WO2008019940A1

WO2008019940A1 - Aqueous media purification method and device comprising a functionalised polyhipe resin

Info

Publication number: WO2008019940A1
Application number: PCT/EP2007/057837
Authority: WO
Inventors: Kathryn Bellamy; Paul Hugh Findlay; Steven Paul Rannard; Philip. Michael Ryan
Original assignee: Unilever Nv; Unilever Plc; Hindustan Unilever Limited
Priority date: 2006-08-17
Filing date: 2007-07-30
Publication date: 2008-02-21

Abstract

The present invention relates to the field of water purification, especially water purification with PoIyHIPE resin. It is an object of the present invention to provide a suitable means for the removal of microbial matter from water. In particular it is an object of the invention to provide a virus removal means capable of at least two Log removal. Accordingly, the present invention provides a method for the purification of aqueous media comprising the step of contacting a contaminated aqueous medium with PoIyHIPE resin. The present invention further provides a polyHIPE resin co-polymer comprising a styrene based monomer and a cross-linker and a second styrene based monomer. The resin is aminated, sulphonated or betainated.

Description

AQUEOUS MEDIA PURIFICATION METHOD AND DEVICE COMPRISING A FUNCT I ONAL I S ED POLYHIPE RESIN

Field of the invention

The present invention relates to the field of water purification, especially water purification with PoIyHIPE resin.

Background

Drinking water is becoming a scarcely available commodity; not only in the developed world, but also in developing and emerging countries (also referred to as D&E countries). It is especially desirable to remove microbial matter from the water for making it suitable and safe for drinking and maintenance of good health. Especially virus removal is a challenge.

Several different methods are known for e.g. filtration of water based on which various devices have been designed and are also commercially available. These methods and devices vary depending on whether the application is for industrial use or for household use and also critically upon the pressure at which the water to be purified is available.

In co-pending applications EP 05077094.0 and EP 06075057.7 carbon based cartridges and carbon block filters are described for the removal of microorganisms from water in a water purification method.

Carbon based filter cartridges have the disadvantage that the log reduction for viruses is too low to be classed as a virus removal agent. A further disadvantage is that the rejuvenation of carbon based filters is cumbersome and often requires heating the filter, which is not a preferred route, especially not for household use. Another known absorbent matrix is PoIyHIPE. PoIyHIPE, which is a highly absorbent material being a Polymerisation product of a High Internal Phase Emulsion, is a known absorption material in the art of household cleaning.

In EP A 0 068 830 and EP A 0 351 907, wipes containing PoIyHIPE absorbent material are disclosed. In these publications, the PoIyHIPE material is used to carry a cleaning composition containing an anti-viral agent.

WO00/34454 and WO04/005355 disclose media for growth of microorganisms which comprise PoIyHIPE and may be cross-linked and/or having sulphonated / aminated groups.

WO97/19347 discloses the use of PoIyHIPE polymers as chromatographic substrate for separation of various organic moities including virus.

It is an object of the present invention to provide a suitable means for the removal of microbial matter from water.

In particular it is an object of the invention to provide a virus removal means capable of two Log removal (i.e. 100 fold reduction or 99% removal), preferably three Log removal and even four Log. Log removal is defined as the logioof the number of input particles minus the log 10 of the number of output particles. In the field of virus removal, a virus removal means can be understood to be an agent which shows a four Log (10,000 fold) or better reduction in the number of virus from the feed stream.

At present there is a widely felt need for filtered and purified water. This is not only restricted to urban localities with sufficient water, but also extending to remote places and water scarce urban centres where online systems are not readily available or functional. There exists a constant need for development of improved means for water purification to fulfil the increasing need of clean and safe drinking water.

It has now been surprisingly found that PoIyHIPE resins can be used to remove virus from water.

Definition of the invention

Accordingly, the present invention provides a method for the purification of aqueous media comprising the step of contacting a contaminated aqueous medium with PoIyHIPE resin.

The present invention further provides a PoIyHIPE resin co-polymer comprising a styrene based monomer and a cross-linker.

The invention further provides a water purification device. The device comprises a water inlet, a water outlet and a holder comprising PoIyHIPE resin.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages of the low environmental detergent product composition unless otherwise indicated. Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated. Detailed description

In one aspect the invention relates to a method for the purification of contaminated aqueous media with PoIyHIPE resin. The contaminated aqueous media may for instance be water or blood plasma.

For the purification of drinking water, the removal of microbial matter from water is a main challenge. In the context of this invention microbial matter includes bacteria, yeasts, cysts, protozoa and virus. The invention particularly relates to the removal of virus from drinking water.

