorption and the change of adsorption capacity between consecutive cycles. Using a 2³ factorial design of experiments, the impact on the performance of the adsorbent of different levels of temperature, pressure, and flow rate of purge gas during desorption was determined. It was found that all the parameters under study have a statistically significant influence on the working adsorption capacity, but only temperature is influential with respect to desorption rate. Regeneration using temperature swing was found to be attractive, as the highest CO₂ adsorption capacity (1.95 mmol g^?1) and the fastest desorption rate (9.82×10^?4 mmol g^?1 s^?1) occurred when desorption was carried out at 150 °C. However, if vacuum is applied, regeneration can be achieved at a temperature as low as 70 °C with only a 13% penalty in terms of working adsorption capacity. It was also demonstrated that under the proper regeneration conditions, TRI-PE-MCM-41 is stable over 100 adsorption–desorption cycles.     

Adsorption Decontamination of Radioactive Waste Solvent by Activated Alumina and Bauxites

Abstract

An adsorption process utilizing activated alumina and activated bauxite adsorbents was evaluated as a function of operating parameters for the removal of low level radioactive contaminants from organic waste solvent generated in the fuel reprocessing facilities and support operations at Savannah River Site. The waste solvent, 30 vol% tributyl phosphate in n-paraffin diluent, was degraded due to hydrolysis and radiolysis reactions of tributyl phosphate and n-paraffin diluent, producing fission product binding degradation impurities. The process, which has the potential for removing these activity-binding degradation impurities from the solvent, was operated downflow through glass columns packed with activated alumina and activated bauxite adsorbents. Experimental breakthrough curves were obtained under various operating temperatures and flow rates. The results show that the adsorption capacities of activated alumina and activated bauxite were in the order of 10⁴ and 10⁵ dpm/g of adsorbent, respectively. The performance of the adsorption process was evaluated in terms of dynamic parameters (i.e., adsorption capacity, the height and the efficiency of adsorption zone) in such a way as to maximize the adsorption capacity and to minimize the height of the mass transfer or adsorption zone.     

Surfactant‐Enhanced Carbon Regeneration in a Vapor‐Phase Application

Abstract

Coal‐based granular activated carbon (GAC) is saturated with trichloroethylene (TCE) by passing air through a fix bed adsorber. In surfactant‐enhanced carbon regeneration, an aqueous solution of anionic surfactant, sodium dodecyl sulfate (SDS), is passed through the bed to induce desorption of TCE. More than 95% of the sorbed TCE was removed in the desorption operation with a 0.1 M SDS solution at a superficial flow rate of 1 cm/min. The desorption rate of TCE from pores of GAC is limited by pore diffusion and not significantly affected by either the concentration of SDS in the regenerant (when well above the critical micelle concentration) or its flow rate. From the breakthrough curve of a subsequent adsorption cycle without a flushing step following the desorption, only 7% of the virgin carbon effective adsorption capacity is observed for the regenerated carbon. With a water flushing step following the regeneration step, the effective adsorption capacity is significantly improved to about 15% of that of virgin carbon. Increased temperature of the flushing water also enhances the effective adsorption capacity of the regenerated GAC. Separate batch adsorption‐desorption isotherms of SDS on GAC support the enhanced desorption of SDS at elevated temperatures. The drastic reduction in the effective adsorption capacity of regenerated GAC results from the residual SDS remaining in the pores of GAC as confirmed by thermal gravimetric analysis. Both the regeneration and water flush steps are rate limited under conditionsused here.     

Non-destructive measurement of residual adsorption capacity of charcoal filters

A non-destructive method has been developed to measure the residual adsorption capacity (RAC) of charcoal filter beds while in use. A small sample of a weakly adsorbed gas is pulsed as a square wave into the gas stream that passes through the adsorption filter. The effluent pulse is detected by means of an appropriate detector. The RAC of the carbon bed is proportional to the retantion time of the gas. The filter is an adsorption bed that behaves as a gas-solid Chromatograph, and only bare sites, not covered by heavy adsorbate, are available to the pulsed gas. The system chosen was M-11 gas mask canisters containing 2.8 cm × 87 cm² ASC Whetlerite charcoal beds loaded to various degrees with highly polar dimethyl methyl phosphonate (DMMP), which simulated a strongly adsorbed pollutant. 10 cm³ aliquots of non-polar test gases methane and ethane were pulsed into a stream of dry air, at flow velocities of 5.47 l./min (1.05 cm/sec) and bed temperature of 25°C.The retention times of CH₄ dropped from 0.9 min over bare ASC Whetlerite to 0.5 min over carbon 50% saturated with DMMP. Ethane times fell from 24 to 7 min. The accuracy of RAC determination using methane was ± 1.0%. The time required for the test was < l min for methane, < 30 min for ethane.     

