Carbon nanotubes with in surface phenyl-iminodiacetic acid groups for the extraction of Fe, Cu and Pb ions
Carbon nanotubes
(CNTs) have been extensively used for the solid phase extraction (SPE) of a
great variety of compounds including not only hydrophobic molecules but also polar
analytes and metal ions. This versatility is based on the easy chemical modification
of the nanotubes which allows the introduction of functional groups that
enhance the interaction with the target analytes. The functionalization of the
CNTs is usually started with the introduction of oxygen-containing groups such
as carboxyl (-COOH) or hydroxyl (-OH) ones, that are further transformed in the
desired moieties. However, this general process requires the use of extreme oxidation
conditions which may eventually produce the CNT shortening as well as defects
on the CNT surface.
In a recent
communication, researchers from the Tongji University at China use the radical
addition with aryl diazonium salts to introduce functional groups in CNTs
surface under mild conditions. In fact, the reaction can be easily performed in
aqueous media just controlling the temperature which are fixed at 60 ºC. The
general synthetic procedure, based on two sequential steps, allows the
introduction of phenyl-iminodiacetic acid groups which will be responsible of
the extraction of metal ions from waters based on an ion exchange mechanism (see
Figure 1). The mild conditions employed in the synthesis overcome the previously
described shortcomings as well as provide a homogeneous coverage of the CNTs
surface.
 |
| Figure 1. Introduction of imino-diacetic groups in CNTs surface for the extraction of Fe, Cu and Pb by ion exchange |
The new material presents
a higher dispersibility in water compared to pristine CNTs due to the inclusion
of hydrophilic groups. The modified CNTs, after a deep chemical
characterization (including UV, IR and XPS studies), have been employed for the
extraction of iron, copper and lead from environmental waters with
preconcentration factors near to 100. The extracted analytes are finally
determined by inductively coupled plasma optical emission spectrometry (ICP-OES)
with limits of detection as low as 0.15 ng/mL and relative standard deviations
lower than 2.5%.
The readers are
referred to the original article where they will find the description of the
CNT derivatization process, the optimization of the extraction method and the
final analytical characterization.
References
Link to the article: Novel
phenyl-iminodiacetic acid grafted multiwalled carbon nanotubes for solid phase
extraction of iron, copper and lead ions from aqueous medium.
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ReplyDeleteThank you so much for your participation. We are nanoparticles enthusiasts. They have a great potential in analytical chemistry (our field) in the development of extraction techniques or sensors. In addition, their application on bio-imaging is also so exciting. Although the use of NP as drugs vehicles is not close to our field, it is also an interesting topic. If you want to share some of these applications in a brief post, we will be glad to publish it.
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