Adsorptive desulfurization of model and real fuel via wire-, rod-, and flower-like Fe3O4@MnO2@activated carbon made from palm kernel shells as newly designed magnetic nanoadsorbents

Abstract

The removal of organic sulphur from liquid fuel via applicable and cheap processes is one of the most challenging energy issues worldwide. Adsorptive desulfurization (ADS) processes can address this issue if highly effective magnetic nanoadsorbents with favourable textural properties are used. In this work, activated carbon produced from palm kernel shells was decorated with wire-, rod- and flower-like magnetic MnO2 by a hydrothermal route to produce reusable magnetic nanoadsorbents with tunable pore volume and pore diameter. The magnetic nanoadsorbents labelled Fe3O4@MnO2-w@AC, Fe3O4@MnO2-r@AC and Fe3O4@MnO2-f@AC were characterized using state-of-the-art spectroscopic techniques and used for sulphur removal from model and real fuels. The results revealed that the prepared magnetic nanoadsorbents had suitable oxygen functionalities, porous morphology and specific surface area of 480 for wire, 312 for rod, and 340 m2/g for flower-like magnetic nanoadsorbents. The newly-designed magnetic nanoadsorbents exhibited superior sulphur removal efficiency at 100 min contact time, 35 °C adsorption temperature, and 0.4 g adsorbent dose per 40 mL of model or real fuel. Among them, a wire-like magnetic nanoadsorbent showed 99 % sulphur removal from model fuel with 530 ppm sulphur content as DBT, 97.6 % and 90 % sulphur removal from commercial kerosene and diesel fuels with 430 and 1050 ppm sulphur content, respectively. The adsorption kinetics, isotherms and thermodynamics disclosed that adsorption of organic sulphur follows the pseudo first-order kinetic model, was an exothermic, and diffusion-controlled process. The magnetic properties enabled the nanoadsorbents to be recovered more easily and reused at least five times.