Title of Invention	"A METHOD FOR RECOVERY OF VAL-DYES FORM THE EFFLUENT CONTAINING VAT DYES"
Abstract	The present invention describes a method of recovery of vat dye, particularly indigo dye, from the effluents of vat dyeing processes. The method/process of recovery of indigo dye involves treatment of effluents with aqueous solution of copolymers comprising of a mixture of acrylamide and dimethyl aminoethyl methacrylate for 15-60 min; separation of copolymer dye complex from effluents; reduction of copolymer dye complex with a reducing agent such as "Rongalite C" for 4-7 h and subsequent solubilization with caustic hydro solution for release of indigo dye for recycle/reuse in textile industry. Indigo dye recovered by this process is 80%. Further the present invention also describes a method for safe disposal of the residual effluent wherein the copolymer dye complex has been separated. This process involves the treatment of effluent with hydrogen peroxide. This results in 90-95% reduction color intensity, which is suitable for direct disposal. This invention also brings forth the use of aqueous solution of safe copolymers for treatment of effluents for recovery of vat dyes particularly indigo dye, which has extensive application in denim industry. No biological material is being employed.

Title of Invention

"A METHOD FOR RECOVERY OF VAL-DYES FORM THE EFFLUENT CONTAINING VAT DYES"

Abstract

The present invention describes a method of recovery of vat dye, particularly indigo dye, from the effluents of vat dyeing processes. The method/process of recovery of indigo dye involves treatment of effluents with aqueous solution of copolymers comprising of a mixture of acrylamide and dimethyl aminoethyl methacrylate for 15-60 min; separation of copolymer dye complex from effluents; reduction of copolymer dye complex with a reducing agent such as "Rongalite C" for 4-7 h and subsequent solubilization with caustic hydro solution for release of indigo dye for recycle/reuse in textile industry. Indigo dye recovered by this process is 80%. Further the present invention also describes a method for safe disposal of the residual effluent wherein the copolymer dye complex has been separated. This process involves the treatment of effluent with hydrogen peroxide. This results in 90-95% reduction color intensity, which is suitable for direct disposal. This invention also brings forth the use of aqueous solution of safe copolymers for treatment of effluents for recovery of vat dyes particularly indigo dye, which has extensive application in denim industry. No biological material is being employed.

