N-CNT/ZIF-8 nano-adsorbent for adsorptive desulfurization of the liquid streams: Experimental and

Abstract

With the aim of providing clean fuels through the desulfurization, the nanocomposite of Nitrogen-doped carbon nanotube/ZiF-8 (NCNT/ZIF-8) was prepared via the hydrothermal method. The nanocomposite sorbents were evaluated in the adsorption of dibenzothiophene (DBT) from the liquid phase. In this regard, the microstructure, morphology, particle size, thermal stability and physicochemical properties of nanoadsorbents were determined by using different characterization techniques. Influences of various parameters on the adsorption capacity of the nanoadsorbents were investigated; such as the adsorbent type, adsorption time, temperature and the initial DBT concentration. The as-prepared nanoadsorbents, ZiF-8 and NCNT/ZIF-8, possessed a high surface area of 1123.9 and 1207.4 m2/g, respectively. The NCNT/ZIF-8 exhibited the DBT adsorption capacity of 81.2 mg/g which is much higher than that of the pure ZIF-8 (69.1 mg/g). This excellent performance can be ascribed to the synergistic effects of both NCNT and ZiF-8, the presence of basic groups in the NCNT structure, and the high surface area and pore volume. Moreover, the DBT equilibrium adsorption was investigated by using Langmuir, Freundlich models. The Langmuir isotherm indicated a good agreement with experimental results. In addition, adsorption kinetics were studied and it was revealed that the pseudo-second-order model exhibited a favorable fitting with the experimental data. Finally, the regenerated NCNT/ZIF-8 provided a good performance even after 3 adsorption-desorption cycles and its adsorption capacity was almost unchanged.