banana peel

Banana Peel Heavy Metal Water Filter

The Use of Banana Peels as a Heavy Metal Extraction Medium in a Water Filter

Emma Georgiana Hewett

STEM Research Project

Massachusetts Academy of Math and Science

February 21, 2012


1

Table of Contents

Abstract 2

Introduction 3

Literature Review 4

Methodology 11

Results 13

Data Analysis and Discussion 16

Conclusions 20

Limitations and Assumptions 21

Applications and Future Experiments 22

Literature Cited 23

Acknowledgements 24


2

Abstract

Copper and lead toxicity from plumbing and pollution affect otherwise potable water supplies,

and current filtration systems are expensive, unavailable, or introduce harmful chemicals. Developing

areas of the world do not have the resources to filter heavy metals out of contaminated water. The goal

of the current research has been to use the peels of banana (Musa acuminata) to create an inexpensive,

effective, and safe filtration system that will be used in areas where other filtration is not available to

remove heavy metals using absorption, especially lead and copper. Filters were made using dried

banana peels and were tested in trials against water contaminated in a copper and lead pipe. The

contaminated water was tested for copper and lead content and placed in a glass container, where it

was combined with the banana peels. Every five minutes, the heavy metal content was again recorded

and compared. The device has been shown to function effectively. Banana peel water filters may

provide a less expensive, more accessible solution to lead and copper contamination than current

methods.


3

Introduction

As the population and industry of our planet increase, the demand for safer drinking water

grows. Even within developed nations such as the United States of America, clean drinking water is not

always available. Water pollution has become a very critical problem among today's scientific

developments, as it affects every aspect of life globally.

Although there are over 700 defined water contaminates, both organic and inorganic, toxic

heavy metal pollution has been deemed the most dangerous. Lead poisoning from home plumbing

systems, not water supply companies, is the leading cause of lead poisoning in the U.S. today. Up to 20

percent of a child’s lead exposure comes from drinking water. In cities with high-rise buildings, the

problem amplifies as pipes travel farther to reach the faucet. In other areas of the world, there are not

many resources to filter out these dangerous toxins. Banana peels, found on nearly every continent, can

be employed to remove the metals easily and effectively.

In homes older than five years, mineral deposits from the passing water have formed on the

inside of the pipes, protecting it from lead and copper contamination. However, in newer houses, this

coating has not yet formed. Households with pregnant women or young children are in a particularly

dangerous position because lead can cause serious brain and growth problems.


4

Literature Review

Lead Contamination

Lead (Pb) is a bluish colored heavy metal (atomic weight 207). The element is pliable, inflexible,

and fusible. Lead is used for cable covering, construction, ammunition, and batteries. Lead will dissolve

slowly in nitric acid, but it is resistant to corrosion by sulfuric and hydrochloric acids. It is normally found

with the valence states Pb(II) and Pb(IV). The element melts at 327.4°C and boils at 1740°C.

Lead compounds are useful in construction, however are toxic. In general commercial lead ores,

the lead content is approximately 10%, but it can be as low as 3%. Inhalation and absorption can cause

serious damage. Lead poisoning can cause headaches, dizziness, and in some cases, insomnia. In

particularly bad cases, a stupor will progress to a coma and eventually death (Shapino & Johnston,

2008).

Under the Safe Drinking Water Act, the safe amount of lead in drinking water has been

determined to be 0 mg/L. Lead contamination in drinking water can come from the source water or

from lead plumbing. Lead is released into the environment from lead smelting and mining, and the

amount of lead released yearly is approximately 144 million lbs (Drinking water contaminants – lead,

n.d.).

Copper Contamination

Copper (Cu) is an abundant, relatively heavy metal. The metal is nonferrous. The majority of the

uses of copper rely on its high electrical conductivity. Most commonly, copper valences are one and two.

8.96 g/cm3 is the pure solid density of copper at 20°C. Depending on the method of manufacture, the

desity of commercial copper ranges from 8.90–8.94 g/cm3 (Schugar, 2008).


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Copper salts in low levels can act as bacteriocides and algicides. Copper-containing proteins

provide a wide variety of functions in life. Cu is a vital trace element to both plants and animals,

however, it can become poisonous to humans in greater amounts (Schugar, 2008).

