D. Nkazi, K. Owusu-Ansah and S.E. Iyuke

Carbon Nano-materials(CHMT - Wits University/ South

Africa)

Cancer treatment

PSI + CNTsSolubilizing agent, FA and Drug

Membrane Filtration

Polymeric membrane + fCNTs

Membrane used in PEAM

fuel cell Polymeric membrane + CNBs

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CNTs

Gases (CO, CO2,C2H2, CH4…)

& Liquids (Ethanol, benzene,…)

Ferrocene: Carbon source & Catalyst

Coal: Pyrolysis

Char (Carbon solid)

Liquid products

Gaseous productsSuch as C2H2 at Very H. Temp

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Low and non-volatile price (compare to Oil) and wide geographically distributed in South Africa;

Purity and production yield depend on the region (origin of coal) and carbon content;

Key technologies to clean coal utilization (Energy saving and environmental protection);

Low temperature: more CH 4 and High temperature: more acetylene C 2H 2

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Apparatus for CNTs production from Coal

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Low Temperature (From 400 0C): CO and CH4 were produced as CNTs sources in the above furnace

Increasing Temp. from 400 to 900 decrease CH4 from 32.41 to 0.89 %

High enough temperature: Formation of acetylene

(Appropriate lab. condition: Plasma pyrolysis)

Coal C2H2H2, Ar

Fe(NO3)3.9H2O3.62 g

Co(NO3)2.6H2O2.46 g

H2O distilled30 ml

(stirring)

Supports(Zeolite or CaCO3)

Droppewise

Dried and calcination (400 0C)

Fe-Co on support

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Set up for Wet impregnation method

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XRD spectrum

Fe-Co on zeolite Fe-Co on CaCO3

(Equipment: Bruker D2 Phaser XRD)

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SEM images for Zeolite and Fe-Co catalyst on zeolite

• Cubic crystalline structures• Few defect on the structure after WIM

SEM images For CaCO3 and Fe-Co catalyst on CaCO3

• Rhombic crystalline structures• Few defect on the structure after WIM

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EDS Zeolite and Fe-Co on zeolite EDS CaCO3 and Fe-Co on CaCO3

Fe and Co imbedded intoMicro-pores of supports

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CVD set up for CNT synthesis

Acid treatment of synthesized CNTs

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TEM images For CNTs grown from zeolite supported Fe-Co catalyst

• CNTs with smaller diameter• After fctnalization, diameters were

reduced

TEM images For fCNTs grown from zeolite supported Fe-Co catalyst

TEM images For CNTs grown from CaCO3 supported Fe-Co catalyst TEM images For fCNTs grown from CaCO3 supported Fe-Co catalyst • CNTs with larger diameter• After fctnalization, diameters were

reduced

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Diameter distribution as grown CNTs for both supports

(Using image processing software)

CNT-zeolite and fCNT-zeolite: 10 nm to 40 nm CNT-CaCO3 and fCNT-CaCO3: 20 nm to 80 nm Difference in pore sizes of CaCO3 and zeolite

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Raman spectra for CNTs and fCNTs

• G band confirm graphene structure• ID/G show the amount of structural defect

in CNTs• increase in ID/G from CNTs to fCNTs :

graphene increase in disorder after fctnalization

• CNTs: C=C at 1600 cm-1 and carboxylic gp at 1030 cm-1

FTIR spectra for CNTs and fCNTs

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TGA profile for CNTs and fCNTs

• CNTs-CaCO3 and fCNTs-CaCO3:Lost of 90% and 97% of weight after

decomposition

• CNTs-zeolite and fCNTs-zeolite:Lost of 40% and 63% of weight after

decomposition

> CNTs grown on CaCO3 supported catalyst are more pure than from zeolite.

DTG profile for CNTs and fCNTs

• CNTs-CaCO3 and fCNTs-CaCO3:2 decomposition peaks – existence of larger

range of outer diameters which double peaks

• CNTs-zeolite and fCNTs-zeolite:> For both, Increase in peak size after acid

treatment confirms the presence of fctional gp in CNT wall

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CNT grown from a zeolite supported catalyst produce tubes with smaller diameter from 10nm to 40nm while that grown from CaCO3 yield larger diameter tubes, from 20nm to 80nm.

CNTs grown from the CaCO3 catalyst support produce almost twice as much as from the zeolite due to the larger pore sizes and surfaces are of the CaCO3 supported catalyst.

 Concentrated HNO3 can be used to purify and functionalize CNTs. This acid removes both CaCO3 supports and any remaining metals from the CNT-cs without affecting their wall structures. The acid failed to remove about 37% of SiO2 from the CNT-zs.

Concentrated HF however e!ectively removes the SiO2 and yields very pristine CNTs with no residual materials without destroying the nanotubes.

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CHIETAChemical Industries Education and Training Authority, South

Africa