Remarkable adsorbent for phenol removal from fuel: Functionalized metal–organic framework

• Metal–organic frameworks (MOFs) were firstly applied in phenol adsorption from fuel.
• Functionalized MOFs showed remarkably enhanced adsorption for phenol via H-bond.
• Detailed adsorption mechanism was clearly shown based on adsorption results.
• Functionalized MOFs can be used for many times by simple solvent washing.

Adsorption of phenol from a model fuel was firstly conducted over activated carbon (AC) and a typical porous metal–organic framework (MOF, MIL-101) in order to understand the possible application of MOFs in fuel purification. MIL-101 showed a remarkable phenol adsorption capacity (∼2.7 times that of AC) under the studied conditions. Moreover, the adsorption capacity enhanced further (up to ∼3.7 times of AC) after introduction of a hydroxyl group on the MOF (even though porosity of the MOF was decreased noticeably) by grafting ethanolamine (EA) on coordinatively unsaturated sites on MIL-101. The adsorption of phenol on EA-grafted MIL-101 (HO-MIL-101) is explained by H-bonding. Comparative adsorption of phenol and anisole on MIL-101 and HO-MIL-101 suggests that H-bonding occurs between the H-atom of the phenolic –OH and the O-atom of HO-MIL-101. HO-MIL-101 is recyclable after simple solvent washing, showing the potential application of MOFs, if suitably functionalized, for phenol adsorption/removal from fuel.

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