research papers presented Rapid emulsifier selection and evaluation of emulsion stability for reformulation Interrelation between surfactant adsorption kinetics, interfacial rheology and emulsion stability Speeding up the evaluation of emulsion stability during normal storage conditions A comparative study of asphaltene precipitation/flocculation by a new non-scanning NIR-technique in accordance with ASTM D 7061 4th World Congress on Emulsions papers LUM at CME Evaluation of long term stability of model emulsions by multisample analytical centrifugation Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions Rapid emulsifier selection and evaluation of emulsion stability by analytical centrifugation Shelf life prediction of liquid food products based on multisample analytical centrifugation New at the preprint server Rapid emulsifier selection and evaluation of emulsion stability by analytical centrifugation Chemistry Preprint Archive, Volume 2004, Issue 5, May 2004, Pages 7-18 New article from Cosmetics and Colloids 2005 Rapid characterization of emulsions for emulsifier selection, quality control and evaluation of stability using multisample analytical centrifugation Paper from the 11th CID Conference, Rome Rapid selection of dispersants and evaluation of emulsion stability by analytical centrifugation New article in GIT Laborfachzeitschrift 12/2005 Optimierung der Prozessbedingungen für die Herstellung stabiler Emulsionen
Stability Analyser LUMiFuge 116 for rapid evaluation of Emulsion Stability and Demulsifier Selection D. Lerche, T. Sobisch, S. Küchler
Scope
# Evaluation of emulsion stability - stability testing or selection of demulsifiers is a frequent task. # Related investigations are generally very time consuming. # The multisample stability analyser LUMiFuge 116 has a broad application field for characterization of separation stability of dispersions also in the range of high concentrations. Intention of the study is to evaluate the suitability of the LUMiFuge for characterization of emulsion stability and optimization of emulsifier and demulsifier selection.
LUMiFuge 116 measuring system  The special analytical centrifuge traces the local and temporal changes of light transmission at 880 nm. Up to 8 samples can be investigated simultaneously at temperatures up to 60 ± 1 °C. Determines the local transmission over the entire sample length simultaneously in preset time intervals during centrifugation, whereby the position of the interfaces can be determined with high precision (resolution < 100 µm). Separation process depicted as time course of the transmission or of the relative position of the interfaces (oil, creaming emulsion layer, water, sediment). Information obtained not only about extent of phase separation but also the kinetics are directly measured. Ranking of emulsion stability can be derived by either comparing the volumes of phases separated or by comparing the velocities of phase separation.
Stability evaluation as function of oil and surfactant polarity and temperature
The LUMiFuge 116 can be used for rapid screening of optimal conditions for emulsion stabilization. Paraffin oil / water and rapeseed oil / water emulsions (1/1 v/v) were stabilized by 5 percent m/m nonionic surfactant (ethoxylated iso tridecanol with 3 to 12 EO).    ABC Increasing the temperature the polarity of the nonionic surfactants is decreased shifting the optimum HLB to higher values. B Rapeseed oil emulsions have a substantially higher stability, especially at higher temperatures. (note different scale) C A ranking of emulsifier performance below HLB 12 is possible at higher centrifugation speed. (as observed for emulsions investigated, enhanced centrifugal speed did not changed the ranking.) Evaluation of optimum preparation conditions
Dissolver speed and time of emulsification have been varied. Stability analysed at 3000 rpm.   Demulsifier selection for crude oil
Screening of demulsifier performance was conducted at 3000 rpm.  With increasing concentration water separation speeds up, however, at 50 ppm the amount of water separated reduces.  A Fastest separation Dissolvan 4490. Dissolvan 4411 more complete separation. B Maximum water separated at 40 ppm Demulsifiers can be selected according to requirements of speed and degree of separation. Conclusions
# The analytical centrifuge LUMiFuge 116 is an efficient tool for characterization of emulsion stability, optimization of preparation conditions, emulsifier and demulsifier selection as well. # Multisample analysis, very suitable for screening purposes. # Information on extent of phase separation and on kinetics. # Time of investigation and centrifugal acceleration can be adapted to avoid conditions where centrifugal forces are the determining factor for phase separation.
|
|
