A remarkable adsorbent for denitrogenation of liquid fuel: Ethylenediaminetetraacetic acid-grafted metal–organic framework, MOF-808

Abstract

• Porous MOF808 was functionalized with EDTA to load much –COOH sites. • MOF808/EDTA showed the highest adsorption for quinoline (625 mg/g). • The adsorption results were interpreted via acid-base and H-bonding interactions. • Reusable MOF808/EDTA showed effectiveness in adsorptive denitrogenation. Removal of nitrogen-containing compounds (NCCs) from the fuel is essential for clean energy. An efficient adsorbent with ample active sites was obtained via grafting ethylenediaminetetraacetic acid (EDTA) onto a metal–organic framework (MOF808). The obtained MOF808_EDTA was firstly applied in adsorptive removal of organics like NCCs from liquid; showed remarkable performances in NCCs removal. For example, MOF808_EDTA showed the maximum adsorption capacity ( Q 0 ) of 667 and 625 mg/g, respectively, in indole (IND) and quinoline (QUIN) removal from fuel. These Q 0 values for QUIN and IND adsorption are the highest and third position, respectively, compared with reported results. Additionally, the Q 0 values for IND and QUIN are > 10 times those of activated carbon. Importantly, the Q 0 value, in volume/weight (0.57 cm 3 / g), is very close to the total pore volume (0.59 cm 3 / g) of MOF808_EDTA, suggesting very effective utilization of pores of the MOF in the adsorption. The adsorption of IND and QUIN over MOF808_EDTA could be interpreted with H-bonding and acid-base interactions, respectively, based on properties of adsorbates and functional groups on MOF808_EDTA and MOF808_EDTA-Na (where hydrogen in EDTA was replaced with Na). The new adsorbent MOF808_EDTA, which is highly reusable, is being suggested as a prominent adsorbent to remove NCCs, especially basic QUIN, from fuel. This work will pave the way to modify MOFs to introduce ample functional groups that will be effective in adsorption.