MIL-100(Fe)@GO composites with superior adsorptive removal of cationic and anionic dyes from aqueous solutions

• MIL-100(Fe)@GO composites have superior adsorptive capacity for MB, CR, MO and AC, respectively. • The adsorption uptake of MIL-100(Fe)@GO is improved due to coating GO. • Two distinct MO and AC adsorption regimes were observed at 20- 500 mg L −1 due to the different adsorption droving forces. The separation of synthetic dyes from industrial wastewaters is an important objective in addressing water pollution. The removal of pollutant dyes from industrial wastewater prior to its release into the environment is an essential task; thus, synthesizing new adsorbent materials with superior adsorption efficiency is an important undertaking. Herein, we report the synthesis of MIL-100(Fe)@GO (graphene oxide) composites exhibiting superior adsorption performance toward methyl orange (MO), Congo red (CR), methylene blue (MB), and acid chrome blue K (AC). The room-temperature adsorption capacities of MIL-100(Fe)@GO-1 for these dyes were 533.7 (MB), 760.1 (MO), 1386.3 (AC), and 1786.6 (CR) mg g –1 , exceeding those values previously reported for pristine MIL-100(Fe) by 31.1%, 17.8%, 54.8%, and 8.9%, respectively. The adsorption behavior of the composites can be described on the basis of the structural and morphological characteristics and zeta potential of MIL-100(Fe)@GO and the adsorption capacity and structural characteristics of the dyes. The adsorption uptakes of MIL-100(Fe)@GO toward the pollutant dyes was controlled by the synergistic effects of the hydrogen-bonding, hydrophobic interactions, and π–π interactions and agglomeration pores of MIL-100(Fe)@GO. The obtained results revealed that the synergetic interplay of electrostatic, hydrogen-bonding, π–π, and hydrophobic interactions and adsorption space led to two distinct adsorption regimes for MO and AC depending on the adsorbate concentration. MIL-100(Fe)@GO composites exhibited superior MB, CR, MO and AC adsorption capacities on account of their distinct adsorption mechanisms .