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The Effect of Common Household Plants and Items on Minimising

Formaldehyde 以植蓋醛

聖保羅男⼥女中學 St.Paul’s Co-educational College

Karis Cheung*

Joyee Au Yeung

Karen Leung

Wai Shan Yam

Mavis Wong

The Effect of Common Household Plants and Items on Minimising Formaldehyde �1

Table of Contents

Introduction --- P.3

Objective --- P.4

Hypothesis --- P.4

More on Formaldehyde --- P.4

More on Phytoremediation --- P.4

Results & Analysis --- P.6

Conclusion --- P.15


Introduction

Formaldehyde is a commonly found chemical in households, classified as ‘carcinogenic to humans’ by the International Agency for Research on Cancer.

This report investigates what items are more efficient at absorbing formaldehyde present in air. Both products sold for formaldehyde absorbing purpose and other household items that we believe to be able to absorb formaldehyde are tested. We also developed methods for improving absorption by maximising absorption rate of products and the minimising impact of absorption to living items under test. Before doing investigation on items’ formaldehyde absorption ability, we would check the amount of formaldehyde in homes so as to better understand the need to absorb formaldehyde.

研習簡介

甲醛是⼀一種蘊含在家具中常⾒見的化學元素，亦被國際癌症研究機構評定是⼀一種致癌物。

本研習會研究甚麼物件最有效於吸收在空氣中的甲醛。我們在測試中將會使⽤用在市場中聲稱能吸收甲醛的物品和其他我們相信能吸收甲醛的⽇日常家居⽤用品。我們亦會尋找⽅方法能提升物品甲醛吸收的有效性和甲醛對於所⽤用吸收⽤用品的影響。在進⾏行任何關於物件吸收甲醛的有效性的實驗前，我們也會測試在⽇日常家居中的甲醛濃度從⽽而更加了解吸收甲醛的必要性。


Objective

To determine the most effective, yet cheaper way to absorb formaldehyde after knowing the concentration of formaldehyde present at home.

Hypothesis

A normal household contains some formaldehyde. Plants are more efficient for lowering level of formaldehyde as we think that it absorbs and breaks down formaldehyde whereas formaldehyde may only be adsorbed by others. We also believe that light, surface area, and a higher concentration increase absorption rate.

More on Formaldehyde

Formaldehyde is used in building materials and production of household products like paints. It may lead to headaches, nosebleeds or even respiratory diseases like nasal cancer.

More on Phytoremediation

What is it?

The treatment of environmental problems (bioremediation) through the use of plants that mitigate the environmental problem without the need to excavate the contaminant material and dispose of it elsewhere.

How does it Work?

1. Roots take in water and nutrients from the contaminated soil, sediment, or groundwater

2. Contaminants are “cleaned up” by the following processes:

• Store the contaminants in the roots, stems, or leaves.

• Convert contaminants to less harmful chemicals within the plant

• Convert contaminants to vapors, which are released into the air

• Adsorb contaminants onto their roots where very small organisms called “microbes” (such as bacteria) that live in the soil break down the sorbed contaminants to less harmful chemicals.


How does it fit into our investigation?

Even though usually phytoremediation refers to the absorption of substances through the roots of a plant from soil or water, we hypothesis that plants can also absorb volatile contaminants via stomata and the substances can then be degraded through similar processes mentioned above.


Results and Analysis

Phase 1: Determine if amount of formaldehyde in normal household is high enough to cause harm.

0.125mgm-3 is the minimum amount of formaldehyde that can cause health damage according to our research.

Part 1:

Results:

All but the bathroom exceeds 0.125mgm-3. The drawer has greatest amount of formaldehyde present. The bathroom has lowest concentration of formaldehyde (0.092mgm-3) as the walls are covered by tiles, not paint.

Part 2:

The maximum amount of formaldehyde recorded in a box with 100g of the paint is 1.84mgm-3, nearly 15 times of 0.125mgm-3. The level of formaldehyde is still rising after we take the last reading so it may contain even more formaldehyde.

Combining the data, formaldehyde is still abundant since low or no-formaldehyde paints can still cause health damages and cheaper paints with more formaldehyde is often used. Investigation on absorption is necessary.


Concentration of formaldehyde at Different Places of an Apartment

Form

alde

hyde

Con

cent

ratio

n / m

gm-3

0

0.175

0.35

0.525

0.7

Place

Closet Living Room Bedroom Bathroom Drawer TV Cabinet

Concentration of formaldehyde that is considered to be harmfulConcentration of formaldehyde

Phase 2: Investigate the formaldehyde absorption capability of various household items and items that claim to be able to absorb formaldehyde.

Results:

The gaps in the lines of the graph, which will also appear in other graphs, are due to instrument limitations.

