Biochar Composite Adsorbent for the Removal of Copper (II) and Lead (II) from Wastewater Prepared by the Pyrolysis of Oil-Based Drilling Cuttings and Orange Peels

Abstract

Oil-based drilling cutting pyrolysis doped orange biochar composite (ODPR-OP) was prepared by the pyrolysis of oil-based drilling cuttings and orange peels (OP) for the adsorption of Cu (II) and Pb (II). The physical and chemical properties of the surface were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and the zeta potential. In addition, the adsorption capacity of the ODPR-OP biochar for Cu (II) and Pb (II) removal from aqueous solutions was investigated. The results show that the ODPR-OP biochar has a lower contact angle, smaller pore size, and higher micropore volume than either oil-based drilling cutting pyrolysis residues (ODPR) or orange-peel biochar, indicating a synergistic effect of co-pyrolysis for enhanced adsorption. Kinetic studies showed that the adsorption of Cu (II) and Pb (II) on ODPR-OP was explained better with the pseudo-second-order kinetic model. The adsorption equilibrium of Cu (II) and Pb (II) was compatible with the Langmuir isotherm, and the maximum monolayer adsorption capacities of the ODPR-OP biochar for Cu (II) and Pb (II) were 95.11 mg/g and 164.08 mg/g, respectively, which are higher than for ODPR or OP. In conclusion, the ODPR-OP composite has great potential for practical Pb (II) and Cu (II) removal from wastewater.