DESC:TECHNICAL FIELD OF THE PRESENT INVENTION
The present invention relates to carbon dioxide capture and more particularly relates to enzyme assisted carbon dioxide capture from mixtures of gases.
More particularly, the present invention provides a composition, method and an enzyme linked polyhydral metal organic framework which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and manner of use thereof. The invention also relates to a composition, method and an enzyme linked polyhydral metal organic framework which causes desorption of carbon dioxide in gaseous form carbon dioxide enriched solution and manner of use thereof. Also, a carbon dioxide absorbing solution and a method of reactivating a carbon dioxide absorbing solution by using enzyme linked polyhydral metal organic framework is disclosed.
The enzyme is entrapped in enzyme linked polyhydral metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme. In the present invention, preferred enzyme is carbonic anhydrase. The enzyme is preferably obtained from one or more of Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028) and the preferred metal organic framework (MOF) is having zinc as preferred metal.

BACKGROUND OF THE PRESENT INVENTION
Currently, the CO2 capture from waste gas stream is performed by various chemical and physical absorption processes like cryogenic, gas-solid absorption, liquid-liquid sorption and immiscible liquid-liquid extraction etc. In general, these techniques are energy inefficient, slow and non-specific. In contrast to these disadvantages, the bio-assisted CO2 capture process present several advantages including enhanced efficiency, high speed, increased specificity and moderate operating conditions. However, despite all these advantages, a variety of problem exist in the bio-assisted CO2 capture like short life span of biocatalyst, limited temperature, pH, salinity tolerance etc., which hampers the industrial applications in its exploitation in large scale.

The present invention provides enzyme compositions which have extended life and wide pH, temperature and salinity tolerance. The enzyme composition can be effectively used for CO2 absorption and/or desorption in aqueous solutions from mixture of the gases.

Enzyme utilization for CO2 capture has been found in large numbers of scientific articles and patents.

CA 2827024 discloses a carbonic anhydrase system and process for CO2 capture. In the said invention, the system has a reaction chamber, liquid inlet, gas inlet, liquid outlet and gas outlet, and uses carbonic anhydrase on or in substrates in suspension in the liquid for catalyzing a reaction of CO2 into bicarbonate and hydrogen ions to obtain a treated gas and an ion-rich solution

WO 2013067648 A1 discloses a method for CO2 capture includes operating a CO2 capture system with a large temperature swing in between the absorption stage and the desorption stage; utilizing a hybrid solvent comprising water, carbonic anhydrase and an absorption compound in the absorption stage; membrane filtering the carbonic anhydrase out of the hybrid solvent in between the absorption stage and the desorption stage and prior to the large temperature swing; and recycling the filtered carbonic anhydrase back into the absorption stage to maintain high enzyme concentration in the absorption stage.

US 20130224842 A1 discloses a carbonic anhydrase bioreactor for treating a CO2-containing gas includes a reaction chamber for receiving a liquid; porous particles with carbonic anhydrase entrapped therein provided in the reaction chamber for catalyzing a reaction of CO2 into bicarbonate and hydrogen ions to obtain a treated gas and an ion-rich solution; a retention device for retaining the porous particles within the reaction chamber; a liquid inlet for providing the liquid; a gas inlet for providing the CO2-containing gas; a liquid outlet for releasing the ion-rich solution; and a gas outlet to release the treated gas. Processes are also described for treating a CO2-containing gas, where particles comprising porous material with entrapped carbonic anhydrase catalyze the reaction and the particles are retained in the reaction chamber.

US 7803575 B2 relates to use of heat-stable carbonic anhydrase in CO2 extraction, e.g., from flue gas, natural gas or biogas. Furthermore, the invention relates to isolated polypeptides having carbonic anhydrase activity at elevated temperatures and isolated polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides.

WO 2014066999 A1 discloses use of Sulfuhhydrogenibium sp. carbonic anhydrase (SspCA) or mutants thereof for catalyzing the hydration reaction of CO2 into bicarbonate and hydrogen ions or catalyzing the desorption reaction to produce a CO2 gas.

US 20140178962 A1 relates to engineered protein constructs with carbonic anhydrase catalytic activity, and their application in CO2 scrubbing.

