عنوان مجله
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Frontiers of Environmental Science & Engineering
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چکیده
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Herein, nitrogen and sulfur co-doped carbon nanotubes (NS-CNT) adsorbents were synthesized via the
chemical vapor deposition technique at 1000°C by employing the camphor, urea and sulfur trioxide
pyridine. In this study, desulfurization of two types of mercaptans (dibenzothiophene (DBT) and
tertiary butyl mercaptan (TBM) as nonlinear and linear forms of mercaptan) was studied. In this regard,
a maximum capacity of NS-CNT was obtained as 106.9 and 79.4 mg/g and also the removal
efficiencies of 98.6% and 88.3% were achieved after 4 h at 298K and 0.9 g of NS-CNT for DBT and
TBM, respectively. Characterization of the NS-CNTs was carried out through exploiting scanning
electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),
and elemental analysis (CHN). The isotherm equilibrium data could be ascribed to the Freundlich
nonlinear regression form and the kinetic data was fitted by nonlinear form of the pseudo second order
model. The negative values of ΔS0
, ΔH0
and ΔG0
specify that the adsorption of both types of
mercaptans was a natural exothermic process with a reduced entropy. Maintenance of more than 96%
of the adsorption capacity even after nine cycles suggest the NS-CNT as a superior adsorbent for
mercaptans removal in the industry. Density functional theory (DFT) calculations were also performed
to peruse the effects of S/N co-doping and carbon monovacancy defects in CNTs toward the adsorption
of DBT and TBM.
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