A Biodegradable Composite Zein Fiber Filter

By Surbhi JainReviewed by Susha Cheriyedath, M.Sc.Feb 16 2022

In an article recently published in the journal Sensors and Actuators A: Physical, the researchers presented a strategic approach for the development of a biodegradable composite filter via the underlaying of commercialized cellulose paper towels under electrospun zein fibers. They also reported a detailed analysis of its applications in air filtering.

Study: A biodegradable composite filter made from electrospun zein fibers underlaid on the cellulose paper towel. Image Credit: Gorodenkoff/Shutterstock.com

Background

Human activities like industrial manufacturing, traffic, and deforestation have all contributed to air pollution, which has become a severe hazard to public health and the environment. The primary component of air pollution is particulate matter (PM). As a result, effective materials with appropriate porous architectures should be designed to enable PM-contaminated air filtration.

The basic ingredients utilized in classic air filters to remove particle pollutants are mostly petroleum-based synthetic polymers. These polymer-based filters are invariably difficult to decompose after usage, and they can easily pollute the environment. Therefore, the development of biodegradable materials capable of air filtering has become critical. Biodegradable materials are increasingly being employed in air filtering. However, there are certain drawbacks to using these filters in practice.

Zein, maize's major storage protein, has a high biodegradability, hydrophobicity, and functional group diversity. Zein-based filters may catch particles through physical filtration and absorption at the same time, making zein a better raw material for filtration. However, there are still a few issues to consider when choosing a zein solvent.

About the Study

In the present study, the authors reported a method for the development of a biodegradable composite filter by underlaying commercialized cellulose paper towels under electrospun zein fibers that can be utilized for air filtering. A detailed description was provided for the fabrication methodology of the as-prepared composite filter.

The morphological characteristics of the electrospun zein fiber were directed in the processing by adjusting the ethanol/ deionized water (EtOH/DI) mixture solvent ratio without modifying the material system. One-step electrospinning yielded a flat and circular ribbon of zein fibers, which were then placed onto cellulose paper towels to produce a filtration material. The zein fibers with round and flat ribbon morphology were produced by altering the weight ratio of EtOH/DI combination solvent.

The performance of the as-prepared composite filters in terms of air filtration was investigated. The impact of zein fiber shape on air filtration performance was studied using both experimental and theoretical techniques.

Observations

In this study, the researchers observed that by altering the weight ratios of EtOH/DI mixture solvent, the morphology of zein fibers was successfully steered, resulting in round or flat ribbon fibers. Furthermore, it was observed that the circular zein fiber filter showed a greater filtration efficiency (99%) for PM_0.3 removal and a smaller pressure drop (109 Pa) as compared to the flat ribbon fiber filter. Furthermore, it was observed that the as-prepared composite filter was easily biodegradable, contributing to a greener ecological environment.

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The morphology of electrospun zein fibers changed from flat ribbon to spherical as the fraction of EtOH dropped. The change in fiber morphology was caused by the evaporation velocity of the solvent on the jet surface. The filtering effectiveness of the flat ribbon zein fiber air filter was maintained over 97% during 40 repeated filtration tests, and the pressure drop increased slightly, suggesting its superior PM capacity and practical application potential. More notably, after 42 hours in cellulase solution, the produced filter was completely destroyed.

Conclusions

In conclusion, this study elucidates an effective method for developing biodegradable filtration materials at a low cost, with easy access to constituting components, and a wide range of possible applications in the air filtration field. According to this study, the filtration ability of the ribbon zein fiber air filter is superior to that of the round zein fiber air filter. The flat zein fiber air filter has a significantly better filtering performance than the round zein fiber air filter, which has a high filtration efficiency of 99% for PM_0.3 removal and a low-pressure drop of 109 Pa.

The authors emphasized that by underlaying commercialized cellulose paper towels under electrospun zein fibers, a biodegradable composite filter can be created which can be potentially utilized in air filtration. Overall, this work demonstrates an effective method for the preparation of biodegradable filtering materials with low respiratory resistance, low cost, and accessible availability of component materials, with a wide range of possible applications in separating sectors.

The authors believe that this research could suggest a viable method for developing composite biodegradable air filtration.

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