US 8871485 B2 relates to a modified carbonic anhydrase enzymes, and a process of using same for the extraction, production and purification of carbon dioxide gas. More particularly, modified carbonic anhydrase enzymes are used for the production, purification of carbon dioxide and the products of the hydration reaction, hydrogen and bicarbonate ions.

CN 102712919 A relates to use of Caminibacter carbonic anhydrase in CO2 extraction, e.g., from flue gas, natural gas, biogas or ambient air. The Caminibacter carbonic anhydrases are especially well suited for these purpose due to their extreme thermostability.

US 20120129236 A1discloses a formulation and a process for CO2 capture, where a CO2-containing gas in contacted with water, biocatalyst and an amino acid compound, enabling the dissolution and transformation of the CO2 into bicarbonate ions and hydrogen ions, producing an ion-rich solution and a CO2-depleted gas. The amino acids may present slow absorption kinetics and having elevated stability such that absorption is enhanced in combination with the biocatalyst. The amino acid compound and the biocatalyst may be selected such that the active sites of the biocatalyst benefit from proton removal facilitated by the amino acid compounds, thus improving the CO2 absorption.

US 8066800 B2 discloses a method for separating CO2 from a processed fluid includes exposing a film to the processed fluid and reacting the CO2 with tetrahedrally coordinated zinc hydroxide moieties contained within the film to facilitate the transport of the CO2 through the film.

EP2354099 discloses a process for conversion of divalent cations present in waste brine into useful carbonates, using waste gas stream containing CO2 in the presence of halotolerant micro-organisms exhibiting carbonic anhydrase activity.

Cooperative insertion of CO2 in diamine-appended metal-organic frameworks, Nature, 519(7543), 303-308. DOI: 10.1038/nature14327) discloses a cooperative process using diamine-appended metal-organic frameworks which result into large CO2 separation with small temperature swings and lower regeneration energies than aqueous amine solutions. The diamine-appended metal-organic framework disclosed in the said publication has an optimum effectiveness at particular CO2 concentration range.

The present invention provides a composition, method and enzyme linked polyhydral metal organic framework which causes carbon dioxide absorption in aqueous solutions from mixture of the gases to overcome problems of the prior art. Also, the present invention provides a composition, method and enzyme linked polyhydral metal organic framework which causes desorption of carbon dioxide in gaseous form from carbon dioxide enriched solution to overcome problems of the prior art. In the present invention, the enzyme composition provides at least 6.5 times increase in Carbon dioxide absorption in comparison to control. In the present invention, the release of Carbon dioxide from the Carbon dioxide enriched solution requires at least 30 % less energy to release carbon dioxide and activate the Carbon dioxide absorbing solution. In the present invention, there is higher carbon dioxide desorption at lower temperature in presence of claimed enzyme composition. The present invention provides enzyme compositions for carbon dioxide absorption which have extended life and wide pH, temperature and salinity tolerance. In the present invention, the enzyme composition provides at least 7 times increase in carbon dioxide absorption in comparison to control. In the present invention, the release of carbon dioxide from the Carbon dioxide enriched solution requires at least 30% less energy to release carbon dioxide and activate the carbon dioxide absorbing solution. In the present invention, CaCO3 produced in presence of enzyme composition is at least 4 times higher. In the present invention, there is higher carbon dioxide desorption at lower temperature in presence of claimed enzyme composition.

OBJECTIVES OF THE PRESENT INVENTION:

An objective of this invention is to develop a composition of enzyme linked polyhydral metal organic framework which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and manner of use thereof.
An objective of this invention is to develop a method for carbon dioxide absorption in aqueous solutions from mixture of the gases.
Another objective of this invention is to develop an enzyme linked polyhydral metal organic framework which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and manner of use thereof.
An objective of this invention is to develop a composition of enzyme linked polyhydral metal organic framework which causes desorption of carbon dioxide in gaseous from carbon dioxide enriched solution and manner of use thereof.
An objective of this invention is to develop a method of desorption of carbon dioxide in gaseous form carbon dioxide enriched solution.
Another objective of this invention is to develop an enzyme linked polyhydral metal organic framework which causes carbon dioxide desorption from carbon dioxide enriched solution and manner of use thereof.
Yet another objective of the present invention is to develop a carbon dioxide absorbing solution.
Another objective of the present invention is to develop a method of reactivating a carbon dioxide absorbing solution by using enzyme linked polyhydral metal organic framework.
Yet another objective of the present invention is to provide enzyme which is entrapped in enzyme linked polyhydral metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme.

