Magnetic Poly(vinylpyridine)‐Coated Carbon Nanotubes: An Efficient Supramolecular Tool for Wastewater Purification

Abstract

Herein, we report the first example of a supramolecular carbon nanotube (CNT)-based magnetic depolluting agent for divalent metal ion (M(2+)) removal from aqueous solutions. In particular, magnetic multi-walled carbon nanotubes (m-MWCNTs) coated with poly(vinylpyridine) (PVPy) self-aggregate in aqueous solutions that contain divalent metal ions (such as Zn(2+), Cu(2+) and Pb(2+)) to form tight insoluble bundles in which the M(2+) ions remain trapped through pyridyl-M(2+)-pyridyl interactions. Magnetic filtration ultimately affords the efficient separation of the depolluted solution from the precipitated M(2+)-CNT agglomerates. Upon acid treatment, the supramolecular threads could be disassembled to afford the free CNT-polymer hybrid, thus allowing recycling of the depolluting agent. All materials and complexation/decomplexation steps were thoroughly characterised by using thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy (TEM and SEM, respectively). The quantification of the M(2+) residual concentrations in water was evaluated by using inductively coupled plasma optical emission spectroscopy (ICP-OES), which showed that, depending on the metal cation, this material can remove up to 99% of the contaminant.

Magnetically Active Carbon Nanotubes at Work

“…This property can be used to recover MNPs–CNTs or to specifically guide the hybrids toward a particular target (as for example in in‐vivo drug‐delivery). As an example, our group reported the possibility to magnetically recycle a polymer‐coated Fe@CNT hybrid used to purify wastewater 95. Raw Fe@CNT hybrids were produced by Fc‐catalyzed CVD and then coated with a poly(vinylpyridine) (PVP) polymer.…”

“…A stable suspension of m ‐PVPy‐MNPs@CNTs (left) precipitates upon addition of Zn(OAc) 2 (middle) and can be separated from the solution with a permanent magnet (right) thus purifying the solution. Reproduced with permission from reference 95.…”

ChemInform Abstract: Magnetically Active Carbon Nanotubes at Work

“…As an example, our group reported the possibility to magnetically recycle ap olymer-coated Fe@CNT hybrid used to purifyw astewater. [95] Raw Fe@CNT hybrids were produced by Fc-catalyzed CVD and then coated with ap oly(vinylpyridine) (PVP) polymer. In the presence of divalent metal ions (such as Zn 2 + ,C u 2 + ,a nd Pb 2 + )c ontained in wastewater,t he hybrid formed insoluble bundles in which the M 2 + cations remained trapped into pyridyl-M 2 + -pyridyl interactions.…”

Simultaneous capture of methyl orange and chromium(vi) from complex wastewater using polyethylenimine cation decorated magnetic carbon nanotubes as a recyclable adsorbent

“…Especially, carbon nanotubes (CNTs) have been widely used as promising adsorptive materials due to their large specic surface areas, excellent stability as well as its broad-spectrum adsorption ability towards different classes of pollutants. 26 However, pristine CNTs still have several drawbacks for practical application such as lower amounts of functional groups, high surface hydrophobicity, poor selectivity, and difficult solid/liquid separation aer being used, which greatly restrain their practical applications in wastewater treatment. To overcome these shortcomings, researchers have modied CNTs by adopting various chemical or physical strategies.…”