Exploiting Properties of Chitosan to Purify Water Chitosan Optimization as a Drinking Water Treatment in Developing Countries Samar T. Adhami, Kevin A. Carpio, Brandon L. Chin, Sung Jun Jang, Kevin Reuter

Faculty Advisor: Dr. James N. Jensen

Undergraduate Academies

Abstract Many developing countries in Africa do not have access to drinking

water since most of the water sources are contaminated. Natural

polyelectrolytes, such as chitosan, are being tested for its

effectiveness as coagulants in water treatment. Chitosan is a poly N-

acteyl-glucosamine biopolymer that is a natural cationic

polyelectrolyte, not toxic and biodegradable. Chitosan is produced

from chitin, a structural element in the exoskeleton of crustaceans,

and is estimated to be produced annually almost as much as

cellulose. The purpose of this research is to test its ability as a

pollution coagulant in water since these particles are electronegative

charged. We identified the optimal concentration of chitosan in dirty

water to coagulate the pollutants and be able to separate easily the

precipitate from water.

Exploring Chitosan

A major concern in the world is water contamination.

Microorganisms and substances harmful to the human body pose a

threat to societies around the globe. Clean drinking water has become

scarce in numerous communities because of these contaminates.

Developing regions are the ones who have trouble finding ways to

filter harmful material. There are certain substances discovered today

that can aid in the filtration of contaminated water. Most of these

substances are cheap while being commonly found in most regions.

Chitosan is one such substance that plays a role in filtrating water.

Chitosan is a chitin derivative that is found in the exoskeleton of

crustaceans, which include crabs, lobsters, and shrimps. The linear

polysaccharide is made by treated shells with alkali sodium hydroxide.

This substance is a weak base and is insoluble in water. It can be

dissolved in acidic solutions with a pH of 6.0 and under, however it is

in soluble in sulfuric and phosphoric acids. Due to its cationic nature,

chitosan absorbs negatively charged particles in solutions. The

particles will conglomerate and settle in the water more easily for

filtration. The substance tends to agglomerate or form a gel in

aqueous solutions. It can also kill microorganisms as well. It is

biodegradable and is harmless in the human body. Chitosan also can

be used as an absorbent in drinking water due to its structure and

chemical properties. It has been used to remove mercury and fluoride

in drinking waters.

Interpretation of Results •In conclusion when dissolved chitosan is introduced to a turbid

sample of water with a dosage of 23.35 mg, the turbidity decreased

profoundly but increased if we exceeded that dosage.

•The chitosan dissolved in diluted Hydrochloric acid proved to be

the most effective in achieving a lower NTU (Nephelometric

Turbidity Unit(water clarity).

•The turbidity increased when the chitosan was unable to dissolve

completely due to fiber that was present in the powder mixture

because fiber is completely insoluble.

•Chitosan is a poor solution for producing clean drinking water and

should be used only in

•We proved that as the research article by Pillai, Paul, and Sharma

states; chitosan could dissolved in acetic acid(vinegar) or HCL

while it is not soluble is sulfuric acid

Social Benefits • Chitosan serves an important role in filtration. Along with sand

filtration (which can remove up to 50% turbidity), chitosan can

remove more unwanted particles in water than the sand

filtration itself.

• Chitosan is also used as a dietary supplement that aides in

weight loss.

• The substance is similar to plant fiber which cannot be easily

digested by the human body. Once ingested, it functions as a fat

sponge. It soaks up to 6 times of its mass in fat.

• Chitosan has properties within itself that allow for blood to clot

quickly benefiting patients suffering from open wounds.

References:

• Kamble, Sanjay P. "Defluoridation of drinking water using chitin, chitosan and lanthanum-modified chitosan." Chemical Engineering Journal. 129.1-3 (2007): 173-180. Print.

• Miretzky, P., and A. Fernandez Cirelli. "Hg(II) removal from water by chitosan and chitosan derivatives: A review." Journal of Hazardous Materials. 167. 2009.

• Pillai, C.K.S, Wlli Paul, and Chandra P. Sharma. "Chitin and chitosan polymers: Chemistry, solubility and fiber formation." Progress in Polymer Science. 34. India: 2009. <http://www.sciencedirect.com/science/article/pii/S0079670009000318>.

