A combined experimental and computational studies on thiophene adsorption from liquid fuels over ZIF-67@ZnFe LDH composites

Abstract

Nowadays, sulfur compounds (e.g., thiophene) in liquid fuels are increasingly recognized as a major source of air pollution, making fuel purification a top priority. A new composite composed of metal-organic framework (ZIF-67) and ZnFe(4:1)-layer double hydroxide (ZnFe LDH) materials was synthesized at room temperature with varying weight ratios of ZIF-67 (20, 40, and 60 wt %) for the removal of thiophene from a model fuel (n-heptane). The characterization techniques (XRD, SEM, TEM, FTIR, and BET) confirmed the successful synthesis of the composite materials. The adsorptive desulfurization performance of the ZIF-67@ZnFe LDH composites was compared with ZIF-67 and ZnFe-LDH via adsorption batch processes. The experimental adsorption data were tested using isotherm and kinetic models to know the adsorption process. The composite material (40 % ZIF-67@LDH) appeared a significantly greater adsorption capacity (395.4 mg/g), exceeding that of the two parent materials (ZnFe-LDH and ZIF-67) by (2.5 and 1.6 times), respectively. Monte Carlo simulation was employed to identify the most favorable adsorption sites for thiophene on ZIF-67 and Zn–Fe LDH. Our results suggest that the combination of ZIF-67 and ZnFe LDH in the composite material has a synergistic effect, leading to a remarkable enhancement in adsorption performance. The ZIF-67, with its large pore volume and high surface area, provides a high capacity for thiophene adsorption. While the LDH offers abundant and more favorable interaction sites with higher adsorption energy for thiophene. The 40 % ZIF-67@LDH composite exhibited promising reusability, maintaining its effectiveness for at least four consecutive adsorption-desorption cycles. This suggests its potential as a low cost, efficient and sustainable solution for thiophene removal.