Blended Nephelium lappaceum and Durio zibethinus wastes for activated carbon production via microwave-ZnCl₂ activation: optimization for methylene blue dye removal

Abstract

Herein, this work targets to employ the blended fruit wastes including rambutan (Nephelium lappaceum) peel and durian (Durio zibethinus) seed as a promising precursor to produce activated carbon (RPDSAC). The generation of RPDSAC was accomplished through a rapid and practical procedure (microwave-ZnCl₂ activation). To evaluate the adsorptive capabilities of RPDSAC, its efficacy in eliminating methylene blue (MB), a simulated cationic dye, was measured. The Box–Behnken design (BBD) was utilized to optimize the crucial adsorption parameters, namely A: RPDSAC dose (0.02–01 g/100 mL), B: pH (4–10), and C: time (2–6 min). The BBD design determined that the highest level of MB removal (79.4%) was achieved with the condition dosage of RPDSAC at 0.1 g/100 mL, contact time (6 min), and pH (10). The adsorption isotherm data is consistent with the Freundlich concept, and the pseudo-second-order versions adequately describe the kinetic data. The monolayer adsorption capacity (q_max) of RPDSAC reached 120.4 mg/g at 25 °C. Various adsorption mechanisms are involved in the adsorption of MB dye onto the surface of RPDSAC, including π–π stacking, H-bonding, pore filling, and electrostatic forces. This study exhibits the potential of the RPDSAC as an adsorbent for removal of toxic cationic dye (MB) from contaminated wastewater.

Keywords:

• Activated carbon
• adsorption
• durian seed
• methylene blue dye
• rambutan peel
• ZnCl₂ activation

Acknowledgments

The authors are thankful to the Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM) Shah Alam, Malaysia for the research facilities. The author Ahmad Hapiz is thankful to the Government of West Nusa Tenggara (NTB) Province, Indonesia, as well as the Education Development Institute (LPP) NTB and the Regional Research and Innovation Agency (BRIDA) NTB for providing a fully funded scholarship. The author (Zeid A. ALOthman) is grateful to the Researchers Supporting Project No. RSP2024R1, King Saud University, Riyadh, Saudi Arabia.