Virus removal is becoming a more and more important aspect of drinking water purification. The virus removal device of the invention preferably removes at least 99% (2-log removal) of the virus in the feed stream, more preferably more than 99.9% (3-log removal). It is still more preferred to remove at least 99.99% (4-log removal).

Preferably the PoIyHIPE resins for the removal of microbial matter from contaminated aqueous media comprise of at least a monomer possessing a vinyl group and a crosslinker. Such PoIyHIPE resins are disclosed in EP A 0 068 830.

The purification method comprises the step of contacting contaminated aqueous medium with PoIyHIPE resin. The method may further comprise other purification steps, such as filtration.

The contacting of the contaminated aqueous medium with PoIyHIPE resin may be achieved by mixing the medium with the resin, passing the contaminated medium through a column comprising PoIyHIPE resin or by any other means as long as the contaminated aqueous medium comes in contact with the PoIyHIPE resin. Water purification device

In another aspect the invention provides a water purification device. The device comprises a water inlet, a water outlet and a holder comprising PoIyHIPE resin.

The device preferably comprises a water inlet filter to remove particulate matter from the feed water.

The PoIyHIPE resin in the holder may for instance be in the form of particles, in the form of a monolith or as a PoIyHIPE functionalised membrane.

When the PoIyHIPE resin in the holder is in the form of particles, the particles preferably have a particle size between 20 and 120μm. The particles in the holder may be packed or unpacked, preferably packed.

The water purification device is particularly suitable for the purification of drinking water or the purification of blood or blood fractions.

PoIvHIPE resin

In another aspect the invention relates to PoIyHIPE resins that are particularly suitable in the context of the invention.

The preferred PoIyHIPE resin according to the invention is a co-polymer comprising at least one styrene base monomer and at least one crosslinker.

The reactive styrene-based monomer is preferably selected from vinyl benzyl chloride (VBC), acetoxy styrene, vinyl benzoic acid, 4-, 3- and 2-vinyl pyridine, N-vinyl carbazole and derivatives and/or mixtures thereof. Vinyl benzyl chloride is particularly preferred. The PoIyHIPE resin according to the invention may further comprise a second styrene based monomer, preferably selected from Styrene (ST) or other vinyl- functionalised aromatics such as vinyl naphthalene. The styrene moiety can be post-functionalised by such methods as sulphonation or chloromethylation to give a sulphonic acid or benzyl chloride group respectively.

In order to get a 3-dimentional polymer network with suitable pore size and porosity, a cross-linker is used. The co-polymer effectively forms a matrix that is suitable for the removal of microbial matter from water, especially the removal of virus from water. A cross-linker is a monomer that when added during the polymerisation process links one polymer chain to another by means of covalent bonds.

Preferred cross linkers according to the invention are linear, branched or cyclic hydrocarbon molecules comprising at least two terminal C=C bonds. The most preferred cross-linker is divinylbenzene (DVB).

The styrene base monomer(s) to crossl inker ratio is preferably between at least 10:90, more preferably at least 25:75, most preferably at least 50:50 % by weight. The ratio is preferably less than 95:5, more preferably less than 90:10, still more preferably less than 85:15 or even less than 75:25 % by weight.

Preparation

PoIyHIPE resins according to the invention may for instance be prepared according to the methods as disclosed in EP-A1 -0 068 830.

Functionalised PoIyHIPE

The PoIyHIPE resin according to the invention may optionally be functionalised to improve the virus removing properties. The functionalisation of this type is matrix is widely known in the art. Preferred functionalised PoIyHIPE resins are aminated and/or sulphonated and/or betainated PoIyHIPE resins. Examples of the functionalisation method are given herein below. Preferred aminated PoIyHIPE is obtained by amination with thalkylamine, more preferably with trimethylamine or thethylamine. Sulphonation is obtained by functionalisation with sulphuric acid. Betainated resin is obtained by functionalisation with a betaine.

The PoIyHIPE resin preferable contains at least 0.5 mmol/g functional groups, more preferably at least 1 mmol/g. The polyHIPE may contain up to 5 mmol/g functional groups. These groups may bind in an associative manner to the virus particle and immobilise it in the polymer matrix. This binding will be dependant on the flow rate and the aspect of the polymer filtration device.

Regeneration The polymer matrix may be regenerated by conventional means e.g. by passing a concentrated electrolyte or acidic or alkaline solution through the filter. For example, in the case of the aminated resin a concentrated solution of acid or metal salt solution such as sodium chloride could regenerate the active site by preferentially replacing the virus particles. This procedure is well known to those familiar with ion exchange resins.

Examples

The invention will now be illustrated by way of the following non-limiting examples, in which all parts and percentages are by weight unless otherwise indicated.

