System and method for using ultramicroporous carbon for the selective removal of nitrate with capacitive deionization

Patent metadata

Field	Value
Publication number	US-2020247693-A1
Application number	US-201916268154-A
Country	US
Kind code	A1
Filing date	Feb 5, 2019
Priority date	Feb 5, 2019
Publication date	Aug 6, 2020
Grant date	—

Abstract

The present disclosure relates to a flow through electrode, capacitive deionization (FTE-CDI) system which is able to adsorb nitrates from water being treated using the system. The system makes use of a pair of electrodes arranged generally parallel to one another, with a water permeable dielectric sandwiched between the electrodes. The electrodes receive a direct current voltage from an electrical circuit. At least one of the electrodes is formed from a carbon material having a hierarchical pore size distribution which includes a first plurality of pores having a width of no more than about 1 nm, and a second plurality of micro-sized pores. The micron-sized pores enable a flow of water to be pushed through the electrodes while the first plurality of pores form adsorption sites for nitrate molecules carried in the water flowing through the electrodes.

First claim

1 . A flow through electrode, capacitive deionization (FTE-CDI) system comprising:
a pair of electrodes arranged generally parallel to one another; a water permeable dielectric arranged between the electrodes so as to be sandwiched between the electrodes; an electrical circuit for applying a direct current voltage across the electrodes; and at least one of the electrodes being formed from a carbon material having a hierarchical pore size distribution, the hierarchical pore size distribution including a first plurality of nano-sized pores having a width of no more than about 1 nm, and a second plurality of pores having micron-sized pores that enable a flow of water to be pushed through the electrode, the first plurality of pores forming adsorption sites for nitrate molecules carried in the water flowing through the at least one electrode.

2 . The system of claim 1 , wherein both of the pair of electrodes comprise carbon material having the hierarchical pore size distribution.

3 . The system of claim 1 , wherein at least one of the electrodes comprises a carbon aerogel.

4 . The system of claim 1 , wherein both of the electrodes comprise carbon aerogel.

5 . The system of claim 1 , wherein the dielectric comprises a non-conductive, water permeable paper.

6 . The system of claim 5 , wherein the dielectric comprises a polymer membrane which allows a flow of the water therethrough.

7 . The system of claim 1 , further comprising a pair of header plates disposed against each of the electrodes, for assisting in channeling a flow of water to be treated by the system into a first one of the pair of electrodes, and for receiving a flow of treated water out from a second one of the pair of electrodes.

8 . The system of claim 7 , wherein at least one of the header plates comprises an ultraviolet transparent acrylic material.

9 . The system of claim 1 , further comprising a pair of current collectors coupled to the electrodes.

10 . The system of claim 9 , wherein the pair of current collectors comprise graphite current collectors.

11 . An ultramicroporous electrode for use in a flow through, capacitive deionization (FTE-CDI) system for adsorbing nitrate molecules contained in water being fed into the electrode for treatment, the electrode comprising:
a carbon aerogel member having a hierarchical pore size distribution, the hierarchical pore size distribution including:
a first plurality of ultramicropores randomly distributed throughout a thickness of the carbon aerogel member, and each forming a slit having a width of no more than about 1 nm; and
a second plurality of micron-sized pores randomly distributed throughout the thickness of the carbon aerogel member and being sufficiently large to enable fluid flow paths to be formed through the entire thickness of the carbon aerogel member, which enable a flow of water to be pushed through the thickness of the carbon aerogel member; and
the first plurality of pores forming adsorption sites for capturing nitrate molecules carried in the water flowing through the carbon aerogel member.

12 . The electrode of claim 11 , further comprising:
an electrical circuit; including an additional carbon aerogel electrode; a dielectric member separating the carbon aerogel member and the additional carbon aerogel member; and the electrical circuit transmitting an electric current to the carbon aerogel members while a quantity of water is flowed through the carbon aerogel member and the additional carbon aerogel member.

13 . A method for making a carbon aerogel electrode material, the method comprising:
making a wet organic sol-gel form; carbonizing the sol-gel form at a temperature of from about 900° C. to about 1000° C., for from about 2 to about 4 hours; and activating the carbonized sol-gel under carbon dioxide flow, for from about 0.5 to about 1.5 hours, at from about 900° C. to about 1000° C.

14 . The method of claim 13 , wherein the wet organic sol-gel form is a resorcinol-formaldehyde sol-gel.

15 . The method of claim 14 , wherein the making a wet organic sol-gel form comprises:
making an aqueous solution of resorcinol and formaldehyde; mixing the aqueous solution with an alcohol (preferably methanol) and an acid (preferably acetic acid) to make a sol-gel precursor; curing the sol-gel precursor in a mold; and aging the sol-gel.

16 . The method of claim 13 , wherein the wet organic sol-gel form is a sheet having a thickness of from about 300 μm to about 700 μm.

17 . The method of claim 16 , wherein the sheet is cut from a block of aged resorcinol-formaldehyde sol-gel.

18 . The method of claim 13 , further comprising washing the sol-gel form with water and exchanging water in the sol-gel form with acetone prior to the carbonizing.

19 . The method of claim 13 , wherein the carbonizing is conducted under nitrogen.

20 . A method for making a carbon aerogel electrode material adapted to adsorb predetermined, non-spherical shaped ions flowing through the carbon aerogel electrode material, the method comprising:
making a wet organic sol-gel form; carbonizing the sol-gel form at a temperature of from about 900° C. to about 1000° C., for from about 2 to about 4 hours; and activating the carbonized sol-gel under carbon dioxide flow, for from about 0.5 to about 1.5 hours, at from about 900° C. to about 1000° C., to form the carbon aerogel electrode material, which has pores shaped to capture the predetermined, non-spherical shaped ions flowing therethrough.

21 . A flow through electrode, capacitive deionization (FTE-CDI) system comprising:
a pair of electrodes arranged generally parallel to one another; a water permeable dielectric arranged between the electrodes so as to be sandwiched between the electrodes; an electrical circuit for applying a direct current voltage across the electrodes; and at least one of the electrodes being formed from a carbon material having a hierarchical pore size distribution, the hierarchical pore size distribution including a first plurality of nano-sized pores each having a predetermined, non-spherical shape and dimensions, and a second plurality of pores having micron-sized pores that enable a flow of water to be pushed through the electrode, the first plurality of pores forming adsorption sites for adsorbing ions which have a shape and dimensions generally in accordance with the predetermined, non-spherical shape of the first plurality of nano-sized pores, and carried in the water flowing through the at least one electrode.

22 . The system of claim 21 , wherein the predetermined, non-spherical shape of each one of the pores of the first plurality of pores comprises a planar, slit-like shape.

23 . The system of claim 21 , wherein the first plurality of pores each comprise a width of no more than about 1 nm.

Assignees

• L Livermore Nat Security Llc

Inventors

• Campbell Patrick
• Hernandez Maira Ceron
• Hawks Steven
• Loeb Colin
• Pham Tuan Anh
• Stadermann Michael

Classifications

• B01D61/428

  Membrane capacitive deionization · CPC title

• B01J13/0091

  Preparation of aerogels, e.g. xerogels · CPC title

• B01J13/0026

  containing a liquid organic phase · CPC title

• C01B32/05

  Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30 · CPC title

• H01G11/32

  Carbon-based · CPC title