Insights into High-Performance and Selective Elimination of Cationic Dye from Multicomponent Systems by Using Fe-Based Metal–Organic Frameworks

Metal–organic frameworks (MOFs), especially Fe-MOFs, have shown prospective application in eliminating organic dyes from wastewater due to their well-developed pores, water stability, easy preparation, and economy. Herein, we synthesized four types of Fe-MOFs (such as MIL-88A, MIL-88B, MIL-100, and MIL-101) using the hydrothermal method. The products were analyzed with several methods. By comparing the adsorption effect of those four types of Fe-MOFs on three kinds of dyes, it has been shown that MIL-100 owns the best adsorption efficiency on cationic organic dyes methylene blue (MB) and Rhodamine B (RhB) in 180 min, while all MOFs have slight removal capacity on methyl orange (MO). MIL-100, as an adsorbent, was studied under various research conditions, and the maximum removal efficiencies to MB, RhB, and MO were found to be up to 97.36%, 88.75%, and 13.00%, respectively. Furthermore, cationic dye MB’s removal by MIL-100 was fitted with a pseudo-second-order model and Langmuir isotherm model (Qm = 411.041 mg/g) by adsorption kinetics and isotherms research, and MIL-100 could rapidly and selectively divide MB from a binary complex aqueous solution of MB and MO. The as-fabricated MIL-100 also exhibited excellent recyclability after four adsorption–desorption recycles and can be treated as a potential substance with high removal efficiency of cationic organic dye-containing industrial effluents.