Example 1

Example 1 shows methods for preparing PolyHIPE according to the invention. Preparation of DVBA/BC, DVB/VBC/Styrene and ST/DVB polvHIPES

Span 80 (Sorbitane monooleate) and divinyl benzene (DVB) were added to chloromethyl styrene (VBC) and or styrene. Potassium persulphate was dissolved in de-ionised water and added slowly to the stirring monomer/surfactant mixture. After complete addition, the emulsion solution was poured into a pre-formed mould and heated to 60 ⁰C for 18 hours.

Following the polymerisation the polymer monolith was washed by continuous extraction with hexane prior to drying under vacuum at 40 ⁰C. The monolith could then be crushed as required prior to the subsequent chemical modifications.

Amination

10 g of VBC/DVB/Styrene PoIyHIPE was placed in round bottomed flask, to this was added 150 cm³ trimethylamine or triethylamine (33 wt % solution in ethanol) (0.8 mols) and another 100 cm³ of ethanol. The mixture was then heating to 70 ⁰C with stirring for 6 hours. The polymer was then filtered off, washed with ethanol (2 x 100 cm ³), acetone (2 x 100 cm³) and then finally continually extracted with acetone for 6 hours before drying under vacuum (40 ⁰C) for 24 hours. This procedure was also performed for the other aminations.

Betainisation

10 g of VBC/DVB/Styrene PoIyHIPE was placed in round bottomed flask, to this was added 150 cm³ of dimethylamine. The mixture was then heating to 70 ⁰C with stirring for 6 hours. The polymer was then filtered off, washed with ethanol (2 x 100 cm ³), acetone (2 x 100 cm³) and then finally continually extracted with acetone for 6 hours before drying under vacuum (40 ⁰C) for 24 hours. This aminated resin was then treated with an excess of chloroacetic acid in THF, heated to 40 ⁰C for 8 hours, filtered off and washed and dried as previously described to give a polyHIPE with carbobetaine functionality. Amination and Sulfonation

10 g of VBC/DVB/Styrene PoIyHIPE was placed in round bottomed flask, to this was added 150 cm³ trimethylamine (33 wt % solution in ethanol) (0.8 mols) and another 100 cm³ of ethanol. The mixture was then heating to 70 ⁰C with stirring for 6 hours. The polymer was then filtered off, washed with ethanol (2 x 100 cm ³), acetone (2 x 100 cm³) and then finally continually extracted with acetone for 6 hours before drying under vacuum (40 ⁰C) for 24 hours. The polymer was then post-sulfonated as described previously to give a resin with both quaternary ammonium and sulfate groups.

Sulphonation

10 g of ground Styrene/DVB PoIyHIPE material was placed in a round bottomed flask. To this was added concentrated sulphuric acid (200 cm³) and dichloromethane 100 (cm³) to help increase swelling and wettability of the polymer. This mixture was then heated to 45 ⁰C with stirring for 24 hours. After this mixture was poured carefully onto a mixture of ice/water. The product was then filtered off and washed with distilled water (5 x 100 cm³) and then acetone (2 x 100 cm³). Finally the product was washed via continuous extraction with acetone for 6 hours and dried under vacuum (40 ⁰C) for 24 hours.

Results

In tables 1 and 2 below the results are shown of materials made using the above methods. S.A is the surface area of the material in m2/g. C, H, N, Cl and Sulphur are the percentage amounts of the respective elements (carbon, hydrogen, nitrogen, chlorine and sulphur) in the PoIyHIPE and nitrogen, chlorine and sulphur are also given as mmol per gram PoIyHIPE. Table 1 : PoIyHIPE analysis

Example 2

In example 2 virus challenge results are shown. Method 1

PoIyHIPE was weighed (0.05g) and added to 5ml deionised water , left overnight to expand and then packed into a chromatography column (10mm internal diameter) the height of the column was approximately 0.9mm depending on the type of polyHIPE. Water was pumped through the column at a rate of 5ml/min^"1 to ensure the polymer was washed free of any monomers . Once the PolyHIPEhad been prepared it was challenged with poliovirus.

Poliovirus Type 1 (LSa ATCC No VR-59)) was grown in Vero cells using a standard method. Virus stock was kept at -70⁰C until required. Just prior to testing the virus stock was thawed and diluted in sterile deionised water. The following aliquots of Poliovirus solution and water were pumped through the column in sequence and the column effluent was collected separately: 1 ) 5ml Poliovirus, 2) 5ml Poliovirus

3) 5ml Water

4) 5ml Water

5) 5ml Water.

Each aliquot was assayed for the presence of virus.

