THERMODYNAMIC BEHAVIOR OF FISH MEAL DURING ADSORPTION

Anchovy fish meal with an approximate uniform moisture content of 10% was used for this study. Vapor adsorption isotherms were determined at 25 ° C, 35 ° C and 45 ° C. The differential and integral thermodynamic properties were estimated using the Othmer method. The isosteric heat or differential enthalpy, as a function of moisture content, showed a maximum value around 4.5 g of water/100 g d. s. The heat of sorption increased gradually with an increase in sorbed water until reaching its maximum value near the monolayer, and at a given moisture content, decreasing with temperature. The molar entropy values obtained were high at low water contents and fell to a minimum near the monolayer value.     

THERMODYNAMIC BEHAVIOR OF FISH MEAL DURING ADSORPTION

ABSTRACT

Anchovy fish meal with an approximate uniform moisture content of 10% was used for this study. Vapor adsorption isotherms were determined at 25 ° C, 35 ° C and 45 ° C. The differential and integral thermodynamic properties were estimated using the Othmer method. The isosteric heat or differential enthalpy, as a function of moisture content, showed a maximum value around 4.5 g of water/100 g d. s. The heat of sorption increased gradually with an increase in sorbed water until reaching its maximum value near the monolayer, and at a given moisture content, decreasing with temperature. The molar entropy values obtained were high at low water contents and fell to a minimum near the monolayer value.     

Sorption Characteristics of Whole Pistachio Nuts (Pistacia Vera L.)

ABSTRACT

Moisture sorption characteristics of whole pistachio nuts were investigated at 10, 20, and 30°C using the static method. The sorption isotherms exhibited hysteresis over the range of 0.10-0.80 water activity which was succesfully interpreted using BET, GAB, Oswin, Smith, Henderson, Chung-Pfost and Halsey mathematical models and from which the BET, GAB and Oswin models were found to give the best fit. Monolayer moisture content of pistachio nuts was determined from BET and GAB equations and the isosteric heat of sorption data were derived using Clausius-Clapeyron equation and presented in graphical form. The information generated can be utilized to optimize the packaging parameters for long term storage of pistachio nuts.     

吸附热预测吸附等温线

实验测定了N2 在沸石分子筛、C2 H6 在活性炭、CO2 在硅胶上的吸附等温线 ,研究用Clausius Clapeyron方程求得等量吸附热、再利用所得的吸附热预测其它温度的吸附等温线数据的方法。将吸附热预测的等温线与实验值及插值法内插得到的吸附等温线数据进行了比较 ,结果表明吸附热预测值与实验值吻合较好。此外还对文献数据利用等量吸附热预测较高压力 ( 65 0kPa)下的等温线 ,均与文献中的实验值一致。为吸附工业操作需要不同温度下的等温线数据和吸附过程的模拟与设计提供了简便、准确的计算方法     

The Adsorption of p-nitrophenol on anion exchange resin at various temperatures

The isotherms of p-nitrophenol adsorbed on the anion exchange resin Ionac AFP-329 at temperatures in the range of 278.1 to 338.1 K are correlated with the Freundlich equation. The temperature dependences of the Freundlich constants and the effect of the amount adsorbed on the isosteric heat of adsorption are discussed. The results indicate that the relationships between k, n and temperature can be expressed as. n = 0.00129 T ln k = 5.12 – 0.0152 T and ln k = 5.05 – 11.63 n and that the isosteric heat of adsorption varies linearly with the logarithm of amount adsorbed.     

MODELING WATER SORPTION IN OKARA SOY MILK

Moisture sorption isotherms of okara soy milk were determined using the gravimetric method in the range 20 - 50 °C. The sorption isotherms exhibited hysteresis along all the water activity range (0·1 - 0·9). The amount of sorbed water increased as the temperature was decreased. The GAB and Halsey models gave a good fit for okara isotherms over the range of water activity 0·1 - 0·9. As temperature increased, GAB k-values increased towards unity where the GAB equation reduces to the BET equation. The influence of temperature on the constants of GAB and Halsey models was evaluated through Arrhenius-type equations. The Clausius Clapeyron equation was used to estimate the isosteric heats of sorption.     

