Search

Today, one of the world's critical environmental issues is air pollution, which is the most important parameter threatening human health and the environment. Synthetic polymers are widely used in industrial air filter production; however, they are incompatible with the environment due to their secondary pollution. Using renewable materials to manufacture air filters is not only environmentally friendly but also essential. Recently, a new generation of biopolymers called cellulose nanofiber (CNF)-based hydrogels have been proposed, with three dimensional (3D) nanofiber networks and unique physical and mechanical properties. CNFs have become a hot research topic for application as air filter materials because they can compete with synthetic nanofibers due to their advantages, such as abundant, renewable, nontoxic, high specific surface area, high reactivity, flexibility, low cost, low density, and network structure formation. The main focus of the current review is the recent progress in the preparation and employment of nanocellulose materials, especially CNF-based hydrogels, to absorb PM and CO 2 . This study summarizes the preparation methods, modification strategies, fabrications, and further applications of CNF-based aerogels as air filters. Lastly, challenges in the fabrication of CNFs, and trends for future developments are presented., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Pollution from particulate matter (PM) and toxic chemicals in the air cause some of the most critical health and environmental hazards in developed and developing countries. It can have a very destructive effect on human health and other living creatures. In particular, PM air pollution caused by rapid industrialization and population growth is a grave concern in developing countries. Oil and chemical-based synthetic polymers are non-environmentally friendly materials that lead to secondary environmental pollution. Thus, developing new and environmentally compatible renewable materials to construct air filters is essential. The goal of this review is to study the use of cellulose nanofibers (CNF) to adsorb PM in the air. Some of CNF's advantages include being the most abundant polymer in nature, biodegradable, and having a high specific surface area, low density, surface properties (broad possibility of chemical surface modification), high modulus and flexural stiffness, low energy consumption, which provide this new class of bio-based adsorbent with promising potential applications in environmental remediation. Such advantages have made CNF a competitive and highly in-demand material compared to other synthetic nanoparticles. Today, refining membranes and nanofiltration manufacturing are two important industries that could use CNF to provide a practical step in protecting the environment and saving energy. CNF nanofilters are capable of nearly eliminating most sources of air pollution, including carbon monoxide, sulfur oxides, nitrogen oxides, and PM 2.5 - 10 μm. They also have a high porosity and low resistance air (pressure drop) ratio compared to ordinary filters made from cellulose fiber. If utilized correctly, humans do not need to inhale harmful chemicals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Nanofilters made with high adsorption freeze-dried modified cellulose nanofiber (CNF) aerogel were produced. The modification was made using functional groups containing phthalimide, and then their ability to adsorb particulate matter (PM) was evaluated and compared with the control filter (HEPA). The results showed that the highest adsorption of PM 2.5 (99.95%) belonged to the nanofilters made of 1.5% phthalimide-modified CNF aerogel, and the lowest adsorption (76.66%) was related to the control samples. Moreover, based on the results, the nanofilter produced from freeze-dried phthalimide-modified CNF aerogel showed high filtration efficiency as well as excellent resistance to temperature and humidity. This modification enables the filter to operate in different environmental conditions, especially for particles less than 0.1 μm that are mainly responsible for reducing air quality, human health, air visibility, and climate change. In conclusion, we developed an environmentally friendly biodegradable nanofilter capable of high-performance filtration functions and structural stability in different environmental conditions., (Copyright © 2022 Elsevier B.V. All rights reserved.)