Although, smelting and mining of copper is responsible for releasing 450 million lbs of copper

yearly into land and water, copper is rarely found in source water. Copper contamination in water

usually results from copper household pipe corrosion. Because of this, it is difficult to be detected or

controlled by water suppliers. The action level of copper (1.3 mg/L) is the smallest amount of copper

that water systems are required to control. (Drinking water contaminants – copper, n.d.).

Current Heavy Metal Reduction Methods

Methods that have been developed to remove or reduce heavy metals from water include

screening, filtration and centrifugation, micro- and ultra-filtration, crystallization, sedimentation and

gravity separation, flotation, precipitation, coagulation, oxidation, solvent extraction, evaporation,

distillation, reverse osmosis, ion exchange, electro dialysis, electrolysis, and adsorption.

Recent studies to improve water quality have focused on absorption because it is significantly

less expensive than the other techniques. Activated carbon absorption is the most favorable method of

heavy metal filtration. This is partly because of the universal uses of it; activated carbon can be used to

absorb inorganic as well as organic contaminates.

Activated carbon is not used on a large scale because of the high production cost. Lost cost

methods of obtaining activated carbon have been investigated. It is achieved after a two-stage

procedure involving carbonization and activation of the raw material at high temperatures.

Carbonization is the step in which pyro lytic decomposition of precursor occurs together with the

concurrent elimination of many non-carbon species (H, N, O and S). Low molecular weight volatiles and


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hydrogen gas are released from the precursor in this stage. Activation is the stage in which the internal

surface area of the material is increased, usually with catalyst impregnation (Ali, 2010).

Materials from scrap rubber tires have been studied as a potential heavy metal filter. This

technique is beneficial because in addition to water filtration, it also takes advantage of waste tires. On

a wide scale, this method is not employed because of costly operations needed to prepare the semi-

active carbon in the rubber material.

Wastes from the timber industry and other common wastes studied extensively as absorption

mediums. Tree bark, nut shells, walnut shells, waste tea, and coffee are all rich in tannin. The active

absorption substances in tannin are the polyhydroxy polyphenol groups. Saw-dust, lignin, conifer leaves,

peat, shrimp, fly ash, and seaweed were all used similarly. These materials all achieved comparable

heavy metal removal rates. Yet, they are not used extensively because of several drawbacks such as a

water discoloration, an added toxicity, large scale inefficiency, and a high cost of preparation (Ali, 2010).

Black liquor is a waste product of paper production. Lignin, a compound containing organic

carbon, from this black liquor can be effective at filtering heavy metals from contaminated water. This

method of absorption, however, is highly dependent on pH and ionic strength. The future development

of the raw material has potential, although the technology today is not usable.

Fly-ash, the fine particles released with waste gases during combustion, is an intense waste

product from several industries. Recently, the silica in this waste has been shown to reduce heavy metal

content. So far, the tests have promised a confident use in the future, however scientists are still

exploring this material (Ali, 2010).

Scientists have tested other organic materials such as red mud, clays, blast furnace slag,

sediment, and soil for their heavy metal absorption. These materials are far less expensive then

prepared active carbon and have so far revealed an effective metal ion reduction. The lack of research


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and development of these materials has stunted their widespread use. It is also difficult to prepare

these materials for use in a commercial filtration system and often require a costly pretreatment.

Fruit parts, such as olive stones, almond shells, apricot stones, peach stones, palm fruit bunch,

and coconuts, are dried and prepared to be used as absorbers as well. These materials are extremely

economical because they cost as little as 0.01% of produced activated carbon (Ali, 2010).

Banana Peel as an Extraction Medium

Toxic heavy metals in water cause health problems in the population and the environment.

Current methods for minimizing the amount of these dangerous metals in the water supply include lime

precipitation, ion exchange, adsorption into activated carbon, membrane processes, and electrolytic

methods. Some problems with these current methods include a high cost, low affectivity, expensive

equipment, high energy requirements, or toxic waste generation (Thirumavalavan, Lai, Lin, & Lee, 2010).

Activated carbon has become a popular choice for heavy metal removal, however, high costs

and a limited supply of materials has posed problems for this method of absorption. Research has

focused on finding new alternatives to activated carbon and have research such materials as seaweeds,

marine algae, activated sludge biomass, crab shells, coconut shell, and fruit peels and fibers. The

advantages to using fruit peels as the absorption material is that it is readily available and less costly

(Thirumavalavan et al., 2010).

