3-mercaptopropyltrimethoxysilane-Modified Multi-walled Carbon Nanotubes as a New Functional Adsorbent for Flow Injection Extraction of Pb(Ⅱ) from Water and Sediment Samples

摘要

In the present study, a novel synthesized adsorbent material based on 3-mercaptopropyltrimethoxysilane-functionalized multi-walled carbon nanotubes was used to increase the Pb~(2+) adsorption from aqueous solutions in a flow injection solid-phase extraction system coupled to flame atomic absorption spectrometry. Spectroscopic and microscopic techniques (Fourier transform infrared spec-troscopy, energy dispersive spectroscopy, and scanning electron microscopy) were employed to confirm the chemical modification of the adsorbent surface. Preconcentra-tion conditions (sample pH, flow rate, buffer solution, and eluent concentrations) were optimized using factorial and Doehlert matrix designs that made it possible to construct a linear graph in the 5.0- to 130.0-μgL~(-1) range (r= 0.9999) and estimate detection and quantification limits (1.7 and 5.7 μgL~(-1), respectively). The method precision was found to be 4.20 and 1.97 % for 5.0 and 100.0 μgL~(-1) Pb~(2+) solutions, respectively. When using the 3-mercaptopropyltrimethoxysilane-functionalized multi-walled carbon nanotubes, the sensitivity for the Pb~(2+) trace determination was improved to 95 % compared with the oxidized multi-walled carbon nanotubes, thus evidencing the significant enhancement of the adsorption capacity. The developed method was successfully applied to the analysis of Pb~(2+) species in different water samples and the PACS-2 marine sediment-certified reference material.