scholarly journals Enthalpy of isopropanol adsorption on zeolite

2019 ◽  
Vol 21 (4) ◽  
pp. 58-65
Author(s):  
Maciej Jabłoński ◽  
Alicja Dzienisz ◽  
Marta Sawicka ◽  
Elwira Wróblewska ◽  
Krzysztof Lubkowski ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Adsorption Isotherms ◽  
Equilibrium Adsorption ◽  
Scanning Calorimetry ◽  
Adsorption Method ◽  
Adsorption Enthalpy ◽  
Water Desorption ◽  
Flow Method ◽  
Static Adsorption ◽  
Evaporation Enthalpy

Abstract The enthalpy of isopropanol adsorption on ZSM-5 (Zeolite Socony Mobil Framework Type MFI) was determined by the static adsorption method at the temperature range from 20°C to 100°C. Langmuir and Huttig models of equilibrium adsorption have been used to calculate the enthalpy of isopropanol adsorption at these conditions. Adsorption isotherms determined by the flow method at 20°C and 30°C have been also used in the calculations. The obtained values of isopropanol adsorption enthalpy were compared with the values of isopropanol evaporation enthalpy and with the results obtained from isopropanol and water desorption measurements with thermogravimetry and differential scanning calorimetry methods.

scholarly journals High-Performance Liquid Chromatography as Physico-Chemical Method for Study of Adsorption from Solutions

1988 ◽  
Vol 5 (1) ◽  
pp. 1-12
Author(s):  
N.A. Eltekova ◽  
Yu.A. Eltekov
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Adsorption Isotherms ◽  
Aromatic Compounds ◽  
High Performance ◽  
Adsorption Method ◽  
Macroporous Silica ◽  
Static Adsorption ◽  
Liquid Adsorption ◽  
Physico Chemical

High-Performance liquid chromatography (HPLC) of anisole and benzaldehyde on macroporous silica (Silochrom C80) with a hydroxylated surface and a surface covered with polyoxyethylene (POE) monolayer have been studied. On the basis of data obtained from liquid adsorption chromatography the adsorption isotherms of aromatic compounds from solutions were calculated. It has been found that adsorption isotherms obtained by HPLC and static adsorption methods coincide for anisole adsorbed either on hydroxylated or modified surfaces. In the case of benzaldehyde adsorption on hydroxylated silica surface the adsorption values obtained by the chromatographic method are smaller than those obtained by static adsorption method due to specific features of adsorption kinetics. Henry's constants, KΓ distribution factors, f, and adsorption solution activity coefficient, γa,i, for anisole and benzaldehyde adsorbed on hydroxylated and POE modified silica have been calculated. The values of KΓ and f obtained by both the static adsorption and HPLC methods have been compared. The enthalpies and entropies of adsorption of aromatic compounds have been compared with the polarity parameters.

THERMAL DESTRUCTION OF CHONDROITIN SULPHATE ISOLATED FROM BARENTS SEA HYDROBIONTS

2019 ◽  
Vol 63 (1) ◽  
pp. 39-44
Author(s):  
Yuliya A. Kuchina ◽  
Vitaliy Yu. Novikov ◽  
Irina N. Konovalova ◽  
Nataliya V. Dolgopiatova
Keyword(s):  
Differential Scanning Calorimetry ◽  
Chondroitin Sulfate ◽  
Thermal Destruction ◽  
Barents Sea ◽  
Chondroitin Sulphate ◽  
Cartilage Tissue ◽  
Scanning Calorimetry ◽  
Water Desorption ◽  
Crystallinity Degree ◽  
Temperature Range

The results of the thermogravimetric analysis of chondroitin sulfate, isolated from the cartilage of salmon, the northern slope, and the blackmouth shark in the temperature range of 40-600 °С are shown. Thermal analysis was performed using differential thermogravimetry and differential scanning calorimetry. The crystallinity degree of the samples was evaluated using diffraction patterns. It was shown, that under experimental conditions, thermal decomposition of the bulk of chondroitin sulfate samples is observed at a temperature of 230 to 530 °C. Differential thermogravimetric curves and differential scanning calorimetry curves contain five endothermic peaks associated with desorption of physically present water. Desorption of bound water occurs almost to a temperature of 150–200 °C, which can be explained by the difficulty of breaking hydrogen bonds between water molecules and polar functional groups of chondroitin sulfate. Small endothermic peaks correspond to the process of removal the physical volume of water. Four consecutive exothermic peaks are associated with the thermal destruction of the acid, pyranose, and finally, residual carbon and sulfur compounds. The rates of mass loss at each site were determined and the activation energies of each event were calculated. The nature of the cartilage tissue from which chondroitin sulfate is extracted affects the rate of destruction. So, in the temperature range of 236-244 °С, the lowest rate of destruction is observed for XC samples isolated from salmon cartilage tissue. The effect of crystallinity degree on the process of thermal destruction of chondroitin sulfate samples is shown. The results of the thermal destruction of chitin / chitosan obtained from the northern shrimp are presented. It was found that less activation energy is required for thermal destruction of chondroitin sulfate compared to chitin/chitosan at all stages.

Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

Optimasi Proses Pembuatan dan Karakterisasi Fisik Niosom Sinkonin

2019 ◽  
Vol 16 (2) ◽  
pp. 178
Author(s):  
Hariyanti Hariyanti ◽  
Sophi Damayanti ◽  
Sasanti Tarini
Keyword(s):  
Differential Scanning Calorimetry ◽  
Particle Size ◽  
Hair Follicle ◽  
Scanning Calorimetry ◽  
Span 60

Sinkonin praktis tidak larut dalam air, sedikit larut dalam kloroform dan alkohol. Hal ini berdampak pada rendahnya penetrasi transfollicular sinkonin, karena hanya bahan aktif hidrofilik yang mampu melewati hair follicle. Dengan demikian dibutuhkan satu sistem penghantaran yang mampu menurunkan hidrofobisitas sinkonin untuk meningkatkan penetrasi sinkonin ke follicle. Niosom merupakan vesikel ampifilik dengan struktur lapisan rangkap yang terbentuk dari hidrasi kombinasi surfaktan nonionik dan kolesterol yang mampu menurunkan hidrofobisitas sinkonin. Penelitian ini bertujuan untuk menentukan proses pembuatan niosom sinkonin yang optimum. Pembuatan niosom sinkonin diawali dengan menentukan temperatur gelasi (Tg) dari span 60 dengan Differential Scanning Calorimetry (DSC), kemudian dilanjutkan dengan optimasi proses meliputi: optimasi kecepatan rotavapor pembentukan film lapis tipis, temperatur hidrasi, kecepatan rotavapor hidrasi, waktu hidrasi, dan waktu sonikasi. Karakteristik vesikel niosom yang optimal meliputi: ukuran partikel dan indeks polidispersitas dengan menggunakan Particle Size Analized (PSA) serta efisiensi penjeratan sinkonin dengan menggunakan KCKT. Temperatur gelasi (Tg) span 60 45±2 oC, kecepatan rotavapor pembentukan film lapis tipis niosom 210 rpm, temperatur hidrasi 55±2 oC, kecepatan rotavapor hidrasi 210 rpm, waktu hidrasi 20 menit, waktu sonikasi suspensi niosom 1 menit. Ukuran vesikel yang diperoleh adalah 100–200 nm, indeks polidispersitas 0,2–0,4 dan efisiensi penjeratan niosom sinkonin 84,49±0,0025%. Proses pembuatan niosom sinkonin memiliki pengaruh besar terhadap hasil ukuran vesikel dan efisiensi penjeratan niosom sinkonin.

Improving Wire Sweep Performance by Measuring Degree of Cure of Epoxy Mold Compounds

2011 ◽  
Author(s):  
Sheila Liza B. Dal
Keyword(s):  
Differential Scanning Calorimetry ◽  
Shelf Life ◽  
Trial And Error ◽  
Active Components ◽  
Scanning Calorimetry ◽  
Degree Of Cure ◽  
Electronic Package ◽  
Viscosity Changes ◽  
Epoxy Mold Compounds

Abstract The choice of epoxy mold compound (EMC) for an electronic package is based mostly on how much protection it provides to the active components in the package. But the choice is not a straightforward process. Rather it is mostly trial and error using different assembly parameters to find the most robust material while assembly defects are monitored. One such defect associated to EMC processing is wire sweep, and many studies have shown that it is mainly caused by viscosity changes in the EMC. In this study, samples of EMC in various stages of shelf life and staging times were analyzed for degree of cure using a method called differential scanning calorimetry (DSC). Samples are then processed at assembly for wire sweep measurement. It was found out that degree of cure increases with staging time at different rates for each shelf life. It was also found out that wire sweep did not only increase with degree of cure but it was also found to be predictable with respect to the latter. Using this information, the age and staging limit for each material was identified that would not cause wire sweep issues.

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