SUMMARY OF THE PRESENT INVENTION:
Accordingly, the present invention provides an enzyme linked polyhydral metal organic framework which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and/or carbon dioxide desorption in gaseous form carbon dioxide enriched solution, wherein the enzyme obtained is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme.
In an embodiment of the present invention, composition of an enzyme linked polyhydral metal organic framework which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and/or carbon dioxide desorption in gaseous form from carbon dioxide enriched solution , wherein the enzyme obtained is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme.

In one of the embodiment of the present invention, the enzyme is carbonic anhydrase which is obtained from Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028).
In another embodiment of the present invention, a method of Carbon dioxide absorption in aqueous solution from mixture of gases by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
i. mixing carbon dioxide absorbing solution with composition of enzyme linked metal organic framework;
ii. sparging carbon dioxide rich gas in microbuble or nanobubble size to the mixture of carbon dioxide absorbing solution and enzyme linked metal organic framework , and
iii. obtaining carbon dioxide enriched solution,
iv. contacting the CO2 enriched solution to same or another enzyme linked metal organic framework
v. getting CO2 and regenerated solvent system
In another embodiment of the present invention, a method of desorption of carbon dioxide in gaseous form carbon dioxide enriched solution by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
contacting the carbon dioxide enriched solution with enzyme linked metal organic framework and releasing of carbon dioxide from carbon dioxide enriched solution, wherein the enzyme is carbonic anhydrase.

In yet another embodiment of the present invention, a method of reactivating a carbon dioxide absorbing solution by using enzyme linked polyhydral metal organic framework, the method comprising the steps of:
i. contacting a carbon dioxide enriched solution with enzyme linked metal organic framework of zinc to release the carbon dioxide; and
ii. obtaining the activated carbon dioxide absorbing solution

In yet another embodiment of the present invention, the carbonic anhydrase from Bacillus thermoleovorans IOC- S3 has high CO2 hydration activity and operates at pH range of 5-13, temperature range -4 to 100 degree C and salinity tolerance range 0-6%.
In yet another embodiment of the present invention, the carbonic anhydrase from Bacillus stearothermophilus IOC S1 (MTCC 25030) has high CO2 dehydration activity and operates at pH range 3-13, temperature range 0-110 degree C and salinity tolerance range 0-5%.
In yet another embodiment of the present invention, the carbonic anhydrase from Bacillus thermoleovorans IOC- S3 (MTCC 25023) and Bacillus stearothermophilus IOC S1 (MTCC 25030) has both CO2 hydration and dehydration activity.

BRIEF DESCRIPTION OF DRAWING:

Fig. 1 relates to scheme of method of carbon dioxide absorption in aqueous solution from mixture of gases by enzyme linked polyhydral metal organic framework. Also, a method of desorption of carbon dioxide in gaseous form from carbon dioxide enriched solution and method of reactivating a carbon dioxide absorbing solution is shown.

DETAILED DESCRIPTION OF THE PRESENT INVENTION:

While the invention is susceptible to various modifications and/or alternative processes and/or compositions, specific embodiment thereof has been shown by way of example in the drawings and tables and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular processes and/or compositions disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims.

The protocols have been represented where appropriate by conventional representations, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

The following description is of exemplary embodiments only and is not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention.

The present invention provides an enzyme linked polyhydral metal organic framework which causes which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and/or carbon dioxide desorption in gaseous form from carbon dioxide enriched solution, wherein the enzyme obtained is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme.
The metal is preferably zinc in the enzyme linked polyhydral metal organic framework and the enzyme is preferably carbonic anhydrase. The enzyme carbonic anhydrase is obtained from Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028).
In an embodiment of the present invention, a composition of an enzyme linked polyhydral metal organic framework which causes which causes carbon dioxide absorption in aqueous solutions from mixture of the gases and/or carbon dioxide desorption in gaseous form from carbon dioxide enriched solution, wherein the enzyme obtained is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme.

