Synthesis and Characterization of Functionalized MOFs for Enhanced Adsorption of Methylene Blue from Wastewater

Abstract

This research has successfully developed a zirconium-centered metal-organic framework, referred to as MOF(Zr)-K, by integrating L-lysine (K) as a modifying moiety to introduce novel characteristics. The material was characterized using FT-IR, FESEM, XRD, XPS, etc., which confirmed the successful synthesis of the material. It was then applied for the adsorption and separation of methylene blue (MB) in wastewater. The experiments demonstrated that, under the conditions of dosage of adsorbent 10 mg, pH = 7, the initial content of MB was 10 mg/L, the adsorption of MB by MOF(Zr)-K reached equilibrium in 6.0 h, with a max adsorption content of 344.83 mg/g. Adsorption data were fitted to isotherm and kinetic models, revealing that the adsorption of MB by MOF(Zr)-K complied with the Freundlich isotherm model and Pseudo-second-order kinetic model. Additionally, results suggested that the adsorption process was an endothermic and spontaneous process. XPS analysis confirmed that the adsorption of MB by MOF(Zr)-K adsorbent principally depended on the electrostatic attraction between MB and the carboxyl and amino groups on the material surface. This study provides valuable insights for the treatment of MB pollution.