# US 9,873,092 B2 · Membrane for filtrating water

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- Number: US 9,873,092 B2
- Document ID: US9873092B2
- Status: Granted
- Kind: B2
- Application number: 14/401,799
- Filed: 2013-05-20
- Published: 2015-05-07
- Granted: 2018-01-23
- Earliest claimed: 2012-05-18
- Assignees: Singapore University of Technology; Massachusetts Institute of Technology
- Applicants: Singapore University of Technology and Design; Massachusetts Institute of Technology
- Inventors: Hui Ying Yang; Rohit Karnik
- Web page: https://patentgrep.com/patent/US9873092B2

## CPC

- B01D 71/12: Cellulose derivatives
- B01D 61/18: Apparatus therefor
- B01D 69/02: characterised by their properties
- B01D 69/10: Supported membranes; Membrane supports
- B01D 69/148: {Organic/inorganic mixed matrix membranes}
- B01D 71/0212: {Carbon nanotubes}
- C02F 1/441: {by reverse osmosis}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

The present invention relates to a material. In particular, it relates to a membrane for filtering water. More particularly, it relates to a membrane comprising carbon nanotubes and mixed cellulose ester porous membranes for water desalination and purification. Still more particular, the membrane comprising a fibrous substrate and carbon nanotubes formed on a fibrous substrate, wherein the surface of the carbon nanotubes is functionally modified. A microfluidic device comprising such a membrane and a method for filtering water are also disclosed.

## Claims

### Claim 1

A membrane comprising a fibrous substrate and carbon nanotubes formed on a fibrous substrate, the carbon nanotubes having a surface modified by an ion beam plasma generated with argon, wherein the modified surface includes a surface roughness, and displays a Raman spectra D speak intensity to G peak intensity ration (ID/IG) greater than 0.8.

### Claim 2 (depends on 1)

The membrane according to claim 1, wherein the fibrous substrate is a mixed cellulose ester porous membrane.

### Claim 3 (depends on 1)

The membrane according to claim 1, wherein the carbon nanotubes are multi-walled carbon nanotubes.

### Claim 4 (depends on 1)

The membrane according to claim 1, wherein the height of the carbon nanotubes are between 100 to 200 μm.

### Claim 5 (depends on 1)

The membrane according to claim 1, wherein the diameter of the carbon nanotubes are between 10 to 20 nm.

### Claim 6 (depends on 1)

The membrane according to claim 1, wherein the carbon nanotubes have a wall number of between 5 to 10.

### Claim 7 (depends on 1)

The membrane according to claim 1, wherein the volume density of the carbon nanotubes on the fibrous substrate is 0.8 g/cm3.

### Claim 8 (depends on 1)

The membrane according to claim 1, wherein the porosity of the membrane is 60%.

### Claim 9 (depends on 1)

A microfluidic device comprising a membrane according to claim 1.

### Claim 10 (depends on 1)

A water filtration method, comprising passing water through the membrane according to claim 1 to filter the water.

### Claim 11 (depends on 10)

The water filtration method of claim 10, wherein the filtration method comprises a reverse osmosis desalination method, a nanofiltration method, or an ultrafiltration method.

### Claim 12 (depends on 1)

The membrane according to claim 1, wherein the ID/IG peak intensity ration is about 1.26.