Abstract
Antimicrobial air filters are required to protect humans from the risk of secondary bioaerosol pollution as well as airborne particles. Three plant extracts (tea-tree oil, rosemary, and garlic) were selected to replace antimicrobial chemicals in air filters. The antimicrobial activity of plant extracts was investigated using Micrococcus luteus and Escherichia coli. Phytochemicals present in the three plant extracts were identified using a gas chromatograph coupled with a mass spectrometer. The extracts were spray-coated on polyethylene terephthalate filter surfaces using silicate polymeric coating and evaluated via X-ray photoelectron spectroscopy and a scanning electron microscope with energy dispersive spectroscopy. After coating, an increase of 9.1% in the pressure drop was observed. The strain Micrococcus luteus was used to evaluate the antimicrobial activity of the air filter. After bioaerosol exposure, the tea-tree oil-coated filters immediately induced M. luteus cell inactivation (40–55%), whereas the rosemary and garlic coated filters did not. However, 48 h after exposure, a significant M. luteus inactivation of 99.99%, 99.0%, and 99.9% was recorded for concentrations of 2.89, 6.73, and 11.51 mg/cm2 for the tea-tree, rosemary, and garlic extracts, respectively. The coated filters exhibited high antimicrobial activity, thereby indicating significant potential for application as self-cleaning air filters.
Highlights
As people engage in indoor activities for increasing amounts of time, keeping indoor air clean is becoming increasingly important [1]
We investigated the antimicrobial activity of these three plant extracts against gram-negative and gram-positive bacteria
All plant extracts showed a dose-dependent pattern of the antimicrobial function
Summary
As people engage in indoor activities for increasing amounts of time, keeping indoor air clean is becoming increasingly important [1]. Fine dust pollution and air quality deterioration induce a negative effect on humans, including contagious diseases, allergies, acute toxicity, and cancer [2]. To reduce these adverse effects, air filtering is used to improve indoor air quality. Methods for removing biological contaminants from indoor environments include UV irradiation [8], photocatalytic oxidation [9], negative air ionization [10], thermal inactivation [11], ozone [12], and electrostatic precipitation [13] Among these methods, the most noticeable is an antimicrobial filtration system
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