Methylene Blue Removal by Sodium Hydroxide Coconut Shell-Based Activated Carbons

The coconut shell-based activated carbons were prepared by NaOH activation for methylene blue (MB) adsorption. The pyrolysis was carried out at 550 °C for 1.5 h. The AC1 (direct activation) exhibits a maximum MB capacity of 100 mg/g, while AC2 (two-stage activation) showed a lower capacity at 59.9 mg/g. The AC1 exhibits a 301 m2/g surface area that explains its superior performance than AC2 (SBET = 126 m2/g). The fitting of adsorption models implies the interplay of physisorption and chemisorption in the removal of MB. The NaOH-activated coconut shell carbon is a promising adsorbent for wastewater treatment applications.