Optimization of Phenol Adsorption Using Activated Carbon Derived from Spent Tea Leaves in a Packed-bed Column

This study investigates the potential of spent tea leaf-derived activated carbon (STLAC) as an adsorbent for phenol removal from simulated wastewater using a packed-bed adsorber. STLAC was prepared via chemical activation through impregnation with potassium hydroxide, followed by carbonization under controlled conditions. The physicochemical characterization of the prepared activated carbon has been confirmed. Response surface methodology (RSM) with central composite design (CCD) was utilized to optimize four operating parameters: flow rate, initial phenol concentration, bed height, and pH. A quadratic mathematical model was developed to describe the relationship between these parameters and removal efficiency. Results demonstrate the high phenol removal capacity of STLAC, achieving a maximum efficiency of 91.92% under optimal operating conditions: flow rate (11.46 mL/min), initial phenol concentration (19 mg/L), bed height (17.8 cm), and pH (6.8). The first breakthrough and saturation points were observed at 31 and 70 min, respectively. Regeneration studies have confirmed the activity of STLAC for reuse in the adsorption after five cycles, with an efficiency exceeding 75%. STLAC exhibited high efficiency in phenol removal, offering advantages in terms of sustainability and cost-effectiveness. To our knowledge, this study is the first to systematically optimize phenol removal using STLAC in a continuous packed-bed column using RSM-CCD methodology and utilize the optimized parameters for determining breakthrough characteristics. This study underscores the potential of converting agricultural waste into value-added products for environmental remediation. These results demonstrate that STLAC is a promising, low-cost, and sustainable adsorbent for removing phenol from industrial wastewater.