In one of the embodiment of the present invention, the carbonic anhydrase from Bacillus thermoleovorans IOC- S3 has high CO2 hydration activity and operates at pH range of 5-13, temperature range -4 to 100 degree C and salinity tolerance range 0-6%.
According to the present invention, the carbonic anhydrase from Bacillus stearothermophilus IOC S1 (MTCC 25030) has high CO2 dehydration activity and operates at pH range 3-13, temperature range 0-110 degree C and salinity tolerance range 0-5%.
Also, in the present invention, the carbonic anhydrase from Bacillus thermoleovorans IOC- S3 (MTCC 25023) and Bacillus stearothermophilus IOC S1 (MTCC 25030) has both CO2 hydration and dehydration activity.
The present invention discloses compositions including a polyhydral metal organic framework of zinc or any other metal including cabonic anhydrase having high pH, temperature and salinity tolerance. The said enzyme compositions can be used for absorption of CO2 from a mixture of gas in a solution and/or desorption of the CO2 from the CO2 enriched solution to a pure form. The absorbed CO2 can also be converted to solid nano -sized carbonates of alkali metal.

Enzyme compositions:
In accordance to present invention, the enzyme compositions (EN-ZN-MOF) contain CA from Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 (MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028) entrapped in MOF of Zn (ZN-MOF) or any other metal like nickel, chromium, having at least one nonoscopic cage which has pore size sufficient for entrapment of the enzyme. The MOF-enzyme composition is stable in the aqueous solution. The EN-ZN-MOF having CA from Bacillus thermoleovorans IOC- S3 has higher CO2 hydration reaction activity. It has pH tolerance in the range of 5-13, temperature tolerance -4 to 100 degree C and salinity tolerance 0-6%. The EN-ZN-MOF having CA from Bacillus stearothermophilus IOC S1 (MTCC 25030) has higher CO2 dehydration activity. It is pH tolerance in the range of 3-13, temperature tolerance 0-110 degree C and salinity tolerance 0-5%. The EN-ZN-MOF having CA from Bacillus thermoleovorans IOC- S3 (MTCC 25023), Pseudomonas fragi IOC S2 (MTCC 25025), Bacillus stearothermophilus IOC S1 (MTCC 25030), Arthrobacter sp. IOC –SC-2 (MTCC 25028) have both CO2 hydration & dehydration activity.

A composition of an enzyme linked polyhydral metal organic framework for carbon dioxide absorption in aqueous solution from mixture of the gases and/or carbon dioxide desorption in gaseous form carbon dioxide enriched solution;
wherein:
said enzyme is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme;
said enzyme is carbonic anhydrase which is obtained from one or more of Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028); and
preferred metal is zinc in enzyme linked polyhydral metal organic framework.

In accordance to present invention, the enzyme composition enhances the CO2 absorption/hydration process in the CO2 absorbing solutions.

An enzyme linked polyhydral metal organic framework:

An enzyme linked polyhydral metal organic framework for carbon dioxide absorption in aqueous solutions from mixture of the gases and/or carbon dioxide desorption in gaseous form carbon dioxide enriched solution, wherein:
said enzyme is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme;
said enzyme is carbonic anhydrase which is obtained from one or more of Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028); and
preferred metal is zinc in enzyme linked polyhydral metal organic framework.

Method of Carbon dioxide absorption in aqueous solution from mixture of gases

In accordance with the present invention, method of carbon dioxide absorption in aqueous solution from mixture of gases by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
i. mixing carbon dioxide absorbing solution with composition of enzyme linked metal organic framework;
ii. sparging carbon dioxide rich gas in microbuble or nanobubble size to the mixture of carbon dioxide absorbing solution and enzyme linked metal organic framework; and
iii. obtaining carbon dioxide enriched solution;
wherein said carbon dioxide absorbing solution comprises of:
buffer or aqueous solution of amino acids, amines, alkanoamines, carbonates, ployalkylene glycol, piperazine, Tris(hydroxymethyl)aminomethane, aminopolycarboxylic acids, their derivatives and/or their mixtures in the concentration of 0.01M to 10M;
a carbon dioxide absorption activator, preferably 1,3,7-Trimethylpurine-2,6-dione and/or (s)-3-[1-methylpyrolidin-2-yl] pyridine in concentration of 1 to 100 ppm; and
in said enzyme linked polyhydral metal organic framework:
preferred metal is zinc and preferred enzyme is carbonic anhydrase obtained from Bacillus thermoleovorans IOC- S3 and/or Arthrobacter sp IOC –SC-2 at pH range of 5 to 13, temperature range -4 to 100 degree C and salinity tolerance range 0 to 6%.