MODELING WATER SORPTION IN OKARA SOY MILK

ABSTRACT

Moisture sorption isotherms of okara soy milk were determined using the gravimetric method in the range 20 - 50 °C. The sorption isotherms exhibited hysteresis along all the water activity range (0·1 - 0·9). The amount of sorbed water increased as the temperature was decreased. The GAB and Halsey models gave a good fit for okara isotherms over the range of water activity 0·1 - 0·9. As temperature increased, GAB k-values increased towards unity where the GAB equation reduces to the BET equation. The influence of temperature on the constants of GAB and Halsey models was evaluated through Arrhenius-type equations. The Clausius Clapeyron equation was used to estimate the isosteric heats of sorption.     

Experimental and theoretical study of methane adsorption on granular activated carbons

The experimental and theoretical study of methane adsorption on granular activated carbons is presented. The adsorption data are modeled by various isotherm equations. Toth equation is found to have the best fit. The isosteric heat decreases with loading and increases weakly with temperature, which is an indication of heterogeneity of the methane and granular activated carbon system. Using optimized parameters from Toth equation, a novel procedure is developed to calculate the integral heat of adsorption, which is the total amount of isosteric heat of adsorption at a given temperature and pressure during the adsorption process. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Moisture Adsorption Isotherms of Watermelon Seed and Kernels

The moisture adsorption isotherms of watermelon seeds and kernels from Citrullus lanatus Cv Mateera and Citrullus vulgaris Cv Sugar baby were obtained using standard static method with saturated salt solutions over a range of water activities from 0.113 to 0.92 at 20–60°C. The adsorption capacity of seeds decreased with the increase in temperature at constant water activity. Sorption models were used to explain the adsorption behavior involving water activity and moisture content (Type I) and also temperature (Type II). Oswin's models gave best fit among Type I with coefficient of determination of 0.953–0.995, standard error of 0.031–0.0571, mean relative error of 0.071–0.152, and scattered residual plots. Modified Oswin was the best fit model among Type II for the seeds and kernels of both the cultivars with coefficient of determination of 0.997–0.999, standard error of 0.151–0.255, mean relative error of 0.018–0.244, and scattered residual plots. The net isoelectric heat of adsorption, estimated from Clausius-Clapeyron decreased from about 27.0 to 0.5 kJ/mol in kernels and 18.0 to 0.5 kJ/mol in seeds of both the cultivars as the moisture content increased from 5 to 25% (dry basis).     

Moisture Adsorption Isotherms of Watermelon Seed and Kernels

The moisture adsorption isotherms of watermelon seeds and kernels from Citrullus lanatus Cv Mateera and Citrullus vulgaris Cv Sugar baby were obtained using standard static method with saturated salt solutions over a range of water activities from 0.113 to 0.92 at 20-60°C. The adsorption capacity of seeds decreased with the increase in temperature at constant water activity. Sorption models were used to explain the adsorption behavior involving water activity and moisture content (Type I) and also temperature (Type II). Oswin's models gave best fit among Type I with coefficient of determination of 0.953-0.995, standard error of 0.031-0.0571, mean relative error of 0.071-0.152, and scattered residual plots. Modified Oswin was the best fit model among Type II for the seeds and kernels of both the cultivars with coefficient of determination of 0.997-0.999, standard error of 0.151-0.255, mean relative error of 0.018-0.244, and scattered residual plots. The net isoelectric heat of adsorption, estimated from Clausius-Clapeyron decreased from about 27.0 to 0.5 kJ/mol in kernels and 18.0 to 0.5 kJ/mol in seeds of both the cultivars as the moisture content increased from 5 to 25% (dry basis).     