Full Text	FIELD OF THE INVENTION : The present invention relates to method for recovery of vat dyes from the effluents containing vat dyes, particularly it relates to method for recovery of indigo dye from the effluents containing indigo dye, more particularly it relates to method for recovery of indigo dye by way of copolymers from the effluents containing indigo dye. BACKGROUND OF THE INVENTION : Vat dyes find their applications in the textile industry and are most commonly used dyes. Among the classes of vat dyes, indigo represents the most widely used dye in the denim industry. Indigo has limitation of low exhaustion on cotton, which results in the release of major percentage of vat dye, particularly of indigo in the waste water from most of the vat dyeing processes, particularly from indigo dyeing processes and such waste water from the vat dyeing processes, particularly from indigo dyeing processes contains significant quantity of the dye, that is about 20 to 30% of the initial amount. Since, the vat dye, particularly the indigo dye is very expensive, its recovery from the waste water, hereinafter referred to as effluent, might make the dyeing process extermely useful and economical. Further, the requirement of the textile industry is that the recovered vat dye, particularly the indigo dye should be suitable for recycling, that is should be suitable for reuse for subsequent dyeing processes. Various products and the methods employing such developed products have been developed to recover the vat dye, particularly the indigo dye from the effluents containing the vat dye, particularly the indigo dye. Such known methods and products for recovery of the vat dye, particularly the indigo dye also have one or the other drawback. One set of products, particularly copolymers, more particularly copolymers of acrylamide and dimethylaminoethyl methacrylate have been developed by the inventors of the present invention, which have been disclosed in the copending patent application number 3603/DEL/1998. The present invention is intended to disclose a method for recovery of vat dyes from the effluents containing vat dyes, particularly a method for recovery of indigo dye from the effluents containing indigo dye, more particularly a method for recovery of indigo dye by way of copolymers, as disclosed in our copending patent application number 3603/DEL/1998, from the effluents containing indigo dye OBJECTS OF THE INVENTION : This is the main object of the present invention to make a complete disclosure of a method for recovery of vat dyes, particularly indigo dye from the effluent containing vat dyes, particularly the indigo dye, which can overcome drawbacks of the known such processes for recovery of vat dyes, particularly indigo dye from the effluent containing vat dyes, particularly the indigo dye. This is further an object of the present invention to make a disclosure of a method for recovery of vat dyes, particularly indigo dye from the effluents containing vat dyes, particularly indigo; particularly of a method for recovery of vat dyes, particularly indigo dye wherein said method employes copolymers of acrylamide and dimethylaminoethyl methacrylate and not biological material, for recovery of dyes. SUMMARY OF THE INVENTION Accordingly, the present invention provides a method of recovery of vat dyes particularly indigo dye from an effluent comprising vat dyes, said method comprising steps of: a. dissolving in water co-polymer of acrylamide and dimethyl aminoethyl methacrylate to obtain a solution of co-polymer; b. adding solution of the co-polymer of step (a) at a concentration in the range of 1.0 to 40.0 % w/v to the effluent containing vat dye mixture, c. allowing to stand the mixture of step (b) for a period of 10 to 140 minutes to settle co-polymer-dye complex, d. separating the settled co-polymer-dye complex of step (c) to obtain a filtrate, e. treating the separated co-polymer-dye complex of step (d) with about 1% w/v of a reducing agent at an ambient temperature for a period of 4 to 7 hrs, and f. solubilizing the reduced co-polymer dye-complex of step (e) using caustic hydro solution, and recovering the vat dye for recycling. DETAILED DESCRIPTION OF THE INVENTION: According to the present invention a method for recovery of vat dyes, particularly indigo dye from the effluents containing vat dyes, particularly indigo; particularly a method for recovery of vat dyes, particularly indigo dye wherein said method employs copolymers of acrylamide and dimethylaminoethyl methacrylate and not biological material, for recovery of dye is disclosed comprising of reaction of effluent containing vat dyes, particularly indigo dye with aqueous solution of copolymer to form copolymer-dye complex, which in-turn is subjected to reduction followed by solubilization for final separation of dye. The separated dye can be recycled or reused for dyeing process. In accordance to one of the preferred embodiments of the present invention the said copolymer-dye complex is separated and the effluent is subjected to reaction with peroxide, particularly hydrogen peroxide, which results in the reduction of colour intensity of the effluent. In accordance to the present invention the effluent containing vat dye, particularly indigo dye having pH between 2 to 9 is reacted with aqueous solution of copolymer of our copending patent application number 3603/DEL/1998 for about 15 to 60 min. The copolymer-dye complex is subjected to reduction with a reducing agent, preferably with rongalite-C at ambient temperature for about 4 to 7 h. The reduced copolymer-dye complex is subjected to solubilization preferably with caustic hydro-solution. In accordance to one of the preferred embodiments the present invention the copolymer-dye complex is separated and the effluent is reacted with a peroxide, preferably hydrogen peroxide for about 20 to 28 h. The reacted effluent is with reduced colour intensity and suitable for direct disposal. The dye recovered in accordance to the preferred embodiments of the present invention is found to be suitable for recycle or reuse in further dyeing processes. The effluent obtained in accordance to the preferred embodiments of the present invetion is suitable for direct disposal. The following are some of the experiments conducted in accordance to the present invention for recovery of vat dyes, particularly indigo dye from the effluent containing vat dyes, particularly indigo dye, which are not intended for limiting the scope of the invention. I. The aqueous solution of said copolymer having concentration of 200-1000 ppm is added to a flask contianing indigo effluent having a pH of about 8.5. The dye concentration in effluent is in the range of 0.18%. The amount of copolymer in indigo effluent is varied in the range of 1-40% (mg). The rection is allowed to settle for 30 minutes. The copolymer-dye complex is separated and is observed to be in the range of 80-96%. II. The copolymer concentration of 1000 ppm is added to a flask containing indigo effluent at different pH of 2-9. The indigo content in effluent was 0.18%. The amount of copolymer was kept constant at 2%(mg.) The reaction is allowed for about 30 minutes. The copolymer-dye complex is separated and is observed to be in the range of 82-95%. III. A 2ml copolymer solution of 1000 ppm concentration was added to 100 ml of the effluent containing about 0.18 wt.% of indigo. The pH of the effluent was kept constant at 5.5. The reaction time was varied from 10 to 140 minutes. The copolymer-dye complex is separated and is observed to be in the range of 92-98%. IV. The copolymer-dye complex, as prepared in any of the above three experiments is separated out and the effluent, as received after separation of copolymer-dye complex is reacted with peroxide, preferably with hydrogen peroxide solution. A-10 ml of hydrogen peroxide solution (30%) was added to the effluent and reaction was allowed for 24 h. A further reduction in the colour intensity up to 95-99% was observed. V. The copolymer-dye complex is reacted with a reducing agent, preferably with rongalite-C. A 2-40 ml Rongalite-C (1%) solution was added to Ig of the complex at ambient temperature. The mixture is allowed to react at the ambient temperature for 6h and subjected to solublization with caustic hydro solution. The maximum dye recovery is found to be as high as 80%. We Claim: 1. A method of recovery of vat dyes particularly indigo dye from an effluent comprising vat dyes, said method comprising steps of: a. dissolving in water co-polymer of acrylamide and dimethyl aminoethyl methacrylate to obtain a solution of co-polymer; b. adding solution of the co-polymer of step (a) at a concentration in the range of 1.0 to 40.0 % w/v to the effluent containing vat dye mixture, c. allowing to stand the mixture of step (b) for a period of 10 to 140 minutes to settle co-polymer-dye complex, d. separating the settled co-polymer-dye complex of step (c) to obtain a filtrate, e. treating the separated co-polymer-dye complex of step (d) with about 1 % w/v of a reducing agent at an ambient temperature for a period of 4 to 7 hrs, and f. solubilizing the reduced co-polymer dye-complex of step (e) using caustic hydro solution, and recovering the vat dye for recycling. 2. A method of claim 1, wherein in step (c), the settling is achieved preferably over a period of 15 minutes to 80 minutes. 3. A method of claim 1, wherein pH of the effluent used is ranging from 2.0 to 9.0. 4. A method of claim 1, wherein in step (e) the reducing agent used is rongalite-C. 5. A method of claim 1, wherein in step (d) the filtrate is reacted with peroxide particularly 30 % w/v hydrogen peroxide solution for a period of 20 to 28 hrs. 6. A method for the recovery of indigo dye from effluent comprising vat dye herein described substantially with reference to examples.

