Ultra-High-Molecular-Weight polyethylene-based nanocomposite for removal of tetracycline in aqueous systems

The application of an ultra-high-molecular-weight polyethylene-based (UHMWPE) nanocomposite with nanohydroxyapatite (HA) and organophilic bentonite (OB) for adsorption of tetracycline (TC) was evaluated. The nanocomposite was prepared by combining the high energy grinding and the muffle heat treatment. Their formulation was investigated through complete experimental design (23), varying amount of OB, temperature and sintering time. The morphology and structure of the UHMWPE/HA/OB (ultra-high-molecular-weight polyethylene-based, nanohydroxyapatite and organophilic bentonite) were characterized using Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM) and Electron Microscopy Transmission (TEM). The adsorption of TC in the composite was investigated through batch and fixed-bed experiments. For the batch experiments, the UHMWPE/HA/OB nanocomposite adsorbed 8.72 mg∙g−1 TC at 328.15 K, at neutral pH and at 24 h of reaction. The experimental adsorption data for kinetics were best described by the pseudo second order model (R2 = 0.989) and the isotherms followed the Freundlich model (R2 = 0.996). The thermodynamic investigation indicated that the adsorption was an endothermic reaction and that there is an affinity between the adsorbent and the adsorbate. According to the results of the fixed-bed column experiment, the breakthrough curve was plotted and the characteristic column parameters were evaluated, and the experimental data were better described by the Yan model (R2 = 0.980). Based on the results of the work the UHMWPE/HA/OB nanocomposite is very promising for the removal of contaminants in aqueous medium.