Phytoremediation of formaldehyde by plant stems

10 Decorative plants can efficiently purify formaldehyde and improve the quality of indoor 11 air. The existing studies primarily revealed that the aerial and underground parts of 12 plants’ capacity to purify formaldehyde, while the performance of stems is unclear. A 13 formaldehyde fumigation experiment was conducted on Pothos ( Epipremnum aureum ) 14 and sacred lily ( Rohdea japonica ) in a sealed chamber. Results showed the stems could 15 removal formaldehyde. The efficiency of removal by the stems of each plant was 0.089 16 mg∙m -3 ∙h -1 and 0.137 mg∙m -3 ∙h -1 , respectively, the rate of purification was 40.0% and 17 61.6%, respectively. Both were related to plant species and the latter was affected by 18 other factors like exposed area. To further explore the mechanism of phytoremediation, 19 the correlation between the concentration of formaldehyde and CO 2 during the 20 experiment was investigated. Results showed when leaves of plants were exposed to 21 formaldehyde, the concentration of CO 2 increased with the decrease in concentration 22 of formaldehyde, and the change in concentration of CO 2 could be used as an indicator 23 of the degree of purification of formaldehyde by the plants.


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With the development of society and the transformation of lifestyles, indoor air quality 34 is garnering increasing amounts of attention as people spend more than 80% of their    of pollutants on the leaf surface exceeds the equilibrium value (Kvesitadze et al., 2006). 68 The adsorption of cuticular wax comprises 46% of the capacity of Dracaena 69 sanderiana to remove benzene (Treesubsuntorn and Thiravetyan, 2012), and 20%, 23%, 70 25%, and 26% of the capacity of Zamioculcas zamiifolia Engl. to remove benzene, 71 toluene, ethylbenzene, and xylene, respectively (Sriprapat and Thiravetyan, 2013). 72 Formaldehyde can also enter the plant directly through the opened stomata, which play 73 a significant role in the purification of pollutants in the aerial part. Kondo et al. (1995)    To address the shortcomings described above, a formaldehyde fumigation 116 experiment on plants in a closed glass chamber was conducted. The capability of stems 117 to purify formaldehyde was studied by analyzing the change of formaldehyde 118 concentration when stems exposed to formaldehyde. In order to further explore the 119 formaldehyde purification mechanism and fill the gap that the change of CO2 120 concentration in the chamber has not been examined, the relative correlation between 121 formaldehyde concentration and CO2 concentration was studied.  Pothos and sacred lily appeared to be the most suitable. Ten plants each of Pothos and 128 sacred lily of the same age and similar growth were purchased from a market and pre-129 cultured for one month in an incubation chamber with a temperature of 22℃, a relative denoted as plant A and plant B. Another individual was used in the control experiment.

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The leaves were wiped with a clean soft towel to prevent dust and particles from 136 affecting the capacity to adsorb and absorb formaldehyde before they were used in the 137 experiment. The chlorophyll content of leaves was monitored before and after each 138 experiment using a chlorophyll meter (SPAD-502 Plus, Konika-Minolta, Tokyo, Japan).

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After the experiment, the leaf area was measured using a leaf area meter (LI-3000C,   1. Plant treatment method. a whole plant exposed to formaldehyde. b underground part 152 exposed to formaldehyde. c aerial part exposed to formaldehyde. d stems exposed to 156 In this experiment, a stainless steel glass chamber with a volume of 1 cubic meter (1 m 157 long × 1 m wide × 1 m high) was selected as the fumigation chamber. A small electric 158 fan was placed in the middle of top of the chamber, which was used to evenly mix the    Table 2.  Table 3 and the results showed that the exposure experiment had 240 no effect on the normal growth of plants to some extent (two-tailed t-test, for Pothos,

The formaldehyde purification capability of each part of the plants 248
When different parts of plants were exposed to the formaldehyde environment, the 249 change in concentration of formaldehyde in the glass chamber is shown in Fig. 3.

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The experimental results showed that both Pothos and sacred lily could effectively   shown were mean for independent replicates. 329 The change in CO2 concentration in the glass chamber during the experiment is shown  However, it could be seen from Fig. 5a that when the underground part and the stem of 343 Pothos and the sacred lily were exposed to the chamber, the CO2 concentration was 344 almost constant. Moreover, as shown in Fig. 5b, the CO2 concentration in the chamber 345 increased considerably when the whole plant, the aerial part, and the leaves of Pothos 346 and the sacred lily were exposed to the chamber. The difference in trends of the change 347 in CO2 concentration could be related to whether the plant leaves were exposed to   368 When the whole plant, aerial parts and leaves of plants were exposed to an environment 369 of formaldehyde, the correlation between CO2 and formaldehyde concentrations is 370 shown in Fig. 6.

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When the plant leaves were exposed to an environment of formaldehyde, according to the data fitting results, there was a quadratic function relationship between the 373 concentration of CO2 and formaldehyde(R 2 >0.97), and as the concentration of 374 formaldehyde decreased during the experiment, the CO2 concentration gradually  The rate of purification of both could reach more than 75%.