Enhancing Methylene Blue Adsorption Performance of Ti₃C₂T_x@Sodium Alginate Foam Through Pore Structure Regulation

Pore structural regulation is expected to be a facile way to enhance the adsorption performance of MXene. In this work, spherical foam composites consisting of Ti₃C₂T_x and sodium alginate (SA) were synthesized via a vacuum freeze-drying technique. By varying the solution volume of Ti₃C₂T_x, four distinct Ti₃C₂T_x@SA spherical foams with honeycomb-like and lamellar structures with a pore diameter in the range of 100-300 μm were fabricated. Their methylene blue (MB) adsorption performances were then systematically compared. The results revealed that the honeycomb-like porous-structured spherical foams have a significantly higher adsorption capacity than their lamellar counterparts. Notably, the Ti₃C₂T_x@SA honeycomb-like porous foam exhibited a remarkable maximum adsorption capacity (q) of 969 mg/g, positioning it at the forefront of MB adsorbent materials. Respective analysis of the adsorption kinetics, thermodynamics, and isotherm model indicated that this MB adsorption of Ti₃C₂T_x@SA honeycomb-like porous foam is characterized to be a physical, endothermic, and monolayer adsorption. The Ti₃C₂T_x@SA honeycomb-like porous foam also demonstrated excellent resistance to ion interference and good reusability, further attesting to its substantial potential for practical applications. X-ray photoelectron spectroscopy (XPS) analysis was employed to elucidate the adsorption mechanism, which was found to involve the synergistic effect of electrostatic adsorption and amidation reaction. This work not only offers new avenues for the development of high-performance adsorption materials but also provides crucial insights into the structural design and performance optimization of porous materials.