Heavy metals enter the water supply through atmospheric deposition, lixiviation of mining areas

and cultivated fields, and industrial discharges. Researchers are constantly studying materials to find a

way to extract these metals from the water supply. Modified silica, alumina, activated carbon, and resins

are among the materials currently in use. These materials, however, are costly and not considered eco-

friendly.


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This has shifted the search to find natural products to extract metal ions from water. Sugar cane,

bagasse, peanut shells, and apple waste are successful metal extracting materials, according to studies.

These materials all contain carboxylic and phenolic acid groups. (Castro et al., 2011).

In a banana peel (Musa acuminata), the biochemical components include cellulose,

hemicellulose, chlorophyll pigments, and pectin substances, which contain galacturonic acid, arabinose,

galactose, and rhamnose. Galacturonic acids cause the pectin to strongly bind to the metal ions because

of the carboxyl functions of the sugar. Cellulose also allows heavy metals to bind, according to research

(Thirumavalavan et al., 2010).

Scientists from the São Paulo State University in Brazil tested minced, dried banana peel,

commonly considered waste, for the extraction of copper and lead ions from contaminated water.

During these tests, scientists determined that it took only about twenty minutes for the concentration of

Cu and Pb to reach equilibrium. The relatively high speed of reaching equilibrium in this process is

important to note (Castro et al., 2011).

Another set of scientists in Taiwan tested banana peels and other fruit peels for their use as

heavy metal extractors. Before the tests, the bananas were washed more than five times to remove any

dirt and moisture that may affect the results. They were then dried in for 48 hours in an oven of 50°C.

These tests showed that the carboxyl and hydroxyl groups of cellulose content will directly affect the

absorption capacity (Thirumavalavan et al., 2010).

The minced banana peel can be used efficiently in an acidic medium; this process reached more

than 90% retention in pH 3 and 98% retention in pH 4 and 5. Below a pH 3, however, the technique is

less effective. This is because carboxylic acids, the main functioning group in metal ion extraction,

undergo protonation in a high H+ concentration. This material was not tested in solutions above pH 5. At

a higher pH of a 6 or 7, the banana peels should still be functional as an extraction medium, but to a

lesser degree Prof. Federico Guazzone noted (personal communications).


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The maximum extraction capacity of Cu was 0.30 mmol g-1 and of Pb was 0.20 mmol g-1. The

difference in the extraction maximum between copper and iron is because carboxylic groups are

regarded as hard bases and have a higher affinity for intermediate or hard acids. Cu ions are

intermediate acids, while Pb ions are considered soft acids because of a higher polarizability larger ionic

radius, causing a lesser extraction result.

The data from these tests showed that the extraction efficiency of the minced banana peel

material at an anion concentration of 10 mg L-1 is about 97-98%. It was also observed that with a

concentration of anions above 10 mg L-1, the efficiency of extraction does not decrease significantly. The

scientists conducting these experiments concluded that banana peel can be employed to extract copper

and lead heavy metal ions from raw river water.

Table 1 compares the absorption rates of Cu and Pb by other materials, obtained from other

studies to the absorption rates of the minced banana peel. Comparing the proposed materials, minced

banana peel seems to be the most appealing option, not only because of its high extraction rates, but

because of its low cost and accessibility. Unlike other materials studied and employed, the minced

banana peel requires no modification. With a high stability, the banana peel can be used for at least 11

cycles before becoming less efficient (Castro et al., 2011).

Type of material Cu(II) (mmol g-1

) Pb(II) (mmol g-1

)

Na-bentonite 0.108

AMP-modified silica gel 0.447 0.380

herbicide-modified silica gel 0.442

modified peanut husk 0.159 0.140

sawdust 0.104 0.106

expanded perlite (EP) 0.136 0.064

minced banana peel 0.330 0.200

Table 1. Copper and lead extraction capacity of various materials

(based on Castro et al., 2011)


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Research Plan

Engineering Problem

Adverse health problems due to harmful copper and lead poisoning affect many communities

through the water supply, and current filtration systems are expensive, unavailable, or they themselves

add harmful chemicals.

Engineering Goal

The goal of this project is to use banana peels to create an inexpensive, effective, and safe

filtration system that will be used in areas where safe drinking water is inaccessible to remove heavy

metals, especially lead and copper.

Construction

The majority of the work will occur at home. Bananas from a local grocery store will be used.

The banana peel will be dried in a food dehydrator and cut up to varying sizes with a standard kitchen

knife.

