Water-stable PEG2000-modified citric acid crosslinked β-CD MOF for efficient removal of tetracycline hydrochloride: synthesis, adsorption behavior, and mechanism.

To address the ecological and health risks associated with residual tetracycline hydrochloride (TCH) in water, a green-synthesized adsorbent composed of β-cyclodextrin (β-CD), citric acid (CA), and polyethylene glycol (PEG) was developed for the effective removal of TCH from wastewater. The synthetic parameters were optimized, and the resulting PEG-CA-β-CD MOF was characterized by FT-IR, XRD, and SE. TGA analysis indicated an increase in the thermal stability. The maximum adsorption capacity of PEG-CA-β-CD MOF for TCH was 221.6 mg/g at pH = 4. Adsorption kinetics were well-described by the Elovich equation model, while the Freundlich isothermal model accurately described the equilibrium data adsorption Thermodynamic analysis revealed that the adsorption process was endothermic and spontaneous. Furthermore, the adsorbent maintained 84 % of its initial adsorption capacity after four reuse cycles. Analysis using zeta potential, FT-IR, and XPS confirmed that the possible adsorption mechanism of TCH mainly involves electrostatic interactions, hydrogen bonding, and cavity encapsulation. Finally, simulated wastewater experiments showed that PEG-CA-β-CD MOF was able to adsorb TCH efficiently even in the presence of other pollutants. Overall, due to its green synthesis process, low cost, ease of regeneration, and multi-mechanistic adsorption capability, the PEG-CA-β-CD MOF exhibits significant potential for TCH removal in wastewater treatment.