Novel activated carbon derived from a sustainable and low-cost palm leaves biomass waste for tetracycline removal: Adsorbent preparation, adsorption mechanisms and real application

Palm leave biomass waste was converted into a new activated carbon through facile chemical activation and pyrolysis. The prepared activated carbon (KAC) was characterized by X-Ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), surface area analyzer (BET), and point of zero charge (pHPZC) measurement. KAC was used as an adsorbent to remove emerging contaminant tetracycline (TC) from water, and systematic TC adsorption studies (i.e. kinetics, isotherm, and thermodynamic) were performed. Moreover, density functional theory (DFT) was applied to simulate the TC adsorption process. The adsorption kinetics data corroborated the pseudo-second-order model perfectly. The maximum monolayer adsorption capacity was 132.94 mg g−1 at 25 °C. According to the thermodynamics study, the adsorption process of TC was favorable and endothermic, while the process increased the randomness of molecules at the interface between water and solid. TC adsorbed onto KAC via π-π interaction, H-bonding, electrostatic interaction, and pore-filling. TC adsorption mechanism elucidated by DFT calculations showed good agreement with the experimental findings. The reusability of KAC in real wastewater was also tested for three cycles. This study shows that converting of the abundant palm leaves biomass waste into a valuable adsorbent for TC removal is promising.