Preparation and characterization of activated carbon from palm bio-waste by H3PO4 for the simultaneous removal of Basic dyes in binary aqueous systems: optimization by central composite design, equilibrium, kinetic and thermodynamic studies

In recent decades, extensive attempts have been made to use biomass-based materials for wastewater treatment1-2. The first aim of this study was to prepare activated carbon (AC), a practical biosorbent from palm bio-waste. It was characterized via Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM), Field Emission-Scanning Electron microscopy(FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area and zeta potential measurement. As the second purpose, use of the prepared activated carbon was assessed and optimized for the simultaneous removal of Basic Blue 41(BB41) and Basic Red 46(BR46) dyes in binary aqueous systems, by Central Composite Design (CCD) under Response Surface Methodology(RSM). The optimum values for removing BB41 and BR46 systems were found to be 8.27 mg of adsorbent dosage, 48 min of contact time, 15 mg L-1 for the concentration of BB41, and 5 mg L-1 for the concentration of BR46 and the removal percentage equal to 99.81% and 95.76% for BB41 and BR46, respectively. In individual solutions, the adsorption process fitted well with Langmuir isotherm and pseudo-second-order kinetic models with the maximum adsorption capacities (qm) of 344.83 and 263.16 mg g-1 for BB41 and BR46, respectively. Extended Langmuir isotherm was used in binary systems to calculate qm for BB41 and BR46 as 271.81 and 127.23 mg g-1, respectively. Finally, it could be concluded that the mechanism of the adsorption procedure is monolayer, physical, spontaneous, endothermic, and more desirable at higher temperatures