September 11, 2025 | Progress in Engineering Science |
The potential of using rambutan (Nephelium lappaceum) seed waste as a sustainable raw material for producing activated carbon in wastewater treatment was explored in a study conducted by Universiti Malaya, Malaysia. The research aimed to provide an environmentally friendly alternative to conventional aluminium- and salt-based coagulants, which pose ecological and health risks.
Activated carbon was synthesized from rambutan seeds through phosphoric acid (H₃PO₄) activation, and its performance in turbidity removal was systematically evaluated. Characterization using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) confirmed the formation of a porous, amorphous carbon structure with active functional groups. The optimal production condition—2 mm particle size, 400 °C activation temperature, and 2 hours of activation—achieved a turbidity removal efficiency of 52.03%, reducing water turbidity from 886 NTU to 425 NTU.
SEM images revealed a well-developed porous structure, while FTIR analysis showed the presence of hydroxyl and alkyne groups and the disappearance of unstable carbonyl species, indicating enhanced adsorption properties. The findings demonstrate that rambutan seed-derived activated carbon is an effective, low-cost, and eco-friendly adsorbent, offering a promising solution for water purification and waste valorization within a circular economy framework.
