Process for the production of graphene sheets with tunable functionalities from seaweed promoted by deep eutectic solvents

• US 10,549,997 B2
• Filed: 11/07/2016
• Issued: 02/04/2020
• Est. Priority Date: 11/07/2016
• Status: Active Grant

• Current Assignee: Council of Scientific & Industrial Research
• Original Assignee: Council of Scientific & Industrial Research
• Inventors: Prasad, Kamlesh, Sharma, Mukesh, Mondal, Dibyendu, Saha, Arka, Singh, Nripat
• Primary Examiner(s): McCracken, Daniel C.
• Application Number:
  US15/330,852
• Publication Number:
  US 20180126368A1
• Time in Patent Office: 1,184 Days
• CPC Class Codes: B01J 27/128 with iron group metals or platinum group metals
• CPC Class Codes: B01J 27/135 with titanium, zirconium, hafnium, germanium, tin or lead
• CPC Class Codes: B01J 27/138 with alkaline earth metals, magnesium, beryllium, zinc, cadmium or mercury
• CPC Class Codes: B01J 31/0239 Quaternary ammonium compounds
• CPC Class Codes: B01J 31/0271 also containing elements or functional groups covered by B01J31/0201 - B01J31/0231
• CPC Class Codes: B01J 31/26 containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
• CPC Class Codes: B01J 31/30 Halides
• CPC Class Codes: B01J 35/27 in a liquid or molten state
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 37/0217 Pretreatment of the substrate before coating
• CPC Class Codes: C01B 2204/22 Electronic properties
• CPC Class Codes: C01B 2204/32 Size or surface area
• CPC Class Codes: C01B 32/184 Preparation
• CPC Class Codes: C02F 1/283 using coal, charred products, or inorganic mixtures containing them
• CPC Class Codes: C02F 1/488 for separation of magnetic materials, e.g. magnetic flocculation
• CPC Class Codes: C02F 2101/14 Fluorine or fluorine-containing compounds
• CPC Class Codes: C02F 2303/16 Regeneration of sorbents, filters
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: H01M 4/90 Selection of catalytic material
• CPC Class Codes: H01M 8/083 Alkaline fuel cells
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

The present invention relates to the process for the scalable production of Fe₃O₄/Fe, Sn & Zn doped graphene nanosheets from a naturally abundant seaweed resources such as Sargassum tenerrimum, Sargassum wighti, Ulva faciata, Ulva lactuca and Kappaphycus alvarezii. The granules remained after the recovery of liquid juice from the fresh seaweeds were utilized as a raw material and a deep eutectic solvents (DESs) generated by the complexation of choline chloride and FeCl₃, ZnCl₂ and SnCl₂ were employed as template as well as catalyst for the production graphene nanosheets functionalized with metals. Pyrolysis of the mixture of seaweed granules and DES at 700-900° C. under 95% N₂ and 5% H₂ atmosphere resulted formation of metal doped graphene sheets with high surface area (120-225 m²·g⁻¹) and high electrical conductivity 2384 mS·m⁻¹ to 2400 mS·m⁻¹. The nanosheets thus obtained could remove substantial amount of fluoride from fluoride contaminated drinking water (95-98%).

Claims

1. A process for the preparation of facile production of functionalized graphene sheets using seaweed biomass as precursor and deep eutectic solvents (DESs) acting as both catalyst and template, comprising the steps of;

(i) crushing the seaweeds mechanically to yield a liquid and residue in granular form;

(ii) separating the liquid part from the residual part;

(iii) obtaining the residual part in the granular form from step (ii);

(iv) treating the granules obtained in step (iii) with deep eutectic solvents followed by pyrolysis under inert atmosphere and high temperature which produces functionalized graphene sheets.

2. The process as claimed in claim 1 wherein the seaweed biomass used is selected from brown seaweeds, green seaweeds, and red seaweeds.

3. The process as claimed in claim 1 wherein the obtained liquid consist of plant micro and macro nutrients and plant growth regulators.

4. The process as claimed in claim 1 wherein the granules obtained from Sargassum seaweed contains Na+ (1-1.5 wt %), K+ (0.5-1 wt %), Ca²⁺ (1.5-2 wt %), Mg²⁺ (1-1.5 wt %), Fe^2+/3+ (0-0.5 ppm), Zn²⁺ (0.01-0.02 wt %), Cu²⁺ (2-3 ppm), Mn²⁺ (15-20 ppm), C (34-35%), H (4-5%), N (1.3-1.6%) and S (0.5-1%).

5. The process as claimed in claim 1 wherein the functionalized graphene either doped with Fe, Sn or Zn depending on the composition of the deep eutectic solvents used to prepare the composites of the seaweeds.

6. The process as claimed in claim 1 wherein the used deep eutectic solvents are obtained by the complexation of choline chloride with Lewis acids.

7. The process as claimed in claim 1 wherein semi-solid composite can also be prepared by mixing seaweed granules with ChoCl—

FeCl₃ (1;

2), ChoCl—

ZnCl₂ (1;

2) and ChoCl—

SnCl₂ (1;

2), respectively with 1;

2 to 1;

3 weight ratio of granule to deep eutectic solvent.

8. The process as claimed in claim 1 wherein the preparation of functionalized graphene sheets involves pyrolysis in 95% N₂ and 5% H₂ atmosphere for different durations.

9. The process as claimed in claim 1 wherein the semi-solid composites of Sargassum granule and ChoCl—

FeCl₃ 1;

2 is calcined at 700°

C.-900°

C. to give heteroatom doped magnetic graphene nanosheets containing various elements.

10. The process as claimed in claim 1 wherein the obtained functionalized graphene samples have reasonably good porosity of 2.7-4.1 nm characteristic of mesoporous material suitable for electrical double layer capacitors (EDLC).

11. The process as claimed in claim 1 wherein the obtained functionalized graphene samples have good electrical conductivity of 2384 mS·

m<sup>−

1</sup> to 2400 mS·

m<sup>−

1</sup>.

12. The process as claimed in claim 1 wherein the obtained functionalized graphene samples have reasonably high BET surface area of 120-225 m²·

g<sup>−

1</sup>.

13. The process as claimed in claim 1 wherein the obtained functionalized graphene can remove 95-98% fluoride from drinking water collected from village of Govind Garh, Rajasthan, India (26°

45′

N, 74°

38′

E).

14. The process as claimed in claim 1 wherein the separation of graphene sheets after the adsorption of fluoride on the sheets can be done by using ordinary magnets in the case of magnetised graphene sheets.

15. The process as claimed in claim 2 wherein the seaweed biomass used includes a brown seaweed, and wherein said brown seaweed is selected from Sargassum tenerrimum and Sargassum wighti.

16. The process as claimed in claim 2 wherein the seaweed biomass used includes a green seaweed, and wherein said green seaweed is selected from Ulva faciata and Ulva lactuca.

17. The process as claimed in claim 2 wherein the seaweed biomass used includes a red seaweed, and wherein said red seaweed is Kappaphycus alvarezii.

18. The process as claimed in claim 6 wherein the Lewis acids are selected from FeCl₃ (ChoCl—

FeCl₃ 1;

2), ZnCl₂ (ChoCl—

ZnCl₂ 1;

2), and SnCl₂ (ChoCl—

SnCl₂ 1;

2).

19. The process as claimed in claim 9 wherein the various elements are selected from Nat, K⁺, Ca²⁺, Mg²⁺, Fe^2+/3+, Zn²⁺, Cu²⁺, Mn²⁺, Sn²⁺, C, H, N and S.