Aloe records the highest rate of absorption with a maximum of 18.85 µl of formaldehyde absorbed per 100g at the 630th minute, which is higher than that of bamboo charcoal and the absorption pack which claim being able to reduce level of formaldehyde present drastically. Pineapple is the least efficient.

Absorption of formaldehyde of all items reaches maximum point at around 630 minutes and drop drastically afterwards.

There is slight increase in the formaldehyde level at the last minutes in some tests. We hypothesised items release formaldehyde absorbed.


Formaldehyde Absorbed Over 24 Hours per 100 cm2 Surface Area

Form

alde

hyde

Abs

orbe

d pe

r 100

cm

2 / m

gm-3

cm-2

0

2

4

6

8

Time / h

0 4 8 12 16 20 24

Pineapple FruitBamboo CharcoalFormaldehyde Absorb PackAloe

Formaldehyde Absorbed Over 24 Hours per 100 g

Form

alde

hyde

Abs

orbe

d pe

r 100

g /

mgm

-3g-

1

0

5

10

15

20

Time / h

0 4 8 12 16 20 24

Pineapple FruitBamboo CharcoalFormaldehyde Absorb PAckAloe

Phase 3: Investigate the amount of formaldehyde released by the items after they have been put into a box with formaldehyde for 24 hours.

Data:

The result shows all items except aloe release formaldehyde absorbed. Our hypothesis is proved correct for all items except aloe.

There is no general trend of release rate shown there are different formaldehyde release paces.. Though the formaldehyde released is a lot lower than amount absorbed, it should be noted that the formaldehyde level in the box is rising towards the end. The items have not finished releasing formaldehyde.

Combining results from Phase 2 and 3, aloe is most suitable for absorbing formaldehyde as it absorbs the most formaldehyde and releases none. We believe plants are efficient at absorbing formaldehyde. Hence, we would investigate the absorption power of other plants.

For bamboo charcoal and formaldehyde absorb pack, claiming to absorb formaldehyde, they are not as efficient as they claim.


Formaldehyde Released Over 24 Hours per 100 cm2 Surface Area

Form

alde

hyde

Rel

ease

d pe

r 100

cm

2 / m

gm-3

cm-2

0

0.08

0.16

0.24

0.32

0.4

Time / h

0 4 8 12 16 20 24


Formaldehyde Released Over 24 Hours per 100 g

Form

alde

hyde

Rel

ease

d pe

r 100

g /

mgm

-3g-

1

0

0.24

0.48

0.72

0.96

1.2

Time / h

0 8 12 16 20 24


Phase 4: To compare the formaldehyde absorption of 3 Different Plants.

First, we compared the formaldehyde absorption of the three plants over 24 hours. The results:

Aloe’s rate of formaldehyde absorption is the highest with the maximum of 2.58 µl formaldehyde adsorbed per 100cm2 and 18.85 µl of formaldehyde absorbed per 100g at the 630th minute. Plants absorb more formaldehyde than household items in Phase 2.


Formaldehyde Absorbed by Different Plants per 100cm2 of Surface Area

over 24 hours

Form

alde

hyde

Abs

orbe

d pe

r 100

cm

2 / m

gm-3

cm-2

0

0.75

1.5

2.25

3

Time (h)

0 4 8 12 16 20 24

Spider PlantAloeGoden Pothos

Formaldehyde Absorbed by Different Plants per 100g over 24 Hours

Form

alde

hyde

Abs

orbe

d pe

r 100

cm

2 / m

gm-3

g-1

0

5

10

15

20

Time (h)

0 4 8 12 16 20 24

Spider PlantAloeGolden Pothos

Results for release of formaldehyde after absorption:

Both aloe and Golden pothos release no formaldehyde. All plants, even for spider plant which releases most, records lower amount of formaldehyde released compared with other items in Phase 3. We think this is because plants can transform organic toxic substances according to our research. It proves that formaldehyde is absorbed by phytoremediation.

Combining the result, aloe is the best among three plants tested. Hence, it is recommended to use aloe for absorption.


Formaldehyde Released Over 24 Hours per 100 cm2 Surface Area of 3

Different Plants

Form

alde

hyde

Rel

ease

d pe

r 100

cm

2 / m

gm-3

cm-2

0

0.001

0.002

0.002

0.003

Time / h

0 4 8 12 16 20 24

AloeSpider PlantGolden Pothos

Formaldehyde Released Over 24 Hours per 100 cm2 Surface Area of 3

Different Plants

Form

alde

hyde

Rel

ease

d pe

r 100

g /

mgm

-3g-

1

0

0.025

0.05

0.075

0.1

Time / h

0 4 8 12 16 20 24

AloeSpider PlantGolden Pothos

Phase 5: Investigate the different factors that affect the rate of formaldehyde absorption.

We further investigate in the effect of light, surface area, and concentration of formaldehyde on the rate of formaldehyde absorption.