In this method, the enzyme linked polyhydral metal organic framework causes CO2 absorption in aqueous solutions from mixture of the gases, the enzyme is carbonic anhydrase and the enzyme is entrapped in metal organic framework having at least one nanoscopic cage having sufficient pore size for entrapment of the enzyme.
In this method, the enzyme is preferably obtained from Bacillus thermoleovorans IOC- S3 operating at pH range of 5-13, temperature range -4 to 100 degree C and salinity tolerance range 0-6% and the preferred metal is zinc.
CO2 absorbing solution:
CO2 capture is achieved with enzyme compositions by contacting it with CO2 absorbing solution. The CO2 absorbing solution consists of:
1. Buffer or Aqueous solution of amino acids, amines, alkanoamines, carbonates, ployalkylene glycol, piperazine, Tris(hydroxymethyl)aminomethane, aminopolycarboxylic acids, their derivatives and/or their mixture. They may be used in the concentration of 0.01M to 10M.
2. A surfactant or mixture of surfactant. It may be used in the concentration of 10 to 500 ppm.
3. The CO2 absorption activator i.e. 1, 3, 7, Trimethylpurine-2, 6, dione and /or (s)-3 [1-methylpyrolidin-2-yl] pyridine. It may be used in the concentration of 1 to 100 ppm.
CO2 sparging:
Any mixture of gases containing CO2 can be treated using present invention. The present invention is effective for gas containing CO2 ranging from 1ppm-40%. The CO2 containing gas and CO2 absorbing solutions may first either be mixed in any suitable device and resulting the gas –liquid system can be passed through enzyme composition or CO2 containing gas and CO2 absorbing solutions can be bring simultaneously in contact of enzyme composition. The CO2 may be sparged in microbuble or nanobubble size. The sparging of CO2 in CO2 absorbing solutions in presence of enzyme composition result to CO2 enriched solution.

The enzyme compositions disclosed in present inventions can be used at least for 50 cycles. The enzyme composition and disclosed CO2 absorbing solutions disclosed in present invention cause at least 7 times increase in CO2 absorption in comparison to control enzyme linked metal organic framework was not used.

Conversion of CO2 enriched solution to solid carbonates/bicarbonates:
To the CO2 enriched solution obtained by this invention, salt of alkali metal or any stream containing metal ions is added to convert the CO2 present in the solution to the solid carbontates/bicarbonates.

Method of preparing solid carbonate/ bicarbonate from carbon dioxide solution by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
1) preparing CO2 solution by bubbling deionized water with gaseous CO2 at 4 °C;
2) preparing reaction mixture in the reaction vessel comprising of :
a) enzyme composition (EN-ZN-MOF) having carbonic anhydrase from both Bacillus thermoleovorans IOC- S3 and Bacillus stearothermophilus IOC S1 (MTCC 25030) in the enzyme linked polyhydral metal organic framework;
b) 1.2 M Tris-HCl buffer solution comprising Polyoxyethylene octylphenyl ether, and (s)-3 [1-methylpyrolidin-2-yl] pyridine;
c) 4.0% salt of alkali metal, preferably CaCl2; and
d) CO2 solution;
3) adding CO2 solution with reaction mixture in the reaction vessel at 4 °C;
4) filtering and drying the precipitated product at different intervals of reaction; and
5) obtaining solid carbonate or bicarbonate, preferably CaCO3.

These bicarbonates are nano in size ranging from 50-250nm.

Method of desorption of the carbon dioxide in gaseous form carbon dioxide enriched solution

The CO2 enriched solution can be brought in the contact of the enzyme composition, EN-ZN-MOF having CA from Bacillus stearothermophilus IOC S1 (MTCC 25030). This helps in release of CO2 from the CO2 enriched solution and reduce at least 30% energy requirement to release the CO2 and activate the CO2 absorbing solution.

In one of the embodiment, the preferred metal is zinc in the enzyme linked polyhydral metal organic framework and the enzyme is preferably obtained from Bacillus stearothermophilus IOC S1 (MTCC 25030).

Method for desorption of carbon dioxide in gaseous form carbon dioxide enriched solution by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
contacting the carbon dioxide enriched solution with enzyme linked metal organic framework and releasing of carbon dioxide from carbon dioxide enriched solution;
wherein the preferred metal is zinc in the enzyme linked polyhydral metal organic framework and the enzyme is preferably obtained from Bacillus stearothermophilus IOC S1 (MTCC 25030).

