Towards practical indoor air phytoremediation: A review

Pettit

et al. 2019

Environ Sci Pollut Res

Self Cite

Volatile organic compounds (VOCs) are of public concern due to their adverse health effects. Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms are not fully understood. This study assessed active botanical biofilters for their single-pass removal efficiency (SPRE) for benzene, ethyl acetate and ambient total volatile organic compounds (TVOC)s, at concentrations of in situ relevance. Biofilters containing four plant species (Chlorophytum orchidastrum, Nematanthus glabra, Nephrolepis cordifolia 'duffii' and Schefflera arboricola) were compared to discern whether plant selection influenced VOC SPRE. Amongst all tested plant species, benzene SPREs were between 45.54-59.50%, with N. glabra the most efficient. The botanical biofilters removed 32.36-91.19% of ethyl acetate, with C. orchidastrum and S. arboricola recording significantly higher ethyl acetate SPREs than N. glabra and N. cordifolia. These findings thus indicate that plant type influences botanical biofilter VOC removal. It is proposed that ethyl acetate SPREs were dependent on hydrophilic adsorbent sites, with increasing root surface area, root diameter and root mass all associated with increasing ethyl acetate SPRE. The high benzene SPRE of N. glabra is likely due to the high wax content in its leaf cuticles. The SPREs for the relatively low levels of ambient TVOCs were consistent amongst plant species, providing no evidence to suggest that in situ TVOC removal is influenced by plant choice. Nonetheless, as inter-species differences do exist for some VOCs, botanical biofilters using a mixture of plants is proposed. Keywords Air pollution; botanical biofilters; phytoremediation; green walls; VOCs 'active green walls', which utilise mechanical assistance to funnel air into the biofilter substrate, improves their bioremediation efficiency to the extent that functional air remediation is probable (Torpy et al. 2015). These systems may also be practical for large infrastructure use, given that they are accessible, robust, cost-effective and have a low-energy footprint. Although the available types of botanical biofiltration systems differ in design, they all use active airflow facilitated with devices such as impellers that increase the airflow across or through the systems and therefore allow larger volumes of air to be processed by the biofilter. Whilst there is a growing body of literature that demonstrates the air pollutant remediation capabilities of this technology (Pettit et al. 2019), to date, the potential for plant selection to enhance botanical biofilters ability to filter some of the more dangerous air pollutants is required. Plant selection is known to have an influence on VOC removal efficiency for static, potted-plant systems (e.g. Kim et al. 2010). Whilst the nature of the plant characteristics that determine these effects have yet to be resolved, there may be phylogenetic associations where certain groups of plants are more effective for the removal of certain forms of VOC (Ki...

Section: Introductionmentioning

confidence: 99%

Does plant species selection in functional active green walls influence VOC phytoremediation efficiency?

Pettit

et al. 2019

Environ Sci Pollut Res

Self Cite

J of Applied Polymer Sci

“…Hence, the levels of chemical and air pollution have increased due to the extensive use of decorative materials . Many buildings are designed and built with a compact construction, resulting in the indoor pollutants being unable to be discharged in a timely manner . A large quantity of pollutant accumulates in the interior, seriously affecting the indoor air quality and harming human health .…”

Section: Introductionmentioning

confidence: 99%

Cellulose‐based formaldehyde adsorbents with large capacities: Efficient use of polyethylenimine for graphene oxide stabilization in alkaline–urea system

Yuan

Wang

et al. 2019

A cellulose-based polyethylenimine modified graphene oxide (PEI-GO) composite aerogel is fabricated through the alkalineurea aqueous system. Inspired from the performance of nanocarriers in gene delivery, this article proposes a pathway to disperse GO in the green environment with strong electrolyte concentrations via the decorated branched PEI. The entire aqueous system shows good miscibility and stability. Meanwhile, the dynamic light scattering results indicate that PEI-GO and cellulose chains become entangled to form a new supramolecular complex in the alkaline-urea solution, and a "hand" model is devised accordingly. The efficient dispersion of PEI-GO (1-0.1%) over the entire cellulose support structure (3%) enables the resultant aerogel to exhibit a gaseous formaldehyde adsorption capacity, that is, 8.51 times greater than the pure cellulose aerogel under ambient temperatures. This dual function opens up enormous opportunities to process cellulose-based GO materials in this green and inexpensive solvent with strong electrolyte concentrations.

“…Despite these benefits, it has been suggested that in some cases, plants may compromise the air quality as their emission of biogenic VOCs interacts with urban NOx to produce ozone [23]. Nonetheless, fusing the removal mechanisms of the plant foliage with biofiltration technology to create active green walls (botanical biofilters) has proven to be an efficient means for the removal of other gaseous pollutants, primarily different species of VOCs [24], however, it is unknown whether botanical biofilters are capable of filtering NO x , and what implications this may have for the ambient O 3 concentration.…”

Section: Introductionmentioning

confidence: 99%

“…Active green walls are a green technology that can simultaneously treat a large number of air pollutants at a relatively low cost. This technology builds upon the vast literature purporting the air phytoremediation potential of potted plants ( [24,[26][27][28], plus references therein). Whilst pollutant reduction by potted plants has been well described, for in situ use, such systems will be severely limited in their efficacy [29].…”

Section: Introductionmentioning

confidence: 99%

“…Several recent studies have reported that green wall systems, in particular active green walls, have a high capacity to phytoremediate several air pollutants including particulate matter (PM) [30,31] and VOCs [32,33]. Regarding green wall VOC removal, biodegradation of VOCs by the rhizospheric bacteria along with substrate adsorption are considered as the primary sinks for VOC removal [24,34], however, plant-associated effects also play a role in VOC removal [35]. In the current experiment, all treatments contained both plants and substrate as discriminating between the substrate and plant effects are of no interest in practical applications of this technology.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Assessment of the Suitability of Active Green Walls for NO2 Reduction in Green Buildings Using a Closed-Loop Flow Reactor

et al. 2019

Self Cite

Nitrogen dioxide (NO 2 ) is a common urban air pollutant that is associated with several adverse human health effects from both short and long term exposure. Additionally, NO 2 is highly reactive and can influence the mixing ratios of nitrogen oxide (NO) and ozone (O 3 ). Active green walls can filter numerous air pollutants whilst using little energy, and are thus a candidate for inclusion in green buildings, however, the remediation of NO 2 by active green walls remains untested. This work assessed the capacity of replicate active green walls to filter NO 2 at both ambient and elevated concentrations within a closed-loop flow reactor, while the concentrations of NO and O 3 were simultaneously monitored. Comparisons of each pollutant's decay rate were made for green walls containing two plant species (Spathiphyllum wallisii and Syngonium podophyllum) and two lighting conditions (indoor and ultraviolet). Biofilter treatments for both plant species exhibited exponential decay for the biofiltration of all three pollutants at ambient concentrations. Furthermore, both treatments removed elevated concentrations of NO and NO 2 , (average NO 2 clean air delivery rate of 661.32 and 550.8 m 3 ·h −1 ·m −3 of biofilter substrate for the respective plant species), although plant species and lighting conditions influenced the degree of NO x removal. Elevated concentrations of NO x compromised the removal efficiency of O 3 . Whilst the current work provided evidence that effective filtration of NO x is possible with green wall technology, long-term experiments under in situ conditions are needed to establish practical removal rates and plant health effects from prolonged exposure to air pollution.