Part 1: Light’s Effect

The results:

The aloe in the dark absorbs less formaldehyde as absorption of formaldehyde in plants may be related to photosynthesis.


A Comparism of the Amount of Formaldehyde Absorbed Over 24

Hours per 100 cm2 Surface Area of Aloe Under Light and In the Dark

Form

alde

hyde

Abs

orbe

d pe

r 100

cm

2 / m

gm-3

cm-2

0

0.75

1.5

2.25

3

Time / h

0 4 8 12 16 20 24

Aloe under LightAloe in the dark


Hours per 100 g of Aloe Under Light and In the Dark

Form

alde

hyde

Abs

orbe

d pe

r 100

g /

mgm

-3g-

1

0

5

10

15

20

Time / h

0 4 8 12 16 20 24

Aloe under LightAloe in the dark

Part 2: Surface Area’s Effect

Results:

Generally, formaldehyde absorb pack of larger surface area is more efficient at absorbing formaldehyde though the difference is unclear in last 800 minutes. A possible explanation is absorption pack of larger surface area absorbed more formaldehyde in first 600 minutes than the one with smaller surface area, hence reaches saturation sooner than the other.

Still, greater surface area increases rate of formaldehyde absorption. For plants, it is because there are more pores for formaldehyde to enter if the leaves have higher surface area. Hence, aloe with greater surface area should be chosen.


A Comparism of Formaldehyde Absorbed by Formaldehyde Absorb Pack of Same Mass but Different Surface Area

Form

alde

hyde

Abs

orbe

d (m

gm-3

)

-2.25

0

2.25

4.5

6.75

9

Time / h

0 4 8 12 16 20 24

Formaldehyde Absorb Pack Larger Surface AreaFormaldehyde Absorb Pack Smaller Surface Area

Part 3: Formaldehyde Concentration Effect

Results:

Aloe absorbs more formaldehyde in an environment with a high concentration of formaldehyde. A possible explanation is there is a lower possibility for the formaldehyde to enter the pores of the leaves at lower concentration.

The difference in the amount of formaldehyde adsorbed is greater than the difference in the formaldehyde concentration, explaining why the amount of formaldehyde drops drastically after the items have absorbed formaldehyde for some time in all other tests on formaldehyde absorption power.


A Comparism of the Amount of Formaldehyde Absorbed by Aloe Over 24 Hours at Different Concentration of Formaldehyde

Form

alde

hyde

Abs

orbe

d (m

gm-3

)

-2.50

0.00

2.50

5.00

7.50

10.00

Time / h

0 4 8 12 16 20 24

High Concentration (5µl)Low Concentration (2.5µl)

Phase 6: To investigate if Leaves Detached from the Plant are able to Absorb Formaldehyde.

Results:

The detached leaves appear to be better at absorbing formaldehyde than the plant with a maximum of 95.34mgm-3 per 100 gram and 2.42 mgm-3 per 100 cm2 at 630th minute. However, we believe detached leaves may not be better at absorption because concentration of formaldehyde decreases as the rate of absorption of formaldehyde decreases. There might be a maximum level of formaldehyde that can be absorbed. The formaldehyde absorbed by the detached leaves and the plant itself is actually quite similar, but the entire plant has a much greater surface area and mass, after the amount absorbed is divided by the mass and surface area, the detached leaves seem to be more efficient.

Detached leaves can be used to absorb formaldehyde for absorbing formaldehyde in small spaces where plants don’t fit and at places with high formaldehyde concentration like a newly renovated home though it is more convenient to place the entire plant at a home that is not newly renovate as the leaves do not have to be changed regularly for the leaves to be green.



Hours per 100cm2 of Spider Plant and its Detached Leaves

Form

alde

hyde

Rel

ease

d pe

r 100

cm

2 / m

gm-3

cm-2

0

0.75

1.5

2.25

3

Time / h

0 4 8 12 16 20 24

Spider PlantDetached Leaves of Spider Plant

A Comparism of the Amount of Formaldehyde Released Over 24 Hours

per 100 g of Spider Plant and its Detached Leaves

Form

alde

hyde

Rel

ease

d pe

r 100

g /

mgm

-3g-

1

0

25

50

75

100

Time / h

0 4 8 12 16 20 24

Spider PlantDetached Leaves of Spider Plant

Conclusion

The high formaldehyde concentration in normal household is likely to harm our health. Efforts to absorb formaldehyde at home is needed.

Products claiming to be able to absorb formaldehyde such as paint or bamboo charcoal were proved to be inefficient in adsorption since they release the formaldehyde adsorbed. Plants, especially aloe, are proved to be more efficient, as they absorb more formaldehyde and release less of it after absorption. Natural and easily accessible items can be more efficient than commercial items. It is advised to put aloe or its detached green leaves of large surface area under presence of light for formaldehyde absorption.


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