Method for reactivating a carbon dioxide absorbing solution by using enzyme linked polyhydral metal organic framework

Method for reactivating a carbon dioxide absorbing solution by using enzyme linked polyhydral metal organic framework, the method comprising the steps of:
i. contacting a carbon dioxide enriched solution with enzyme linked metal organic framework of zinc to release the carbon dioxide; and
ii. obtaining the activated carbon dioxide absorbing solution.
wherein the preferred metal is zinc in the enzyme linked polyhydral metal organic framework and the enzyme is preferably obtained from Bacillus stearothermophilus IOC S1 (MTCC 25030).

Having described the basic aspects of the present invention, the following non-limiting examples illustrate specific embodiment thereof.

Example-1:
Enzyme linked metal organic framework mediated CO2 absorption enhancement in solvent system:

The experiment was carried out in a column (50 ml volume) having gas inlet from bottom and liquid inlet from the top. The reactor was loaded with 0.5 g of enzyme linked metal organic framework containing 57 mg of CA/g preparation. In the column, the gas mixture containing CO2 and CO2 absorption solution were bring continuous flow in contact of enzyme composition simultaneously at 70 degree C with hydraulic retention time of 5 min. The CO2 absorption solution used contained: aqueous solution of K2 CO3 (30% w/w) along with 10 ppm of Polyoxyethylene octylphenyl ether and 10 ppm of 1, 3, 7, Trimethylpurine-2, 6, dione. The gas mixture contained 35% CO2. The enzyme composition used was EN-ZN-MOF containing CA from Bacillus thermoleovorans IOC- S3 and Arthrobacter sp. IOC –SC-2 (MTCC 25028). Control without enzyme compositions was also run parallel under same operating conditions. The result indicated 0.96 moles CO2/mol of solvent absorption in presence of enzyme in comparison to 0.13 moles CO2/mol solvent in control without enzyme linked metal organic framework.

Example-2:
Enzyme linked metal organic framework mediated CO2 absorption enhancement in solvent system:

The experiment was carried out in a column (20ml) having gas inlet from bottom and liquid inlet from the top. The reactor was loaded with 0.1 g of enzyme linked metal organic framework containing 57 mg of CA/g preparation. In the column, he gas mixture containing CO2 and CO2 absorption solution were bring in contact of enzyme composition simultaneously at 90 degree C. The CO2 absorption solution used contained: aqueous solution of monoethanol amine (10% w/w) along with 10 ppm of Polyoxyethylene octylphenyl ether and 10 ppm of (s)-3 [1-methylpyrolidin-2-yl] pyridine. The gas mixture contained 30% CO2. The enzyme composition used was EN-ZN-MOF containing CA from Bacillus thermoleovorans IOC- S3. Control without enzyme compositions was also run parallel under same operating conditions. The result indicated 0.86 moles CO2/mol of solvent absorption in presence of enzyme linked metal organic framework in comparison to 0.12 moles CO2/mol solvent in control without enzyme linked metal organic framework..

Example-3:
Enzyme linked metal organic framework mediated CO2 absorption enhancement in solvent system:

The experiment was carried out in a column (100 ml volume) having gas inlet from bottom and liquid inlet from the top. The reactor was loaded with 0.5 g of enzyme linked metal organic framework containing 49 mg of CA/g preparation. In the column, the gas mixture containing CO2 and CO2 absorption solution were bring continuous flow in contact of enzyme composition simultaneously at 100 degree C with retention time of 10 min. The CO2 absorption solution used contained: aqueous solution of MEA (30% w/w) and 0.5% piperazine along with 5 ppm of Polyoxyethylene octylphenyl ether and 5 ppm of 1, 3, 7, Trimethylpurine-2, 6, dione. The gas mixture contained 40% CO2. The enzyme composition used was EN-ZN-MOF containing CA from Bacillus thermoleovorans IOC- S3. Control without enzyme compositions was also run parallel under same operating conditions. The result indicated 1.16 moles CO2/mol of solvent absorption in presence of enzyme linked metal organic framework in comparison to 0.17 moles CO2/mol solvent in control without enzyme linked metal organic framework, surfactant and CO2 absorption activator.

