Biodegradation of Bioplastic and Oregano Oil Mix in Simulated Soil Conditions

Greg Howard
12th July, 2024

Biodegradation of Bioplastic and Oregano Oil Mix in Simulated Soil Conditions

This study demonstrates that essential oil from Oregano (Origanum vulgare, pictured) significantly enhances the biodegradation of poly(hydroxybutyrate-co-hydroxyvalerate) bioplastic films, highlighting its potential to control the degradation rate for active packaging applications.

Photographer: Yann Kemper

Key Findings

  • Researchers at Universidade Federal de Santa Catarina found that adding oregano essential oil (OEO) to PHBV films significantly increased their biodegradation rate
  • PHBV films with OEO showed a 46% mass loss after 12 weeks in simulated soil, compared to 32% for films with clay nanoparticles
  • The study suggests that OEO enhances biodegradation by creating a rough, layered surface with visible cracks, promoting a layer-by-layer erosion mechanism
The increasing environmental concerns related to plastic waste have driven significant research into biodegradable alternatives. One of the promising candidates is poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), a biopolymer known for its potential to degrade in various environmental conditions. A recent study by researchers at Universidade Federal de Santa Catarina[1] has focused on enhancing the biodegradation properties of PHBV films by incorporating halloysite clay nanoparticles and oregano essential oil (OEO). The study aimed to evaluate the influence of these additives on the biodegradation behavior of PHBV films. Five different samples were prepared, including compositions with 3 wt% clay and varying amounts of OEO (8 wt% and 10.4 wt%). The results showed that the PHBV compositions containing OEO had the highest rate of biodegradation, achieving a 46% mass loss after 12 weeks in simulated soil. In contrast, the addition of clay nanoparticles reduced the polymer's biodegradation to 32%. The findings of this study are significant in the context of previous research on PHBV biodegradation. For instance, it was previously observed that PHBV ternary biocomposites containing nature-based plasticizers and nucleation agents had different degradation rates in various environments, with the highest biodegradation rate in thermophilic composting conditions[2]. The current study builds on this by demonstrating that the addition of OEO can further enhance the biodegradation rate of PHBV, particularly in soil conditions. The study also revealed that the compositions containing OEO exhibited a rough and layered surface with visible cracks, indicating a layer-by-layer erosion mechanism of degradation. This was confirmed by the chemical changes on the surface of all samples and a slight decrease in molar masses. Interestingly, the composition with 8 wt% OEO showed an increase in crystallization degree due to the preferential consumption of the amorphous phase. In contrast, for compositions containing clay nanoparticles, both crystalline and amorphous regions degraded at similar rates. These results are consistent with earlier findings that the physical properties of plastics, such as crystallinity, play a crucial role in their biodegradability[3]. The study by Universidade Federal de Santa Catarina highlights that the combination of additives like OEO and clay nanoparticles allows for controlled biodegradation of PHBV, making it suitable for the production of active packaging. This is particularly relevant given the need for biodegradable plastics to replace petrochemical-derived polymers in various applications[4]. Moreover, the study underscores the potential of using biobased cosubstrates for the sustainable production of PHBV. Previous research demonstrated that cocultures and biobased cosubstrates like valeric acid and volatile fatty acids (VFAs) could promote PHBV accumulation[5]. The current study adds to this by showing that the use of natural additives like OEO can enhance the biodegradation rate of PHBV, providing a more environmentally friendly solution for plastic waste management. In conclusion, the study by Universidade Federal de Santa Catarina demonstrates that the incorporation of halloysite clay nanoparticles and oregano essential oil significantly influences the biodegradation behavior of PHBV films. The findings suggest that the use of these additives can enhance the biodegradation rate of PHBV, making it a viable option for active packaging applications. This research not only builds on previous studies but also opens new avenues for the development of sustainable and biodegradable plastic alternatives.

EnvironmentSustainabilityBiotech

References

Main Study

1) Biodegradation study of poly(hydroxybutyrate-co-hydroxyvalerate)/halloysite/oregano essential oil compositions in simulated soil conditions.

Published 8th July, 2024

https://doi.org/10.1016/j.ijbiomac.2024.133768

Related Studies

2) The Influence of Additives and Environment on Biodegradation of PHBV Biocomposites.

https://doi.org/10.3390/polym14040838

3) Biodegradability of plastics.

https://doi.org/10.3390/ijms10093722

4) Biodegradation Studies of Polyhydroxybutyrate and Polyhydroxybutyrate-co-Polyhydroxyvalerate Films in Soil.

https://doi.org/10.3390/ijms24087638

5) Exploring New Strategies for Optimizing the Production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from Methane and VFAs in Synthetic Cocultures and Mixed Methanotrophic Consortia.

https://doi.org/10.1021/acssuschemeng.3c08570


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