Xylene removal from dilute solution by palm kernel activated charcoal: Kinetics and equilibrium analysis

Xylene is an aromatic hydrocarbon that is a highly toxic compound. Therefore, it is essential to remove this component from wastewater before discharging it to the environment. In this research work, palm kernel biomass was activated chemically by H3PO4 and synthesized activated charcoal was applied to separate xylene from aqueous media. The prepared activated charcoal was characterized using FTIR, BET, SEM, pHzpc measurement, Boehm analysis methods. The characterization tests indicated that the produced activated carbon has acidic character with various functional groups and micropores structure. The values of external mass transfer coefficients ranged from 1.87×10-5 to 1.90×10-5. By increasing the temperature, the pore and surface diffusion coefficients were increased from 1.15×10-9 to 1.91×10-9 and 6.98×10-16 to 7.58×10-16, respectively. Sensitivity analysis indicated which the pore diffusion and film diffusion are the main mass transfer parameters. Equilibrium analysis also revealed that the multilayer model with saturation could well describe the data. The number of adsorbate ions for one site, the number of adsorption layers, density of receptor site, and the energy of adsorption at layers were determined using statistical physics modelling. The maximum capacity of prepared activated charcoal at the experimental condition for xylene adsorption was 23.48 mg g-1.