Adsorption capacity of activated carbon derived from date seeds: Characterization, optimization, kinetic and equilibrium studies

Agricultural wastes have the potential to be reused in applications such as water/wastewater treatment. Several studies have focused on activating organic waste, such as date seeds, to produce activated carbon. However, these studies have always assumed that all date seeds behave similarly to each other. In this study, we evaluated different types of date seeds and characterized their physical-chemical properties. The results showed variation in the seed-to-fruit weight percentage, ash content, and moisture content among different seed types. Different activation procedures were performed to find the optimum combination of physical and chemical interventions. KOH impregnation yielded better results than H₃PO₄ impregnation. The maximum adsorption capacity was measured for nine different types of date seeds, and the Khalas seed type yielded the highest methylene blue (MB) adsorption capacity of 165 mg of MB/g of activated date seeds (ADS), which is 71% of the capacity of commercial activated carbon (CAC). Kinetics model was fitted to the experimental data, and the pseudo-second-order model provided the best fit, indicating that the adsorption process occurred following a chemical process rather than being controlled by intraparticle diffusion only. The results showed no significant difference among the three isotherm models used to fit the experimental data. The results indicated that there is a significant difference among various types of seeds regarding adsorption performance. The application of ADS in treating synthetic produced water showed that its performance is one third that of CAC. ADS showed promising potential in comparison with CAC, mostly considering the costs involved with CAC.