新型高效复合吸附剂开发及系统仿真

针对一种新型高效复合吸附剂开展了吸附性能实验研究,并假想将该复合吸附剂装填于一固体吸附式空调样机吸附床内进而开展仿真研究。对比研究表明该复合吸附剂不但具有比硅胶强得多的吸附能力,而且再生温度较低。装填该复合吸附剂的吸附式空调不但可以获得比装填纯硅胶时高得多的比制冷功率SCP,而且系统性能系数COP也明显高于纯硅胶系统。     

A novel cartridge type powder feeder

In the present work, a novel cartridge type powder feeder is developed by applying ‘subliminal fluidization’, which is defined as partial aeration to the bed below minimum fluidization, but only for a limited region above the distributor, and by discharging solids together with the air through the tube located at the centre of the distributor. The distinct advantage of cartridge type feeder developed in this work lies in its simplicity of construction and operation giving quite an advantage for particulate material handling, transportation and metric feeding.Temporal solid efflux rates were measured for charcoal of mean sizes 220, 290 and 430 μm, glass beads of 265, 535 and 930 μm and spherical activated alumina (Neo beads) of 145 and 595 μm and density in the range of 1250 to 2500 kg/m³. Temporal flow rates of solids indicated that the solids efflux was independent of time and amount of material inside the bed and was only determined by the air supply from the distributor plate. Solids efflux rate was found to decrease with increased particle size and internal friction and reduced fluidization air flow rate. Solids efflux was found to vary slightly with the change in air humidity. A dimensionless correlation for solids efflux was developed as a function of fluidization number and the internal friction angle.     

Preparation of activated carbon from olive mill solid residue

A process was developed for producing high quality activated carbon from Algerian mill waste. The solid olive mill residue was carbonized at 800 °C and physically activated with CO₂, air or steam. An optimum activation temperature of about 850 °C was determined for all the activation agents used. Steam appeared to be the most efficient activator as compared with air and CO₂. An optimal activation time of about 2 h was then determined with steam as the optimum activation agent. The porous structure of the activated carbon was characterized by nitrogen adsorption at −196 °C, and in all cases the surface areas, calculated by DR and BET methods, confirmed the production of a material with good microstructural characteristics and specific surfaces exceeding 1500 m² g⁻¹ for the carbon prepared by steam activation. Phenol adsorption isotherms gave the adsorption properties and the adsorption capacity of about 11.24 mg of phenol per gram of the activated carbon produced. The kinetics of the phenol adsorption onto the porous material was evaluated by means of two models: the external resistance model and the linear model. The second model appeared to constitute a more appropriate fit for the experimental data. © 2000 Society of Chemical Industry     

Bio‐Regeneration of Desulfurization Adsorbents by Selected P. delafieldii R‐8 Strains

Abstract

Adsorption properties of different adsorbents such as reduced NiY, AgY, alumina, 13X, and activated carbon were studied with dibenzothiophene (DBT) and naphthalene as model compounds. The desorption of DBT was carried on thermo gravimetric–differential thermal analysis (TG‐DTA). The interaction of DBT with different adsorbents follows the sequence: activated carbon > reduced NiY > AgY > activated alumina > 13X. The bio‐regeneration of these adsorbents was studied with P. delafieldii R‐8 as desulfurization strains. Adding P. delafieldii R‐8 cells can improve DBT desorption from adsorbent AgY. The desorption of DBT from adsorbents by bio‐regeneration of adsorbents follows the sequence: 13X > alumina > AgY > reduced NiY>activated carbon. The presence of naphthalene can decrease the desorption of sulfur compounds. The adsorption capacity of AgY decreases for the first time recycling and then changes little. The decrease of the adsorption capacity is due to the loss of Ag⁺ ions.     

The rate of gas adsorption by activated carbon

A study was made of the rate of gas adsorption by activated carbon in terms of the functional dependence of the pseudo first order adsorption rate constant. Benzene was used as the adsorbate vapor and a packed bed column of a Pittsburgh activated carbon as the adsorbent. Benzene at a concentration of 2 × 10^?6 g/cm³, equivalent to a relative pressure of 0·005 at 25°C, was flowed into the carbon bed at superficial linear velocities ranging from 2 to 50 cm/sec. The time at which 1% of the inlet concentration appeared in the exit stream of the bed was the breakpoint time. By applying the Wheeler adsorption kinetic equation to the experimental plot of breakpoint time vs bed weight pseudo first order adsorption rate constants at various linear velocities were determined. Using a presumed mathematical model and an overdetermined set of six equations the Univac 1108 computer provided the coefficients for an expression showing the dependence of the adsorption rate constant on the linear flow velocity.     

Production of the fungal exopolysaccharide scleroglucan by cultivation of Sclerotium glucanicum in an airlift reactor with an external loop

Sclerotium glucanicum NRRL 3006 was cultivated in a 120 dm³ working volume airlift reactor with external recirculation loop for the production of the exopolysaccharide (EPS), scleroglucan. When culture pH was not controlled EPS production, at a range of air flow rates, was poor (<2 kg m^?3). Biomass formation generally increased with increasing aeration rate. When culture pH was controlled at 4·5 ± 0·2 EPS production was maximal at an air flow rate of 100 dm³ min^?1 and fell as air flow rate decreased. Operation of the reactor at a high (100 dm³ min^?1) air flow rate for the early part of the process (up to 96 h), followed by a low air flow rate (20 dm³ min^?1), led to reduced biomass and oxalate formation, and a slight increase in EPS concentration relative to operation at a constant air flow rate of 100 dm³ min^?1. EPS production in this pneumatically-agitated reactor was equal to the highest levels reported in small-scale stirred tank reactors.