Carbon nanotube

membranes: Fabrication

and application to

desalination

Course:Membranes

Dilshad Bajwa

Roll#11

Introduction

Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater).

various water treatment technologies have been

proposed

Primary technologies

(screening,filtration, centrifugation, separation,

sedimentation,

Secondary technologies

(aerobic and anaerobic treatments);

Tertiary technologies

Distillation, Crystallization, Evaporation,

Solvent extraction,Precipitation,

Reverse osmosis (RO), Nanofiltration (NF),

Ultrafiltration (UF) and Microfiltration (MF)

Nanotechnology for water treatmentRecently nanotechnology has given immeasurable opportunities to purify water even at ionic state

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Carbon nanotubes membrane Technology

CNTS are a type of carbon crystal in a cylindrical shape

Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair.

Their structures are hexagonal, effectively tubes of graphite sheets .

MWCNTs

SWCNTs

Both SWCNTs and MWCNTs have beenused for water desalination

Vertically aligned CNT membrane

How Nanotubes are Made

1. Silicon carbide (SiC) is the material used to make the nanotubes.

2. A catalyst are placed on the SiC.

3. The nanotubes grow off the SiC.

4. Si3N4 is deposited on it

5. .

5 XeF2 is used to dissolve part of the silicon to open one side of the nanotubes.

6 Silicon Nitride and Argon are used to remove the catalyst particles.

7. The nanotube is uncapped with the addition of reactive ions.

Plasma enhanced CVD (PECVD) is a currently availabletechnology used for straight and perpendicular growth of carbon nanotubes

Carbon nanotubes can, block particles that are bigger than the diameter of the carbon nanotube.

The pores are big enough to let water molecules through.

It could be used to replace the expensive membranes that are currently being used in desalination through reverse osmosis.

Filtration and Desalination

Functionalization of CNT tips

The smooth and hydrophobic inner core of the hollow CNTs can allow the uniterrupted and spontaneous passage of water moleculeswith very little absorption Frictionless movement of water molecules with high velocities from 9.5 to 43.0 cm s−1/bar

The flow rates are four to five times faster than other mebranes. filler contents provide support present between the tubes.such as epoxy and silicon nitride

Low energy solution for water treatmentAnti_fouling membraneAnti microbial even can rupure bacterial cellSelf cleaning application Selective adsorption properties of nanotube surfacesIncredibly large surface areaManmade nanotube membranes allow fluid flow 10,000 to 100,000 times faster than conventional fluid flow theory would predict

.

Species

Sodium Chloride, NaCl 99%

Sodium Sulfate, Na2SO4 99%

Calcium Chloride, CaCl2 99%

Magnesium Sulfate, MgSO4 >99%

Sulfuric Acid, H2SO4 98%

Hydrochloric Acid, HCl 90%

Fructose, MW 180 >99%

Sucrose, MW 360 >99%

Humic Acid >99%

Viruses 99.99%

Proteins 99.99%

Bacteria 99.99%

conclusion:

Carbon Nanotube technologies potentially lead to more effective means of filtration that not only remove more impurities than current methods but do so faster, more economically and more selectively.

Hurdle is the complicated methods for thesynthesis of CNTs with uniform pore size and distribution.

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