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Dissolved solute or colloid
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Nalgene
Diffusional transport of water or solvent through membrane gel microstructure
Differs From Micropore Filtration Pressurized
pipet won't
break Micropore filter
H e r e ' s t h e quality pipet that doesn't require kid glove treatment. It stands up under rough, daily use. It's the reliable pipet . . . in accuracy, readability and handling. E a s y - t o - r e a d liquid levels because there is no meniscus—thanks to the non-adherent surface of chemically-resistant polypropylene. Transfer, serological and measuring models in 1, 2, 5 and 10 ml capacities. May be assorted with other Nalgene Labware for maximum discount. Ask your lab supply dealer, or write Dept. 26221, The Nalge Co., Inc., 75 Panorama Creek Drive, Rochester, New York 14625. F R E E P I P E T : May we send you a Nalgene pipet to try in your lab? Just drop us a note on your letterhead, and we'll put your pipet in the mail.
NALGENE &
LABWARE
Leader in quality plastic labware since 1949
46
C&EN
O C T . 4, 196 5
Mechanical entrapment of colloid particles in micropores of filter medium
Membranes Spur Ultrafiltration Study In joint effort, Dorr-Oliver supplies device, Amicon the polyelectrolyte membranes Dorr-Oliver is experimenting with ultrafiltration involving Diaplex polyelectrolyte membranes developed by Amicon Corp., Cambridge, Mass. The two companies have joined forces in a program aimed at developing aqueous ultrafiltration processes for treating water and purifying beet sugar. D - 0 (Stamford, Conn.) and Amicon regard ultrafiltration as an emerging new unit operation with considerable potential utility in the chemical process industries. Amicon is supplying the membrane technology for the joint effort; D - 0 is contributing its device and process development capabilities. The synthetic hydrated membranes are based on Amicon's Ioples polyion complex resins. These resins are made by reacting cationic and anionic polyelectrolytes to produce an ionic cross-linked structure. The membranes are mechanically sound and have good chemical and thermal stability. The most distinctive characteristic
of the membranes is high permeability to water under hydraulic pressure. The membranes exhibit water permeabilities 10 to 100 times higher than existing cellophane or cellulose acetate ultrafiltration membranes. In addition, they have equal or better solids retention characteristics in some applications than do existing membranes, according to Amicon. Since the membranes are nonporous, filtration is by diffusive transport. Diffusive ultrafiltration (hyperfiltration or reverse osmosis) is based on rapid diffusion of water or solvent across a permselective membrane which has a low diffusivity for solutes. According to Amicon, this difference in diffusivity for solute and solvent can be tailored into the microstructure of its membranes. Amicon can make loose membranes that have water permeabilities of 10 to 15 ml. per hr.-sq. cm.-mil at 100 p.s.i. These membranes retain, nearly completely, solutes which have molecular weights of 10,000 and above. Also, the company can fabricate tighter
membranes which have water permeabilities of 2 to 5 m l . p e r . hr.-sq. cm.m i l a t 100 p.s.i. T h e s e m e m b r a n e s a r e almost i m p e r m e a b l e to solutes w i t h m o l e c u l a r w e i g h t s of 5 0 0 or greater. The nonporosity and relatively s m o o t h surface of t h e A m i c o n m e m b r a n e s m i n i m i z e i n t e r n a l clogging a n d surface fouling. H o w e v e r , h i g h solute c o n c e n t r a t i o n s on t h e u p s t r e a m side of t h e m e m b r a n e m a y cause caking a t t h e m e m b r a n e ' s surface a n d r e d u c e t h e flow r a t e . This p r o b l e m can b e alleviated b y p r o v i d i n g t h e p r o p e r d e g r e e of t u r b u l e n c e on t h e u p s t r e a m side of t h e m e m b r a n e . This will sust a i n a h i g h flux r a t e , t h e c o m p a n y says. T h e Amicon membranes aren't t h e only ones b e i n g t e s t e d b y D - O . T h e c o m p a n y is t e s t i n g various k i n d s of membranes, including cellophane and cellulose a c e t a t e . B u t D - 0 has f o u n d t h a t t h e A m i c o n m e m b r a n e s h a v e imp r o v e d flow rates for those applications u n d e r s t u d y . Prototypes. D - 0 is w o r k i n g on p r o t o t y p e devices for w a t e r t r e a t m e n t a n d b e e t sugar purification as well as for o t h e r applications. It will b e r e a d y to field test t h e sugar u n i t b y late this m o n t h or early N o v e m b e r . It should h a v e t h e w a t e r t r e a t m e n t p r o t o t y p e r e a d y for field testing before t h e first of t h e year. D - 0 is going into t h e field w i t h its p r o t o t y p e devices to uncover unexpected problems. Beet s u g a r is a g o o d field for s t u d y . I t r e p r e s e n t s a large m a r k e t ( w o r l d cons u m p t i o n of b e e t sugar is a b o u t 3 0 million tons a y e a r ) a n d D - O is alr e a d y heavily involved in this i n d u s try. C o n v e n t i o n a l l y , t h e p r i m a r y purification of b e e t sugar juice is a s e d i m e n tation-filtration operation. L i m e a n d c a r b o n dioxide a r e a d d e d to t h e juice to precipitate calcium carbonate, w h i c h adsorbs impurities. The precipitate is t h e n r e m o v e d b y s e d i m e n t a tion a n d filtration. This operation m i g h t b e e l i m i n a t e d , D-O says, b y using a n ultrafiltration m e m b r a n e t h a t retains all i m p u r i t i e s t h a t h a v e m o l e c u lar w e i g h t s h i g h e r t h a n t h a t of sucrose. Long-Range. T h e D - O w a t e r t r e a t m e n t p r o g r a m is a l o n g - r a n g e project. Its p r i m a r y objective is to m a k e surface w a t e r s p o t a b l e b y r e m o v i n g colloidal m a t e r i a l s a n d dissolved organics. Its i m m e d i a t e t e c h n i c a l objective is to test t h e d e v i c e on surface w a t e r s . D - O feels t h a t it is possible to p r o d u c e
