High-purity porous silica glass

High-purity porous silica glass

News and Views signing of a cooperative R&D agreement between Sandia National Laboratories, developers of the foams, a n d Permacharge Corporation of ...

178KB Sizes 5 Downloads 159 Views

News and Views signing of a cooperative R&D agreement between Sandia National Laboratories, developers of the foams, a n d Permacharge Corporation of Albuquerque, New Mexico, USA. The agreement extends the previous relationship between Sandla a n d Permacharge. In J u n e 1990 Sandia granted a n exclusive license for filter media p r o d u c t i o n a n d between J a n u a r y a n d J u l y 1991 Permacharge was funded by the National Science F o u n d a t i o n to continue the development of polypropylene foam for filtration applications. Permacharge h a s been developing p r o d u c t s in three m a r k e t a r e a s covered by the original Sandia license: HEPA filters for use in hospitals, semiconductor cleanrooms, a n d c o m p u t e r disk drives; liquid pre-filters to extend the life of a m e m b r a n e filter; battery separators for improved automobile batteries u n d e r development. The goal of the present cooperative R&D agreement is to opt(raise the materials and processes n e c e s s a r y for commercial(sat(on. According to Permacharge President, Ioana McNamara, several large m a n u f a c t u r e r s of filtration media a n d battery separators have already expressed interest in investment once the Joint research h a s been completed. F u r t h e r information can be obtained from: Roy Ham(l, S a n d i a National Laboratories, Albuquerque, NM 87185, USA. Tel +1 (505) 844 7143, or Ioana McNamara, Permacharge, Tel +1 (505) 344 1415.

High-purity porous silica glass Co-development or strategic partnership arrangements are being sought by GELTECH, of Florida, USA, to exploit its high-purity p o r o u s silica glass, Gelsis - - a mechanically strong, h a r d monolithic material with fully interconnected a n d uniform porosity which also retains the excellent electrical a n d optical properties of pure silica. Porous Gelsil h a s potential for use as a filter or separator of c o m p o u n d s due to its rigidity a n d high temperature capability a n d can be tailored to customer specifications for pore diameter, total pore volume or specific surface area by controlling the sol-gel m a n u f a c t u r i n g route. The proprietary m a n u f a c t u r i n g technology was developed at the University of Florida. The material m a y be used 'as is', b u t can also be chemically modified or impregnated with a variety of organic, inorganic or polymeric dopants. Parts can be machined or polished to a limited extent to achieve exact shapes and dimensions. S t a n d a r d window sizes range from 5 to 40 m m diameter, with thicknesses of 3 to 7 nun, in pore size diameters of 25 to 200 A.

Specifications of Gelsfl porous glass Composition

Silica

99.9%

Cation impurities

- 1 ppm

Total pore volume

1. I to 0.400 c m 3 / g

Surface area (BET) Appearance

241 to 610 m 2 / g Translucent to transparent ( dependentt on pore size)

Impact of fracture

1.36 to 0.4 J

Vickers h a r d n e s s Strength factor

74.0 to 18 k g / m m 2 0.83 to 0.06 MPa

Optical properties

UV cutoff (50%) IR cutoff (50%)

290 n m 2150 n m

Impregnation

Can be readily impregnated with polymers, dyes, catalysts or other materials with particle sizes small e n o u g h to reside in the pores.

Absorption / handling

Will absorb up to 30% of its dry weight in water vapour u n d e r ambient conditions. The water can be evaporated t h r o u g h heating the monolith. May t u r n yellow on standing due to the absorption of atmospheric organic materials.

Physical properties (25 to 200 A pore size)

Mechanical properties (25 to 200 A pore size)

Table 1.

2

Membrane Technology

News and Views Windows c a n c u r r e n t l y be m a d e a s large a s 50 m m in d i a m e t e r a n d c u s t o m m a n u f a c t u r i n g of c o m p l e x c o n f i g u r a t i o n s - - convex s h a p e s , p r i s m s , r o d s - - is also available. F u r t h e r i n f o r m a t i o n from: Tricia B a c h u s , Geltech Inc, Two i n n o v a t i o n s Drive, A l a c h u a , FL 32615, USA. Tel +1 (904) 462 2358. F a x +1 (904) 462 2993.

Vokes adds to microfilter range Ecofil is a low-cost g e n e r a l p u r p o s e c a r t r i d g e microfflter b a s e d on p o l y p r o p y l e n e a n d u t i l i s i n g a p l e a t e d c o n s t r u c t i o n to give a h i g h s u r f a c e a r e a a n d low c l e a n p r e s s u r e drop. A d d i t i o n a l benefits c l a i m e d over w o u n d b o b b i n a n d o t h e r d e p t h - t y p e filters are a high d l r t - h o l d i n g c a p a c i t y , low e x t r a c t a b l e s a n d the non-fibre s h e d d i n g p r o p e r t y of the media. A b s o l u t e pore sizes from 0.6 to 90 m i c r o n s a r e available. M a x i m u m differential p r e s s u r e is 14 b a r at 20°C or 8.5 b a r a t 80°C. The Ecofil c a r t r i d g e j o i n s Vokes' Hydrofil (nylon m e m b r a n e ) , Chemffil (polypropylene m e m b r a n e ) , Fluoroffl (PTFE m e m b r a n e ) , Biofll (cellulose t r i a c e t a t e m e m b r a n e ) a n d Polyffl (hot s p u n p o l y p r o p y l e n e fibre) c a r t r i d g e r a n g e s . F u r t h e r information: J u l i a n Grifflths, Vokes Limited, Henley Park, Guildford, S u r r e y GU3 2AF, UK. Tel +44 (0)483 69971. F a x +44 (0)483 235384.

Japanese activity in f u n c t i o n a l separation membranes F u n c t i o n a l m e m b a n e s - - defined h e r e a s high m o l e c u l a r weight o r g a n i c or polymeric m e m b r a n e s - is t h e sector of t h e m e m b r a n e i n d u s t r y a t t r a c t i n g the g r e a t e s t r e s e a r c h a t t e n t i o n in J a p a n . A s t r a t e g i c a s s e s s m e n t of J a p a n e s e d e v e l o p m e n t s a n d the c o m p a n i e s involved is the claim m a d e by DIA for its r e c e n t t e c h n o l o g y report. An a n a l y s i s of R&D t r e n d s is provided, b a s e d on a s u r v e y of J a p a n e s e Kokai. The r e p o r t c o s t s $2 000 a n d is available from: Ken-ichi Itoh, DIA R e s e a r c h I n s t i t u t e Inc, Ryoka Building, 1-30, S h i b a 2-chome, M i n a t o - k u , Tokyo 105, J a p a n . Tel +81 3 3798 2611. F a x +81 3 3798 1229.

Membrane Technology

Highly s e l e c t i v e polyaniline membrane Workers at UCLA, USA, have developed a highly selective m e m b r a n e s y s t e m for g a s s e p a r a t i o n b a s e d on polyaniline. D o p i n g - u n d o p i n g - r e d o p i n g cycles are s a i d to r e s u l t in very high s e p a r a t i o n factors - - greater t h a n 3500. For h y d r o g e n / n i t r o g e n m i x t u r e s , d o p i n g the m e m b r a n e with 4M HCI, r e m o v i n g the d o p a n t by a b a s e solution, a n d t h e n r e d o p i n g in d i l u t e d acid c a n p r o d u c e a s e p a r a t i o n factor of 3590.

Le Carbone e x t e n d s Pervap range Two m e m b r a n e s a n d a b a t c h u n i t have b e e n a d d e d to Le C a r b o n e ' s r a n g e of p e r v a p o r a t l o n e q u i p m e n t . Pervap m e m b r a n e 1170 h a s b e e n developed for solvent recovery from toxic effluent a n d is now available on an i n d u s t r i a l scale. The m e m b r a n e is p r o d u c e d by i m b e d d i n g a h y d r o p h o b i c stlicalite into a layer of polydimothylsfloxane a n d p e r f o r m a n c e figures s u p p l i e d by Le C a r b o n e show, for example, t h a t a n effluent s t r e a m c o n t a i n i n g 8 600 p p m of d i c h l o r o e t h a n e c a n be s e p a r a t e d into water with a c o n t a m i n a n t level of only 5 p p m a n d solvent at a c o n c e n t r a t i o n of 99.7%. Most o r g a n i c s c a n be r e m o v e d from a q u e o u s solution. The PVA-based 1005 m e m b r a n e h a s b e e n d e s i g n e d specifically for u s e with acetic acid, where p e r v a p o r a t l o n r e p r e s e n t s a viable a l t e r n a t i v e to distillation with economic a d v a n t a g e s c l a i m e d for a p p l i c a t i o n s n e e d i n g to d r y u p to 100 000 t of p r o d u c t p e r year. The 1005 m e m b r a n e is also s a i d to be s u i t a b l e for d r y i n g esters. Aimed at c o m p a n i e s which n e e d to d e h y d r a t e a wide variety of organic solvents in s m a l l b a t c h e s , the Pervap B a t c h Unit is a s e l f - c o n t a i n e d a n d p r e - a s s e m b l e d s y s t e m with a choice of two m e m b r a n e a r e a s - - I0 or 75 m z. The u n i t c o n s i s t s of a single v a c u u m vessel which for r a p i d i n s t a l l a t i o n is m o u n t e d with p u m p s a n d h e a t e x c h a n g e r s on a skid. The small m e m b r a n e option p e r m i t s the p r o c e s s i n g of a b o u t 250 kg p e r b a t c h of p r o d u c t ; over 3 000 kg per d a y c a n be p r o d u c e d by the larger m e m b r a n e , at c o n c e n t r a t i o n s of u p to 99.9%. F u r t h e r i n f o r m a t i o n from: Mike Denyer, Chemical E n g i n e e r i n g Division, Le C a r b o n e (GB) Ltd, S o u t h Street, Portslade, E a s t S u s s e x BN41 2LX, UK. Tel +44 (0)273 415701.

3