Editorial Feature

Thermal Degradation of Used Surgical Masks

The mounting pile of used masks is posing a grave environmental and health hazard. Existing disposal methods, including landfill and incineration, are not sustainable and add to greenhouse gas emissions. Thermal degradation, a scientific process, could offer a more sustainable solution to the current crisis.

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In the following sections, we delve into the technicalities of thermal degradation and its potential applications for the sustainable use of masks.

The Science of Thermal Degradation

Thermal degradation is a chemical process that involves breaking down the polymer molecules in a material through the application of heat. This process converts the long polymer chains into shorter molecules, which can then be easily recycled.

In the case of surgical masks, thermal degradation involves heating the masks to a specific temperature range that will break down the polypropylene into shorter chains. The resulting material can be reused in the production of new masks or other plastic products, such as plastic bags or containers.

Thermal Degradation for Sustainability

A study published in the Science of The Total Environment journal reviewed sustainable alternatives to single-use face masks and discussed the challenges in scaling bio-based PPE, including the need for a cradle-to-grave life cycle assessment and the challenge of disposing of hazardous waste. Thermochemical transformation through pyrolysis was proposed as a suitable alternative to recycling face masks.

Beyond surgical masks, thermal degradation has the potential to address the environmental impact of other personal protective equipment (PPE) used during the COVID-19 pandemic, such as N95 respirators and gloves.

Furthermore, thermal degradation can be applied to other plastic waste streams, contributing to a more sustainable approach to waste management and promoting a circular economy.

The potential applications of thermal degradation for mask sustainability and waste reduction demonstrate the significance of this technology in addressing the challenges of the COVID-19 pandemic and advancing sustainability more broadly.

Current Research on the Thermal Degradation of Used Surgical Masks

The process of thermal degradation is not new, and it has been used to recycle other types of plastic waste, such as bottles and bags. However, applying this process to surgical masks is a recent innovation, and there are ongoing studies to determine the optimal temperature range and conditions for breaking down mask waste using modeling approaches.

One such is a recent study published in the Journal of the Taiwan Institute of Chemical Engineers. The study investigated the thermal degradation of used facial mask waste, which poses a serious threat to the environment.

The thermal degradation behavior of three different parts of the mask (ribbon, body, and corner) was studied using Thermogravimetric Analysis (TGA) to determine the reactivity of individual mask components at different temperatures. The study estimated kinetic parameters such as activation energy and pre-exponential factor, as well as thermodynamic quantities such as the change in enthalpy, entropy, and Gibbs-Free energy.

The researchers used a Machine Learning model known as Artificial Neural Network (ANN) to predict the TGA experimental curves of the mask components, and it showed excellent agreement with the experimental data.

This study successfully modeled the complex chemical process of thermal degradation using Machine Learning and demonstrated the feasibility of using machine learning to model the thermal degradation process, which can potentially aid in developing sustainable management strategies for used mask waste.

Another study published in the Heliyon Journal investigates the thermal degradation of wasted masks as a potential solution for the mismanagement of medical waste during the COVID-19 pandemic.

The masks were isolated, characterized, and subjected to thermal degradation via thermogravimetric analysis at different heating rates in a nitrogen atmosphere. The gases produced were then analyzed by gas chromatography and mass spectrometry. The kinetic models such as Coats and Redfern, Horowitz and Metzger, Kissinger-Akahira-Sunose were employed to find the best-fit models between the experimental and calculated data.

The results showed high conversion rates, and long-chain branched hydrocarbons, cyclic hydrocarbons, and CO2 were obtained as products. The study demonstrates the feasibility and high potential of energy recovery from wasted masks, with a composition including polypropylene, polyethylene terephthalate, nylon, and spandex, which have higher calorific values than traditional fuels.

Technical Considerations for Thermal Degradation of Surgical Masks

The thermal degradation process for surgical masks requires careful consideration of technical parameters such as the heating temperature and time, as well as the potential emissions of toxic gases during the process.

In addition, there is a need for adequate infrastructure for collecting and processing used masks, as well as for monitoring and regulating the thermal degradation process to ensure safety and environmental sustainability.

These technical considerations demonstrate the need for further research and development to fully realize the potential of thermal degradation for surgical mask sustainability. Nevertheless, the potential benefits of this process make it an exciting avenue for addressing the challenges of mask waste and advancing a circular economy.


The COVID-19 pandemic has brought about an unprecedented increase in the use of surgical masks, leading to significant amounts of mask waste that can have negative environmental and health impacts.

Thermal degradation offers a promising solution for reducing the amount of mask waste and creating a more sustainable approach to mask production and disposal. By converting used masks into new materials, thermal degradation can contribute to a circular economy that reduces greenhouse gas emissions, creates new job opportunities, and reduces the cost of producing new masks.

While there are technical considerations that need to be noted for the thermal degradation process, ongoing research and development are advancing the use of this technology for surgical mask sustainability. As we continue to address the challenges of the COVID-19 pandemic, it is important to consider the environmental impact of mask use and disposal. Thermal degradation offers a promising avenue for creating a more sustainable future.

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References and Further Reading

Chaudhary, A.S., Kiran, B., Sivagami, K., Govindarajan, D., Chakraborty, S. (2023). Thermal degradation model of used surgical masks based on machine learning methodology. Journal of the Taiwan Institute of Chemical Engineers 144, 104732. https://doi.org/10.1016/j.jtice.2023.104732

Jain, S. (2022). Pyrolysis of Face Mask Waste from the COVID-19 Pandemic [Online]. AZoM.com. URL https://www.azom.com/news.aspx?newsID=58748 (accessed 2.19.23).

Montero-Calderón, C., Tacuri, R., Solís, H., De-La-Rosa, A., Gordillo, G., Araujo-Granda, P. (2023). Masks thermal degradation as an alternative of waste valorization on the COVID-19 pandemic: A kinetic study. Heliyon 9, e13518. https://doi.org/10.1016/j.heliyon.2023.e13518

Torres, F.G., De-la-Torre, G.E. (2021). Face mask waste generation and management during the COVID-19 pandemic: An overview and the Peruvian case. Science of The Total Environment 786, 147628. https://doi.org/10.1016/j.scitotenv.2021.147628

Yu, J., Sun, L., Ma, C., Qiao, Y., Yao, H. (2016). Thermal degradation of PVC: A review. Waste Management 48, 300–314. https://doi.org/10.1016/j.wasman.2015.11.041

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Blaise Manga Enuh

Written by

Blaise Manga Enuh

Blaise Manga Enuh has primary interests in biotechnology and bio-safety, science communication, and bioinformatics. Being a part of a multidisciplinary team, he has been able to collaborate with people of different cultures, identify important project needs, and work with the team to provide solutions towards the accomplishment of desired targets. Over the years he has been able to develop skills that are transferrable to different positions which have helped his accomplish his work.


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