Time was when Aluminum Alkyls weren't even considered for commercial processes... B u t t h a t w a s before T e x a s A l k y l s ! Tod a y ' s story is g r o w t h . . . g r o w t h in dem a n d , in applications, in availability. Processes merely in l a b o r a t o r y evaluation a s recently a s five y e a r s ago a r e now commercially commonplace — for example, production of s t r a i g h t - c h a i n alcohols a n d a l p h a olefins, stereospecific polymerizations yielding heavy-duty synthetic r u b b e r s or s u p e r i o r plastics. E v e n n e w e r applications, such a s t h e s e l e c t i v e r e d u c t i o n of s t e r o i d s , a r e now s t a n d a r d i n - p l a n t o p e r a t i o n s . A n d ,
p r e s e n t r e s e a r c h promises equally significant a d v a n c e s for t h e f u t u r e . In alkylation . . . rocket fuels . . . olefin disp l a c e m e n t . . . oxidation . . . a l u m i n u m plating. P e r h a p s it's time for you t o re-evalua t e t h e potential of A l u m i n u m Alkyls in your processing. W e will be h a p p y to send i n f o r m a t i o n on a n y of our products or t h e i r homologs—or, b e t t e r still, have a technical r e p r e s e n t a t i v e call. J u s t fill in t h e coupon below a n d a t t a c h i t to y o u r l e t t e r h e a d .
COMMERCIAL PRODUCTS: TEAL Triethylaluminum • TNPRAL Tri-n-propylaluminum • TNBAL Tri-n-butylaluminum • TIBAL Triisobutylaluminum • DIBAL-H Diisobutylaluminum hydride • ISOPRENYL Isoprenylaluminum • EADC Ethylaluminum dichloride • DEAC Diethylaluminum chloride • DEAI Diethylaluminum iodide • EASC Ethylaluminum sesquichloride • IBADC Isobutylaluminum dichloride • DIBAC Diisobutylaluminum chloride. DEVELOPMENT PRODUCTS: TNHEXYL Tri-n-hexylaluminum • TRIISOHEXYL Triisohexylaluminum • TNOCTYL Tri-n-octylaluminum • TNDECYL Tri-n-decylaluminum • MASC Methylaluminum sesquichloride • DEAB Diethylaluminum bromide • DEAF Diethylaluminum fluoride.
TEXAS ALKYLS, INC. P.O. Box 600, Deer Park, Texas 77536 Please send me: • Brochure: "Organoaluminum Products—Glamor Petrochemicals"
• Have a representative call. I am interested in
• Data Book: "Aluminum Alkyls" • Bulletin: "DIBAL-H" • Brochure: "Safety and Handling: Aluminum Alkyls" •
Safety Film: We are interested in showing about(Date)
TEXAS ALKYLS, INC: P. O. Box 600, Deer Park, Texas 77536 Exclusive Sales Agent STAUFFER CHEMICAL COMPANY Specialty Chemical Division 380 Madison Avenue, New York, N. Y. 10017
OCT. 4, 1 9 6 5 C & E N
47
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48
C&EN
APPLETON COATED PAPER COMPANY Appleton • Wis • 5 4 9 1 0 Dept. CE-lO
OCT.
4,
1965
MEMBRANE. An Amicon technician examines a typical unsupported ultrafiltration membrane of the type Dorr-Oliver and Amicon are studying in their joint program to develop ultrafiltration
high-purity effluents with existing membranes. It does not, however, see an immediate market. But one will eventually develop, the company feels. Other Uses. Ultrafiltration isn't the only use for its membranes, Amicon points out. The company says that the unusual ion-transport characteristics of the membranes also suggest their use in dialysis and in electrochemical devices—battery- and fuelcell separators and electrodes. Ionloaded membranes function as solid electrolytes of extremely high d.c. conductivity. Also, their high water-absorption capacity enables them to function as water scavengers in porous-electrode fuel cell systems, Amicon explains. Besides being in a joint venture with D-O, Amicon is selling ultrafiltration membranes for applications such as rapid concentration of blood and urinary proteins for subsequent purification and identification as well as for rapid concentration and purification of viruses and bacteria. Also, Amicon is offering laboratory-size ultrafiltration cells and associated hardware and auxiliary equipment necessary for batch or continuous ultrafiltration.
Rocket Exhaust Generates Electricity Scientists of Hercules Powder's magnetohydrodynamics research group have produced 1.5 million watts for one second by using the exhaust from a small solid-propellant rocket. The method involves passing the rocket exhaust through a field generated by a 4-ton magnet. This creates electricity in the exhaust. The electricity is then drawn off by electrodes placed in the exhaust flow. The fuel used in the rocket motor is the same type that's used in the motors for Minuteman and Polaris and differs only in that it was seeded with alkali metals to increase its conductivity. Hercules scientists point out that the method could easily be scaled up to yield 300 million watts. This is equivalent to about one third the output of Hoover dam. Extension of the technique offers power-density levels in small volume that have not been obtainable before, Hercules says. The new system could be used as a power source for highvelocity wind tunnels, particle accelerators, x-ray machines, sonic transducers, shock tubes, high-field-strength magnets, and standby power sources.