Full Text

FIELD OF THE INVENTION :
The present invention relates to method for recovery of vat dyes from the effluents containing vat dyes, particularly it relates to method for recovery of indigo dye from the effluents containing indigo dye, more particularly it relates to method for recovery of indigo dye by way of copolymers from the effluents containing indigo dye.
BACKGROUND OF THE INVENTION :
Vat dyes find their applications in the textile industry and are most commonly used dyes. Among the classes of vat dyes, indigo represents the most widely used dye in the denim industry. Indigo has limitation of low exhaustion on cotton, which results in the release of major percentage of vat dye, particularly of indigo in the waste water from most of the vat dyeing processes, particularly from indigo dyeing processes and such waste water from the vat dyeing processes, particularly from indigo dyeing processes contains significant quantity of the dye, that is about 20 to 30% of the initial amount. Since, the vat dye, particularly the indigo dye is very expensive, its recovery from the waste water, hereinafter referred to as effluent, might make the dyeing process extermely useful and economical. Further, the requirement of the textile industry is that the recovered vat dye, particularly the indigo dye should be suitable for recycling, that is should be suitable for reuse for subsequent dyeing processes.

Various products and the methods employing such developed products have been developed to recover the vat dye, particularly the indigo dye from the effluents containing the vat dye, particularly the indigo dye. Such known methods and products for recovery of the vat dye, particularly the indigo dye also have one or the other drawback. One set of products, particularly copolymers, more particularly copolymers of acrylamide and dimethylaminoethyl methacrylate have been developed by the inventors of the present invention, which have been disclosed in the copending patent application number 3603/DEL/1998. The present invention is intended to disclose a method for recovery of vat dyes from the effluents containing vat dyes, particularly a method for recovery of indigo dye from the effluents containing indigo dye, more particularly a method for recovery of indigo dye by way of copolymers, as disclosed in our copending patent application number 3603/DEL/1998, from the effluents containing indigo dye
OBJECTS OF THE INVENTION :
This is the main object of the present invention to make a complete disclosure of a method for recovery of vat dyes, particularly indigo dye from the effluent containing vat dyes, particularly the indigo dye, which can overcome drawbacks of the known such processes for recovery of vat dyes, particularly indigo dye from the effluent containing vat dyes, particularly the indigo dye.
This is further an object of the present invention to make a disclosure of a method for recovery of vat dyes, particularly indigo dye from the effluents containing vat dyes, particularly indigo; particularly of a method for recovery of vat dyes, particularly indigo dye wherein said method employes copolymers of acrylamide and dimethylaminoethyl methacrylate and not biological material, for recovery of dyes.