Titration of virus: Monolayers of Vero cells were cultured in 96 well cell culture plates at 37°C in a humidified incubator (95%air/5% carbon dioxide atmosphere). Ten-fold dilutions of virus suspension i.e. separate sets of dilutions from each eluent (in cell culture medium) were prepared. One hundred micro litres of each dilution was added to five replicate wells of the 96 well plate. Plates were incubated at 37°C in a humidified incubator for 7 days, then the plates were examined under an inverted microscope for cytopathic effects caused by the virus on the cells. The infective dose was calculated using the Karber formula. Results

The table below shows the recovered virus for each of the process steps described above.

Table 2: Comparative data

Calculation of Challenge and Virus Break Through

The challenge is given in TCID₅o/O.1 ml. In the above experiments, 10 ml is passed through the PoIyHIPE column, resulting in a multiplication factor of 100.

Total virus = Multiplication factor x 10^Λ(Challenge[TCID₅₀/0.1 ml])

The virus breakthrough is calculated in the same way as the total virus, and the Total Virus Breakthrough is the sum of challenges 1 and 2 and Postwashes 1 ,2 and 3.

Calculation of Virus Retention

Virus retention % = 100 - (Virus Breakthrough / challenge) X 100.

Table 3: Comparative data

Thus, the results show that Polio virus can be removed from water. The results also show that a 4-log polio virus reduction is possible with PoIyHIPE resin and the disclosed method of the invention, whereas only 2-log could be obtained with known PoIyHIPEs.

Method 2

PoIyHIPE was weighed (0.05g) and added to 5ml deionised water, left overnight to expand and then packed into a chromatography column (10mm internal diameter) the height of the column was approximately 0.9mm depending on the type of polyHIPE. Water was pumped through the column at a rate of 5ml/min to ensure the polymer was washed free of any monomers. Once the PolyHIPE had been prepared it was challenged with poliovirus. Poliovirus Type 1 (LSa ATCC No VR-59)) was grown in Vero cells using a Standard method. Virus stock was kept at -70⁰C until required. Just prior to testing the virus was thawed and diluted in sterile deionised water. The following was pumped through in sequence and the column effluent collected separately: 10 X 5ml virus challenge.

The effluent from each 5ml aliquot was collected and assayed for the presence of virus. The polyHIPE was then eluted with 10X 5ml deionised water and effluent from each 5ml aliquot collected and assayed for virus.

Titration of virus: Monolayers of Vero cells were cultured in 96 well cell culture plates at 37°C in a humidified incubator (95%air/5% carbon dioxide atmosphere). Ten-fold dilutions of virus suspension i.e. separate sets of dilutions from each eluent (in cell culture medium) were prepared. One hundred micro litres of each dilution was added to five replicate wells of the 96 well plate. Plates were incubated at 37°C in a humidified incubator for 7days, then the plates were examined under an inverted microscope for cytopathic effects caused by the virus on the cells. The infective dose was calculated using the Karber formula

Results

Challenge

Wash

Calculation of % retention is as above except that the volume of challenge is 50ml therefore the inverse log is multiplied by 500. The virus breakthrough is calculated from the challenge 10 X5ml and the wash 10 X 5ml. Method 2 : Calculation of virus retention by PoIyHIPE (in Deionised water)

Thus, the results show that Polio virus can be removed from water. The results also show that only a 2-log polio virus reduction is possible with PoIyHIPE resins disclosed in the art.

Higher log reduction in virus titre may be achieved in an increased weight of polyHIPE is used for a defined volume of water or the poyHIPE is cast in a particular shape.

Claims

1 A PoIyHIPE resin co-polymer comprising:

(a) 50-90% of a styrene based monomer;

(b) 10-40% a cross-linkerAnd

(c) A second styrene based monomer

Wherein the resin is aminated, sulphonated or betainated.

2 A PoIyHIPE resin according to claim 1 , wherein the styrene based monomer is selected from vinyl benzyl chloride (VBC), acetoxy styrene, vinyl benzoic acid, A-, 3- and 2-vinyl pyridine, N-vinyl carbazole and derivatives and/or mixtures thereof.

3 A PoIyHIPE resin according to any one of claims 1 or 2, wherein the cross-linker is divinylbenzene.

4 A PoIyHIPE resin according to any one of claims 1 -3, wherein a second styrene based monomer is present.

5 A method for the purification of aqueous media comprising the step of: (a) Contacting a contaminated aqueous medium with the PoIyHIPE resin according to anyone of claims 1 -4.

6 A method according to claim 5, wherein the aqueous medium is drinking water.

7 A method according to any one of claims 4 or 5, wherein the contamination is virus. A water purification device comprising:

(a) a water inlet

(b) a water outlet

(c) a holder comprising the PoIyHIPE resin according to anyone of claims 1 -4.

A water purification device according to claim 8, further comprising a coarse filter to remove particulate matter from the feed water.