Title of Invention

"A PROCESS FOR THE PREPARATION OF A NOVEL POLYURETHANE AND ITS APPLICATION AS MEMBRANE FOR SELECTIVE SEPARATION OF ORGANIC POLLUTANTS(PHENOLIC COMPOUNDS)FROM AQUEOUS SOLUTINS BY PERVAPORATION".

Abstract A novel polyurethaneurea which is a hydroxy-terminated polybutadiene (HTPB) based polyurethaneurea and to a pervaporation membrane obtained of said HTPB based polyurethaneurea for efficient removal of organic pollutants by membrane pervaporation. The invention also relates to a method of selective separation of organic pollutants such as phenolic compounds from aqueous solution by pervaporation with high efficiency using the said HTPB polyurethaneurea based membrane. The novel polyurethaneurea, would provide for preparation of pervaporation membranes of higher efficiency in terms of desired total flux and separation factor.Importantly the novel polyurethaneurea is directed provide a selective HTPB based pervaporation membrane which would have excellent pervaporation performance in terms of separation factor or selectively for separation of organic pollutants by membrane pervaporation especially selectively of phenol from phenol-water mixture.
Full Text Field of the Invention
The present invention relates to a novel and its process of manufacture. In particular, the invention reiates to a novel polyurethaneurea, which is a hydroxy-terminated polybutadiene (HTPB) based polyurethaneurea and to a pervaporation membrane obtained of said HTPB based polyurethaneurea for efficient removal of organic pollutants by membrane pervaporation. The invention also relates to a method of selective separation of organic pollutants such as phenolic compounds from aqueous solution by pervaporation with high efficiency using the said HTPB polyurethaneurea based membrane.
Background Art
The problem of environmental pollution arising out of industrial effluents is a global concern. Most industrial effluents contain a range of toxic organic compounds and elements, which pose a great threat to the living system in the environment.
The process of selective removal of organic pollutants by membrane pervaporation is a known technique. Polymeric membranes have been tested for separation of pollutants or organic compounds from aqueous solutions of low concentration by this technique.
Membranes used so far for aqueous/organic separations by pervaporation include polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), polystyrene (PS), polysulfone (PSF), polyvinyl chloride (PVC), cellulose acetate (CA), polyvinyl acetate (PVAc), polyurethane (PU), polydimethyl siloxane (PDMS).
In particular, membranes used so far for phenol separation are Crosslinked polyvinyl alcohol (PVA)/ Polyacrylic acid (PAA) which is used for selective removal of water from aqueous phenol solution (Rhim et al. Journal of Applied Polymer Science, Vol. 52 (1994), 1217-1222.
Also possible use of organofunctionalised PDMS membrane for the pervaporation recovery of phenolic compounds from aqueous streams is published (Wu et al, Journal of Membrane Science 190 (2001) 147-357).

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Moreover, it is also known to use polyurethane membranes for selective removal of phenol from aqueous phase. Maximum 65% phenol concentration in the permeate is also reported where PU membrane is of different chemical composition viz. polytetramethylene glycol + H12PI (Hosbi et al., J. Appl. Polym. Sci., 65 (1997), 469-479)
While several polymeric membrane are thus presently available for use in pervaporation it is found that such presently available membranes suffer from certain limitations in their efficiency in terms of total flux and separation factor. There is thus need to improve upon the membrane quality and characteristics to favour achieving higher efficiency in terms of flux and separation by pervaporation technique.
Objects of the Invention
It is thus the basic object of the present invention to develop novel polyurethaneurea, which could provide for preparation of pervaporation membranes of higher efficiency in terms of desired total flux and separation factor.
Another object of the present invention is directed to the development of polyurethaneurea based pervaporation membrane which would have excellent pervaporation performance in terms of separation factor or selectively for separation of organic pollutants by membrane pervaporation.
A further object of the present invention is directed to development of polyurethaneurea membrane with excellent pervaporation performance in terms of separation factor or selectively of phenol from phenol-water mixture.
Yet another object of the present invention is directed to the development of HTPB based polyurethaneurea membrane for selective separation of organic pollutants especially phenolic compounds from aqueous solutions by pervaporation with high efficiency.
Yet another object is directed to improvement in the method of selective separation of organic pollutants especially phenolic compounds from aqueous phenolic solutions by

