Efficient Adsorption and Removal of the Herbicide 2,4-Dichlorophenylacetic Acid from Aqueous Solutions Using MIL-88(Fe)-NH2

Ahmad A Alluhaybi; Ahmed Alharbi; Khaled F Alshammari; Mohamed G El-Desouky

doi:10.1021/acsomega.3c05818

Efficient Adsorption and Removal of the Herbicide 2,4-Dichlorophenylacetic Acid from Aqueous Solutions Using MIL-88(Fe)-NH₂

ACS Omega. 2023 Oct 20;8(43):40775-40784. doi: 10.1021/acsomega.3c05818. eCollection 2023 Oct 31.

Authors

Ahmad A Alluhaybi¹, Ahmed Alharbi², Khaled F Alshammari³, Mohamed G El-Desouky⁴

Affiliations

¹ Department of Chemistry, College of Science and Arts, King Abdulaziz University, 25732 Rabigh, Saudi Arabia.
² Department of Chemistry, Faculty of Sciences, Umm Al-Qura University, 21955 Makkah, Saudi Arabia.
³ Department of Criminal Justice and Forensics, King Fahad Security College, 11461 Riyadh, Saudi Arabia.
⁴ Egyptian Propylene and Polypropylene Company, Port Said 42511, Egypt.

Abstract

Metal-organic frameworks (MOFs), a material known for its multifunctionality, chemical stability, and high surface area, are now commonly utilized as an adsorbent for water treatment. The MOF (MIL-88(Fe)-NH₂) was synthesized and used to remove the commonly used toxic herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water. The MIL-88(Fe)-NH₂ MOF was fully characterized using multiple techniques. A systematic investigation was conducted to evaluate the key parameters that impact the adsorption process, which include coexisting anions, adsorbent dosage, and solution pH. The adsorption isotherm was fitted using the Langmuir model, while the kinetics were fitted using pseudo-second-order. The adsorption process was both chemisorption and endothermic. The capacity for adsorption increased with rising temperatures. The MIL-88(Fe)-NH₂ adsorbent has a maximum adsorption capacity of 345.25 mg g^-1 for removing 2,4-D, significantly higher than previous adsorbents used for this purpose. The adsorption mechanism could be ascribed to hydrogen bonding, pore filling, π-π conjugations between the 2,4-D molecules and the MIL-88(Fe)-NH₂ adsorbent, and electrostatic interactions. Furthermore, the adsorption capacity of MIL-88(Fe)-NH₂ adsorbent showed only a slight decrease after five successive recycles, and it could be easily regenerated through solvent washing. When used in environmental water samples, especially those containing electronic wastes, the MIL-88(Fe)-NH₂ adsorbent demonstrated satisfactory adsorption capacity and reusability. The MIL-88(Fe)-NH₂ adsorbent is more practical and reusable and has better adsorption capacity and shorter equilibrium time compared to previously reported adsorbents.