汽油饱和蒸气吸附用活性炭的制备

以煤为原料,KOH为活化剂制备活性炭。建立了静态吸附装置,并通过该装置研究了90#汽油在不同活性炭样品上的吸附性能。在制备过程中,考察了碱炭比、活化温度、活化时间对活性炭吸脱附性能的影响。研究发现,常温常压下活性炭对汽油饱和蒸气的吸附性能受多个参数的影响,其中BET比表面积影响最大,另外较大的孔、较宽的孔径分布,有利于脱附。同时得到最优的制备条件,碱炭比为5：1、活化温度800℃、活化时间1h。     

Moisture sorption isotherm of fresh lean beef and external beef fat

The moisture sorption isotherm (MSI) of lean beef and fat beef was experimentally determined. The experimental procedure used was that of the COST 90 project with some modifications to accelerate equilibration. The procedure was validated with the standard reference material microcrystalline cellulose. The MSI of the beef at the highest humidity range was obtained by accelerating equilibration with changes of salts, using a low water activity salt for some time. This procedure was reliable for beef samples but not for the fat samples. No significant changes were found for lean beef in the temperature range 5–40 °C. Three models, GAB, Peleg and Lewicki, were used to fit the experimental data. The best fit was obtained with the GAB equation. The fat MSI was determined at 5, 15 and 25 °C and it was best fitted with the Lewicki model.     

Regeneration von mit Ammoniak beladenem Klinoptilolith durch ein nicht‐thermisches Plasmaverfahren

Adsorbents are widely‐used in the area of cleaning as well as enrichment of gas components. For the regeneration of clinoptilolite loaded with ammonia, a packed‐bed reactor was developed on the basis of a dielectric barrier discharge. It was proved that adsorbed NH₃ is released at relatively low temperature and low energy consumption. For the further optimization of the method the influence of the power and the pulse break ratio of sustaining voltage were tested. It was shown that with the chosen plasma method the absorber material was loaded repeatedly and subsequently regenerated.     

TRAPPING SKINNING IN POLYMERS: THEORETICAL PREDICTIONS

During the desorption of certain saturated polymer films, a thin skin of glassy polymer can form at the exposed surface. Not only does this inhibit desorption, but also trapping skinning, in which an increase in the desorption driving force decreases the accumulated flux, can occur, These behaviors cannot be described by a simple Fickian flux. A theoretical framework is presented for modeling such a system. It is shown that though increasing the driving force will increase the instantaneous flux, the time of accumulation will decrease, thus reducing the accumulated flux. In addition, the model is shown to exhibit sharp fronts moving initially with constant speed, another distinctive feature of non-Fickian polymer-penetrant systems.     

DESORPTION OF ETHYL ACETATE-WATER MIXTURE BY USING CROSS-LINKED POLY(VINYLALCOHOL) MEMBRANE AND COMPARISON OF RESULTS WITH PERVAPORATION

In this study using poly(vinylalcohol) (PVOH) membranes cross-linked with tartaric acid (Tac) desorption experiments were performed for selected concentrations of binary ethyl acetate (EtAc)-water mixture at temperatures of 30°, 40°, and 50°C to determine sorption of components. Sorption values measured were compared with those estimated by the Flory-Huggins approach. Additionally, desorption results were compared with pervaporation results of another study in terms of solution-diffusion theory, and the effect of thermodynamic interactions on selective transport of the binary mixture and membrane system was investigated. The results obtained show that selective transport of EtAc-water mixture was influenced by increasing temperature and water content in the feed. It is shown that preferential sorption is more effective for pervaporation selectivity than diffusion selectivity.     

Determination of the order of surface reactions in Li2O

An analysis of the different surface reactions taking place in Li₂O was performed in order to determine whether adsorption and desorption of tritium are first or second order reactions. Data from BEATRIX-II Phase I and CRITIC-I were used as basis for calculations.It was found that only second order adsorption/desorption on the surface of Li₂O can predict the tritium behavior observed experimentally.     

A New Approach for Process Development of Plant‐Based Extraction Processes

Over the last few years the impact of products from natural sources in food, nutraceuticals, cosmetics, flavors/fragrances, and also the pharmaceutical industry has increased due to the consumer demand for nature‐derived products. Meeting this demand requires that existing manufacturing processes have to be optimized and process development for a variety of new products, sometimes with short life cycles, has to be accelerated. A scientific literature review covering equipment and modeling for plant‐based extractions shows an enormous demand for new approaches in process design for solvent extraction, isolation, and purification of ingredients from botanical sources and its transfer from academic research into manageable solutions for industrial use. An approach combining the design of experiments and rigorous process modeling on the one hand and an intensified collaboration between different disciplines including process engineering, botany, and analytical chemistry on the other hand seems to be the only way forward to address the current issues and shortcomings systematically and efficiently. Hence, a standard apparatus for the assessment of the governing process parameters for plant‐based extraction processes is proposed.     

First principles study on desorption of chemisorbed hydrogen atoms from single-walled carbon nanotubes under external electric field

Based on first principles calculations, we suggest a new way to release chemisorbed hydrogen atoms from the single-walled carbon nanotubes. The transverse external electric field serves as the key source for this mechanism. As the electric field strength increases, there is a notable increase in the C–H bond lengths at the sharp highly curved sites of the carbon nanotube. The compression of the tube along the direction of electric field results in the release of hydrogen atoms from the sharp sites. The synergetic action of electric field and compression turns out the desorption process easier at favorable field strengths. This present investigation provides a new alternative way to release hydrogen atoms from the hydrogenated carbon nanotubes under the influence of external electric field that requires comparatively lower temperature suitable for hydrogen based fuel cells used in mobile applications.     

Effect of Ultrasound on SO2 Desorption from Sodium Alkali Desulphurization Regeneration Solution

The influence of an ultrasonic field on SO₂ desorption from sodium alkali desulfurization regeneration solution was studied in this work. The SO₂ desorption experiments were carried out in the presence and absence of ultrasound at 25 kHz. The results showed that the use of ultrasound could enhance the SO₂ desorption rate from the sodium alkali desulfurization regeneration solution. By analyzing the composition of regeneration solutions with different pH values, two steps for the desorption process were proposed, both with and without ultrasound conditions, i.e., the first step was the decomposition of sulfurous acid (H₂SO₃), and the second step was the decomposition of sodium bisulfite (NaHSO₃). Furthermore, the use of ultrasound was seen to promote the first step, while it was not seen to have a significant effect on the second step. It was also found that the decomposition of H₂SO₃ in the first step could be considered as a gas mass transfer process from the liquid phase to the gaseous phase and the overall volumetric mass transfer coefficient, K_L·a, increased on using ultrasound compared to the value in the absence of an ultrasonic field.     

用Swc树脂提取钼的研究

研究用Ｓｗｃ弱碱性阴离子树脂从废催化剂的氨浸溶液中提取钼的使用条件、吸附性能和解吸性能。