Ce-MOF coated with polyethyleneimine-modified chitosan hydrogel offers synergistic removal of an anionic dye.

Adsorption technology is essential for water remediation and resource recovery to reduce environmental pollution. Although Metal-organic frameworks (MOFs) exhibit outstanding adsorption capabilities, their high preparation cost hinders their wide application. Alternatively, chitosan (CS) hydrogels offer wastewater treatment at an affordable cost. Herein, polyethyleneimine-modified CS hydrogel coated with MOF (Ce-BTC/CS-PEI) was prepared as a high-capacity sorbent for methyl orange (MO) sequestration. A comprehensive characterization of the Ce-BTC/CS-PEI composite was carried out, involving morphological and elemental analysis (SEM-EDS), crystal phase identification (XRD), surface area and porosity measurements (BET), surface charge evaluation (zeta potential), molecular structure determination (FTIR), and surface chemical state analysis (XPS). The increased interfacial contact area and the positively charged zeta potential of Ce-BTC/CS-PEI enabled efficient adsorption of MO in MO/methylene blue mixtures. The experimental data demonstrated strong agreement with the Langmuir equilibrium isotherm and second-order rate equations. Ce-BTC/CS-PEI demonstrated exceptional uptake performance, reaching 819.67 mg·g-1 after 18 h. Thermodynamic analysis showed that adsorption was a natural exothermic procedure. After four cycles, the material retained 70% of its adsorption efficiency. Therefore, Ce-BTC/CS-PEI exhibits excellent capability as an excellent, ecologically friendly, and inexpensive adsorbent for selective MO removal.