Scrap tires have always been an environmental concern. In 2005, more than 299 million scrap tires were generated in the U.S., 259 million of which were utilized in the end-use scrap tire markets such as: tire-derived fuel generation, civil engineering applications, and ground rubber applications. The different applications and usages in the scrap tire market have helped utilize up to 87% of annually generated scrap tires in the U.S. Sixteen percent of the scrap tires were utilized in civil engineering applications in 2005 because of their beneficial properties for vibration and sound control, lightweight fill, drainage and collection for underground leachate.
The ability of scrap tire rubber to
absorb and retain contaminants in landfill collection systems has been studied in the last two decades.
This research study included an analysis of the sorption properties of crumb rubber derived from scrap tires.
The study consisted of batch test analysis for ethylbenzene (EB) solution mixed with crumb rubber sizes of 1.4 mm, 850 μm, 425 μm, and 180 μm. High pressure liquid chromatography (HPLC) was used to measure the initial and equilibrium concentrations of EB in the study. The analysis tested for significant differences between the partitioning coefficients of the different crumb rubber sizes. The results indicate that 850 μm crumb rubber had the highest partitioning coefficient. When equilibrium concentrations of EB were compared with the percent concentration of crumb rubber relative to EB on a mass basis, the particle size did not show significant differences. The results helped to develop an isotherm model that was validated with crumb rubber mixtures of ambient 8-14 mesh (2.4 -1.4 mm), ambient 20-30 (850-600μm), -30 mesh (600 μm), and cryogenic 30-40 mesh (600-425 μm). The results showed that the validation data showed good fit to the model, however, the predictability was better at higher crumb rubber to EB ratios.