Maple wood biochar-supported nickel nanoparticles: One pot synthesis for simultaneous removal of cationic and anionic dye mixture

This work reports on a facile and efficient technique to synthesize nickel particles supported on maple wood biochar to form magnetic nanocomposite able to remove dyes like methyl orange (MO) and rhodamine B (RhB) from water. Methodology involves wet impregnation with aqueous nickel nitrate solution followed by a pyrolysis at 500 ºC. This resulted in homogeneously and uniformly distributed irregular shaped Ni particles in the size range of 16 – 68 nm on the biochar surface. X-ray diffraction characterization confirms the presence of Ni particles and X-ray photoelectron spectroscopy reveals their slight surface oxidation. Their ability to answer to a magnetic field has been confirmed by recording the variation of their magnetization as a function of the magnetic field at room temperature using a Vibrating Sample Magnetometer. The G Raman band of the biochar appeared to be less intense in the nanocomposite, compared to pristine biochar prepared as a reference, meaning Ni nanoparticles hinder carbonaceous graphitization during pyrolysis. This can be attributed to the porosity creation, as suggested by SEM observations. Ultimately, magnetic nanocomposites were successfully applied for the removal of RhB and MO from aqueous solutions. The adsorption capacity for the RhB is found to be 54.21 mg/g. Thanks to the magnetic properties of the engineered nanocomposites; they can be separated by a magnet and reused. Reusability test of adsorbent have shown 99.41 %, 74.58 %, and 49.78 %, adsorption efficiency after first, second and third cycles, respectively. This work opens up a future perspective to create filters for treating waste water coming from textile industries. This work well aligns with UN Sustainable Development Goals 6 (clean water and sanitation), 11 (sustainable cities and communities) and 13 (climate action).