Performance and Mechanism of Diclofenac Adsorption Onto 3d Poly(M-Phenylenediamine)-Grafted Melamine Foam Via Batch Experiment and Theoretical Studies

Abstract

Seeking high-efficient adsorbents for pharmaceuticals and personal care products (PPCPs) removal has been a worldwide continuing endeavor. A new 3D composite material was synthesized in this study by covalently anchoring Poly(m-Phenylenediamine) onto 3D polyvinyl alcohol modified foam framework (PmPD-MF-PVA). The PmPD-MF-PVA was characterized and applied for the removal of diclofenac (DCF), which is a kind of widely detected PPCPs presents in both wastewaters and surface waters. Results showed that the adsorption capacity of PmPD-MF-PVA toward DCF was 1.5 times higher than that of PmPD-MF due to the presence of polyvinyl alcohol. Batch adsorption experiments exhibited that the adsorption of DCF was better fitted with Langmuir isotherm and pseudo-second-order kinetic models. The maximum adsorption capacity of PmPD-MF-PVA was 115 mg/g. Meanwhile, PmPD-MF-PVA exhibited much better separation ability than the hard-to-separate PmPD. The characterization analysis as well as density functional theory (DFT) calculation revealed the main DCF adsorption mechanisms on PmPD-MF-PVA, which were electrostatic attraction, hydrogen bonding, π−π interaction and hydrophobic interaction. This study provides an attractive strategy to overcome the drawbacks of PmPD, namely recycling difficulty and agglomeration problems, offering useful information for the design of polymers-based adsorbents.

Keywords: Poly(m-Phenylenediamine), adsorption, Intermolecular interaction, Pharmaceuticals and personal care products (PPCPs), 3D foam framework