The high content of NH2-MIL-101(Fe) in NH2-MIL-101(Fe)/Fe3O4/GO enables selective adsorption removal of five parabens

The efficient removal of water-soluble parabens presents a challenge. To address this, NH2-MIL-101(Fe)/Fe3O4/GO with high NH2-MIL-101(Fe) content was synthesized to remove five parabens from water selectively. The adsorption capacities of methylparaben, ethylparaben, propylparaben, methyl 3,5-dichloro-4-hydroxybenzoate, and ethyl 3,5-dichloro-4-hydroxybenzoate increased from 2.57 to 8.34 mg/g, 1.08 to 3.01 mg/g, 1.62 to 4.80 mg/g, 5.71 to 11.76 mg/g, and 5.31 to 15.07 mg/g, respectively, when the concentration of parabens ranged from 5 to 30 mg/L. The adsorption process was exothermic and driven by hydrophobic interactions. The Freundlich model described the adsorption isotherms better than the Langmuir model. The Pseudo-second-order model adequately described the adsorption process. Among the various anions tested, SO42- exhibited the highest inhibitory effect on adsorption. Adjusting NH2-MIL-101(Fe) loading improved selective and total adsorption of more toxic methyl 3,5-dichloro-4-hydroxybenzoate and ethyl 3,5-dichloro-4-hydroxybenzoate, while Fe3O4 loading had little effect on adsorption. Mutual influence between methylparaben and ethylparaben indicated competitive adsorption due to strong hydrophobicity and enhanced π-π interactions.