Lead toxicity continues to pose a serious environmental and public health challenge worldwide due to the persistent, non- biodegradable nature of lead and its ability to bioaccumulate in living organisms. Exposure to lead, even at low concentrations, can result in severe neurological, renal, and developmental disorders, making its removal from contam-inated water sources a critical priority. Conventional methods for lead removal, such as chemical precipitation, ion exchange, and membrane filtration, are often costly, energy-intensive, and generate secondary pollutants. Therefore, the development of low-cost, sustainable, and environmentally benign alternatives is highly desirable. In this context, the present study explores the utilization of snail shell waste as an eco-friendly and economically viable biosorbent for the removal of lead (Pb²⁺) ions from aqueous systems. Snail shells, which are abundantly generated as waste from food and seafood processing industries, represent an underutilized biological resource rich in calcium carbonate and functional groups capable of binding heavy metals. In this study, collected snail shells were thoroughly washed, dried, and me-chanically pulverized to produce a fine biosorbent material suitable for adsorption studies. Batch adsorption experiments were systematically conducted to assess the lead removal efficiency of the prepared snail shell biosorbent under varying operational parameters, including solution pH, contact time, adsorbent dosage, and initial lead concentration. The results revealed a substantial reduction in lead concentration, with maximum adsorption achieved under optimized ex-perimental conditions. The adsorption process was found to be strongly influenced by pH, indicating the importance of surface charge and metal speciation in determining biosorption efficiency. The underlying mechanism of lead removal by snail shell waste is attributed to a combination of ion exchange, surface complexation, and electrostatic interactions between Pb²⁺ ions and the functional groups present on the biosorbent surface. The high affinity of calcium carbonate matrices toward heavy metal ions further enhances the biosorption capacity of the snail shell material. These interactions facilitate effective immobilization of lead ions, thereby reducing their bioavailability and toxicity. Overall, the findings of this study demonstrate that snail shell waste is an efficient and sustainable biosorbent for controlling lead toxicity in contaminated water systems. The utilization of this biological waste not only offers a cost-effective solution for heavy metal remediation but also contributes to waste valorisation and environmental sustainability. This approach aligns with the principles of circular economy and sustainable development, highlighting the potential application of snail shell-based biosorbents in large-scale wastewater treatment and environmental remediation strategies.

Lead Toxicity, Snail Shell Waste, Biosorption, Heavy Metal Removal, Wastewater Treatment, Environmental Remedia-tion