Sorption study of toluene and xylene in aqueous solutions by recycled tires crumb rubber.

Sorption of toluene and xylene by tire crumb rubber (TCR) and its main components: carbon black (CB) and styrene-butadiene polymer (SBP) were evaluated. The 12 starting concentrations of adsorbates in aqueous solutions ranged from 0.05 mg/L to 100.0mg/L. The amounts of CB and SBP used in the sorption tests were determined considering their typical contents in tire crumb rubber (30% and 60% w/w, respectively). Freundlich's isotherms and Scatchard plot parameters suggested a two-step sorption process when TCR was used as the sorbent; whereas a single-step route was apparent when the sorption experiments were carried out with CB or SBP. Freundlich's n parameter was estimated at 0.65 for CB and 1.0 for both TCR and SBP. A removal of 60% of toluene and 81% of xylene from starting 50 ppm solutions was attained in the first 30 minutes of contact using 5 g/L of TCR.