Easy Recovered Magnetic Bark Biochar for Methylene Blue Removal: Preparation Characterization and Adsorption Parameters Study

Abstract

In this study, two types of magnetic biochars (Magnetic Bark Biochar with protocol 1 (MBB1) and Magnetic Bark Biochar with protocol 2 (MBB2)) were synthesized using pristine poplar bark biochar (PBB) via co‐precipitation. The two prepared magnetic biochars were tested to investigate the aqueous methylene blue (MB) removal performances. MB dye was used as a common pollutant for biochar quality evaluation and the obtained performance in this work was compared with literature. Different analysis techniques such as Scanning Electron Microscope (SEM), Energy Dispersive X‐ray Spectroscopy (EDS), Brunauer‐Emmett‐Teller (BET), porosimetry, Raman spectrometry and Fourier Transform Infrared spectroscopy (FTIR) were used to characterize the obtained materials. Biochars have a microporous structure with an average pore diameter of less than 0.26 nm. Magnetization of bark biochar leads to a loss in specific surface area (from 263.45 m2/g for PBB to 39.22 and 73.02 m2/g for MBB1 and MBB2, respectively) and an increase in total porosity by 85.11 and 12.72 %, respectively. MB adsorption process on MBB1 and MBB2 was best described by the pseudo‐first‐order kinetic model (R2=0.98) and by pseudo‐second‐order kinetic model for PBB (R2=0.9). The Langmuir monolayer adsorption and Marczewski‐jaroniec (M‐J) models presented the best fit for both PBB and MBB2 showing favourable adsorption process. Based on maximum adsorption capacity (qm: 32.98 mg/g) and the highest R2 value (0.96), MBB1 adsorption isotherm was well described by Langmuir model. Isotherm study revealed that MBB2 has the highest adsorption capacity of 49.02 mg/g followed by PBB with 37.85 mg/g. MB‐biochar interactions are dominated by chemisorption regarding the PBB and by physisorption concerning the magnetic biochars.