| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 3 / 3
Na začetekNa prejšnjo stran1Na naslednjo stranNa konec
1.
Extraction and separation of active compounds by supercritical fluids extraction and preparative supercritical chromatography
Alejandro Bartolome Ortega, 2017, doktorska disertacija

Opis: This doctoral dissertation is focused on the benefits of supercritical fluids technology in several industry processes. Although, supercritical CO2 is currently the most employed supercritical fluid at laboratory scale, its presence in the industry field is still limited, due to the necessity of high investment costs. Despite that fact, operations with supercritical CO2 are cheap, environmentally friendly and simple, which make it an excellent alternative to organic compounds. Extraction and separation of highly pure active compounds, such as xanthohumol or beta-sitosterol, are demanded for pharmaceutical or food industries, which create an excellent opportunity for supercritical CO2 operations, since they are solvent free. This manuscript is divided into three different parts. In the first part, conventional extraction processes and supercritical fluid process are theoretically compared and supercritical fluid extraction from saw palmetto berries is presented. In the second part, conventional chromatographic techniques and supercritical fluid chromatography are theoretically compared and separation of xanthohumol from hop extracts by supercritical fluid chromatography is presented. In the last part, different encapsulation and emulsification processes are listed and defined. These processes are very important for food and pharmaceutical companies, since several active compounds are not water soluble which create the necessity of different formulations in order to be solved in an appropriate media. Regarding the experimental part, extractions from saw palmetto berries were performed at various pressures and temperatures, which were higher than the ones that were applied in previous studies, in order to estimate and calculate different parameters (solubility, extraction kinetic curves, composition,…), and to compare different studies. Separation of xanthohumol was carried out in a homemade supercritical chromatography, which manageable variables were temperature, pressure, mass flow-rate, modifier, and stationary phase. The results were compared with those ones which were obtained using conventional techniques, in order to prove the suitability and the improvement of this technique against others tecniques.
Ključne besede: supercritical CO2, supercritical fluid extraction, supercritical fluid chromatography, xanthohumol, saw palmetto berries, Beta-Sitosterol, encapsulation
Objavljeno v DKUM: 13.07.2017; Ogledov: 2013; Prenosov: 243
.pdf Celotno besedilo (3,20 MB)

2.
Supercritical fluid chromatography and scale up study
Miha Oman, Petra Kotnik, Mojca Škerget, Željko Knez, 2014, izvirni znanstveni članek

Opis: The influence of process parameters on supercritical fluid chromatography (SFC) and scale-up on to the preparative scale was investigated. In this scope, dependency of pressure, temperature, type and concentration of modifier, and type of stationary phase on the separation were examined separately. Experiments were performed on silica stationary phases in the range of pressures from 100 bar to 250 bar and temperatures from 30°C to 65°C, with use of ethanol and methanol as modifier. Results obtained on analytical scale were used for scale up on preparative (to production) scale. The aim of this study is presentation of the state-of-the-art of SFC through separate effects of process parameters on the separation and investigation of development, benefits and drawbacks of scaling-up process of the SFC.
Ključne besede: supercritical fluids, supercritical fluid chromatograpy, chromatography, scale up study, SFC
Objavljeno v DKUM: 21.12.2015; Ogledov: 1520; Prenosov: 153
.pdf Celotno besedilo (842,20 KB)
Gradivo ima več datotek! Več...

3.
Supercritical fluid adsorption and desorption of lipids on various adsorbents
Mojca Škerget, Željko Knez, 2007, izvirni znanstveni članek

Opis: In present work the feasibility of using supercritical fluid chromatography (SFC) for separation of free fatty acids (FFA) and triglycerides has been examined. Lipids such as oleic acid and sunflower oil (containing 96% of triglycerides) were used; adsorption and desorption on adsorbents such as silica gel and neusilin using supercritical $CO_2$ as mobile phase was investigated. The experiments were performed at 40 °C and in the pressure range from 13 to 30 MPa. Adsorption kinetic lines were determined by analysingbreakthrough curves. Several parameters such as rate of adsorption and desorption, loading, desorbed quantity and diffusion coefficients in solid phase were calculated.
Ključne besede: supercritical fluid chromatography, lipids, oleic acid, triglycerides, adsorption, desorption
Objavljeno v DKUM: 31.05.2012; Ogledov: 2391; Prenosov: 110
.pdf Celotno besedilo (167,88 KB)
Gradivo ima več datotek! Več...

Iskanje izvedeno v 0.11 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici