Hollow fibre module

II

Patents

Palladiumgraphite membrane A n o t h e r p a t e n t from Texaco, t h i s time c o v e r i n g e v e n m o r e exotic m a t e r i a l t h a n t h e p r e c e d i n g one. It is well k n o w n t h a t p l a t i n u m a n d p a l l a d i u m at h i g h t e m p e r a t u r e s will allow h y d r o g e n to diffuse a c r o s s a t h i n layer of t h e metal. If t h e m e t a l is electrodeposited on a porous g r a p h i t e b o d y (acting a s a n electrode d u r i n g the m e t a l d e p o s i t i o n p r o c e s s ) t h e n t h e layer of m e t a l c a n b e t h i n n e r t h a n is possible by conventional metal f o r m i n g m e t h o d s , while yet b e i n g free of p o r o s i t y f a u l t s w h i c h w o u l d c o m p r o m i s e its performance. The m e m b r a n e is m a d e b y immersing an anode and a porous graphite cathode in a m o l t e n s a l t b a t h . The c o n s t i t u e n t s of the b a t h are alkali(ne) e a r t h m e t a l h a l i d e s , p r e f e r a b l y e u t e c t i c m i x t u r e of l i t h i u m fluoride a n d s o d i u m fluoride, a n d a p l a t i n u m or p a l l a d i u m halide. A p l a t i n u m or p a l l a d i n m anode can be u s e d as the noble m e t a l s o u r c e , i n s t e a d o f - - or a s well as - - t h e n o b l e m e t a l salt. The t e m p e r a t u r e of the b a t h is 500-1300"C, preferably 600-800°C; c u r r e n t density d u r i n g t h e e l e c t r o d e p o s i t i o n is 10--400 A / m 2. T h e n o b l e m e t a l layer so d e p o s i t e d is 0 . 2 - 5 0 m i c r o n s thick, p r e f e r a b l y 15 m i c r o n s .

Patent number: US 5 1 8 1 9 4 1 Date: 26 J a n u a r y 1993 Inventors: M.S. Najjar, C.A. H u l t m a n Applicant: Texaco I n c

Hollow fibre module The m o d u l e is i m m e r s e d i n c o n t a m i n a t e d w a t e r i n o r d e r to p r o d u c e a flow of p u r i f i e d water. I n t h e s e c i r c u m s t a n c e s f o u l i n g of t h e m e m b r a n e s is p o s s i b l e , a n d for t h e i n d i v i d u a l fibres its effects can be mitigated by backwashing.

10

If the w a t e r is h e a v i l y c o n t a m i n a t e d , however, t h e w h o l e b o d y of t h e m o d u l e c a n b e c o m e clogged b y a b u i l d u p of algae. This d e s i g n of t h i s m o d u l e m i n i m i z e s t h e likelihood of t h a t outcome. A n a r r a y of fibres is b e n t i n t o a U - s h a p e a s s h o w n i n the d i a g r a m . The c u t e n d s are a t the b o t t o m of the m o d u l e a n d are s e a l e d into a collector for p u r i f i e d water. E a c h fibre f o r m s a loop, held in place by the supporting a r m s a t the top of the u n i t . Purified w a t e r p a s s e s u p the t u b e a t the c e n t r e of t h e u n i t before l e a v i n g at t h e outlet. B e c a u s e t h e fibres a r e n o t h e l d s e c u r e l y i n place t h e y a r e free to move i n the flow of c o n t a m i n a t e d w a t e r a n d a r e therefore less likely to foul t h a n is a u n i t of c o n v e n t i o n a l t u b e - a n d - p l a t e design.

Patent number: J P 5 0 2 3 5 4 9 Date: 2 F e b r u a r y 1993 Inventor: O. F u t a m u r a Applicant: E b a r a Corp

~

. filtere¢ I water outlet supporting arm

water collector

HoUow fibre module

Composite chitosan membrane The s u p p o r t layer, of m i c r o p o r o u s s t r u c t u r e , is cellulose s u l p h a t e with a degree of s u b s t i t u t i o n v a l u e of 0 . 9 - 2 . 2 . A layer of c h i t o s a n - - the p o l y s a c c h a r i d e derived from the s h e l l s of

crustaceans by processing them w i t h a n a l k a l i to l i b e r a t e c h i t i n is l a m i n a t e d to the cellulose sulphate. The cellulose layer ls 1 0 - 3 0 m i c r o n s thick; t h e c h i t o s a n layer Is t h i n n e r t h a n the cellulose. The c o m b i n a t i o n of the two m a t e r i a l s gives a m e m b r a n e s u i t a b l e for p e r v a p o r a t l o n , particularly in a process s u c h as t h e s e p a r a t i o n of w a t e r / a l c o h o l mixtures: the m e m b r a n e posesses a h i g h t r a n s m i s s i o n s p e e d with a high s e p a r a t i o n factor. Patent number: JP 5031338

Date: 9 F e b r u a r y 1993 Inventor: S. Y a n a s e Applicant: A s a h l C h e m i c a l I n d u s t r y Co. Ltd

Separating racemic mixtures This m e m b r a n e , of p o l y a m i n o acid i n a n a l p h a - h e l i x conformation, can separate an a q u e o u s s o l u t i o n of a r a c e m i c m i x t u r e i n t o the D- a n d L-optically active forms. No p a r t i c u l a r r a c e m i c m i x t u r e is specified : it is n o t clear how b r o a d are t h e a p p l i c a t i o n s of the m e m b r a n e . Its p e r f o r m a n c e , i n t e r m s of t h e p e r m e a t i o n rate, is c l a i m e d to be i m p r o v e d b y the a d d i t i o n of a s m a l l q u a n t i t y of a n alkali or a l k a l i n e - e a r t h m e t a l salt to t h e s o l u t i o n of the r a c e m l c mixture. The p o l y a m i n o acid p o l y m e r is p r e p a r e d b y the r e a c t i o n of polylysine (having the alpha-helix structure) with a n amphiphatic c o m p o u n d s u c h as a polyalkylene oxide h a v i n g a r o m a t i c derivatives as end-groups. One s u c h c o m p o u n d is n a m e d a s poly(oxyethylene)nonylphenol ether. The p o l y m e r is a p p l i e d to silicone r u b b e r or p o l y i m i d e support materials.

Patent number: J P 5 0 2 5 0 6 0 Date: 2 F e b r u a r y 1993 Inventor: N. O g a t a Applicant: Daicel C h e m i c a l I n d u s t r i e s Ltd

M e m b r a n e T e c h n o l o g y No. 4 3