Effective adsorption of Congo red by an innovative biochar/LDH-derived MIL-100(Al): Investigation of coexisting pollutants and mechanism revelation

Herein, the innovative use of 2-aminoterephthalic acid on biochar/LDH(Mg/Al) derivatization succeeded in obtaining BL@MIL-100(Al), which was applied as an excellent adsorbent for the efficient removal of Congo red (CR). The adsorption capacity of BL@MIL-100(Al) was 5 times that of biochar and 2.5 times that of LDH(Mg/Al), respectively. The experimental results showed that the maximum adsorption capacity of BL@MIL-100(Al) reached 1672.34 mg/g at 303 K, which was much higher than that of the reported adsorbents. The Langmuir model and Elovich model described the adsorption process of BL@MIL-100(Al) better. In addition, the thermodynamic results indicated that the higher temperature favored the adsorption process of CR. Besides, BL@MIL-100(Al) showed strong immunity to chloride and sodium salts, and the presence of microplastics facilitated the adsorption of CR onto BL@MIL-100(Al). Meanwhile, BL@MIL-100(Al) still achieved ∼ 81 % removal efficiency after 6 cycles and showed long-term water purification in fixed-bed column experiment, indicating its outstanding stability. Additionally, the excellent adsorption performance in different kinds of natural water environments and binary systems demonstrated its wide applicability. Moreover, the adsorption mechanism of BL@MIL-100(Al) was systematically explored based on XRD, FT-IR, and XPS characterizations, in which amino protonation contributed prominently to the adsorption process. Thus, an innovative and facile approach to synthesize BL@MIL-100(Al) as an adsorbent for the removal of CR from wastewater is feasible. © 2024 Elsevier B.V.