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pervaporation with high efficiency using a selective HTPB based poiyurethaneurea membrane
Summary of Invention
A process for the manufacture of poiyurethaneurea of Formula I

reacting selective diols of Formula II
HO — R ---- OH, wherein R= poiybutadiene, ethylene, neopentelene
with Diisocyanate of Formula III;
OCN — R' — NCO, wherein R' = C6H3CH3, 4,4'diphenylmethane, hexamethylene, methyl 3,5,5'
trimethylcyclohexane, at selected mole ratios to prepolyurethane at -10°C to 60°C
to thereby obtain isocyanato terminated polyurethane of formula IV;

subjecting the said isocyanate terminated prepolyurethane of formula IV to chain extension with
diamines of Formula V
H2N — R — NH2, wherein R = C6H4SO2C5H4, C6H4OC6H4, C6H4S2C6H4
0 to 100 mole % at the same temperature for one hour
to thereby obtain the desired polyurethane of formula I;


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Brief description of the Invention
Thus according to one aspect of the present invention there is provided a polyurethaneurea of general Formula I:

According to another aspect of the invention there is provided a process for the manufacture of polyurethaneurea of Formula I:


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OCN — R -— NCO, wherein R' = C6H3CH3, 4,4'diphenylmethane, hexamethylene,
methyl 3,5,5' trimethylcyclohexane,
to thereby obtain isocyanato terminated polyurethane of formula IV;

subjecting the said isocyanate terminated prepolyurethane of formula IV to chain
extension with diamines of Formula V
H2N — R — NH2, wherein R = C6H4S02C6H4, C6H4OC6H4, C6H4S2C6H4
to thereby obtain the desired polyurethane of formula I;

According to another aspect of the present invention there is provided polyurethaneurea membrane for use in selective separation of organic pollutants by membrane pervaporation comprising:
a polyurethaneurea composition comprising of polyurethane polymer of formula I in amount of 40-60% and solvent in amount of 60-40% casted on a smooth substrate.
According to another aspect of the present invention there is provided a process for manufacture of polyurethane based membrane for use in selective separation of organic pollutants by membrane pervaporation comprising;
a. providing a pre-cast composition comprising the polyurethaneurea polymer of
formula .1 in amount of 40-60% by wt. and a solvent in amount of 60-40%;
b. casting the composition of a) above on a smooth substrate;
c. curing the polyurethaneurea membrane thus obtained to desired moisture content; and
d. conditioning the membrane to obtain desired membrane morphology.

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According to yet further aspect of the present invention there is provided an improved
method of selective removal of organic pollutants such as phenolic compounds from
aqueous solutions by pervaporation using the polyurethaneurea based membrane
comprising;
a pervaporation method of selectively enriching the phenolic content of the permeate of
an aqueous phenolic feed solution comprising:
contacting the feed side of a polyurethaneurea based membrane such as herein defined
with the aqueous phenolic feed solution such that the phenols in the feed solution
preferentially permeate said membrane leaving a phenol depleted water retentate on the
feed side of the membrane.
According to another aspect the present invention provides for improvement in preparation of pervaporation membrane such as polyurethane urea based membranes by way of selective polymer : solvent ratio and fluidity of the polymer solution prior to casting, unique curing and conditioning of the membrane for better pervaporation performance.
Detailed Description of the Invention
The present invention basically deals with the development of a polyurethaneurea of formula (!) followed by casting of membrane from this polymer in solution in a solvent having a critical concentration, The membrane thus developed is found to have excellent pervaporation performance in terms of separation factor or selectivity for separation of phenol from phenol-water mixture. The polymer membrane used in the process is based on a selective composition and process of preparation. It is basically hydroxy-terminated polybutadiene (HTPB) based polyurethaneurea made from various diisocyanates under the influence of various catalysts and specific conditions by solution polymerization technique as shown in the reaction scheme below.

