Efficient adsorption and photocatalytic degradation of cationic dyes based on rod-shaped rare-earth-based MOFs

Dyes play an important role in dyeing textiles, but it also brings water pollution and other negative effects. To address the issue of printing and dyeing wastewater pollution, three different kinds of rare-earth-based metal-organic frameworks (MOFs) were prepared via the solvothermal approach. Among the three MOF adsorbents, the rod-like Tb-MOF has high acid-base stability and excellent thermal stability, as well as a high specific surface area of 47.4 m 2 /g. In the meantime, Tb-MOF adsorbent possessed the best adsorption effect and could adsorb methylene blue at about 300 mg/g. The Langmuir model was found to agree with the adsorption of methylene blue on Tb-MOF, as well as the adsorption between them was homogeneous monolayer adsorption. Methylene blue adsorption on Tb-MOF is more in line with the pseudo-second-order kinetic model, suggesting that chemical adsorption is the primary method of adsorption. Additionally, Tb-MOF has a photocatalytic ability for methylene blue dye. Since it is capable of producing free-moving electrons that react with other substances to produce strongly oxidizing substances that oxidize methylene blue dye. Therefore, the effect of adsorption-degradation synergy treatment of methylene blue dye can be achieved. • Three rare-earth-based MOFs were synthesized via a solvothermal method. • The three MOFs exhibit excellent acid-base stability and thermal stability. • The environmentally friendly and non-toxic ellagic acid is employed as a ligand for MOF materials. • The Tb-MOF material exhibits dual functionality, combining adsorption capacity with photocatalytic performance.