Highly Sensitive and Selective In-Situ SERS Detection of Pb2+, Hg2+, and Cd2+ Using Nanoporous Membrane Functionalized with CNTs

Abstract

Porous Anodic Alumina (PAA) membrane was functionalized with CoFe2O4 nanoparticles and used as a substrate for the growing of very long helical-structured Carbon Nanotubes (CNTs) with a diameter less than 20 nm. The structures and morphologies of the fabricated nanostructures were characterized by field emission- scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and Raman spectroscopy. By uploading the CNTs on PAA, the characteristic Raman peaks of CNTs and PAA showed 4 and 3 times enhancement, respectively, which leads to more sensitive Surface-Enhanced Raman Spectroscopy (SERS) substrates. For comparison, PAA and CNTs/PAA arrays were used as SERS substrates for the detection of Hg2+, Cd2+, and Pb2+. The proposed sensor demonstrated high sensitivity and selectivity between these heavy metal ions. CNTs/PAA sensor showed excellent selectivity toward Pb2+ over other metal ions, where the enhancement factor is decreased from ~17 for Pb2+ to ~12 for Hg2+ and to ~4 for Cd2+. Therefore, the proposed CNTs/PAA sensor can be used as a powerful tool for the determination of heavy metal ions in aqueous solutions.

Rapid detection of mercury contamination in water by surface enhanced Raman spectroscopy

“…10,57 Other SERS sensors for Hg(II) have been demonstrated in the literature. For example, Shaban et al 59 developed a SERS sensor for Hg(II) by functionalising porous anodic alumina membrane with CoFe 2 O 4 nanoparticles and growing carbon nanobers on the inner walls of the functionalised membrane to capture the target analyte. The method development of the sensor was complex and the detection limit for Hg(II) was only 1 mg per L (1 PPb).…”

TiO2 Nanoribbons/Carbon Nanotubes Composite with Enhanced Photocatalytic Activity; Fabrication, Characterization, and Application

“…Modification of TiO 2 was performed through different methods including doping of TiO 2 by metals, non-metals, semiconductors nanoparticle, graphene, and carbon nanotubes (CNTs) 11 , 14 . In particular, carbon nanotubes (CNTs) became desirable material for its specific mechanical, physical, chemical, electroconductive, and field emission properties 15 , 16 . So, there is considerable interest in the synthesis of hybrid materials from TiO 2 nanomaterials and CNTs as enhanced production of high photocatalytic efficiency 14 , 17 .…”

Innovative 2D nanomaterial integrated fiber optic sensors for biochemical applications

“…By the best logistic fitting of the experimental data (Fig. 8b), the LOD was estimated below 0.25 ppb for Pb 2+ ions, which is 4-fold better than CNTs functionalized heavy metal sensor 25 . Meanwhile, this LOD of 0.25 ppb is only one fortieth of WHO's permissible limit of 10 ppb for lead in drinking-water 26 .…”