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The polyurethaneurea based membrane of the invention has been found to be highly effective in selective isolation of organic pollutants such as phenols from aqueous streams. For the purpose, such membrane can be used in a system for carrying out such separation as illustrated in accompanying Figure 1. As shown in said figure 1 the system ' basically comprise of feed inlet (1), stirrer (2), thermometer pocket (3), feed chamber (4), permeate chamber (5), sintered SS disk (6), condenser-cum-coollector(7), cryostat (8), manometer (9) and a vacuum pump (10)
As discussed above, the invention deals with Polybutadiene based Polyurethaneurea developed from the following materials:
Diols selected from Hydroxyterrninated Polybutadiene Neopentyl glycol Ethylene glycol
Diisocyanates selected from 2,4-toluene diisocyanate (TDI) 4;4'-diphenylmethane diisocyanate (MDI) Hexamethylene diisocyanate (H12DI)l isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane(IPDI)
Diamines selected from 4,4'-diaminodiphenyl sulfone (DADPS) 4,4,-diaminodiphenyl ether (ODA) 4,4'-diaminodiphenyl disulfide (DADS)

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Catalysts selected from Triethylamine (TEA) and Dibutyltindilaurate (DBTDL)
Solvents selected from N,N-dimethyl fomamide (DMF), 1,4-dioxane; Tetrahydrofuran (THF); Benzene, Toluene, Phenol.
The polymer membrane was made from its solution by casting technique on a smooth substrate surface followed by curing at elevated temperature. For obtaining efficient pervaporation characteristics, the membrane was properly conditioned through solvent and heat treatment. The pervaporation characteristics of the said membrane have been found to depend on its chemical nature, composition and morphology.
Waste streams from several industries like chemical, petrochemical, polymer, etc. contain phenolic compounds as toxic components. Using the selective polyurethane-urea based membranes of the invention, it is now possible to achieve selective removal of such compounds from the waste streams.
In particular, the aforesaid membrane of the invention can be used for the separation of phenol from phenol-water mixture by pervaporation technique.
Examples
The invention is explained hereunder in greater detail in relation to the non-limiting exemplary illustrations.
Example 1
Membrane Preparation
Polyurethane-urea membranes were prepared by reacting HTPB with diisocyanates at various mole ratios to prepolyurethane at -10 °C to 60 °C followed by chain extension with diamines [0 (PPUD) to 100 (PUUSD100) mole %] at the same temperature for one hour. The viscous polymer solution was cast on a smooth substrate ( Teflon) surface with the help of an applicator at room temperature and relative humidity of 60 to 90%. The cast polyurethane was allowed for 15 to 72 hours moisture curing. The membrane thus obtained was having a thickness of 0.1 to 0.15 cm and was exposed to 60 to 100 0C for 3 to 5 hours for residual curing. Membranes were conditioned with some solvent and heat treatment for getting suitable membrane technology for optimum permeation during pervaporation.

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Specification Table for Polyurethane and Polyurethaneureas



Membrane Specifications
Composition (by volume) of the polyurethane-urea prior to casting

Polymer Solvent

Viscosity of the polymer solution prior to casting
Intrinsic viscosity Inherent viscosity
Film thickness 0.1-0.15 cm. Gel time 30-50 min.
Phenol absorption behavior of the PUUSD 100 membrane


Example II Pervaporation Study
The condition membranes were equilibrated with aqueous phenol solution of varying concentration in the range of 1- 7% (w/w). The membranes were then used in the pervaporation cell for selective removal of phenol from mixtures with water. The feed

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chamber was kept at atmospheric pressure while a pressure of 5 mm Hg was maintained on the permeate side for all experiments. The feed temperature was varied in the range of 30- 75 °C. Permeate containing more than 70 wt % of phenol was obtained from a feed containing only 1 wt % phenol at a temperature of 75 °C. The phenol concentration in permeate was found to increase with increased feed phenol concentration in the range studied and the maximum of S3 wt % phenol was obtained with feed containing 7 wt % phenol at a temperature of 75 °C. A maximum total flux of 41 g m-2h-1 was obtained at 75 °C with feed containing 7 wt % phenol.
Performance of the membrane PUUSD 100 in pervaporative separation of phenol
from phenol-water mixture.

a= [cone, of phenol in permeate /cone, of water in permeate] / [cone, of phenol in feed /cone, of water in feed]
Figure 2 to 6 describe results of pervaporation study for selective separation of phenol from aqueous solutions using the PUUSD100 membrane of the invention. Figure 7 to 11 describe the results of pervaporation study for separation of phenol from aqueous solution using 3% phenol as feed with membranes prepared by different diamine concentrations. The invention thus provides a novel HTPB based polyurethane-urea suitable for preparation of membrane for efficient pervaporation separation of organic pollutants. By use of the membrane it is now possible to selectively separate organic pollutants (phenolic compounds) from aqueous solutions by pervaporation with high efficiency. The invention thus provides for highly selective removal of phenolic compounds from aqueous solutions.

