Histidine functionalized multi-walled carbon nanotubes as sorbent for flow injection-electrothermal atomic absorption spectrometric ultrasensitive determination of trace vanadium (V) in biological and environmental samples

Performance comparison of activated carbon and ferric oxide-hydroxide–activated carbon nanocomposite as vanadium(v) ion adsorbents

Recently, a great deal of attention has been paid to water treatment using nanoparticles such as ferric nanoparticles. In this work, a ferric oxide-hydroxide–activated carbon nanocomposite has been used as new adsorbent for vanadium(v) ion.

Speciation and determination of inorganic arsenic species in water and biological samples by ultrasound assisted-dispersive-micro-solid phase extraction on carboxylated nanoporous graphene coupled with flow injection-hydride generation atomic absorption spectrometry

In this paper, carboxylated nanoporous graphene as a nanoadsorbent was evaluated in two types of ultrasound assisted-dispersive micro-solid phase extraction for speciation of trace As(v) and As(iii) ions in natural water and human biological samples.

Triethylenetetramine modified multiwalled carbon nanotubes for the efficient preconcentration of Pb(ii), Cu(ii), Ni(ii) and Cd(ii) before FAAS detection

Triethylenetetramine modified multiwalled carbon nanotubes (TETA-MWCNTs) were prepared and used as an efficient adsorbent for the solid phase extraction of heavy metal ions.

Unanticipated favoured adsorption affinity of Th(iv) ions towards bidentate carboxylate functionalized carbon nanotubes (CNT–COOH) over tridentate diglycolamic acid functionalized CNT: density functional theoretical investigation

CNT–COOH has higher adsorption affinity for Th⁴⁺ in aqueous solution compared to CNT–DGA, whereas pristine CNT has nil.

Synthesis of polyethyleneimine capped carbon dots for preconcentration and slurry sampling analysis of trace chromium in environmental water samples

Carbon dots capped with polyethyleneimine (CD-PEI) were synthesized and applied in selective separation and preconcentration of trace Cr(VI). Dispersed particle extraction (DPE) slurry sampling with flame atomic absorption spectrometry (FAAS) was used to selectively and sensitively determine Cr(VI) in water samples. The as-synthesized CD-PEI was confirmed by Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, elemental analysis, fluorescence and zeta potential measurement. The adsorption of Cr(VI) on CD-PEI was evaluated. Its isothermal adsorption was studied and fitted in the Langmuir model. Nearly 85% of Cr(VI) was adsorbed within 10 min showed that the CD-PEI exhibited fairly fast kinetics for the sorption of Cr(VI). Experimental conditions, including the content and size of CD-PEI, sample pH, adsorption time, sample volume, slurry volume and interfering ions, were further optimized to obtain efficient preconcentration and high-precision determination of Cr(VI). CD-PEI with small size turned to be a good candidate for the preparation of slurry. CD-PEI served not only as a promising adsorbent for separation and preconcentration of Cr, but also a signal-enhancing agent in FAAS. The method achieved an enhancement factor of 30 and a detection limit (S/N=3) of 0.21 µg L(-1) Cr(VI) with a consumption of 14.0 mL sample and an adsorption time of 5 min, which provided two times of signal enhancement. The RSD for 11 replicate measurements of 5.0 µg L(-1) Cr(VI) was 2.8%. The possible signal enhancement mechanism was proposed. The developed method has been applied to determine trace Cr(VI) in a variety of water samples.

Characterizing Covalently Sidewall-Functionalized SWCNTs by using 1H NMR Spectroscopy

Unambiguous evidence for covalent sidewall functionalization of single-walled carbon nanotubes (SWCNTs) has been a difficult task, especially for nanomaterials in which slight differences in functionality structure produce significant changes in molecular characteristics. Nuclear magnetic resonance (NMR) spectroscopy provides clear information about the structural skeleton of molecules attached to SWCNTs. In order to establish the generality of proton NMR as an analytical technique for characterizing covalently functionalized SWCNTs, we have obtained and analyzed proton NMR data of SWCNT-substituted benzenes across a variety of para substituents. Trends obtained for differences in proton NMR chemical shifts and the impact of o-, p-, and m-directing effects of electrophilic aromatic substituents on phenyl groups covalently bonded to SWCNTs are discussed.