Adsorption of diclofenac from aqueous solution using UiO-66-type metal-organic frameworks

UiO-66 type metal organic frameworks (MOFs), including UiO-66 and UiO-66-NH2, were synthesized, characterized, and applied for the adsorptive removal of diclofenac (DCF) from aqueous solutions. The effect of synthetic conditions (e.g., different linkers and activation temperatures) and adsorptive conditions (e.g., contact time, initial concentration, temperature, and pH) on DCF removal was examined. UiO-66-NH2 showed a higher adsorption capacity than UiO-66, and the increase of activation temperature can improve the adsorption capacity of UiO-66-NH2 towards DCF. The adsorption of DCF by UiO-66-NH2 was endothermic and almost not affected by pH in the range of 4.8-7.7. The adsorption of DCF onto UiO-66 type MOFs conformed to the pseud second-order kinetic model and the Langmuir isothermal model, with adsorption capacity of 357 mg g(-1) for UiO-66 and 555 mg g(-1) for UiO-66-NH2. Electrostatic interaction and H-bonding possibly played a vital role for DCF adsorption. The as-prepared UiO-66 type MOFs were efficient adsorbent for DCF removal from aqueous solution.