Colorimetric Response of Dithizone Product and Hexadecyl Trimethyl Ammonium Bromide Modified Gold Nanoparticle Dispersion to 10 Types of Heavy Metal Ions: Understanding the Involved Molecules from Experiment to Simulation

Abstract

A new kind of analytical reagent, hexadecyl trimethyl ammonium bromide (CTAB), and dithizone product-modified gold nanoparticle dispersion, is developed for colorimetric response to 10 types of heavy metal ions (M(n+)), including Cr(VI), Cr(3+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+). The color change of the modified gold nanoparticle dispersion is instantaneous and distinct for Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+). The color change results from the multiple reasons, such as electronic transitions, cation-π interactions, formation of coordination bonds, and M(n+)-induced aggregation of gold nanoparticles (AuNPs). The different combining capacity of heavy metal ions to modifiers results in the different broadening and red-shifting of the plasmon peak of modified AuNPs. In addition, Cr(VI), Cu(2+), Co(2+), Ni(2+), and Mn(2+) cause the new UV-vis absorption peaks in the region of 360-460 nm. The interactions between the modifiers and AuNPs, and between the modifiers and M(n+), are investigated by using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results confirm that AuNPs are modified by CTAB and dithizone products through electrostatic interactions and Au-S bonds, respectively, and the M(n+)-N bonds form between M(n+) and dithizone products. Furthermore, the experimental and density functional theory calculated IR spectra prove that dithizone reacts with NaOH to produce C6H5O(-) and [SCH2N4](2-). The validation of this method is carried out by analysis of heavy metal ions in tap water.

Dithizone-etched CdTe nanoparticles-based fluorescence sensor for the off–on detection of cadmium ion in aqueous media

“…Since the coordination between DZ and Cd 2+ can reduce the atom number of the conjugated system, it leads to an increase in the electronic transition energy. 49 Similar spectral blue shis (up to 11 nm) were also found in the corresponding uorescence spectra of NPs-DZ (in Fig. 5).…”

Zn(II)-concentration dependent Raman spectra in the dithizone complex on gold nanoparticle surfaces in environmental water samples

“…We check the purity of H 2 Dz by infrared spectra, which seemed to be consistent with the previous report [20]. The tap water, river water and the seawater samples were obtained from Soongsil University (Seoul, Korea), Han river (Banpo district, Seoul), and Yellow Sea (Tae-an, Chungcheongnam-do Province, Korea), respectively.…”

Synthesis of multi-ion imprinted polymers based on dithizone chelation for simultaneous removal of Hg2+, Cd2+, Ni2+ and Cu2+ from aqueous solutions

“…On [21][22][23] and has excellent selectivity advantages due to its -SH and -NH-functional groups. 9,12,[21][22][23][24][25] The traditional view expects a tautomeric equilibrium for dissolved dithizone between the ketone form (Ph-NH-NH]CS-N]N-Ph) and the enol form (Ph-NH-N]C(SH)-N]N-Ph).…”

“…9,12,[21][22][23][24][25] The traditional view expects a tautomeric equilibrium for dissolved dithizone between the ketone form (Ph-NH-NH]CS-N]N-Ph) and the enol form (Ph-NH-N]C(SH)-N]N-Ph). As pH increases, it is easy for S with a lone-pair electron to bind with H to form a thiol group, which would easily form a complex with metal ions.…”