Efficient adsorptive denitrogenation of model fuel using phosphomolybdic acid encapsulated in bio-sorbents synthesized from walnut-based activated carbon and UiO-66(Zr) metal–organic framework

PMA-Y/AC-X/UiO-66 composites were prepared and used for the elimination of indole (IND) from a model fuel. The composites were synthesized by hydrothermal technique. The phosphomolybdic acid-encapsulated into bio-sorbents synthesized with walnut-based activated carbon and UiO-66(Zr) metal organic framework were investigated through FTIR, FE-SEM, EDX, XRD, BET, and TGA methods. The role of several parameters, such as phosphomolybdic acid (PMo) content, activated carbon (AC) to metal-organic framework (MOF) ratio, process time, temperature, adsorbent dosage, initial concentration of nitrogen-containing compounds (NCCs), aromatic co-solvent, removal of other basic and neutral NCCs like quinoline (QUI), and carbazole (CBZ), and selectivity was investigated on the adsorptive removal of NCCs. The optimal adsorption capacity for IND (558.2 mg.g −1 ) was resulted in adsorbent dosage= 1 g/L, C 0 =1500 ppm, T=25°C for 240 min over PMA-6/AC-30/UiO-66(Zr). Moreover, the experimental data were applied using various isothermal models such as Temkin, Freundlich, Langmuir, and Dubinin-Radushkevich. The isotherm model of Langmuir had a proper fit to the experimental data over PMA-6/AC-30/UiO-66 (R 2 =0.9965). The maximum adsorption capacity of PMA-6/AC-30/UiO-66 for IND was 588.235 mg.g −1 . Based on the experimental data the pseudo-second order kinetics model showed the best fit over PMA-6/AC-30/UiO-66 for IND with linear regression R 2 of 0.9998. The reusability of PMA-Y/AC-X/UiO-66 composite was affirmed via regeneration through ethanol as solvent. π-complexation of IND with activated carbon (AC) has created a significant role, resulting in an enhancement in Q 0 . From isothermal studies and adsorption kinetics, it was proved that the synthesized composite showed a great potential in removing of NCCs.