Biomass consumption and fossil fuel combustion are key contributors to particulate matter (PM) pollution, resulting in ecological disturbances, climate change, and an increase in serious global health problems, related to common respiratory and cardiovascular diseases. Strategies have been initiated to curb the filtration of PM. Specifically, nanofibrous mats render high filtration efficiency for removing PM from the gas stream due to their low basis weight, wide area to volume ratio, and small pore size. In this review, we holistically took into account the raw materials and fabrication techniques of nanofibrous filters constituting electrospinning, blow spinning, and natural/freeze-drying. We highlighted the mechanism of PM capture and the basic parameters for PM filtration which entail efficiency removal, pressure drop, quality factor, and reusability. Additionally, challenges in filter cleaning, low airflow rate, and filtration efficiencies, coupled with future perspectives using biobased nanofiber mats still need to be addressed going forward.

Magnetic chitosan has received considerable attention over the decades due to its low cost, biodegradability, green sources, magnetic intensity. In this review, we reviewed the preparation methods of magnetic chitosan using co-precipitation, cross-linking and electrochemical. Therein cross-linking methodologies involved in the reaction of amino groups are facile to introduce additional reaction groups and improve anti-swelling of chitosan layers, mostly in an acidic environment. Besides, we focused on the applications of magnetic chitosan in various fields such as wastewater treatment, for example, removal of heavy metal ions, organic/inorganic dyes, fluorides, and pesticides. Moreover, magnetic chitosan also reveals great potential application in the field of medical, pharmaceutical, food and electronic screening. Above all, magnetic chitosan is economically and operationally beneficial as it can be easily separated and controlled with an external magnetic field and can be modified to maximize its functions.

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