Novel Fe <sub>3</sub> O <sub>4</sub> ‐Modified Biochar Derived from Citrus Bergamia Peel: A Green Synthesis Approach for Adsorptive Removal of Methylene Blue
Swagatika Tripathy, Sumanta Sahu, Raj Kishore Patel, Rahas Bihari Panda, Pravin Kumar Kar
Abstract
Abstract The present study reveals the enhanced bio‐sorption of methylene blue (MB) from an aqueous solution using iron oxide immobilized citrus bergamia biochar (Fe 3 O 4 CBC). The adsorption efficiency was increased dramatically from 64 % to 98 % after the magnetic iron oxide modification to citrus bergamia biochar (CBC) due to electrostatic interaction. Physico‐chemical alterations of CBC surface prior and post‐modification and after dye adsorption were evaluated using the following surface techniques such as FTIR, XRD, SEM, BET, Raman, TGA‐DTA, Zeta potential analysis. The retention of C−OH, C=O, C−O, C−H, and Fe 3 O 4 groups were confirmed from FTIR spectra. BET analysis revealed that Fe 3 O 4 CBC showed an elevated surface area of 136.72 m 2 g −1 with a reduced pore diameter of 3.73 nm than CBC. The Pseudo second order and Langmuir isotherm model was best fitted with R 2 =0.99 and adsorption capacity of 31 mg/g. The thermodynamic data (ΔS=0.1455 kJ mol −1 K −1 , ΔH=33.87 kJ mol −1 ) revealed the spontaneity, endothermic nature, and feasibility of adsorption process. Regeneration studies revealed that the material has excellent sorption‐based performance over five consecutive cycles. The current work demonstrates that Fe 3 O 4 CBC can serve as a highly efficient, cost‐effective, bio adsorbent for the removal of MB with easy magnetic separation from aqueous medium.