This Chemistry Extended Essay discusses the effect of time and pH on the zinc leaching of vulcanized crumb rubber using stimulated rainwater made from HNO3 solutions of pH 5.0 to 3.5. Crumb rubber are granulate-sized particles produced from grinding scrap tires. Its production involves the vulcanization process, whereby zinc oxide is used as an activator and is not chemically reacted, hence small amounts of it are found in crumb rubber, which is repurposed as material for artificial turfs and athletic tracks. Groundwater run-offs exposed to artificial turf has been shown to leach zinc ions, contaminating waters with high zinc concentration which has detrimental effect on the growth of aquatic species.

Grade: A