Mr. Hamid, as per my experience you should us HCl in place of HNO3 as HCl will work more effectively than HNO3 on metal impurities without effecting SWCNT. In case of HNO3 (eg 2.6M); HNO3 is a strong oxidizing agent and it will break surface of SWCNT and introduced oxygen containing functional, hrydrophilic groups on the surface of SWCNT leading to the rapture of the surface. HNO3 is the easiest green way to make carbon nanostructures water soluble. In addition to that it will cut the CNTs. whereas HCl does not effect the S(M)WCNT in any way but removes metal impurities. For more effect of HNO3 you can go through with our publications.

So, in my point of view if you want to study hydrophilic SWCNT in biological studies then use HNO3 as it make them water soluble but if you want to use SWCNT as SWCNT then use HCl. and 2M HCl is very fine or you can optimize. There was one paper regarding effect on acids on SWCNT, right now i do not have link but if you look you can find that publication. any query is most welcome.

Microwave irradiation is helpful in this regard.

Thank you Sujata for you answer. Could you please give more details about the treatment conditions.

reflux in 4M HNO3 aqueous solution overnight.

Dr. Kaddami, you can use concentarted HNO3 twice with reflux overnight, but you must check if this procedure cause hydroxylation of you CNTs. I use HNO3 with ultrasound for 20 min in order to homogenize the slurry.

Martinez, M. T.; Callejas, M. A.;

Benito, A. M.; Maser, W. K.;

Cochet, M.; Andre´s,J.M.;

Schreiber, J.; Chauvet, O.; Fierro,

J. L. G. Microwave Single Walled

Carbon Nanotubes Purification.

Chem. Commun. 2002, 9,

1000–1001.

Mr. Hamid, as per my experience you should us HCl in place of HNO3 as HCl will work more effectively than HNO3 on metal impurities without effecting SWCNT. In case of HNO3 (eg 2.6M); HNO3 is a strong oxidizing agent and it will break surface of SWCNT and introduced oxygen containing functional, hrydrophilic groups on the surface of SWCNT leading to the rapture of the surface. HNO3 is the easiest green way to make carbon nanostructures water soluble. In addition to that it will cut the CNTs. whereas HCl does not effect the S(M)WCNT in any way but removes metal impurities. For more effect of HNO3 you can go through with our publications.

So, in my point of view if you want to study hydrophilic SWCNT in biological studies then use HNO3 as it make them water soluble but if you want to use SWCNT as SWCNT then use HCl. and 2M HCl is very fine or you can optimize. There was one paper regarding effect on acids on SWCNT, right now i do not have link but if you look you can find that publication. any query is most welcome.

Hi Every body. Thanks to all of you for your help. I will try your suggestions.

Kind regards

For HNO3 treatment check Rosca paper in Carbon 2005. If you want try other acid treatment, check Galiotis paper in CArbon 2008, if you would like to know its effect on properties, look at my papers.

Best regards

Look up on the following article: CARBON 46 (2008) 2003–2025

In the following link you can obtain a copy:

http://ch.imr.ac.cn/bitstream/321006/32809/1/163.pdf

the best acid for removing the catalyst particles is 30% w/w of nitric in water,but if your catalyst contains Co,Fe or Ni using phosphoric acid is better as I have used before, but try to use nitric because after refining the CNT's but heating the samples the acid will dissociated.

Many thanks.

Many thanks