碳基吸附剂储氢吸附热的密度泛函理论

为比较狭缝孔、纳米管两种典型碳基吸附剂的储氢性能,应用非局域密度泛函理论、微观物理学、吸附平衡原理、典型吸附剂储氢试验结果计算并分析了典型碳基吸附剂的氢等量吸附热.结果表明,两类吸附剂的氢等量吸附热相差不大,等温线变化规律相似,并且只有在低温（液氮）、适度压力时吸附储氢的质量密度才有望达到DOE标准.     

Enhancement of CO2 Adsorption and CO2/N2 Selectivity on ZIF‐8 via Postsynthetic Modification

Imidazolate framework ZIF‐8 is modified via postsynthetic method using etheylenediamine to improve its adsorption performance toward CO₂. Results show that the BET surface area of the modified ZIF‐8 (ED‐ZIF‐8) increases by 39%, and its adsorption capacity of CO₂ per surface area is almost two times of that on ZIF‐8 at 298 K and 25 bar. H₂O uptake on the ED‐ZIF‐8 become obviously lower compared to the ZIF‐8. The ED‐ZIF‐8 selectivity for CO₂/N₂ adsorption gets significantly improved, and is up to 23 and 13.9 separately at 0.1 and 0.5 bar, being almost twice of those of the ZIF‐8. The isosteric heat of CO₂ adsorption (Q_st) on the ED‐ZIF‐8 becomes higher, while Q_st of N₂ gets slightly lower compared to those on the ZIF‐8 Furthermore, it suggests that the postsynthetic modification of the ZIF‐8 not only improves its adsorption capacity of CO₂ greatly, but also enhances its adsorption selectivity for CO₂/N₂/H₂O significantly. ©2013 American Institute of Chemical Engineers AIChE J, 59: 2195–2206, 2013     

温度-压力-吸附方程在计算煤岩等量吸附焓的应用

用鄂尔多斯盆地的长焰煤、肥煤、瘦煤和贫煤4个煤样的系列等温吸附实验数据来验证一个温度-压力-吸附方程,并探讨等量吸附时吸附平衡压力与温度之间的函数关系。用克劳修斯-克拉佩龙方程求等量吸附焓。提出单位等量吸附焓的概念及计算方法。结果表明：煤样等量吸附焓为负值,证实吸附过程是个放热过程;对于同一煤样,单位等量吸附焓随吸附量的增加而下降是由于吸附介质表面的能量不均匀性所造成。正因为吸附过程是个放热过程,所以吸附先发生在能量较高的位置上,以便放出更多能量;在相等吸附温度和压力条件下,高阶煤有较大的单位等量吸附焓,必有较大的吸附量。同时高阶煤吸附量随着吸附温度的升高而快速衰减,而中低阶煤吸附量衰减却没有那么明显。     

正庚烷在5A分子筛上的高温吸附/脱附及扩散性能

用智能重量分析仪(IGA-100)在较高温度下测定了5A分子筛(自制)对正庚烷吸附/脱附等温线及其滞后环;计算TIE庚烷在5A分子筛上的吸附热和吸附、脱附扩散系数,分析了正庚烷在5A分子筛微孔内吸附作用.结果表明:吸附温度升高,正庚烷吸附等温线优惠程度明显降低,有吸附滞后环;在523 K下,5A对正庚烷的平衡吸附量为0...     

