Technology And Application Of Recycling Waste Rubber By Microorganisms

Nowadays, the number of waste rubbers is increasing every year in China. But only few of them have been recycled in an appropriate way. Large number of waste rubbers, which cannot be degraded by nature, causes a big environmental problem. The microbial desulfurization technology is of simple facilities, mild reaction, low energy-consuming and eco-friendly; therefore, this technology attracts many researchers’ attention.Firstly, this paper reports the influence of different Tween surfactants on biodesulfurization of ground tire rubber (GTR) by Sphingomonas sp..Tween surfactants can effectively improve biodesulfurization effect by increasing the affinity between rubbers and microbes. Among the three surfactants (Tween20, Tween60and Tween80), Tween20shows the best effect on improving biodesulfurization of GTR. S-S and S-C bonds on GTR surface decreased27.5%and63.1%, respectively. The amount of surficial sulfur on desulfurized GTR that had been mixed with Tween20(DGTR20) decreased by67.0%. Also, mechanical properties of DGTR2o/styrene butadiene rubber composite were improved.Secondly, this paper reports biodegradation and biodesulfurization effects among isoprene rubber (IR), styrene butadiene rubber (SBR) and GTR by Gordonia sp.. Culture conditions were optimized. After20days co-culture, Gordonia sp. can degrade IR through cutting C=C bonds on IR surface. The density of IR was decreased by13.7%. Also, Gordonia sp. can selectively de-crosslink SBR through cutting S-S and S-C bonds on SBR surface. The density of SBR was decreased by22.1%. Gordonia sp. also can degrade C=C bonds on GTR surface after10days co-culture. The swelling value of GTR was increased by6.4%. Also, the treated GTR showed good cohesion on GTR/SBR composite. Thirdly, this paper firstly reports a testing method on desulfurized enzymes during biodesulfurization. To study the mechanism of producing desulfurized enzymes, dibenzothiophene (DBT) was used to react with these enzymes. Change of DBT concentration after reaction was measured by high performance liquid chromatography (HPLC). The results of HPLC show that the desulfurized enzymes produce in Gordonia cells. When SBR in culture medium, desulfurized enzymes can be induced and moved intracellular to extracellular.