Biochar Produced from Co-Pyrolysis of Olive Pomace Crude Oil as an Adsorbent for Cr (VI) Removal from Aqueous Solutions

This study investigated aqueous solution treatment to remove Cr (VI) using a biochar-based adsorbent. Olive pomace and crude oil were used to synthesize the biochar adsorbent via co-pyrolysis for the first time. The biochar properties were examined with Fourier Transform Infra-Red (FT-IR) spectroscopy, scanning electron microscopy (SEM), and Energy Dispersive X-ray (EDX) analyses before and after adsorption. The adsorption experiments were carried out in a batch process under different experimental conditions. The optimum adsorption efficiency was experimentally found to be at pH of 1.5, contact time of 15 min, Cr (VI) initial concentration of 20 mg/L, adsorbent dose of 0.4 g, and 303 K. Langmuir and Freundlich isotherms were used to evaluating the adsorption performance of biochar, and the Langmuir isotherm model was well fitted to experimental data with a maximum adsorption capacity of 9 mg/g. Kinetic experimental data was best described using a pseudo-second-order kinetic model. The thermodynamic parameters of the adsorption process were examined in detail, and the process was exothermic and spontaneous in nature. It is concluded that biochar can be successfully used as an adsorbent for the treatment of Cr (VI) contaminated water. Additionally, the evaluation of olive pomace provided not only a decrease in waste accumulation in the olive production industry but also the synthesis of an inexpensive and environmentally friendly adsorbent.