Example-4
Use of enzyme linked metal organic framework for CO2 mineralization:

The reaction mixture consists of 5 mg enzyme composition (EN-ZN-MOF) having Carbonic anhydrase from both Bacillus thermoleovorans IOC- S3 and Bacillus stearothermophilus IOC S1 (MTCC 25030), 15 mL of 1.2 M Tris-HCl buffer solution containing 10 ppm (w/w) of Polyoxyethylene octylphenyl ether, and (s)-3 [1-methylpyrolidin-2-yl] pyridine, 4.0% CaCl2 and 30 mL of the CO2 solution. The CO2 solution was prepared by bubbling deionized water with gaseous CO2 at 4 °C. The reaction started when the CO2 solution was added into the reaction vessel. In all experiments the temperature was maintained at 4 °C. The mixture was then filtered and dried at different intervals of reaction to determine the weight of CaCO3 precipitated (enzymatic assay). A control was also run parallel by replacing the enzyme with deionized water (non-enzymatic assay).

The CaCO3 produced in presence of enzyme composition was 556 mg CaCO3 in comparison to 139 mg than without enzyme compositions. The TEM analysis showed nano-particle of CaCO3 with size from 60 to 150 nm in presence of enzyme composition while without enzyme composition the size of CaCO3 was not irregular in shape with size around 500 nm.

Example-5:
Enzyme linked metal organic framework mediated CO2 desorption

The CO2 rich solution obtained from example-3was heated in presence and absence of enzyme composition EN-ZN-MOF having CA from Bacillus stearothermophilus IOC S1 (MTCC 25030) in a column.A control was run without enzyme linked metal organic framework. The result showed at 85 degree C the CO2 desorption was 88% in presence of enzyme linked metal organic framework while without enzyme linked metal organic framework, the 88% desorption was achieved at 130 degree C suggesting at lower temperature requirement for desorbtion of CO2 in presence of enzyme linked metal organic framework. .

Advantages of present invention:
1. The present invention provides enzyme compositions for carbon dioxide absorption which have extended life and wide pH, temperature and salinity tolerance.
2. In the present invention, the enzyme composition provides at least 7times increase in carbon dioxide absorption in comparison to control.
3. In the present invention, the release of Carbon dioxide from the Carbon dioxide enriched solution requires at least 30% less energy to release Carbon dioxide and activate the Carbon dioxide absorbing solution.
4. In the present invention, CaCO3 produced in presence of enzyme composition is at least 4 times higher.
5. In the present invention, there is higher carbon dioxide desorption at lower temperature in presence of claimed enzyme composition.
,CLAIMS:We Claim:
1. Method of carbon dioxide absorption in aqueous solution from mixture of gases by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
i. mixing carbon dioxide absorbing solution with composition of enzyme linked metal organic framework;
ii. sparging carbon dioxide rich gas in microbuble or nanobubble size to the mixture of carbon dioxide absorbing solution and enzyme linked metal organic framework; and
iii. obtaining carbon dioxide enriched solution;
wherein said carbon dioxide absorbing solution comprises of:
buffer or aqueous solution of amino acids, amines, alkanoamines, carbonates, ployalkylene glycol, piperazine, Tris(hydroxymethyl)aminomethane, aminopolycarboxylic acids, their derivatives and/or their mixtures in the concentration of 0.01M to 10M;
a carbon dioxide absorption activator, preferably 1,3,7-Trimethylpurine-2,6-dione and/or (s)-3-[1-methylpyrolidin-2-yl] pyridine in concentration of 1 to 100 ppm; and
in said enzyme linked polyhydral metal organic framework:
preferred metal is zinc and preferred enzyme is carbonic anhydrase obtained from Bacillus thermoleovorans IOC- S3 and/or Arthrobacter sp IOC –SC-2 at pH range of 5 to 13, temperature range -4 to 100 degree C and salinity tolerance range 0 to 6%.
2. The method as claimed in claim 1, wherein the carbon dioxide absorbing solution further comprises a surfactant or mixture of surfactant in the concentration of 10 to 500 ppm.
3. The method as claimed in claim 1, wherein mixture of gases contains the carbon dioxide ranges from 1ppm-40%.
4. The method as claimed in claim 1, wherein the enzyme linked polyhydral metal organic framework causes CO2 absorption in aqueous solutions from mixture of the gases, the enzyme is entrapped in metal organic framework having at least one nanoscopic cage having sufficient pore size for entrapment of the enzyme.

