Indoor air quality is an important matter of concern within closed residential and office environments. Recent efforts to improve energy efficiency of building structures have led to poor ventilation systems, resulting in higher risk for build up of air contaminants. Air contaminants, including microbial contaminants, have proven to have serious health effects on the human body and can be pathogenic or cause an allergic reaction when inhaled. These contaminants can also increase human exposure to infectious diseases via inducing surface contamination.

In attempts to fight against air contaminants, air disinfection technologies have been strongly driven to develop a new solution for improving indoor air quality. Antimicrobial technologies include conventional chemical disinfect...[ Read more ]

Indoor air quality is an important matter of concern within closed residential and office environments. Recent efforts to improve energy efficiency of building structures have led to poor ventilation systems, resulting in higher risk for build up of air contaminants. Air contaminants, including microbial contaminants, have proven to have serious health effects on the human body and can be pathogenic or cause an allergic reaction when inhaled. These contaminants can also increase human exposure to infectious diseases via inducing surface contamination.

In attempts to fight against air contaminants, air disinfection technologies have been strongly driven to develop a new solution for improving indoor air quality. Antimicrobial technologies include conventional chemical disinfectants, photocatalytic oxidation technology, microplasma technology, ozone treatment, and ultraviolet (UV) technology. Research shows, however, that these technologies have various after-use effects such as resulting in harmful chemical residues hazardous to human health, or may be too powerful a disinfectant and require appropriate after measures such as deozonation. The various air disinfection technologies and its disadvantages are introduced in the study to recognize the importance of discovering air disinfection technology without any drawbacks.

This work explores the possible use of essential oils extracted from natural plants as disinfection agent against airborne microorganisms and format of their delivery, proposing inorganic gel form. The fundamental technology of the inorganic gel was announced by Professor King Lun Yeung’s group, and the study reveals the advantages of the gel as a disinfectant and its potential for application in commercial air disinfection products. This study focuses especially on essential oils, a natural substance with antimicrobial properties, which have received considerable attention because of the safety concern of synthetic compounds. With essential oil incorporated inorganic gel, this research aims to discover the relationship between the sol-gel process and the corresponding air disinfection performance of essential oil.

The sol-process which is incorporated with essential oil was investigated to find optimal formula for inorganic gels, improving the mechanical properties, transparency and syneresis of the inorganic gels.

The study examines the characteristics and the disinfectant capacities of the essential oil via inorganic gel form for its controlled release of fragrance and disinfectant, and illustrates the absence of potential drawbacks revealed by other existing technologies. Box tests for antimicrobial activities of the inorganic gels showed more than 3 log reduction 2 h exposure to the fragrance vapor from the gel and they are effective against all tested pathogens including S. aureus, P. aeruginosa, Enterococcus faecalis, Salmonella typhimurium, Legionella pneumophila, and Srreptococcus pneumonia.

In the research, the various characteristics and properties of essential oils were carefully examined and selected to form a new alcogel through a two-step sol-gel process. The essential oils were impregnated into inorganic gel network, which enables the gel to have controlled release of the essential oils. The anti-microorganism activities of the gels, including their accelerated released rates, were compared to commercial organic gels. The controlled release property of the gel is 7 times greater than that of the commercial water based gel. Long-term performances were also investigated to elucidate the controlled release property of the gels. The gels remain bactericidal even after 60% weight lost which equal to the use of more than 5 months.

The study concludes in successful development of long-lasting effective gas disinfectants with natural essential oils released in a controlled manner from inorganic gels. The gels were proven to possess efficient anti-microbial properties.