Removal of benzonitrile and carbazole from model green-diesel derived from microalgae using metal-organic frameworks with protonated amines

Abstract

The utilization of microalgae-derived fuel is very important for our sustainability. Here, adsorptive denitrogenation of model green-diesel (with considerable nitrogen-containing compounds, NCCs) was investigated to check the feasibility of adsorptive purification of fuel, derived from microalgae that is composed of NCCs. A highly porous MIL-101(Cr) (named M101) metal–organic framework was firstly modified to introduce protonated amino groups on both the linker and metallic sites of the MOF. The functionalized MOFs including P-M101-NH2-ED (P and ED mean ‘protonated’ and ethylenediamine, respectively), M101-NH2-ED, and M101-NH2 were applied (together with pristine M101 and a conventional activated carbon) in the adsorptive removal of N-containing compounds like benzonitrile (BENZ) and carbazole (CARB) from model green-diesel. The prepared P-M101-NH2-ED showed the most effective performances in the adsorption, compared with any other adsorbents known thus far. For instance, P-M101-NH2-ED adsorbed 15.6 and 3.6 times of BENZ and CARB, respectively, that of the activated carbon. The observed remarkable performances of P-M101-NH2-ED (Q0 values for BENZ and CARB are 500 and 455 mg/g, respectively), although with lower porosity than other M101s, for BENZ and CARB adsorption could be explained mainly with hydrogen bonding and hydrogen bonding/cation-π interactions, respectively. Moreover, P-M101-NH2-ED was recyclable in several cycles after simple ethanol washing. Therefore, P-M101-NH2-ED could be suggested as a plausible adsorbent to remove NCCs from green-diesel, based on remarkable performances and facile reusability.