Study of pharmaceutical contaminant adsorption using HKUST-1 as metal-organic framework model

Tetracycline (TTC) and doxycycline (DXC) are antibiotics commonly used to treat infections; however, overuse of these antibiotics impacts human health and the environment. Metal-organic frameworks (MOFs) arose as a recent potential adsorbent has a coordinative crystalline porous framework constructed through metal cluster coordination bridged towards organic ligands exhibiting high surface area, adjustable pore size, and high stability. In this study, HKUST-1 synthesized at room temperature was used for the first time for the adsorption of TTC and DXC as single and binary components. The pseudo-first-order equation can well represent the adsorption kinetics of TTC and DXC data on HKUST-1, while the adsorption isotherm data for TTC and DXC are well represented by the Redlich-Paterson equation. The extended Langmuir, Sips, Toth, and Redlich-Patterson equations failed to represent binary component adsorption isotherm data in HKUST-1. By modifying the adsorption affinity parameter of the extended Redlich-Paterson equation, the adsorption isotherm data of the TTC and DXC binary components can be represented by this equation. Adsorbed TTC and DXC in the HKUST-1 framework could not be recovered through water regeneration. If organic solvents or highly concentrated base solutions were used as solvents, the structure of HKUST-1 would be disrupted.