Lead it Go: Purifying Lead Contaminated Water with Common Seashells
Olivia Li
Southridge School
Floor Location : M 109 V

In many parts of the world - especially poorer countries - lead contamination is a huge problem. In this experiment, seashells were studied to create an effective, efficient and eco-friendly filter that takes out lead. Because lead contamination is a common problem in poor countries, an ideal filter should be both inexpensive and made from abundant materials. Tests were done to determine if the settling time, alkalinity of the water and size of the seashells affected the extraction rate of lead. Seashells are porous, nanostructures that are composed of mostly calcium carbonate. The CaCO3 in the seashells eagerly swap its calcium atoms for lead atoms, locking them into a solid form. The longer the shells are soaked in the contaminated water the more lead is taken out. When the pH of the lead-contaminated water goes below neutral 7 the seashells start to leak lead, but this is easily fixed by adding more seashells. Seashells are naturally basic with a pH of 8.3. The higher the alkalinity of the water the more efficient the seashells are of taking out lead. Crushed seashells take out lead quicker and more efficiently than non crushed seashells because this creates a greater surface area for potential lead extraction sites.