Fabrication and Characterization of Bimetallic Modified Biochar

School of Life and Environmental Sciences, Shaoxing University, Shaoxing, 312000, China

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

This study presents the fabrication and characterization of Fe-Mn bimetallic oxide-modified corn stalk biochar (FM@BC) for the removal of Cd(II) from aqueous solutions. The biochar was synthesized via oxygen-limited pyrolysis at 600°C, followed by chemical impregnation with iron and manganese salts. SEM-EDS analysis confirmed successful modification, revealing corroded surfaces with aggregated particles and altered pore structures compared to pristine biochar. Adsorption experiments demonstrated that Cd²⁺ uptake increased progressively over time, reaching a maximum capacity of 112.5 mg/g. Kinetic modeling indicated that the pseudo-second-order model provided the best fit (R²> 0.99), suggesting chemisorption as the dominant mechanism. Isotherm studies showed that the Langmuir model fitted the data better than the Freundlich model (R² = 0.984), indicating monolayer adsorption on homogeneous surfaces. Speciation analysis revealed that free Cd²⁺ ions predominated at pH < 8, while Cd(OH)2 precipitation occurred at pH > 8. The bimetallic modification effectively enhanced Cd(II) removal efficiency by overcoming the limitations of unmodified biochar. This cost-effective and environmentally sustainable approach utilizing agricultural waste biomass demonstrates significant potential for remediating Cd-contaminated water and soil, contributing to sustainable environmental management practices.