Functionalization of Shorea faguetiana biochar using Fe2O3 nanoparticles and MXene for rapid removal of methyl blue and lead from both single and binary systems

Abstract

The synthesis of polymeric magnetic composites is a promising strategy for the rapid and efficient treatment of wastewater. Lead and methyl blue are extremely hazardous to living organisms. The sorption of Pb²⁺ and the dye methyl blue (MB) by biochar is an ecologically sustainable method to remediate this type of water pollution. We functionalized Shorea faguetiana biochar with Fe₂O₃ and MXene, resulting in Fe₂O₃/BC/MXene composites with an efficient, rapid, and selective adsorption performance. Based on X-ray photoelectron and Fourier transform infrared spectrometry, we found that the Fe₂O₃/BC/MXene composites had an increased number of surface functional groups (F⁻, CO, CN, NH, and OH⁻) compared with the original biochar. The batch sorption findings showed that the maximum sorption capacities for Pb²⁺ and MB at 293 K were 882.76 and 758.03 mg g⁻¹, respectively. The sorption phenomena obeyed a pseudo-second-order (R² = 1) model and the Langmuir isotherm. There was no competition between MB and Pb²⁺ in binary solutions, indicating that MB and Pb²⁺ did not influence each other as a result of their different adsorption mechanisms (electrostatic interaction for Pb²⁺ and hydrogen bonding for MB). This illustrates monolayer sorption on the Fe₂O₃/BC/MXene composite governed by chemical adsorption. Thermodynamic investigations indicated that the sorption process was spontaneous and exothermic at 293–313 K, suggesting that it is feasible for practical applications. Fe₂O₃/BC/MXene can selectively adsorb Pb²⁺ ions and MB from wastewater containing multiple interfering metal ions. The sorption capacities were still high after five reusability experiments. This work provides a novel Fe₂O₃/BC/MXene composite for the rapid and efficient removal of Pb²⁺ and MB.