Scrap tires are being recycled into many products in order to bypass slow degradation in landfills. Recycled rubber tire mulch contains zinc oxide used in tire formation that can be released through the creation of leachates. This study examines the relationship between temperature environment and leachate zinc concentration. After observing rubber mulch surface temperatures in conjunction with other factors, it was hypothesized that higher temperatures would lead to increased zinc release by rubber mulch and higher leachate zinc concentrations. Leachates were created by mixing 10 grams of mulch and 200 mL distilled water and placing in 5ºC, 29ºC, and 71ºC environments for 24 hours. Zinc content in ppm was then tested and statistically analyzed with ANOVA at alpha=0.05. A significant decrease in mean leachate zinc concentration as temperature increased was shown between the 29ºC (M = 5.733, SD = 1.486) and 71ºC (M = 4.133, SD = 0.516) treatments and the 5ºC (M = 6.533, SD = 0.743) and 71ºC treatments (F(2, 42) = 22.19, p< 0.01). Therefore, within these intervals, decreasing temperatures increased rubber mulch breakdown and leachate zinc concentration. Because tires are created at high temperatures during the vulcanization process, it is reasonable to consider that tires are strongest at higher temperatures. Studying the effect of rubber mulch leachates on soil and various organisms would provide a direct study to more accurately deduce potential environmental impacts.
"The Effect of Temperature on Zinc Leaching from Rubber Tire Mulch,"
Journal of the South Carolina Academy of Science: Vol. 15:
2, Article 15.
Available at: https://scholarcommons.sc.edu/jscas/vol15/iss2/15