Technology And Evaluation Of The Microbial Desulfurization Of Ground Tire Rubber

With the rapid development of traffic transport industry, Ten million ground tire rubbers were discarded every year. If these scrap rubber can not be used properly, they would become a big trouble. On one side, the stacked rubber called ’black pollution’ provide places for mosquitoes and insects growing, on the other side, some active ingredients in the rubber are wasted. Our group has been committed to the role of microbial desulfurization rubber for many years. So this paper can be divided into four parts based on the previous study.Firstly, Intermittent stirring process was used to co-culture the Sphingomonas sp.(PL1)and ground tire rubber(GTR). The effects of desulfurization were evaluated systematically. The results showed that the new process(intermittent stirring for 12 hours) could make more PL1 attach to the rubber compared with the traditional treatment method; The contact angle of desulfurization rubber powders’surface were decreased,what’s more, the surface’s oxygen-containing groups increased, which indicated that intermittent stirring process increase the contact time of microbes and waste vulcanized rubber without affecting the normal growth of PL1. Desulfurization powder which treated by intermittent stirring process were filled with SBR,What improved the rubber’s mechanical properties significantly. The SEM photographs of rubber fracture surface showed that desulfurization powder-based glue combined closely. All the above showed that Intermittent mixing technology has advantage in saving energy and increasing desulfurization effect.Secondly, Continuous and intermittent stirring process were respectively used to the co-cultured desulfurization systems of Sphingomonas (PL1) /SBR and PL1/NR, and the effects of desulfurization were evaluated systematically. The results showed that both the continuous and intermittent stirring process can achieve high biomass of PL1, but the intermittent mixing technology can make more PL1 attached to the SBR or NR sheets, which improved the contact area with the surface of the bacteria and vulcanized rubber. After the desulfurization, The surface S content (0.71%) of SBR rubber which treated by Intermittent stirring process fell 45.8% compared with the original crumb rubber (1.31%), The surface S content (0.64%) of SBR rubber which treated by Intermittent stirring process fell 32.6% compared with the original crumb rubber (0.95%). However, The surface S content of both SBR and NR sheets which treated by continuous stirring process were respectively reduced to 32.8% and 11.6%. After the desulfurization, the surface’s oxygen-containing groups of the SBR increased. Whereas the C=C bonds of the NR were destroyed. The swelling degree of rubber sheets which treated by the batch stirring desulfurization process were higher than the continuous mixing stirring method.Thirdly, extracellular enzyme solution of PL1 has been extracted with different rubber as inducing agent. We found that Sphingomonas PL1 can metabolize DBT, what’s more, the PL1 co-cultured with SBR can produce more extracellular enzyme solution which can metabolize DBT.Finally, two strains were separated during the experiment and identified to be human ochrobactrum and Pantoea sp. The two strains were co-cultured with natural rubber, found that human ochrobactrum and Pantoea can desulfurize the nature rubber in some extent. the contact angle of rubber with water were reduced and its film surface polarity increases. the crosslink density of the film decreased after desulfurization.