An assessment of botanical air purification as a formaldehyde mitigation measure under dynamic laboratory chamber conditions

doi:10.1016/0269-7491(89)90092-4

Environmental Pollution

Volume 62, Issue 1, 1989, Pages 13-20

https://doi.org/10.1016/0269-7491(89)90092-4 Get rights and content

Abstract

This study was designed to determine the effectiveness of spider plants (Clorophytum elatum var. vittatium) as a botanical air purification measure for formaldehyde under dynamic laboratory chamber conditions. Significant reductions in chamber formaldehyde levels were observed when spider plants were placed in experimental chambers. However, highest reductions occurred when spider plants were defoliated. Observed reductions in formaldehyde levels appeared to have been associated with soil medium factors and a source moisture storage phenomenon associated with the use of particleboard as a formaldehyde source inside the chambers. The results of this study do not support the conclusions of previous studies which suggest that botanical air purification using only plant leaves is an effective means of reducing residential formaldehyde levels.

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Botanical biofiltration using active green walls is showing increasing promise as a viable method for the filtration of volatile organic compounds (VOCs) from ambient air; however there is a high level of heterogeneity reported amongst VOC removal efficiencies, and the reasons for these observations have yet to be explained. Comparisons of removal efficiencies amongst studies is also difficult due to the use of many different VOCs, and systems that have been tested under different conditions. The current work describes a procedure to determine whether some of these differences may be related to the chemical properties of the VOCs themselves. This work used an active green wall system to test the single pass removal efficiency (SPRE) of nine different VOCs (acetone, benzene, cyclohexane, ethanol, ethyl acetate, hexane, isopentane, isopropanol and toluene) and explored which chemical properties were meaningful predictor variables of their biofiltration efficiencies. Ethanol was removed most efficiently (average SPRE of 96.34% ± 1.61), while benzene was least efficiently removed (average SPRE of 19.76% ± 2.93). Multiple stepwise linear regression was used to determine that the dipole moment and molecular mass were significant predictors of VOC SPRE, in combination accounting for 54.6% of the variability in SPREs amongst VOCs. The octanol water partition coefficient, proton affinity, Henry's law constant and vapour pressure were not significant predictors of SPRE. The most influential predictor variable was the dipole moment, alone accounting for 49.8% of the SPRE variability. The model thus allows for an estimation of VOC removal efficiency based on a VOC's chemical properties, and supports the idea that system optimisation could be achieved through methods that promote both VOC partitioning into the biofilter's aqueous phase, and substrate development to enhance adsorption.'
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Citation Excerpt :
This indicates that the biological removal of VOCs may primarily be carried out by the soil microcosm. Increased removal of formaldehyde by removing leaves of Chlorophytum elatum has previously been reported with an explanation that leaves covering the soil surface hindered diffusion of the pollutant into the soil for microbial degradation (Godish and Guindon, 1989). The leaves of H. helix partially covered the soil surface in this study and could potentially hinder the diffusion of the gasoline mixture into the soil.
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The deployment of complex biological systems in urban settings has evolved as a technology to mitigate what has come to be known as the sick building syndrome. Indoor air quality (IAQ) is a rising concern as people are spending more time indoors and buildings are increasingly sealed to reduce energy consumption. Accumulation of gaseous contaminants, including volatile organic compounds (VOCs), in the indoor air can negatively affect occupant health and productivity. This article addresses the popular and scientific literature relating to the potential for biological systems containing plants to improve IAQ through the removal and degradation of gaseous indoor contaminants. Historical literature implicates simple potted plants and their associated microbes as the means for reducing VOCs in the aerial environment. However, these claims are supported by anecdotal evidence and very few realistic, systematic investigations. In addition, these claims are not in agreement with models of microbial kinetics and gas transfer. On the other hand, botanical biofiltration, which actively forces air through a complex ecosystem, has been the subject of numerous detailed studies and received considerable attention as a means of reducing the accumulation of VOCs in occupied spaces. Evidence supporting various interpretations of the mechanisms of biological filtration will be addressed.
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Citation Excerpt :
Orwell et al. (2006) suggested that this was a result of toluene supporting a specific microbial population and inducing within that population the activity of the enzyme catechol 1,2 dioxygenase which is used for the biodegradation of both pollutants, however when toluene concentrations become limiting, m-xylene was then more effectively biodegraded. Numerous studies have noted the innate ability of plant growth substrates to adsorb VOCs (Godish and Guindon, 1989; Hörmann et al., 2017), and consequently substrates of different compositions have been trialled in experiments for their capacity to influence VOC removal. Aydogan and Montoya (2011) noted the substrate’s contribution to removal efficiency as their activated carbon substrate treatment demonstrated larger reductions in formaldehyde in comparison to expanded clay and growstone substrates, and concluded that substrates that have high adsorption capacities and provide sufficient microbial sites could lead to increased VOC removal.
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An assessment of botanical air purification as a formaldehyde mitigation measure under dynamic laboratory chamber conditions

Abstract

Report of the federal panel on formaldehyde

Environ. Health Perspectives

Formaldehyde release from particleboard—Evaluation of a mathematical model

Holz als Rah- und Werkstoff

Health status of residents in homes insulated with urea formaldehyde foam

Formaldehyde exposure in nonoccupational environments

Arch. Environ. Health

Interpretation of one-time formaldehyde sampling results from measurements of environmental variables

The effects of temperature and humidity on formaldehyde emission from U-F bonded boards: A literature critique

For. Prod. J.