Preparation of a rubber nanocomposite for oil/water separation using surface functionalized/silanized carbon black nanoparticles

Clean water is the basic need of living organisms on the earth. Oil spills to free waters is one of the most important threats to living beings. It has been believed that using sorbents is the most effective method for this purpose. In this research, usage of tire rubber with improved hydrophobic properties is considered. For this purpose, carbon black nanoparticles (CBNs) were surface modified with vinyltrimthoxysilane (VTMS) at concentrations of 1, 5 and 10 by sol-gel method. Before, the CBNs were hydroxylated to increase silane grafting content. The surface modified was evaluated using XPS, FTIR, TGA, BET and FESEM analysis. Results showed a great change in the CBNs nature from hydrophilic to hydrophobic after silane modification that could help in more oil absorption and water repletion at the same time. In fact, the water contact angle (WCA) of the CBNs changed from 40 to 135°. The pure and silane grafted CBNs were added to the tire tread compound to prepare elastomeric nanocomposites as oil sorbent. The results showed that the modified nanocomposite had a higher reinforcement index than the samples contained pure and hydroxylated CBNs. The effects of CBNs on WCA, OCA and oil absorption capacity of the samples were also determined. It was found that silane modification a considerable increase in the WCA from 61.2° to 125.03° and a decrease in the oil contact angle (OCA) from 70.01° to 17.74°. Also, the oil absorption capacity of rubber enhanced from 0.55 to 1.95 g/g.