Structure-Activity Relationship of a Zr Metal-Organic Framework for the Adsorption of Emerging Organic Contaminants in Water.

Metal-organic frameworks (MOFs) are promising adsorption materials for emerging organic contaminants. However, their structure-activity relationship studies are often simplified, which hinders their broader environmental applications. In this work, Zr-MOF (MOF-808) was selected as a representative adsorbent to study its structure-activity relationship toward the adsorption of various emerging organic contaminants containing different functional groups such as carboxyl (-COOH), sulfonic acid (-SO3H), hydroxyl (-OH), and amino group (-NH2). It was found that the structure of organic functional groups in the contaminants significantly affected the adsorption selectivity of MOF-808, with the adsorption capacity decreasing in the order of -COOH > -SO3H > -OH ≈ -NH2. Linear solvation energy relation (LSER) was employed to analyze the adsorption mechanism and estimate the contribution of each descriptor. It was shown that the adsorption was governed by interactions in the order: electrostatic > π-π stacking, while hydrogen bonding was relatively weaker. This work provides insights into the structure-activity relationship between MOFs and emerging organic contaminants and may be useful for designing porous adsorbents.