Characteristics of activated carbon derived from Camellia oleifera cake for nickel ions adsorption

This study used Camellia oleifera cake to prepare activated carbon (AC) for nickel removal from aqueous solutions. After carbonization at 700 °C for 2h, activation was subsequently carried out with four different activators (Na₂CO₃, KOH, NaOH, H₃PO₄). The results showed that the four ACs had well-developed microporous structures. The AC with NaOH activation had the highest specific surface area of 512.18 m² g⁻¹, and the largest pore volume of 0.356 cm³ g⁻¹. The adsorption of Ni(II) on the ACs showed that the removal ratio of Ni²⁺ reached 95.7% at 25 °C on AC with Na₂CO₃ activation when the input amount was 5 g L⁻¹, while AC with NaOH as activator had the highest Ni²⁺ removal ratio of 86.75% when the input amount was 1g L⁻¹ at 25 °C. In addition, the adsorption capacity of AC was increased when the temperature rose between 25 and 60 °C. Compared to pseudo-first-order (PFO) model, the adsorption of Ni²⁺ on ACs is better suited by pseudo-second-order (PSO) model, and the ion precipitation in chemical adsorption is proved as adsorption mechanism.