Copper-based metal organic framework (MOF), HKUST-1, as an efficient adsorbent to remove p-nitrophenol from water

p-Nitrophenol (PNP), a toxic phenolic compound, must be removed from water to avoid the damage to the aquatic ecology, animals and even human beings. While adsorption appears to be the most widely used approach, it is critical to develop an efficient and high-capacity adsorbent to reduce PNP below the regulated concentration. In this study, a new class of microporous adsorbents, metal organic frameworks (MOFs), was proposed for the PNP adsorption in water. A representative MOF, HKUST-1, was selected to adsorb PNP owing to its exceptionally stable in water. The adsorption kinetics, isotherms and thermodynamics were investigated. HKUST-1 was found to possess an adsorption capacity of ~400 mg/g. The mechanism for such a high adsorption capacity was proposed and attributed to affinity of NO2 of PNP to the metal site of HKUST-1 as well as affinity between the benzene rings of PNP and HKUST-1. The presence of phenol did not hinder the adsorption of PNP to HKUST-1, showing HKUST-1's high selectivity towards PNP. HKUST-1 can be an efficient and highly-selective adsorbent to remove PNP from water via the adsorption process.