Biological devulcanization of ground natural rubber by Gordonia desulfuricans DSM 44462T strain

Abstract

Due to the rapid increase of waste vulcanized rubber products, the development of low-cost, efficient, and selective devulcanization processes is needed. In this paper, the devulcanization ability of Gordonia desulfuricans DSM 44462(T) was evaluated by a design of experiments. The aim of the experimental design was to investigate the importance of parameters influencing the bacterial growth, such as the glucose concentration (C), dibenzothiophene concentration (DBT), and initial biomass (optical density, OD) in biodevulcanization process. The complex viscosity (η*) was chosen as experimental response for the experimental design. A multiple linear regression was used to model the relationship between the response and the process variables. In addition, the crosslink density and gel fraction were measured. Furthermore, the automated ribosomal intergenic spacer analysis (ARISA) as a microbiological method was performed to assess the persistence of the inoculated strain during the experiments. Reduced regression models were obtained considering only the significant variables and interactions. The glucose concentration C and OD variables and C-DBT and DBT-OD interactions resulted to the relevant parameters for the process. The fingerprinting showed the persistence of G. desulfuricans DSM 44462(T), despite the presence of other bacterial population after the VGNR sterilization. These results highlight the importance to support the physics analysis with microbiological analyses to evaluate the bacterial persistence during the treatment.

Microwave devulcanization of ground tire rubber and applicability in SBR compounds

“…Consequently, the amount of recycled rubber in a new rubber product can be increased without compromising its mechanical properties. There are various methods for rubber devulcanization, including thermomechanical, thermochemical, mechanochemical, physical, and biological techniques, as well as methods using microwaves and ultrasound …”

“…Consequently, the amount of recycled rubber in a new rubber product can be increased without compromising its mechanical properties. There are various methods for rubber devulcanization, including thermomechanical, 16,17 thermochemical, 18 mechanochemical, 19 physical, and biological 20,21 techniques, as well as methods using microwaves 1,13,14,22 and ultrasound. 23,24 Currently, microwave devulcanization is one of the most promising technologies because of the good properties of the treated material and the promise of high productivity as well as relative low costs.…”

Assessing the Biodegradation of Vulcanised Rubber Particles by Fungi Using Genetic, Molecular and Surface Analysis

“…Several tyre-recycling processes have been described, and most of them are focused on the modification of the chemical structure and, thus, achieving devulcanisation. These include chemical processes using different peroxides ( Rooj et al, 2011 ; Sabzekar et al, 2015 ; Hejna et al, 2019 ), physical processes such as grinding, ultrasound, microwaves or thermo-mechanical processes ( Feng and Isayev, 2006 ; Wang et al, 2013 ; Formela and Cysewska, 2014 ; Garcia et al, 2015 ; Asaro et al, 2018 ; Formela et al, 2019 ; Li et al, 2020 ) and biological processes using microorganisms, mainly bacteria ( Tatangelo et al, 2016 ; Ghavipanjeh et al, 2018 ; Aboelkheir et al, 2019 ; Kaewpetch et al, 2019 ).…”

Recycling of resin cured IIR-based ground bladder rubber with the assistance of subcritical fluids

“…According to the difference in reaction mechanisms, the devulcanizing process can be classified as physical, 2,3 chemical, [4][5][6] and biological ones. 7,8 In the physical process, waste rubbers are devulcanized with the assistance of external energy such as mechanical, 9,10 thermomechanical, 11 cryomechanical, 12 microwave, 13 or ultrasonic energies. [14][15][16][17]3 In the chemical process, phenol sulfide and disulfides 18,19 have been developed to reclaim waste rubbers.…”