At home, banana peels will be dried and placed into a sack made out of various materials (coffee

filters and cheesecloth). The sack will then be placed in the coffee press (Melior brand, glass container,

metal insert, 1,005.5 ml) with the contaminated water. Copper and lead contaminated water will be

obtained from leaving lukewarm water inside a pipe (copper pipe, with melted lead insert, 4cm

diameter, roughly 88cm in length) for at least 24 hours.

The water being used will come directly from the pipe. The copper and lead levels of the water

will be measured immediately before being put into the filtering device with a copper water content test

and a lead water content test and at different times afterward. The test results will be compared.


11

Methodology

Bananas (Musa acuminata, slightly green, approximately 20 cm in length) were obtained, and

the bananas were washed with soap and water and rinsed well. They were then peeled. Any of the fruit

on the inside of the banana peels that still remained was removed with a knife so that only the peel

remained. The peels then were sliced into sizes manageable for a food processer (Oskar Jr. Chopper Plus

Food Processor Slicer, Sunbeam brand). They were then processed in the food processer until the pieces

of banana peel were approximately 2 mm pieces. Another setting of banana peels were cut into 50 mm

squares, 100 mm squares, and 150 mm squares.

The banana peels were then placed on a sheet of wax paper (wax-side down, cut to fit in the

tray) inside a food dehydrator (five-tray, electric) at approximately 95° C. The peels were placed on the

top two trays, and the air vents on both the top and bottom were set to level two. The banana peels

were left in the dehydrator for twenty hours. The peels were then removed from the dehydrator. The

smallest pieces of banana peel were ground using a mortar and pestle.

The remainder of the procedure was done in a 28°C room. A pipe (copper, lead soldering, with

solid lead inserts melted to either end of it, (4cm diameter, approx. 88cm in length) was filled with water

(from home tap, well water, room temperature). The water was allowed to sit in the pipes for at least

twenty-four hours.

After twenty-four hours, the water was emptied into the glass container of a coffee press

(Melior brand, glass container, metal insert, 1,005.5 ml). Using a copper test (Pool Check,3-in-1 Pool &

Spa Test Strips: Copper, total alkalinity, pH) and a lead test (Abotex, Lead Inspector Lead Test Kit, most

surfaces), the levels of copper and lead were recorded.

A sack was made out of coffee filters (Melitta, Junior basket filters, 4-6 cup). Four coffee filters

were hand-sewed around the edges and the peels were placed in the sack so that two layers of coffee


12

filters were surrounding the peels. The sack was sewed shut and was introduced into the water in the

container. Every five minutes, the levels of copper and lead in the water were again recorded.


13

Results

All test samples were done with 300 ml of water and 30 ml of banana peels.

150 mm dried banana peel pieces

Copper Content Lead Content

Time (min)

0 5 10 15 20 25 30 0 5 10 15 20 25 30

mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L

T1 2.0 1.5 1.5 0.7 0.4 0.2 0.2 10.0 7.0 5.0 4.0 2.0 2.0 2.0

T2 2.0 1.5 1.5 0.7 0.4 0.2 0.1 8.0 5.0 3.0 2.0 2.0 1.0 <1.0

T3 2.0 1.5 1.0 0.7 0.5 0.3 0.2 10.0 7.0 5.0 3.0 2.0 2.0 1.0

T4 2.0 1.5 0.7 0.7 0.5 0.3 0.3 5.0 4.0 3.0 2.0 1.0 1.0 <1.0

T5 2.0 1.5 1.0 0.7 0.5 0.3 0.3 6.0 5.0 4.0 3.0 2.0 1.0 1.0

T6 2.0 1.5 0.7 0.5 0.3 0.3 0.3 4.0 3.0 3.0 2.0 1.0 1.0 1.0

T7 2.0 1.5 0.7 0.5 0.3 0.3 0.3 4.0 3.0 2.5 2.0 2.0 2.0 2.0

T8 2.0 1.7 0.9 0.7 0.5 0.4 0.4 4.0 3.0 1.5 1.0 1.0 1.0 1.0

T9 2.0 1.7 0.9 0.7 0.5 0.3 0.3 5.0 4.0 3.0 2.0 1.0 1.0 <1.0

Average 2.0 1.5 1.0 0.7 0.4 0.3 0.3 6.3 4.6 3.3 2.3 1.6 1.3 1.3

contaminated water

banana peels contained in

a coffee filter bag

mesh plate (prevents banana peels from exiting when water is poured)

Table 2. Test results of the device with the use of 150mm square dried banana peel. The lead and copper contents were recorded every five minutes in the table below. During these tests, there was no noticeable debris left in the water, but there was a brownish, visible discoloration. The pH of the water remained at 6 throughout.

