The Utilization of Silica–Lignin Composite as a Green Adsorbent for Cobalt and Lead Metal Ions in Aqueous Phase

ABSTRACT Heavy metals in environmental waste can pollute the environment and disrupt human health if not managed properly. Heavy metal contamination from industrial waste, particularly cobalt (Co) and lead (Pb), poses serious environmental and health risks due to their toxicity, persistence, and bioaccumulative nature. Conventional remediation methods like chemical precipitation and membrane filtration often face limitations in cost and sustainability, making adsorption a preferred alternative. This research aimed to develop a silica–lignin composite as an adsorbent for removing cobalt (Co 2+ ) and lead (Pb 2+ ) from the aqueous phase. The composite was synthesized by modifying silica with tetraethoxysilane (TEOS) and activating lignin to enhance its surface properties. Characterizations using BET, FTIR, and SEM were conducted to evaluate the composite's surface area, functional groups, and morphology. Adsorption experiments were performed by varying metal ion concentrations, contact time, and solution pH. The adsorption performance was evaluated using atomic absorption spectroscopy (AAS) to determine the adsorption capacities for Co 2+ and Pb 2+ , which showed maximum adsorption capacities of 62.89 mg/g for Pb 2+ and 22 mg/g for Co 2+ . These results highlight the potential and effectiveness of the silica–lignin composite as a green and sustainable adsorbent for heavy metal removal from aqueous waste.