- Email: [email protected]
UF-friendly antifoam
News and Views
UF-friendly antifoam Membrane fouling is a d r a w b a c k to more widespread use of ultraflltration a s a m e a n s of separation a n d purification in m a n y industries and, In particular, liquid antifoams have been f o u n d to c a u s e significant problems. The thickeners a n d s u r f a c t a n t s in both silicone a n d organic antifoam emulsions tend to form deposits on the m e m b r a n e surface, inhibiting the flux of liquid a n d at times c a u s i n g p e r m a n e n t m e m b r a n e damage. Dow Corning h a s developed a silicone antifoam in powder form - - 1920 EU m to c o u n t e r a c t m e m b r a n e fouling problems, particularly in enzyme fermentation systems. The antlfoam does not inhibit enzyme growth. 1920 EU c a n act as both a defoamer a n d antffoam in a wide range of chemical processes, says Dow Coming. The powdered antffoam c a n also be incorporated into dry p r o d u c t s to control foaming when liquids are a d d e d at the point of use, reducing downtime a n d filter replacement costs while improving productivity a n d process efficiency.
Further information from: J-C. Dangotte, Dow Cornlng Europe, rue General de GauUe 62, B-1310 La Hulpe, Belgium. Tel +32 2 655 21 11. Fax +32 2 655 20 01.
differently t h a n they do in bulk", says J o n a s . The mater!al.q are Jolted with radio waves in the presence of large magnetic fields a n d the relaxation tlme - - the time it takes for a molecule to r e t u r n to its original state - - is recorded at various t e m p e r a t u r e s a n d pressures. Using a simple theoretical picture for the relaxation of various nuclei of deuterium, carbon- 13 a n d nitrogen- 14, a s well a s protons, J o n a s claims to have been able to m e a s u r e for the first ~me how liquid molecules behave in the surface layer adjacent to the pore walls. "NMR c a n s t u d y very complex liquids a n d p r o d u c e extremely detailed informstion for various types of motions, including h o w fast the molecules are rotating, tumbling a n d behaving in the close proximity of the solid pore walls," says J o n a s .
Further lnformatlon fiom: Professor Jlri Jonas, Department of Chemistry, School of Chemical Sciences, University of Illinois, Urbana, IL 61801, USA. Tel +1 217 333 1085.
...and 'guests' in z e o l i t e pores NMR techniques are also being u s e d b y workers in the universities of California a n d Toronto to look at the motion of atomic a n d molecular 'guests' within the nano-size pores of zeolltes a n d other molecular sieves materials with m a n y potential applications in separations a n d catalysis. The novel 'double rotation NMR' technique h a s allowed the team to observe the interplay between electronic interactions of the h o s t lattice a n d the guests, a n d the spacial restrictions within the zeolite cages, both of which affect the motion of the encapsulated species. -
NMR s t u d i e s of liquids in pores... Understanding the behaviour of surface molecules is critical in m a n y applications, from the way lubricants coat metals to the m o v e m e n t of sludge t h r o u g h pipes, liquid fats t h r o u g h arteries, a n d liquids reacting in the pores of catalysts. Although scientists have good models for the behaviour of solids (crystalline structures) a n d gases (randomly moving molecules), they have no corresponding model for liquids, particularly for how they interact with solid surfaces. Now researchers at the University of Illinois at U r b a n a - C h a m p a l g n have developed a n experimental technique which u s e s nuclear magnetic resonance (NMR) - - popularly associated with non-invasive medical imaging m to examine characteristics of individual molecules of liquids in confined spaces u n d e r pressure. Professor Jiri J o n a s , director of the University's School of Chemical Sciences, uses a sol gel process to create glass containing pores ranging from 20 to 70 a n g s t r o m s in diameter which are then filled with liquid. "The pores restrict the motion of the liquid molecules a n d the confined liquids behave very
M e m b r a n e Technology No. 2 8
-
Further Informatlon from: Dr Raz Jellnek, Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA.
