Biochar-deep eutectic solvent-metal oxide nanoparticles composites for removal of pollutants in water
Abstract
In this study, ternary recyclable adsorbents, composed of rice husk and sugarcane bagasse biochar (RBC and SBC) doped with deep eutectic solvent (DES) and Fe3O4-ZnO nanoparticles, were successfully synthesized and used for the removal of Cr(VI), Pb(II), and diclofenac sodium (DFC) from aqueous solutions. The characterization results using XRD, FTIR, SEM-EDS, TGA, TEM, and surface area analysis, confirmed that the modified nanosorbent surface offered more active adsorption sites, facilitating the adsorption of Cr(VI), Pb(II), and DFC. Introducing metal oxide nanocomposite (Fe3O4-ZnO) effectively led to superior kinetic removal efficiency. At equilibrium conditions, mesoporous rice husk-based adsorbent (FZRBC-DES15) showed maximum adsorption capacity (Qmax) of 66.23, 384.62 and 24.33, and similarly sugarcane bagasse-based adsorbent (FZSBC-D15) had capacity of 71.43, 434.78 and 26.60 mg/g for Cr(VI), Pb(II), and DCF, respectively. The adsorption kinetics fit the pseudo-second-order model for each sorbent, suggesting chemisorption is the dominant removal mechanism. The adsorption behavior coincided with homogeneous adsorption materials as reflected by well-fitting the Langmuir model for Cr(VI) and Pb(II) and the heterogenous mechanism for DCF as fit with the Freundlich model. The synthesized adsorbents are excellent adsorbents that remove selected heavy metal ions and diclofenac sodium from aqueous solutions. It is used in waste resource utilization as it is easily recycled.