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WE CLAIM
A process for the manufacture of polyurethaneurea of Formula I



comprising:
reacting selective diols of Formula II
HO — R — OH, wherein R=polybutadiene, ethylene, neopentelene with Diisocyanata of Formula III;
OCN— R'- NCO, wherein R' = C6H3CH3, 4,4'diphenylmethane, hexamethylene, methyl 3,5,5' trimethylcyclohexane, in the range of mole ratios of NCO:OH from 1.5:1.0 to 2.5:1.5 to prepolyurethane at -10°C to 60ºC to thereby obtain isocyanato terminated polyurethane of formula IV;



subjecting the said isocyanate terminated prepolyurethane of formula IV to chain extension with diamines of Formula V

H2N — R — NH2, wherein R=
0 to 100 mole % at the same temperature for one hour
to thereby obtain the desired polyurethane of formula I;

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2. A process for the manufacture of polyurethaneurea of as claimed in claim 1 wherein the diols are selected from Hydroxyterminated Polybutadiene Neopentyl glycol, Ethylene glycol.
3. A process for the manufacture of polyurethaneurea as claimed in anyone of 1 or 2 wherein the diisocyanates are selected from 2,4-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), Hexamethylene diisocyanate (H12DI),l-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (IPDI).
4. A process for the manufacture of polyurethaneurea as claimed in anyone of claims 1 to 2 wherein the diamines are selected from 4,4'-diaminodiphenyl sulfone (DADPS), 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenyl disulfide (DADS).
5. A process for the manufacture of polyurethaneurea of as claimed in anyone of claims 1 to 3 wherein the diol Formula II is reacted with Diisocyanate of Formula III in the presence of a catalyst selected from Triethyamine (TEA) and Dibutyltindilaurate (DBTDL).
6. A process for the manufacture of Polyurethaneurea of Formula I as claimed in claim 1 wherein said diisocyanates are selected from 2,4-toluene diisocyanate (TDl)f 4,4'-diphenylmethane diisocyanate (MDI), Hexamethylene diisocyanate (H12DI),l-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane(IPDI).
7. A process for the manufacture of Polyurethaneurea of Formula I as claimed in anyone of claims 1 or 6 wherein the diamines are selected from 4,4'-diaminodiphenyl sulfone (DADPS), 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenyl disulfide (DADS).
8. A polyurethaneurea membrane comprising:
a polyurethaneurea composition comprising of polyurethane polymer of formula I obtained following the process as claimed in claim 1 to 7 in amount of 40-60% and solvent in amount of 60-40% casted on a smooth substrate.

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9. A polyurethaneurea membrane as claimed in claim 8 wherein the solvent is selected from N,N-dimethyl formamide (DMF); 1,4-dioxane; Tetrahydrofuran (THF), Benzene; Toluene; Phenol.
10. A polyurethaneurea membrane as claimed in anyone of claims 8 or 9 having a thickness of 0.1 to 0.15 cm.
11. A polyurethaneurea membrane as claimed in anyone of claims 8 to 10 wherein the membrane is obtained selectively based on
composition (by volume) of the polyurethaneurea prior to casting comprise of Polymer 40 - 60% Solvent 60 - 40%
viscosity of polymer solution prior to casting comprise of intrinsic viscosity 3.0 - 4.0 X 102 dL/g inherent viscosity 0.4 - 0.8 dL/g film thickness range from 0.1- 0.15 cm. gel time in the range of 30 - 50 min

12. A process for manufacture of polyurethane based membrane as claimed in claim 8 for use in
selective separation of organic pollutants by membrane pervaporation comprising:
a. providing a pre-cast composition comprising the polyurethaneurea polymer of formula I in
amount of 40-60% by wt. and a solvent in amount of 60-40%; b. casting the composition of a) above on a smooth substrate;
c. curing the polyurethaneurea membrane thus obtained to desired moisture content; and
d. conditioning the membrane to obtain desired membrane morphology.