Fibres b o o s t optical isomer separation The separation of chiral mixtures into the constituent left- a n d right-handed optical isomers is a n important process, particularly in the p h a r m a c e u t i c a l industry. Because the optical isomers, or enantiomers, have identical physical a n d chemical properties the separation is difficult to accomplish a n d requires large
3
UF-friendly antifoam Membrane fouling is a d r a w b a c k to more widespread use of ultraflltration a s a m e a n s of separation a n d purification in m a n y industries and, In particular, liquid antifoams have been f o u n d to c a u s e significant problems. The thickeners a n d s u r f a c t a n t s in both silicone a n d organic antifoam emulsions tend to form deposits on the m e m b r a n e surface, inhibiting the flux of liquid a n d at times c a u s i n g p e r m a n e n t m e m b r a n e damage. Dow Corning h a s developed a silicone antifoam in powder form - - 1920 EU m to c o u n t e r a c t m e m b r a n e fouling problems, particularly in enzyme fermentation systems. The antlfoam does not inhibit enzyme growth. 1920 EU c a n act as both a defoamer a n d antffoam in a wide range of chemical processes, says Dow Coming. The powdered antffoam c a n also be incorporated into dry p r o d u c t s to control foaming when liquids are a d d e d at the point of use, reducing downtime a n d filter replacement costs while improving productivity a n d process efficiency.
Further information from: J-C. Dangotte, Dow Cornlng Europe, rue General de GauUe 62, B-1310 La Hulpe, Belgium. Tel +32 2 655 21 11. Fax +32 2 655 20 01.
differently t h a n they do in bulk", says J o n a s . The mater!al.q are Jolted with radio waves in the presence of large magnetic fields a n d the relaxation tlme - - the time it takes for a molecule to r e t u r n to its original state - - is recorded at various t e m p e r a t u r e s a n d pressures. Using a simple theoretical picture for the relaxation of various nuclei of deuterium, carbon- 13 a n d nitrogen- 14, a s well a s protons, J o n a s claims to have been able to m e a s u r e for the first ~me how liquid molecules behave in the surface layer adjacent to the pore walls. "NMR c a n s t u d y very complex liquids a n d p r o d u c e extremely detailed informstion for various types of motions, including h o w fast the molecules are rotating, tumbling a n d behaving in the close proximity of the solid pore walls," says J o n a s .
Further lnformatlon fiom: Professor Jlri Jonas, Department of Chemistry, School of Chemical Sciences, University of Illinois, Urbana, IL 61801, USA. Tel +1 217 333 1085.
...and 'guests' in z e o l i t e pores NMR techniques are also being u s e d b y workers in the universities of California a n d Toronto to look at the motion of atomic a n d molecular 'guests' within the nano-size pores of zeolltes a n d other molecular sieves materials with m a n y potential applications in separations a n d catalysis. The novel 'double rotation NMR' technique h a s allowed the team to observe the interplay between electronic interactions of the h o s t lattice a n d the guests, a n d the spacial restrictions within the zeolite cages, both of which affect the motion of the encapsulated species. -
NMR s t u d i e s of liquids in pores... Understanding the behaviour of surface molecules is critical in m a n y applications, from the way lubricants coat metals to the m o v e m e n t of sludge t h r o u g h pipes, liquid fats t h r o u g h arteries, a n d liquids reacting in the pores of catalysts. Although scientists have good models for the behaviour of solids (crystalline structures) a n d gases (randomly moving molecules), they have no corresponding model for liquids, particularly for how they interact with solid surfaces. Now researchers at the University of Illinois at U r b a n a - C h a m p a l g n have developed a n experimental technique which u s e s nuclear magnetic resonance (NMR) - - popularly associated with non-invasive medical imaging m to examine characteristics of individual molecules of liquids in confined spaces u n d e r pressure. Professor Jiri J o n a s , director of the University's School of Chemical Sciences, uses a sol gel process to create glass containing pores ranging from 20 to 70 a n g s t r o m s in diameter which are then filled with liquid. "The pores restrict the motion of the liquid molecules a n d the confined liquids behave very
M e m b r a n e Technology No. 2 8
-
Further Informatlon from: Dr Raz Jellnek, Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA.
Fibres b o o s t optical isomer separation The separation of chiral mixtures into the constituent left- a n d right-handed optical isomers is a n important process, particularly in the p h a r m a c e u t i c a l industry. Because the optical isomers, or enantiomers, have identical physical a n d chemical properties the separation is difficult to accomplish a n d requires large
3