Microbial desulfurization for ground tire rubber by mixed consortium-Sphingomonas sp. and Gordonia sp.

Sphingomonas sp., Gordonia sp. and their mixed consortium were used to desulfurize ground tire rubber (GTR), respectively. The microorganisms' growth characteristic was studied and desulfurization effect on GTR was evaluated systematically by measuring the water contact angle, swelling values, crosslink density and element content of rubber samples. Besides, the mechanical properties of SBR (styrene butadiene rubber) composite filled with GTR and DGTR (desulfurized ground tire rubber) were studied and the morphology of tensile fracture surface was observed. The results showed that the biomass of the mixed bacteria was higher than any single bacteria during co-culture desulfurization process, which indicated that these two kinds of bacteria can promote each other and grow together. After desulfurized by the mixed bacteria, the crosslink density of DGTR decreased by 9.5% and sulfur content on surface decreased by 32.4%, which changed more obvious than DGTR treated by single strain. Besides, the mechanical properties of SBR/DGTR composites were higher than those of SBR/GTR composites, and among all these SBR composites, the one filled with DGTR treated by the mixed bacteria had best mechanical properties. The interface coherence between DGTR and SBR matrix was enhanced, too. It indicated that these two kinds of bacteria can promote each other to grow together and get better desulfurization effect.