Figure 1. Diagram of the banana peel heavy metal extraction device. The water is poured into the container, and the

banana peels (contained in the coffee filter bag) are introduced into the water. The cover (and attached mesh plate) is

replaced and the container is left to sit for at least 20 minutes. The mesh plate is not a necessary feature, but is helpful

when pouring to keep the coffee filter inside the container.


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Time (min)

0 5 10 15 20 25 30 0 5 10 15 20 25 30


T1 2.0 1.0 0.4 3.0 2.0 <0.1 <0.1 10.0 5.0 4.0 2.5 <1.0 <1.0 <1.0

T2 2.0 1.5 1.5 0.7 0.4 0.2 0.1 8.0 5.0 3.0 2.0 2.0 1.0 <1.0

T3 2.0 1.5 1.0 0.7 0.5 0.3 0.2 10.0 7.0 5.0 3.0 2.0 2.0 1.0

T4 2.0 1.5 1.5 0.7 0.5 0.4 0.2 5.0 4.0 3.0 2.5 2.5 2.0 2.0

T5 2.0 1.0 0.7 0.4 0.3 0.1 0.1 6.0 4.0 3.0 2.0 1.0 <1.0 <1.0

T6 2.0 1.0 0.7 0.5 0.3 0.2 0.2 3.0 1.5 1.0 1.0 1.0 1.0 1.0

T7 2.0 1.0 0.7 0.5 0.3 0.3 0.3 4.0 2.0 1.5 1.0 <1.0 <1.0 <1.0

T8 2.0 1.5 0.7 0.7 0.4 0.2 <0.1 4.0 3.0 1.5 1.0 1.0 1.0 1.0

T9 2.0 1.5 1.5 0.9 0.5 0.4 0.3 5.0 4.0 3.0 2.5 2.0 2.0 2.0

Average 2.0 1.3 1.0 0.9 0.6 0.3 0.2 6.1 3.9 2.8 1.9 1.5 1.0 1.0



Time (min)

0 5 10 15 20 25 30 0 5 10 15 20 25 30


T1 2.0 1.0 0.4 0.2 0.1 <0.1 <0.1 10.0 5.0 3.0 5.0 <1.0 <1.0 <1.0

T2 2.0 1.0 0.7 0.5 0.4 0.2 0.1 8.0 4.0 2.0 1.0 <1.0 <1.0 <1.0

T3 2.0 0.9 0.5 0.3 0.2 0.1 <0.1 10.0 5.0 3.0 2.0 1.0 <1.0 <1.0

T4 2.0 1.0 0.7 0.5 0.3 0.1 <0.1 5.0 3.0 2.0 1.5 1.0 <1.0 <1.0

T5 2.0 1.0 0.7 0.5 0.3 0.1 0.1 6.0 4.0 3.0 2.0 1.0 <1.0 <1.0

T6 2.0 1.0 0.7 0.3 0.1 <0.1 <0.1 4.0 2.0 1.5 1.0 <1.0 <1.0 <1.0

T7 2.0 1.0 0.5 0.2 <0.1 <0.1 <0.1 4.0 2.0 1.5 1.0 <1.0 <1.0 <1.0

T8 2.0 1.0 0.7 0.5 0.4 <0.1 <0.1 5.0 2.0 1.0 <1.0 <1.0 <1.0 <1.0

T9 2.0 1.0 0.7 0.5 0.3 0.1 0.1 5.0 3.5 2.0 1.5 1.0 <1.0 <1.0

Average 2.0 1.0 0.6 0.4 0.3 0.1 <0.1 6.4 3.4 2.1 1.9 <1.0 <1.0 <1.0

Table 3. Test results of the device with the use of 100mm square dried banana peel. The lead and copper contents were recorded every

five minutes in the table below. Once again, no debris was left in the water, but a brownish discoloration of the water was noticed. The

pH remained at 6.

Table 4. Test results of the device with the use of 50mm square dried banana peel. The lead and copper contents were recorded every

five minutes in the table below. There was no debris or discoloration. The pH remained 6.