5. Method for desorption of carbon dioxide in gaseous form carbon dioxide enriched solution by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
contacting the carbon dioxide enriched solution with enzyme linked metal organic framework and releasing of carbon dioxide from carbon dioxide enriched solution.
wherein the preferred metal is zinc in the enzyme linked polyhydral metal organic framework and the enzyme is preferably obtained from Bacillus stearothermophilus IOC S1 (MTCC 25030).

6. Method for reactivating a carbon dioxide absorbing solution by using enzyme linked polyhydral metal organic framework, the method comprising the steps of:
i. contacting a carbon dioxide enriched solution with enzyme linked metal organic framework of zinc to release the carbon dioxide; and
ii. obtaining the activated carbon dioxide absorbing solution.
wherein the preferred metal is zinc in the enzyme linked polyhydral metal organic framework and the enzyme is preferably obtained from Bacillus stearothermophilus IOC S1 (MTCC 25030).

7. A composition of an enzyme linked polyhydral metal organic framework for carbon dioxide absorption in aqueous solution from mixture of the gases and/or carbon dioxide desorption in gaseous form carbon dioxide enriched solution;
wherein:
said enzyme is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme;
said enzyme is carbonic anhydrase which is obtained from one or more of Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028); and
preferred metal is zinc in enzyme linked polyhydral metal organic framework.

8. The composition as claimed in claim 7, wherein the enzyme carbonic anhydrase is obtained from Bacillus thermoleovorans IOC- S3 and/ or Arthrobacter sp IOC –SC-2 having high CO2 hydration activity and said enzyme operates at pH range of 5 to 13, temperature range -4 to 100 degree C and salinity tolerance range 0 to 6%.

9. The composition as claimed in claim 7, wherein the enzyme carbonic anhydrase is obtained from Bacillus stearothermophilus IOC S1 (MTCC 25030) having high CO2 dehydration activity and said enzyme operates at pH range 3 to 13, temperature range 0 to 110 degree C and salinity tolerance range 0 to 5%.

10. The composition as claimed in claim 7, wherein the enzyme carbonic anhydrase is obtained from Bacillus thermoleovorans IOC- S3 (MTCC 25023) and Bacillus stearothermophilus IOC S1 (MTCC 25030) having both CO2 hydration and CO2 dehydration activity.
11. The composition as claimed in claim 7, wherein the composition is stable in aqueous solution.
12. The composition as claimed in claim 7, wherein the enzyme compositions can be used at least for 50 cycles.
13. An enzyme linked polyhydral metal organic framework for carbon dioxide absorption in aqueous solutions from mixture of the gases and/or carbon dioxide desorption in gaseous form carbon dioxide enriched solution, wherein:
said enzyme is entrapped in metal organic framework having at least one nanoscopic cage and the nanoscopic cage has sufficient pore size for entrapment of the enzyme;
said enzyme is carbonic anhydrase which is obtained from one or more of Bacillus thermoleovorans IOC- S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 ( MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC –SC-2 (MTCC 25028); and
preferred metal is zinc in enzyme linked polyhydral metal organic framework.

14. Method of preparing solid carbonate/ bicarbonate from carbon dioxide solution by enzyme linked polyhydral metal organic framework, the method comprising the steps of:
1) preparing CO2 solution by bubbling deionized water with gaseous CO2 at 4 °C;
2) preparing reaction mixture in the reaction vessel comprising of :
a) enzyme composition (EN-ZN-MOF) having carbonic anhydrase from both Bacillus thermoleovorans IOC- S3 and Bacillus stearothermophilus IOC S1 (MTCC 25030) in the enzyme linked polyhydral metal organic framework;
b) 1.2 M Tris-HCl buffer solution comprising Polyoxyethylene octylphenyl ether, and (s)-3 [1-methylpyrolidin-2-yl] pyridine;
c) 4.0% salt of alkali metal, preferably CaCl2; and
d) CO2 solution;
3) adding CO2 solution with reaction mixture in the reaction vessel at 4 °C;
4) filtering and drying the precipitated product at different intervals of reaction; and
5) obtaining solid carbonate or bicarbonate, preferably CaCO3.