The biodegradative effect of Tenebrio molitor Linnaeus larvae on vulcanized SBR and tire crumb

The overall world consumption rate of rubber tends to increase by an average of 2.8% per year in the period between 2017 and 2025. Rubber residues represent a severe problem to both health and environment due to their cross-linked structure that offers a prolonged degradation rate. A good solution to eliminate this problem is recycling and recovery, aiming at the production of new materials. The tire crumb can be recycled by chemical/biological recovery, where the elastomer is devulcanized, or by physical recovery, where the three-dimensional network is transformed into small fragments. In this study, we investigated the bio-degradation effect caused by Mealworms (the larvae of Tenebrio molilor Linnaeus) on vulcanized SBR-rubber and tire crumb as a desulphurization method. The surface modifications of both rubbers were studied by instrumental techniques: FTIR-ATR, TGA, XRD, and SEM. The cross-linking degree of the rubber was determined via circular condensation method. The obtained results show that the Tenebrio molitor could survive after three weeks of direct contact with SBR-rubber and tire crumb as the only alimentation. There was a declining effect of cross-linking degree by increasing the contact time between the rubbers and larvae. The FTIR results indicate surface/chemical modifications of the rubbers and the SEM results show the free sulfur after it was released in the form of sulfur flower-like. Also, the TGA results highlight a difference in the degrading behavior and residues of the treated and non-treated rubbers. Therefore, the reported results were promising, demonstrating the biodegradation effect caused by the Tenebrio molitor mealworms, highlighting an alternative and natural mean of degrading vulcanized rubber residues. (C) 2018 Elsevier B.V. All rights reserved.