15

2 mm banana peel pieces, undried


Time (min)

0 5 10 15 20 25 30 0 5 10 15 20 25 30


T1 2.0 1.5 0.7 0.4 0.2 0.1 <0.1 10.0 6.0 5.0 4.0 2.0 2.0 1.5

T2 2.0 1.5 1.0 0.7 0.4 0.2 0.2 8.0 5.0 4.0 3.0 1.0 1.0 1.0

T3 2.0 1.5 0.7 0.5 0.3 0.2 0.1 10.0 7.0 5.0 3.0 3.0 2.0 1.0

T4 2.0 1.5 1.0 0.7 0.4 0.2 0.2 5.0 3.5 3.0 2.5 2.0 1.5 1.0

T5 2.0 1.5 1.0 0.7 0.5 0.2 0.2 6.0 4.0 3.0 2.0 2.0 2.0 2.0

T6 2.0 1.5 0.7 0.5 0.3 0.2 0.2 4.0 4.0 3.0 2.0 1.5 1.5 1.5

T7 2.0 1.5 0.9 0.5 0.3 0.2 0.2 4.0 3.0 2.5 1.5 1.0 1.0 1.0

T8 2.0 1.5 1.0 0.7 0.4 0.2 0.2 5.0 5.0 4.0 3.0 2.0 1.0 <1.0

T9 2.0 1.5 1.0 0.7 0.4 0.2 0.2 5.0 3.5 3.0 2.0 1.5 1.0 1.0

Average 2.0 1.5 0.9 0.6 0.4 0.2 0.2 6.4 4.6 3.6 2.6 1.8 1.4 1.3

Dried powdered banana peel


Time (min)

0 5 10 15 20 25 30 0 5 10 15 20 25 30


T1 2.0 1.0 0.4 0.2 <0.1 <0.1 <0.1 10.0 5.0 2.0 2.0 <1.0 <1.0 <1.0

T2 2.0 0.7 0.4 0.2 0.1 0.1 <0.1 8.0 4.0 2.0 1.0 <1.0 <1.0 <1.0

T3 2.0 1.0 0.7 0.4 0.2 <0.1 <0.1 10.0 7.0 4.0 2.0 1.0 <1.0 <1.0

T4 2.0 1.0 0.5 0.3 0.2 0.1 <0.1 5.0 3.0 2.0 1.5 1.0 <1.0 <1.0

T5 2.0 0.7 0.5 0.3 0.1 <0.1 <0.1 6.0 4.0 3.0 2.0 1.0 <1.0 <1.0

T6 2.0 1.0 0.4 0.2 <0.1 <0.1 <0.1 4.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

T7 2.0 1.0 0.7 0.4 0.2 <0.1 <0.1 4.0 2.0 1.0 <1.0 <1.0 <1.0 <1.0

T8 2.0 1.0 0.4 0.2 <0.1 <0.1 <0.1 5.0 2.0 1.5 1.0 <1.0 <1.0 <1.0

T9 2.0 0.7 0.4 0.1 <0.1 <0.1 <0.1 5.0 2.0 1.5 1.0 <1.0 <1.0 <1.0

Average 2.0 0.9 0.5 0.3 0.1 <0.1 <0.1 6.4 3.6 2.1 1.5 <1.0 <1.0 <1.0

Table 5. Test results of the device with the use of undried, 2mm banana peel pieces. The lead and copper contents were recorded every

five minutes in the table below. In these tests, the bananas were minced as small as possible, but not dried. There is still a recordable

effect on the water. The pH was 6. The water color turned a slight brownish-yellowish.

Table 6. Test results of the device with the use of dried, powdered banana peel. The lead and copper contents were recorded every five

minutes in the table above. The lost copper and lead results were achieved using dried peels. There was no debris or discoloration. The

pH was 6 throughout.


16

Data Analysis and Discussions

0.0

0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30

Co

pp

er

Co

nte

nt

(mg/

L)

Time (minutes)

Dried Banana Peel and Undried Banana Peel Copper Content vs. Time

Dried, powdered

Undried, 2 mm


Time (min)

0 5 10 15 20 25 30 0 5 10 15 20 25 30


Dried, powdered

2.0 0.9 0.5 0.3 0.1 <0.1 <0.1 6.4 3.6 2.1 1.5 <1.0 <1.0 <1.0

Undried, 2 mm

2.0 1.5 0.9 0.6 0.4 0.2 0.2 6.4 4.6 3.6 2.6 1.8 1.4 1.3

Dried, 50 mm

2.0 1 0.6 0.4 0.3 0.1 <0.1 6.4 3.4 2.1 1.9 <1.0 <1.0 <1.0

Dried, 100 mm

2.0 1.3 1 0.9 0.6 0.3 0.2 6.1 3.9 2.8 1.9 1.5 1 1

Dried, 150 mm

2.0 1.5 1 0.7 0.4 0.3 0.3 6.3 4.6 3.3 2.3 1.6 1.3 1.3

Table 7. Data summary table. The averages of the 9 trials from each setting were placed in the table below. The dried,

powdered banana peel achieved the greatest results, however, every setting successfully reduced the copper and lead

contents.

