Utilization of peanut hull hydrochar /beta cyclodextrin/FeO magnetic composite for lead ion removal from water solution.

This study involves synthesizing peanut hull hydrochar (PHH) and a PHH/β-CD/FeO magnetic composite through hydrothermal and chemical precipitation methods, respectively, to use as effective adsorbents for Pb removal. Vibrating-sample magnetometry (VSM) and Brunauer-Emmett-Teller (BET) analyses revealed that the magnetic saturation value and specific active surface area of PHH/β-CD/FeO are 31.543 emu/g and 32.123 m/g, respectively. The impact of key variables on adsorption efficiency was evaluated using the response surface method - central composite design. ANOVA results (F-value: 166.22 and p-value: <0.05) demonstrated that the model effectively assesses the interaction of variables in the adsorption process. Additionally, R, Adjusted R, and Predicted R values were 0.999, 0.986, and 0.975, respectively, indicating the model's high adequacy in describing response changes. The maximum efficiency for Pb adsorption was found to be 95.35% using PHH and 99.73% with the PHH/β-CD/FeO magnetic composite. These measurements were taken at a temperature of 25 °C, an adsorbent dose of 1 g/L, a pH of 6, and a Pb concentration of 5 mg/L, with respective contact times of 130 min and 50 min. Thermodynamic analysis revealed negative enthalpy and Gibbs free energy values, indicating that the adsorption process is exothermic and spontaneous. The negative entropy parameter suggests a reduction in random interactions during the process. The Pb adsorption data for both PHH (R: 0.982) and PHH/β-CD/FeO (R: 0.985) were best described by the Pseudo 2nd order kinetic model. Equilibrium data followed the Freundlich model, with R values of 0.981 for PHH and 0.990 for PHH/β-CD/FeO, highlighting the importance of heterogeneous surfaces in the removal process. The maximum adsorption capacities for Pb were 26.72 mg/g for PHH and 33.88 mg/g for PHH/β-CD/FeO. Reuse and stability tests confirmed the structural stability and reusability of the adsorbents. Therefore, the PHH/β-CD/FeO magnetic composite is a promising option for removing Pb from aqueous solutions.