New insights on manganese dioxide nanoparticles loaded on cellulose-based biochar of cassava peel for the adsorption of three cationic dyes from wastewater

Herein, a cost-effective nanomaterial with excellent adsorption capacity, simply prepared, using manganese dioxide (MnO2) nanoparticles (NP) loaded on cellulose-based biochar of an agricultural waste, which is cassava peel carbon (CPC) and denoted as MnO2-NP-CPC. MnO2-NP-CPC is an environmental-friendly, and efficient adsorbent analyzed using different technics such as x-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and energy dispersive x-ray spectroscopy (EDX). MnO2-NP-CPC was used to remove three different toxic dyes; methylene blue (MB), malachite green (MG), and rhodamine b (RB) from a single (MB), (MG), (RB), binary (MB + MG), (MG + RB), (MB + RB) and ternary (MB + MG + RB) wastewater systems, the impact of pH, adsorbent dose (2–8), initial dye concentrations (10–30 mg/L), temperature (15–35 °C) were fully studied. Furthermore, all the sorption experiments were done including adsorption isotherms, kinetics, and thermodynamics to explore all the mechanisms involved in the sorption of the three ionic dyes in single, binary, and ternary systems. The equilibrium experiments data fitted well the monolayer Langmuir isotherm for the single dye system with correlation coefficients close to 1 (0.98 for MB, 0.99 for MG, and 0.86 for RB), while the extended Langmuir and extended Freundlich isotherms were investigated to study the interaction of the three dyes in their binary systems, the obtained results indicate clearly that the sorption fellows the extended Langmuir model. Besides, the kinetic study showed the applicability of the pseudo-second model for the three dyes. Finally, the thermodynamic adsorption was controlled by physisorption, endothermic, and spontaneous in nature.