Efficient removal of organophosphate esters by ligand functionalized MIL-101 (Fe): Modulated adsorption and DFT calculations

Sheng Fan; Xinru Lu; Haoliang Li; Xiaodong Du; Xiaoyu Huang; Yao Ma; Juan Wang; Xueqin Tao; Zhi Dang; Guining Lu

doi:10.1016/j.chemosphere.2022.134881

Efficient removal of organophosphate esters by ligand functionalized MIL-101 (Fe): Modulated adsorption and DFT calculations

Chemosphere. 2022 Sep:302:134881. doi: 10.1016/j.chemosphere.2022.134881. Epub 2022 May 10.

Authors

Sheng Fan¹, Xinru Lu², Haoliang Li¹, Xiaodong Du¹, Xiaoyu Huang², Yao Ma¹, Juan Wang¹, Xueqin Tao², Zhi Dang³, Guining Lu⁴

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
² College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
³ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou 510006, China.
⁴ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, China. Electronic address: lutao@scut.edu.cn.

PMID: 35561783
DOI: 10.1016/j.chemosphere.2022.134881

Abstract

Organophosphate esters (OPEs) are a new class of flame retardants present in diverse waters. The study focused on the removal of aqueous OPEs using functionalized MIL-101(Fe), which was a representative of the metal-organic frameworks (MOFs). Adsorption kinetics of tris(2-chloroethyl) phosphate (TCEP), tributyl phosphate (TnBP), and triphenyl phosphate (TPhP) were investigated. Additionally, TCEP was selected as the model contaminant to study the adsorption isotherms, thermodynamics, and effect of solution matrix properties. Adsorption mechanisms obtained from the experiments were confirmed using density functional theory (DFT) calculations. Adsorption kinetics indicated that functionalized MOFs provided a significant enhancement to the removal of TCEP. The maximum adsorption capacities q_m of MIL-101(Fe), MIL-101(Fe)-NH₂, MIL-101(Fe)-OH, and MIL-101(Fe)-CH₃ at 298 K for TCEP were 76.040, 282.940, 119.680, and 181.274 μmol/g, respectively. By comparing the adsorption behavior of functionalized MOFs, MIL-101(Fe)-NH₂ was proved to be most efficient for TCEP removal. Based on the adsorption experiments and DFT calculations, TCEP removal was dominated by physical adsorption. The van der Waals (vdW) interactions and hydrogen bonding were assumed to be involved in the adsorption. This work proves that appropriate ligand functionalization is promising for the removal of aqueous OPEs, which also provides a new insight for the control of OPEs pollution.

Keywords: Adsorption mechanism; Density functional theory; Ligand functionalization; Metal-organic frameworks; Organophosphate esters adsorption.

MeSH terms

Adsorption
Density Functional Theory
Esters
Ligands
Metal-Organic Frameworks*
Organophosphates
Water

Substances

Esters
Ligands
MIL-101
Metal-Organic Frameworks
Organophosphates
Water