Figure 2. Dried banana peel and undried banana peels copper content against time. The dried banana peels are

represented by the blue dots and the undried banana peels, and the undried banana peels are represented by the red

dots.


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According to the data, the banana peels function better when dried than when undried when

the pieces of similar sizes. With an average copper content level of 2.0 mg/L at time 0 minutes, the dried

banana peels reduced the copper content to less than 0.1 mg/L after 20 minutes. The undried banana

peels are still effective, reducing a 2.0 mg/L to 0.2 mg/L after 20 minutes. The lead content varied at

time 0 from test to test, but the average lead content at time 0 minutes was 6.4 mg/L. After 20 minutes,

the dried banana peels brought the lead level down to less than 1.0 mg/L, and the undried banana peels

brought the lead down to 1.3 mg/L. The undried banana peels had also left a brownish-yellow

discoloration in the water.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0 5 10 15 20 25 30

Lead

Co

nte

nt

(mg/

L)

Time (minutes)

Dried Banana Peel and Undried Banana Peel Lead Content vs. Time

Dried, powdered

Undried, 2 mm

Figure 3. Dried banana peel and undried banana peels lead content against time. The dried banana peels are represented

by the blue dots and the undried banana peels, and the undried banana peels are represented by the red dots.


18

0.6

1.6

2.6

3.6

4.6

5.6

0 5 10 15 20 25 30

Lead

Co

nte

nt

(mg/

L)

Time (minutes)

Size of Banana Peel Lead vs. Time

Dried, Powdered

Dried, 50 mm

Dried, 100 mm

Dried, 150 mm

0.0

0.5

1.0

1.5

2.0

0 5 10 15 20 25 30

Co

pp

er

Co

nte

nt

(mg/

L)

Time (minutes)

Size of Banana Peels Copper vs. Time

Dried, powdered

Dried, 50 mm

Dried, 100 mm

Dried 150 mm

Figure 3. Dried banana peel compared as powder, 50 mm pieces, 100 mm pieces, and 150 mm pieces for lead against

time. The graph above is based on the data from the summary table above. All of the settings successfully reduced the

lead content.

Figure 4. Dried banana peel compared as powder, 50 mm pieces, 100 mm pieces, and 150 mm pieces for copper against

time. The same shape can be observed with all of the sizes of the pieces. The reduction levels off around 20 minutes.


19

The powdered banana peels performed the best. The 50 mm pieces had very similar results as

the powdered peels, especially in the copper test. The discoloration of the water occurred most

frequently in the larger pieces. When the 150 mm and 100 mm pieces were introduced into the water,

they created a brownish discoloration in the water.

All of the settings begin to level off at about 20 minutes. This can especially be seen with the

powdered banana peels where the last three data points are the same reading. After 20 minutes, the

dried and powdered banana peels had eliminated at least 95% of the copper and at least 84% of the

lead at a pH of 6. There was no discoloration of the water with the use of the powdered peels, and only

minor debris was left in the water, if any at all.


20

Conclusions

The project met the design goal in that the device is an inexpensive, effective, and safe filtration

system. The final device takes advantage of the carboxylic and phenolic acid groups that can be found in

the peels of banana. This device can be beneficial to communities with polluted water for various

reasons. First and foremost, this device and method remove almost all traces of copper and lead from

drinking water. Second, banana peels are generally considered an unwanted product, helping to reduce

waste. Third, the device is easy to construct and operate. To maximize the results of this device, the

banana peels should be dried and powdered. For 300 ml of water, about 35 ml of dried, powdered

banana peels (equivalent to about one average sized banana) is sufficient to filter out a significant

amount of lead and copper. With a pH of 6, a near-neutral pH, the filters still functioned. The conditions

in this experiment are very easy to replicate in developing areas, and these filters can reduce the copper

content in water by at least 95% and the lead content by at least 84%.


21

Limitations and Assumptions

In the design of this device, it was assumed that peoples in communities with fewer resources

and contaminated water would have knowledge of a heavy metal health problem and would want to

use this method to filter their water. Furthermore, it was presumed that these communities would have

access to bananas.

The bananas that were used in this experiment were assumed to have comparable results to

those used by other peoples from other climates. Limited by wet weather, short days, freezing outdoor

temperatures, and time inconvenience, a food dehydrator replaced sun drying the banana peels. The

amount of time the banana peels were in the food dehydrator varied for up to two hours among

instances because timing conflicts. Other inconsistencies may have been in the size of each piece of

banana peel, the ripeness of each banana, and the amount of contamination in each water sample. The

temperature and pH of the water and test room were controlled as much as possible.

There were limitations with the aquarium and pool tests used to test the water for copper and

lead. Both tests did not measure the levels to a very accurate degree. This was especially a problem with

the case of the lead test as the amount of lead lowered closer to 0 ppm. At this point, this data had to be

described as being less than one part per million.


22

Applications and Future Experiments

The heavy metal banana filter provides a more affordable means of removing heavy metals from

water. This is an ecologically friendly method using renewable, naturally abundant resources. The filter

can be applied in areas where water is contaminated, but no other means of removal is available or

reasonably feasible. The filter is useable in the current state and will help to greatly reduce eliminate

traces of copper or lead in water. Developing countries and remote communities would especially find

this device practical. The device can be furthered with an improved system to insert the banana peels.

The coffee filter (crepe paper) is a cheap material, but is not naturally available in every part of the

world. Other directions for research may include an in depth study of sun drying the peels rather than

dehydrating with a food dehydrator. To maximize the effects of the banana peels, an exploration of the

effects of pH and amount of banana peels.


23

Literature Cited

Ali, I. (2010). The quest for active carbon adsorbent substitutes: Inexpensive adsorbents for toxic metal

ions removal from wastewater, separation & purification reviews. Separation & Purification

Reviews, 39(3-4), 95-171. Retrieved from http://dx.doi.org/10.1080/15422119.2010.527802

APEC. (n.d.). Drinking water contaminants - copper. Retrieved from http://www.freedrinkingwater.com

APEC. (n.d.). Drinking water contaminants - lead. Retrieved from http://www.freedrinkingwater.com

Castro, R. S. D., Caetano, L., Ferreira, G., Padilha, P. M., Saeki, M. J., Zara, L. F., Martines, M. A. U., &

Castro, G. R. (2011). Banana peel applied to the solid phase extraction of copper and lead from

river water: Preconcentration of metal ions with a fruit waste. Industrial & Engineering

Chemistry Research, 50(6), 3446-3451. Retrieved from pubs.acs.org/IECR

Schugar, H. (2008). Copper. In Access science McGraw-Hill Companies. Retrieved from

http://www.accessscience.com

Shapino, H., & Johnston, J. D. (2008). Lead. In Access science McGraw-Hill Companies. Retrieved from

http://www.accessscience.com

Thirumavalavan, M., Lai, Y. L., Lin, L. C., & Lee, J. F. (2010). Cellulose-based native and surface modified

fruit peels for the adsorption of heavy metal ions from aqueous solution: Langmuir adsorption

isotherms. American Chemical Society, 55, 1186-1192. Retrieved from

http://portal.acs.org/portal/acs/corg/content

United States Environmental Protection Agency. (2011, October 04). Actions you can take to reduce lead

in drinking water. Retrieved from http://water.epa.gov/drink/info/lead/lead1.cfm

http://dx.doi.org/10.1080/15422119.2010.527802

http://www.accessscience.com/

http://www.accessscience.com/

http://portal.acs.org/portal/acs/corg/content

http://water.epa.gov/drink/info/lead/lead1.cfm


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Acknowledgements

The author wishes to thank several mentors who assisted in various aspects of this project. Mrs.

Julia Nasrani-Wildfong, her advisor, provided ongoing guidance and support. Her parents willingly

contributed time, funding, and space in the basement to perform the tests. The author would also like

to thank Dr. Judith Sumner for her guidance with the paper, her advice throughout my project, and the

initial inspiration for the water filter. Finally, she expresses gratitude to Mike Frias for providing her with

a copper and lead pipe to contaminate water.

banana peel

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