Comparative evaluation of banana and pineapple peel-derived activated carbons for formaldehyde removal from aqueous solution

This study investigated the preparation of activated carbons from banana peels (BP) and pineapple peels (PP) using potassium hydroxide (KOH) activation for aqueous formaldehyde (HCHO) removal. The prepared activated carbons, denoted as BP-AC and PP-AC, were characterized using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), CHN elemental analysis, and Brunauer–Emmett–Teller (BET) surface area analysis. BP-AC exhibited a significantly higher BET surface area (561.2 m 2 /g) and total pore volume (0.286 cm 3 /g) than PP-AC (148.1 m 2 /g and 0.062 cm 3 /g, respectively). Adsorption experiments conducted at HCHO concentrations of 1–10 ppm and contact times of 5–60 min showed that both adsorbents achieved maximum removal performance at 7 ppm. PP-AC exhibited slightly higher rapid adsorption at 5 min, whereas BP-AC demonstrated superior adsorption performance at longer contact times due to its more developed porous structure. These findings demonstrate the potential of agricultural waste-derived activated carbons as sustainable and low-cost adsorbents for low-concentration HCHO removal in aqueous systems.