Adsorption Isotherms,Kinetics, and Desorption of 1,2-Dichloroethane on Chromium-Based Metal Organic Framework MIL-101

Adsorption equilibrium and kinetics of 1,2-dichloroethane on a chromium-based metal-organic framework MIL-101 were studied. Desorption activation energies of 1,2-dichloroethane on the MIL-101 were measured using temperature program desorption (TPD) experiments. Results showed that the adsorption capacity of the MIL-101 for 1,2-dichloroethane is 19 mmol/g at 288 K, being much higher than those of some activated carbon, zeolite, and MWCNTs. The isotherms of 1,2-dichloroethane were well fitted by the Langmuir equation. The isosteric heat and diffusion coefficients of 1,2-dichloroethane adsorption on the MIL-101 were separately within the range of 42.0–61.6 kJ/mol and range of 0.854–2.246 × 10^?10 cm²/s. TPD spectra exhibited two types of adsorption sites on the MIL-101 with desorption activation energy of 48.6 and 87.6 kJ/mol separately. Multiple recycle runs of 1,2-dichloroethane adsorption-desorption at 298 K (10 mbar for adsorption and 0.05 mbar for desorption) showed the 1,2-dichloroethane adsorption on the MIL-101 is highly reversible, and desorption efficiency is up to 98.42%.     

A thermodynamic investigation of adsorbate‐adsorbate interactions of carbon dioxide on nanostructured carbons

A thermodynamic study of carbon dioxide adsorption on a zeolite‐templated carbon (ZTC), a superactivated carbon (MSC‐30), and an activated carbon (CNS‐201) was carried out at temperatures from 241 to 478 K and pressures up to 5.5?10⁶ Pa. Excess adsorption isotherms were fitted with generalized Langmuir‐type equations, allowing the isosteric heats of adsorption and adsorbed‐phase heat capacities to be obtained as a function of absolute adsorption. On MSC‐30, a superactivated carbon, the isosteric heat of carbon dioxide adsorption increases with occupancy from 19 to 21 kJ?mol^?1, before decreasing at high loading. This increase is attributed to attractive adsorbate–adsorbate intermolecular interactions as evidenced by the slope and magnitude of the increase in isosteric heat and the adsorbed‐phase heat capacities. An analysis of carbon dioxide adsorption on ZTC indicates a high degree of binding‐site homogeneity. A generalized Law of Corresponding States analysis indicates lower carbon dioxide adsorption than expected. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1026–1033, 2018     

淀粉基多孔碳材料的制备及其吸附CO2/CH4性能

以淀粉为原料,使用水热法将其碳化后用活化剂KOH对其活化,制备了淀粉基多孔碳材料,并对其进行结构表征和CO₂/CH₄的吸附性能测试,计算吸附热以及材料对CO₂/CH₄的吸附选择性,讨论了碳材料结构对其吸附性能的影响。结果表明：在制备过程中,随着活化剂KOH用量比例的增大,所制得的材料其比表面积和孔容增大,其孔径分布也就越宽。所制得的碳材料其比表面积可达2972 m²·g^-1。这些淀粉基多孔碳材料对水蒸气的吸附等温线呈现出Ⅳ类等温线。所制备材料对CO₂吸附容量主要取决于其孔径小于0.8 nm的累积孔容（Vd < 0.8 nm）。材料的超微孔的孔容越大,其对CO₂吸附容量也越大。所制备的C-KOH-1材料在101325 Pa和298 K条件下,对CO₂的吸附量达到4.2 mmol·g^-1,其对CO₂的吸附热明显高于其对CH₄吸附热,其对CO₂/CH₄吸附选择性为3.7～4.26,同时本文通过对材料的水蒸气吸附等温线进行测试,结果表明所得材料主要表现为中等憎水性,这对材料在实际工况的应用奠定了基础。     

Metal ion concentration,time, and pH dependence of metal ion binding to a transferrin metalloprotein affinity chromatography (MAMC) matrix

The adsorption of transition metal, lanthanide, and actinide ions to avotransferrin (conalbumin) immobilized to sepharose (via the cyanogen bromide method) has been examined. Adsorption of ions as a function of time and adsorption isotherms at pH 8 have been determined and analyzed using the Freundlich model, distribution coefficients between the pH vales 2 and 9 have been measured. The results indicate that immobilization of the protein has little effect on its interactions with metal ions compared with the protein in solution, and important prerequisite for use of this matrix in metalprotein affinity metal homatography (MAMC).