Study on the Adsorption Performance of Magnetic Eggshell on Methyl Orange in Water

Methyl orange (MO) is a low toxicity soluble dye that poses serious harm to the environment and human health. In order to avoid environmental pollution caused by discarded eggshells and fully utilize their adsorption properties, magnetic biochar was prepared using discarded eggshells as raw materials. Its adsorption performance on MO was studied using static adsorption method, and its adsorption mechanism was studied through kinetic and thermodynamic model fitting. The single factor experimental results showed that the removal effect of magnetic eggshell on MO increased with the increase of dosage, first increased and then decreased with the increase of pH, and decreased with the increase of initial concentration of MO. However, the effect of oscillation time, oscillation rate and temperature were not significant. The orthogonal experimental results showed that the optimal adsorption conditions were at an oscillation temperature of 298 K, an oscillation time of 1.5 h, an oscillation rate of 200 r/min, a magnetic eggshell dosage of 4.5 g, and a pH of 8. At this time, the removal rate of the magnetic eggshell on the 8 mg/L MO solution could reach a maximum of 99.76%. The order of importance of the experimental influencing factors was the amount of magnetic eggshell added, the initial concentration of MO, and pH. The adsorption was more in line with the Pseudo-second-order kinetic model and Langmuir adsorption isotherm model, with chemical adsorption as the main method and single-molecule layer adsorption. This study demonstrated that eggshell is a potential adsorption material.