FeOCl-Modified Peanut Hull As Novel Bio-Sorbent for Fast Adsorption of Methylene Blue: Kinetics, Isotherms, and Mechanisms

This study focused on removing methylene blue with FeOCl modified peanut hull. FeOCl modification altered the surface structure of peanut hull such that PH FeOCl had a rough surface with irregular pore holes. The absorption equilibrium of PH FeOCl was achieved after only 6 min of oscillation, and the removal efficiency was 85.1% when the solution pH was 6.0, the concentration of MB was 100 mg·L –1 , the temperature was 25 °C, and the dosage was 1.0 g·L –1 . Besides, PH FeOCl could be used to achieve the maximal MB adsorption capacity of 132 mg·g –1 . The MB adsorption followed pseudo-first-order and pseudo-second-order models and conformed to the Redlich-Peterson and Langmuir models. Based on the results obtained from the thermodynamic analysis, it was concluded that the adsorption process was endothermic and spontaneous. The adsorption mechanisms involve the participation of hydrogen bonds, electrostatic, and Van der Waals force.