SUMMARY OF THE INVENTION
Accordingly, the present invention provides a method of recovery of vat dyes particularly indigo dye from an effluent comprising vat dyes, said method comprising steps of:
a. dissolving in water co-polymer of acrylamide and dimethyl aminoethyl
methacrylate to obtain a solution of co-polymer;
b. adding solution of the co-polymer of step (a) at a concentration in the range of 1.0
to 40.0 % w/v to the effluent containing vat dye mixture,
c. allowing to stand the mixture of step (b) for a period of 10 to 140 minutes to settle
co-polymer-dye complex,
d. separating the settled co-polymer-dye complex of step (c) to obtain a filtrate,
e. treating the separated co-polymer-dye complex of step (d) with about 1% w/v of a
reducing agent at an ambient temperature for a period of 4 to 7 hrs, and
f. solubilizing the reduced co-polymer dye-complex of step (e) using caustic hydro
solution, and recovering the vat dye for recycling.
DETAILED DESCRIPTION OF THE INVENTION:
According to the present invention a method for recovery of vat dyes, particularly indigo dye from the effluents containing vat dyes, particularly indigo; particularly a method for recovery of vat dyes, particularly indigo dye wherein said method employs copolymers of acrylamide and dimethylaminoethyl methacrylate and not biological material, for recovery of dye is disclosed comprising of reaction of effluent containing vat dyes, particularly indigo dye with aqueous solution of copolymer to form copolymer-dye complex, which in-turn is subjected to reduction followed by solubilization for final separation of dye. The separated dye can be recycled or reused for dyeing process.
In accordance to one of the preferred embodiments of the present invention the said copolymer-dye complex is separated and the effluent is subjected to reaction with peroxide, particularly hydrogen peroxide, which results in the reduction of colour intensity of the effluent.
In accordance to the present invention the effluent containing vat dye, particularly indigo dye having pH between 2 to 9 is reacted with aqueous solution of

copolymer of our copending patent application number 3603/DEL/1998 for about 15 to 60 min. The copolymer-dye complex is subjected to reduction with a reducing agent, preferably with rongalite-C at ambient temperature for about 4 to 7 h. The reduced copolymer-dye complex is subjected to solubilization preferably with caustic hydro-solution.
In accordance to one of the preferred embodiments the present invention the copolymer-dye complex is separated and the effluent is reacted with a peroxide, preferably hydrogen peroxide for about 20 to 28 h. The reacted effluent is with reduced colour intensity and suitable for direct disposal.
The dye recovered in accordance to the preferred embodiments of the present invention is found to be suitable for recycle or reuse in further dyeing processes. The effluent obtained in accordance to the preferred embodiments of the present invetion is suitable for direct disposal.
The following are some of the experiments conducted in accordance to the present invention for recovery of vat dyes, particularly indigo dye from the effluent containing vat dyes, particularly indigo dye, which are not intended for limiting the scope of the invention.
I. The aqueous solution of said copolymer having concentration of 200-1000 ppm
is added to a flask contianing indigo effluent having a pH of about 8.5. The dye
concentration in effluent is in the range of 0.18%. The amount of copolymer in indigo
effluent is varied in the range of 1-40% (mg). The rection is allowed to settle for 30
minutes. The copolymer-dye complex is separated and is observed to be in the range
of 80-96%.
II. The copolymer concentration of 1000 ppm is added to a flask containing indigo
effluent at different pH of 2-9. The indigo content in effluent was 0.18%. The amount

