Adsorption of Cu2+, Cd2+, and Zn2+ by engineered biochar: Preparation, characterization, and adsorption properties

Abstract Lemonwood‐derived biochar was created by biomass pyrolysis (600°C) and modified with zeolite, sodium alginate, and magnetic nanoparticles to design an efficient adsorbent. The characterizations of the nanocomposite were studied employing X‐ray diffraction, field emission scanning electron microscope, EDAX, Brunauer–Emmett–Teller, and Fourier transform infrared spectrophotometer. The sorption of Zn(II), Cu(II), and Cd(II) ions from an aqueous single metal solution was evaluated for the influence of contact time, adsorbent dose, solution pH, initial concentration, and individual adsorption. Four isotherm models (Langmuir, Freundlich, Temkin, and Dubinin‐Radushkevich) were employed to analyze the equilibrium data by nonlinear regression. The capacity for adsorption of Zn(II), Cu(II), and Cd(II) at pH = 4, contact time 90 min, and 293°K from wastewater is as high as 98.22, 109.37, and 80.15 mg/g, respectively. The kinetics analysis demonstrated that the adsorption mechanism agreed with the pseudo‐second‐order rate law. In addition, the adsorption of metal ions onto engineered adsorbent exhibited that the process is exothermic, and with increasing the temperature, the adsorption capacity decreased, showing the spontaneous nature. The adsorbent was regenerated and reused three consecutive in adsorption–desorption without considerable loss of its adsorption capacity. The results indicated that it could be employed as an effective adsorbent for eliminating metal ions from an aqueous media.