• Qin, Caiqin, Huirong Li, Qi Xiao, Yi Liu, Juncheng Zhu, and Yumin Du . "Water-solubility of chitosan and its antimicrobial activity." Carbohydrate Polymers. 63. 2006.

Methodology • Accuracy and reliability were important for this experiment, therefore we had to create a standardized “dirty water” to

keep approximately the same turbidity levels for all our tests. To create the “dirty water” we mixed ~1.2118 g of clay

and ~6.7193 g of sodium bicarbonate as a buffer (NaHCO3) into 20 L of distilled water to make water with a high

turbidity level that would make it unsafe to drink. We choose clay as a water pollutant because of the impurities it

contains and its density (1.9-2.5 g/cm3), which makes it perfect to float in water for some time but also to be able to

settle.

• We did four different experiments using, liquid chitosan, solid chitosan, chitosan dissolved in acid (solution), and lastly

diluted acid. All tests were made using 1 L of “dirty water”, mixed at 100 rpm for the first minute and ~40 rpm for 9

minutes using a six paddle stirrer, and finally measured in a turbidity meter.

• Our first test was with the liquid chitosan (a solution of chitosan diluted in distilled water) adding 1 ml and 4 ml to the

containers with dirty water. After 8 minutes we decided to add 4 ml more in each container because we didn’t see any

significant change. The results show that the turbidity levels didn’t have a significant change after 10 min nor did after

29 hours. In a second test we mixed 15 ml and 30 ml into 1 L of the dirty water where we didn’t find any difference

from the first one. Since we didn’t know the chitosan concentration of chitosan in the solution, we weren’t able to make

any progress.

• After this, Dr. James N. Jensen found chitosan pills used as a dietary supplement that contained 42.46% of chitosan in

each pill, combined with fiber, calcium, and phosphorus. At this time we weighed 250 mg, 500 mg, 750 mg, and 1.00 g

of a powder made out of pellets were added to the 1 L beakers. Due to high concentration of fiber in the pill the

powder was insoluble, therefore the turbidity of the water increased greatly.

• According to the research paper made by Pillai, Paul, and Sharma, the chitosan easily dissolves in solutions with a pH

of 6 or lower. Hydrochloric acid, Acetic acid, and Sulfuric acid were used for this purpose. After mixing the chitosan

powder into the acids, we filtered the solutions to take apart the other components from the pill to only keep the

polymer dissolved in the acid. Unfortunately the gravitational filtration was not effective for the solution made out of

the acetic acid, only acquiring a small amount of filtrate from the original sample. Therefore, we were only able to use

2.2 ml of each acid containing 23.353 mg of chitosan. After stirring the mixture for 10 minutes and settling down for

another 10 minutes, we found out that the acetic acid had the biggest difference of turbidity levels with respect of the

standard .

• Unfortunately testing the vinegar solution once again, the turbidity remain consistent dismissing the effectiveness of

the vinegar solution. Finally, we wanted to prove that the chitosan was the element that changed the turbidity levels in

water. Therefore we tested again the solution with hydrochloric acid and chitosan against the diluted HCl without

chitosan, this time in the range of 2 to 8 ml since we saw the best performance at these levels on our previous test. The

results show that the hydrochloric acid was able to reduce the turbidity levels, but with a small efficiency compared with

the chitosan solution.

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Standard Vinegar HCl H2SO4

Comparison of Varying Acids

Future Development • Chitosan is hard to obtain from the hard outer skeleton of the

shellfish. Creating an efficient way to crush the shells will

improve the collection of this material.

• Now that we have found conditions in which chitosan dissolves

in, we would like to search for a safe substance or solution that

will not only dissolve the chitosan but make that water safe to

drink without affecting taste.

• An effective technique of filtration, especially for the vinegar

solution, is necessary in order to obtain the dissolved chitosan

to get rid of the solid particles.

• frankdulcich.wordpress.com • www.gmp-chitosan.com

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HCl w/ Chitosan (30 min)

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Liquid Chitosan Test

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Liquid Chitosan Testing Higher Concentration

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Acknowledgement:

We would like to thank Dr. James N. Jensen for giving us the opportunity to work on this research project. Without your help we would have never been able to conduct our experiments. You have been with us every step of the way giving your free time to us so we would be able to progress in our experiments. We are truly grateful and we will not forget your generosity.