Cationic graphene-based polymer composite modified with chromium-based metal-organic framework [GP/MIL-53(Cr)] for the degradation of 2,4-dichlorophenol in aqueous solution

Abstract

Owing to its remarkable water stability, chromium-based metal-organic framework (MIL-53(Cr) has the capacity to remove 2,4-dichlorophenol (2,4-DCP) from aqueous solutions, but the weak adsorptive capacity of the adsorbent limits its utilization. In this work, cationic graphene-based polymer composite (GP) was successfully synthesized with (MIL-53(Cr)) [GP/MIL-53(Cr)] through one-step solvothermal technique and characterized with XRD, SEM, BET, XPS, TEM, and FTIR. Adsorbent dose, pH, initial concentration, and contact time were enhanced to improve the performance of GP/MIL-53(Cr). GP/MIL-53(Cr) displayed a marginal adsorptive performance relative to MIL-53(Cr) and GP. The adsorption of 2,4-DCP mainly depends on the nature of MIL-53(Cr) and the electrostatic attractions of the functional groups on GP surface. Due to the high magnetic properties of GP/MIL-53(Cr), effective solid–liquid separation can be easily achieved. The adsorbate mineralization process stabilizes at 200 min. The pseudo-second-order model adequately fits the adsorption kinetic data, while the Freundlich and Langmuir models gave a good fit with the equilibrium data. The maximum adsorptive capacity of the adsorbents for the adsorbate as calculated from the Langmuir isotherm are 64.9 (GP), 28.2 MIL-53(Cr), and 98.4 mg/g (GP/MIL-53(Cr). The thermodynamic studies revealed that the adsorption process is spontaneous, feasible, and endothermic. Additionally, the excellent performance of GP/MIL-53(Cr) shows that the adsorbent has potential application in treating wastewater.