Study on the performance of micro-flow injection preconcentration method on-line coupled to thermospray flame furnace AAS using MWCNTs wrapped with polyvinylpyridine nanocomposites as adsorbent

Abstract

This work describes the synthesis and characterization of a new adsorbent nanocomposite based on multiwalled carbon nanotubes (MWCNTs) and polyvinylpyridine and its use in the development of a highly sensitive micro-flow injection preconcentration method coupled to TS-FF-AAS for the determination of very low levels of Cd. The characterization of the nanocomposite was performed by FT-IR, TGA, SEM, TEM and textural data measurements using the BET and BJH methods. The optimized conditions of the micro-flow injection preconcentration method involved a preconcentrated sample (8.8 mL) at pH 8.0 flowed through 50.0 mg of nanocomposite packed into a mini-column at a flow rate of 4.4 mL min À1.The on-line elution of Cd(II) ions towards the TS-FF-AAS detector was carried out in countercurrent at a flow rate of 0.6 mL min À1 using 1.0 mol L À1 HCl. The analytical curve ranged from 0.12 to 6.0 mg L À1 (r ¼ 0.997), and an enhancement factor of 19.5, sample throughput of 15 h À1 and consumptive index of 0.45 mL were achieved. In terms of sensitivity, the uniquely high adsorption capacity of the nanocomposite was confirmed by the low limit of detection (36 ng L À1) achieved after implementing the preconcentration step in TS-FF-AAS. In terms of selectivity, the proposed method was shown to be tolerable to several foreign ions and applicable to different kinds of waters (tap, mineral, lake, and synthetic seawater), cigarettes, a food sample (powder chocolate), a medicinal herb (Ginkgo biloba) and a certified reference material (fish protein DORM-3).

Preparation of Molecularly Imprinted Poly(methacrylic acid) Grafted on Iniferter-Modified Multiwalled Carbon Nanotubes by Living-Radical Polymerization for 17β-Estradiol Extraction

“…Such an outcome is somewhat expected considering the nature of the grafting process grafting-from herein used in which the polymerization in the solution is avoided and preserves the morphological features of the nanostructure substrate. Previous studies reported by our research group have pointed out a significant decrease in the surface area of nanocomposite when grafting to approach has been used . The higher surface area of MIP/MWCNT compared to NIP/MWCNT can be attributed to the presence of a template molecule in the synthesis.…”

“…Previous studies reported by our research group have pointed out a significant decrease in the surface area of nanocomposite when grafting to approach has been used. 63 The higher surface area of MIP/MWCNT compared to NIP/MWCNT can be attributed to the presence of a template molecule in the synthesis. In this case, most likely the solubility of template-monomer is lower in the porogenic solvent, which makes the removal of solvent easier and then giving rise to an adsorbent with a higher surface area.…”

A Chelating Resin of EDTA-Type Modified Cross-Linking Polystyrene to Preconcentrate Trace Metals for Seawater Detection

“…e stability of the obtained resins through polymerization by using acrylate monomers is insufficient for long-term use because there will be decomposition of the esters of acrylate to a certain extent when purged by acid or buffer solution during desorption, which may lead to the disintegration of the resin system. ere were other chelating polymeric resins developed by introducing inorganic graphene [20], multiwalls carbon nanotubes (MWCNTs) [21], magnetic hollow porous oval shape NiFe 2 O 4 [22] or organic ionic liquid [23], chitosan etc. [24].…”