of copolymer was kept constant at 2%(mg.) The reaction is allowed for about 30 minutes. The copolymer-dye complex is separated and is observed to be in the range of 82-95%.
III. A 2ml copolymer solution of 1000 ppm concentration was added to 100 ml of the
effluent containing about 0.18 wt.% of indigo. The pH of the effluent was kept constant
at 5.5. The reaction time was varied from 10 to 140 minutes. The copolymer-dye
complex is separated and is observed to be in the range of 92-98%.
IV. The copolymer-dye complex, as prepared in any of the above three experiments is
separated out and the effluent, as received after separation of copolymer-dye complex is
reacted with peroxide, preferably with hydrogen peroxide solution. A-10 ml of hydrogen
peroxide solution (30%) was added to the effluent and reaction was allowed for 24 h. A
further reduction in the colour intensity up to 95-99% was observed.
V. The copolymer-dye complex is reacted with a reducing agent, preferably with
rongalite-C. A 2-40 ml Rongalite-C (1%) solution was added to Ig of the complex at
ambient temperature. The mixture is allowed to react at the ambient temperature for 6h
and subjected to solublization with caustic hydro solution. The maximum dye recovery is
found to be as high as 80%.

We Claim:
1. A method of recovery of vat dyes particularly indigo dye from an effluent
comprising vat dyes, said method comprising steps of:
a. dissolving in water co-polymer of acrylamide and dimethyl aminoethyl
methacrylate to obtain a solution of co-polymer;
b. adding solution of the co-polymer of step (a) at a concentration in the range
of 1.0 to 40.0 % w/v to the effluent containing vat dye mixture,
c. allowing to stand the mixture of step (b) for a period of 10 to 140 minutes to
settle co-polymer-dye complex,
d. separating the settled co-polymer-dye complex of step (c) to obtain a
filtrate,
e. treating the separated co-polymer-dye complex of step (d) with about 1 %
w/v of a reducing agent at an ambient temperature for a period of 4 to 7 hrs,
and
f. solubilizing the reduced co-polymer dye-complex of step (e) using caustic
hydro solution, and recovering the vat dye for recycling.
2. A method of claim 1, wherein in step (c), the settling is achieved preferably over a
period of 15 minutes to 80 minutes.
3. A method of claim 1, wherein pH of the effluent used is ranging from 2.0 to 9.0.
4. A method of claim 1, wherein in step (e) the reducing agent used is rongalite-C.
5. A method of claim 1, wherein in step (d) the filtrate is reacted with peroxide
particularly 30 % w/v hydrogen peroxide solution for a period of 20 to 28 hrs.
6. A method for the recovery of indigo dye from effluent comprising vat dye herein
described substantially with reference to examples.

Documents:

3623-del-1998-abstract.pdf

3623-del-1998-claims.pdf

3623-del-1998-correspondence-others.pdf

3623-del-1998-correspondence-po.pdf

3623-del-1998-description (complete).pdf

3623-del-1998-form-1.pdf

3623-del-1998-form-13.pdf

3623-del-1998-form-19.pdf

3623-del-1998-form-2.pdf

3623-del-1998-form-3.pdf

3623-del-1998-form-6.pdf

3623-del-1998-gpa.pdf

3623-del-1998-petition-137.pdf

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Patent Number

215289

Indian Patent Application Number

3623/DEL/1998

PG Journal Number

10/2008

Publication Date

07-Mar-2008

Grant Date

22-Feb-2008

Date of Filing

01-Dec-1998

Name of Patentee

DEAN, INDUSTRIAL RESEARCH AND DEVELOPMENT (IRD)

Applicant Address

INDIAN INSTITUTE OF TECHNOLOGY DELHI (IITD), HAUZ KHAS, NEW DELHI-110016, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	BHUVANESH GUPTA	DEPARTMENT OF TEXTILE TECHNOLOGY, INDIAN INSTITUTE OF TECHNOLOGY DELHI (IITD), HAUZ KHAS, NEW DELHI - 110016, INDIA.
2	ANANDA KUMAR MUKHERJEE	DEPARTMENT OF TEXTILE TECHNOLOGY, INDIAN INSTITUTE OF TECHNOLOGY DELHI (IITD), HAUZ KHAS, NEW DELHI - 110016, INDIA.
3	PARTHA PRATIM CHAKARBARTI	DEPARTMENT OF TEXTILE TECHNOLOGY, INDIAN INSTITUTE OF TECHNOLOGY DELHI (IITD), HAUZ KHAS, NEW DELHI - 110016, INDIA.

PCT International Classification Number

D06P 1/22

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA