Competitive adsorption of heavy metals in a quaternary solution by sugarcane bagasse – LDPE hybrid biochar: equilibrium isotherm and kinetics modelling

Abstract Sugarcane is a notable crop grown in the tropical region of the world. It is an abundant waste material of the sugar industry which is a low cost and low combustion fuel thus the bagasse can be exploited to manufacture adsorbents for water treatment. Because the presence of contaminants in polluted water is not uniform, pollutant species compete for active sites during the adsorption process. Investigation of the competitive adsorption of Zn(II), Cu(II), Pb(II), and Fe(II) in a quaternary solution using hybrid biochar developed from sugarcane bagasse (SCB) mixed Low-Density Polyethylene (LDPE) and pure SCB biochar is the main aim of this study. The biochar was developed using the retort carbonisation process and characterised via SEM (Scanning Electron Microscopy), BET (Branueur Emmett Teller) analysis, and FTIR (Fourier Transform Infrared Spectroscopy). Both biochar species mixture possessed some orbicular properties with mesoporous heterogeneous superficial morphology. The biomass biochar and hybrid biochar specific surface area are 533.6 m2/g and 510.5 m2/g respectively. For the two used adsorbents, >99% removal efficiency was recorded over the sphere for dosage investigation. Thus, this implies they are capable of removing heavy metals from the aqueous solution simulated. The Langmuir isotherm fitted best in each domain however there was an exception for Pb(II) ions in biomass biochar with the experimental adsorption capacity of ∼ 22 mg/g for the HMs. Based on the correlation coefficient (R 2); the experimental data fitted the pseudo-first-order kinetic model well having a correlation coefficient value of greater than 0.9. The mechanism of adsorption for the HMs was chemisorption. This study has a three-pronged benefit of water treatment, resource conservation, and solid waste utilisation.