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13. A process as claimed in claim 12 wherein the specification of the membrane prior to casting
are selected to
composition (by volume) of the polyurethaneurea prior to casting of Polymer40 - 60% Solvent 60 - 40%

viscosity of polymer solution prior to casting of intrinsic viscosity inherent viscosity film thickness: gel time:
14. A process as claimed in anyone of claims 12 or 13 wherein said polymer membrane was made from its solution by casting technique on a smooth substrate surface followed by curing at ambient atmosphere and at elevated temperatures.
15. A process as claimed in anyone of claims 12 to 14 wherein the substrate used is selected from glass, Teflon substrate preferably smooth Teflon substrate.
16. A process as claimed in anyone of claims 12 to 15 wherein the membrane is properly conditioned through solvent and heat treatment.
17. A process as claimed in anyone of claims 12 to 16 wherein the viscous polymer solution is cast on a smooth substrate (Teflon) surface at room temperature and relative humidity of 60 to 90%.
18. A process as claimed in anyone of claims 12 to 17 wherein the cast polyurethane was allowed for 15 to 72 hours moisture curing.

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19. A process as claimed in anyone of claims 12 to 18 wherein membrane is conditioned with some solvent and heat treatment for providing suitable membrane morphology for optimum permeation during pervaporation.
20. An improved method of selective removal of organic pollutants from aqueous solutions by pervaporation using the polyurethaneurea based membrane as claimed in anyone of claims 8 to 10 comprising;
a pervaporation method of selectively enriching the phenolic content of the permeate of an aqueous phenolic feed solution comprising:
contacting the feed side of said polyurethaneurea based membrane with the aqueous phenolic feed solution such that the phenols in the feed solution preferentially permeate said membrane leaving a phenol depleted water retentate on the feed side of the membrane.
21. An improved method of selective removal of organic pollutants from aqueous solution as claimed in claim 20 wherein said feed solution comprise any conventional or other waste source containing phenolic compounds.
22. A method as claimed in anyone of claims 20 or 21 wherein it is carried out using a system comprising :
a feed chamber having a feed inlet;
a permeate chamber;
a sintered disk member therebetween said feed chamber and permeate chamber ;
a condenser-cum-collector ;
cryostat;
manometer; and
a vacuum pump,
wherein a polyurethane membrane as claimed in anyone of claims 8 to 11 is used for
separation of organic pollutants.

23. A process for manufacture of polyurethane of general Formula I and a poiyurethane membrane obtained thereof including its use substantially as hereindescribed and illustrated with reference to the accompanying examples.


A novel polyurethaneurea which is a hydroxy-terminated polybutadiene (HTPB) based polyurethaneurea and to a pervaporation membrane obtained of said HTPB based polyurethaneurea for efficient removal of organic pollutants by membrane pervaporation. The invention also relates to a method of selective separation of organic pollutants such as phenolic compounds from aqueous solution by pervaporation with high efficiency using the said HTPB polyurethaneurea based membrane.
The novel polyurethaneurea, would provide for preparation of pervaporation membranes of higher efficiency in terms of desired total flux and separation factor.Importantly the novel polyurethaneurea is directed provide a selective HTPB based pervaporation membrane which would have excellent pervaporation performance in terms of separation factor or selectively for separation of organic pollutants by membrane pervaporation especially selectively of phenol from phenol-water mixture.

Documents:

00102-cal-2002-abstract.pdf

00102-cal-2002-claims.pdf

00102-cal-2002-correspondence.pdf

00102-cal-2002-description(complete).pdf

00102-cal-2002-description(provisional).pdf

00102-cal-2002-drawings.pdf

00102-cal-2002-form-1.pdf

00102-cal-2002-form-18.pdf

00102-cal-2002-form-2.pdf

00102-cal-2002-form-3.pdf

00102-cal-2002-form-5.pdf

00102-cal-2002-letters patent.pdf


Patent Number 206371
Indian Patent Application Number 102/CAL/2002
PG Journal Number 17/2007
Publication Date 27-Apr-2007
Grant Date 27-Apr-2007
Date of Filing 22-Feb-2002
Name of Patentee INDIAN INSTITUTE OF TECHNOLOGY
Applicant Address KHARAGPUR, PIN-721-302,
Inventors:
# Inventor's Name Inventor's Address
1 TARAKRANJAN GUPTA MEDICAL SCEINCE CENTER, DEPARTMENT OF CHEMICAL ENGINEERING,INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR 721 302
2 NARAYAN C. PRADHAN MATERIAL SCEINCE CENTER, DEPARTMENT OF CHEMICAL ENGINEERING, INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR 721 302
3 BASUDAM ADHIKARI MATERIAL SCEINCE CENTER, DEPARTMENT OF CHEMICAL ENGINEERING, INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR 721 302
PCT International Classification Number C08G 18/08
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA