Fabrication of Partially Graphitic Biochar for the Removal of Diclofenac and Ibuprofen from Aqueous Solution: Laboratory Conditions and Real Sample Applications

Abstract

In this study, partially graphitic biochar was synthesized using peanut shell biomass and potassium ferrate (K2FeO4) with a simple strategy and applied for the removal of two commonly used nonsteroid anti-inflammatory drugs (ibuprofen [IBU] and diclofenac [DCF]) from water. K2FeO4 0.1 M was found to be the suitable concentration for the conversion from pristine biochar to partially graphitic biochar. After modification, the scanning electron microscopy image revealed an extremely rough and heterogeneous surface of the modified biochar (PK01), while the HRTEM, X-ray diffraction, and Raman spectra analyses indicated the presence of graphitic component in PK01 structure. Characterization results indicated that the synthesized nanomaterial simultaneously possessed the properties of graphitic carbon and porous biochar with relatively large specific surface area (374.0 m2/g), as well as micro/mesopore structure. The effect of ambient conditions (contact time, temperature, and solution pH) on the adsorption processes of two contaminants was investigated. The experimental results suggested that the pseudo-second-order, Langmuir, and Freundlich models could well describe the attached behavior of IBU and DCF onto the adsorbent (PK01). In all experiments (single, binary, and real water sample systems), DCF exhibited higher adsorption capacity compared to that of IBU, due to the more H-bond acceptor of the DCF molecule compared with IBU. The H-bonding interactions could be the major driving force for the attachment of two adsorbates onto the adsorbent surface, followed by electrostatic attractions, and π-π EDA interactions. Based on the experimental results, PK01 can be suggested as a potential adsorbent for the removal of nonsteroidal anti-inflammatory drugs from water bodies.