Advancing Water Treatment: Harnessing Cyclodextrin Metal-Organic Frameworks with Dual Protonation Sites for Enhanced Sulfate Adsorption Efficiency

TTH-CD-MOF was synthesized for sulfate ion adsorption from aqueous solutions, employing cross-linking modification of γ-CD-MOF with N-hydroxyethyl-morpholine as the modifier and triisocyanate as the cross-linking agent. The adsorbent underwent characterization through Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption-desorption, and other analytical methods. Additionally, the impact of factors such as pH, adsorbent dosage, initial concentration, and ionic strength on adsorption performance was investigated. Adsorption experiments demonstrated the robust efficiency of TTH-CD-MOF for SO42- up to 95.3%, conforming to Langmuir isothermal and pseudo-second-order kinetic models, and higher temperatures favored SO42- adsorption. The maximum adsorption capacity was 189.51mg·g-1 (25 °C). The adsorption mechanism comprised electrostatic interaction, adsorption within the cavities and pores of γ-CD-MOF. TTH-CD-MOF demonstrates effective sulfate removal from aqueous solutions, establishing its potential as an efficient anion adsorbent.