Electrolytic cleaning

Patents reserve. W h e n t h e c o m p r e s s o r r e s t a r t s , therefore, t h e m e m b r a n e d r y i n g p e r f o r m a n c e is n o t hindered by a high partial p r e s s u r e of w a t e r v a p o u r a t the p e r m e a t e side of t h e m e m b r a n e .

Patent number: J P 8 0 7 1 3 5 4 Date: 19th M a r c h 1996 Inventors: H. T a m a i , M. K o b a y a s h i Applicant: Railway T e c h n i c a l Research Institute; Orion M a c h i n e r y Co. Ltd

Chiral compounds separation Many natural and synthetic c o m p o u n d s exhibit ' h a n d e d n e s s ' so t h a t p a r t or all of t h e r e l e v a n t m o l e c u l e c a n b e s y n t h e s i s e d to give two different s t r u c t u r e s , o n e of w h i c h is a m i r r o r i m a g e of t h e other. S e p a r a t i n g t h e s e two versions, known as enantiomers, from t h e r e a c t i o n m i x t u r e (a r e c e m i c m i x t u r e ) is a classic chemical problem, since the e n a n t i o m e r s h a v e very s i m i l a r a t t r i b u t e s s u c h as m e l t i n g p o i n t , solubility and diffusion characteristics. The u s e of a chiral or 'handed" c o m p o u n d to r e a c t with o n e of t h e two e n a n t i o m e r s , followed b y t h e r e v e r s a l of t h e r e a c t i o n , is the logical w a y of c a r r y i n g o u t s u c h a s e p a r a t i o n . In this p a t e n t the chiral c o m p o u n d is s e p a r a t e d from t h e r a c e m i c mixture by a semipermeable m e m b r a n e , a n d is a s s o c i a t e d w i t h or b o n d e d to a g e l - f o r m i n g m a t e r i a l w h i c h h a s a particle size g r e a t e r t h a n t h a t of t h e m e m b r a n e pores. P r e v i o u s s e p a r a t i o n t e c h n i q u e s involved solvent extraction between i m m i s c i b l e liquids, w h i c h it is a r g u e d is a slower p r o c e s s t h a n membrane separation. The p o s s i b l e s e p a r a t i o n s a n d chiral c o m p o u n d s listed i n t h e p a t e n t a r e wide, a n d p r o c e s s modifications include tailoring the p o l a r i t y of t h e m e m b r a n e to t h a t of t h e e x t r a c t i n g liquid, a n d

M e m b r a n e T e c h n o l o g y No. 79

u s i n g h i g h - d e n s i t y p a r t i c l e s so t h a t gravity a i d s the s e p a r a t i o n .

Patent number: WO 9 6 1 1 8 9 4 Date: 2 5 t h April 1996 Inventors: C.P.M G. A'Campo, M.S. Leloux Applicant: Akzo Nobel NV

Vibration suppression T h e e n d s of hollow fibre m e m b r a n e s are s e c u r e d b y p a t t e r n e d e n d - c a p s or b y 'potting' i n a fluid m a t e r i a l w h i c h is t h e n solidified. If the flow rate of the gas or liquid i n t h e m e m b r a n e m o d u l e is h i g h e n o u g h , the fibres, if n o t s e c u r e d b y s o m e m e a n s , m a y oscillate i n t h e t u r b u l e n t flow a n d c a n b e d a m a g e d . F r a m e s c a n be u s e d to r e s t r a i n the fibres a l o n g t h e i r l e n g t h b u t this i n v e n t i o n u s e s loose layers of m a t e r i a l s a t the e n d s of the fibres to r e d u c e t h e b e n d i n g forces exerted o n the fibre e n d s . In this w a y t h e r i s k of b r e a k a g e is r e d u c e d . T h e buffer layers are m a d e u p of m i c r o g r a n u l e s of p o l y p r o p y l e n e or p o l y e t h y l e n e for the top e n d of a vertical m e m b r a n e m o d u l e , a n d s m a l l b e a d s of glass for t h e b o t t o m end. The m a t e r i a l s are c h o s e n to h a v e a d e n s i t y respectively less t h a n (top) a n d g r e a t e r t h a n (bottom) the liquid b e i n g filtered.

Patent number: J P 8 1 1 2 5 1 7 Date: 7 t h May 1996 Inventors: M. K i y o m u r a Applicant: NOK Corp.

Safer swimming pools In this p a i r of p a t e n t s , t h e h i g h e r n u m b e r e d p a t e n t covers a w a t e r p u r i f i c a t i o n s y s t e m for o n e pool a n d the lower n u m b e r e d p a t e n t a p p l i e s the s a m e c o n c e p t to two

or m o r e l i n k e d pools. A conventional water treatment s e q u e n c e - - c o a r s e c e r a m i c filter followed b y a d i s i n f e c t i o n step - h a s a n u l t r a f i l t r a t i o n step a d d e d to it. T h e a d v a n t a g e c l a i m e d i n t h e s e p a t e n t s is t h a t t h e pore size of t h e m e m b r a n e e m p l o y e d i n this step is specified to b e s m a l l e n o u g h to r e t a i n v i r u s e s a s well as b a c t e r i a . I n this w a y t h e p o s s i b i l i t y of viral d i s e a s e s b e i n g contracted through swimming, w h i c h is a k n o w n e v e n t t h o u g h m o r e often l i n k e d to b a t h i n g i n seawater c o n t a m i n a t e d by i n a d e q u a t e l y t r e a t e d sewage, is eliminated.

Patent numbers: EP 7 1 5 8 7 4 , EP 7 1 0 4 9 8 Dates: 12th J u n e 1996, 8 t h May 1996 Inventor a n d Applicant: A Sugimoto

Electrolytic cleaning M e m b r a n e a n d filter c l e a n i n g to m a i n t a i n p e r f o r m a n c e is addressed here by m a n u f a c t u r i n g t h e s e p a r a t i o n device from two different p o r o u s m a t e r i a l s , o n e of w h i c h h a s good electrical conductivity. O n e e x a m p l e given i n the p a t e n t is of a t i t a n i u m dioxide c o a t i n g o n a s t a i n l e s s steel sintered metal base. Rather t h a n u s e fluid b a c k w a s h i n g to c l e a n the s u r f a c e a n d p o r e s of the m e m b r a n e , a n electrical c u r r e n t is p a s s e d t h r o u g h t h e m e m b r a n e , at a voltage h i g h e n o u g h to electrolyse water. B u b b l e s of h y d r o g e n a n d oxygen a r e formed i n t h e c o n d u c t i v e l a y e r of t h e m e m b r a n e a n d also to s o m e e x t e n t i n t h e p o r e s of t h e t i t a n i u m dioxide layer, t h u s cleaning the m e m b r a n e without s u b j r e c t i n g it to r e v e r s e flow a n d to p o s s i b l e l o n g - t e r m d a m a g e .

Patent number: WO 9 6 1 0 4 5 3 Date: 1 l t h April 1996 Inventors: D.J. Bray, A.P D a v i d s o n Applicant: IMAS (UK) Ltd

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