Surface modification of cotton fabric by kaolin-derived zeolite N to enhance efficient removal of particulate matter

Abstract

Reducing the amount of fine particulate matter (PM) in the atmosphere is essential for preserving a secure and healthy environment. Here, we synthesized zeolite N (potassium ion form, KN) from kaolin clay minerals, coated it on cotton fabric using a simple refluxing method and then removed PM from the air. The following conclusion can be drawn. The average cation exchange capacity (CEC) of KN was 512 meq/100 g, and a CEC value > 400 meq/100 g indicated pure zeolite with a Si/Al ratio of approximately 1.0. The synthesized KN, containing a high proportion of Al, proved highly effective in removing particulates. For instance, KN/cotton (746 GSM (weight of fabric in g/m²) cotton, coated with approximately 1.46 wt% KN) demonstrated an 8-times higher removal efficiency (RE) for PM2.5 and PM1.0 than bare 746 GSM cotton, with only a 7 Pa increase in the pressure drop. PM may have been removed by electrostatic interactions between the charged PM and KN (with charge-balancing cations) owing to the charges and polarity of the outer layer of PM particles. According to the increases in RE and the quality factor, KN/cotton (746 GSM) was the most effective in removing PM from the air compared to other materials. The results suggested that KN, when applied to the surface of cotton fabric, is highly efficient due to its EDI framework structure and high Al content. Finally, biodegradation tests revealed that used filters disintegrated into pieces after being buried for one month in soil, indicating their environmental friendliness.