IB Chemistry Extended Essay

Pratyaksha Sinha 004881-0036

Aluminium sulphate coagulation should make seawater purification a viable source of fresh water for Qatar


Chemistry Extended Essay Word Count: 3865 words Abstract Word Count: 254 words Research Question: How effective is flocculation of metal ions using the coagulant aluminium sulphate (Al2(SO4)3.16H2O) for the treatment of seawater?

International School of London, Qatar Candidate Number: 004881-0036 Candidate Name: Pratyaksha Sinha

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Abstract

I am exploring treatment of seawater by coagulation, using the question: How efficient is flocculation of ions i ons using the coagulant aluminium sulphate (Al 2(SO4 )3.16H2O) for the treatment of seawater ? To carry out this investigation, I compared the efficiency, in terms of

the comparative result of the highest percent yield, using aluminium sulphate as a coagulant for three different types of water and then evaluated its practicality as a coagulant for large-scale water treatment.

A coagulant was dissolved in the water to neutralize the ions i ons carried by the colloidal particles suspended in the water and precipitate them. But for effective coagulation, there were many variables to keep in mind such as concentration of coagulant and the type of coagulant. To determine these controls, a preliminary experiment was conducted where the trial and error method was used to determine the masses of coagulant and coagulant aid that were to be used. It was found that

≈7.930×10− Al (SO ) .16H O was the only 2

4 3

2

concentration of the coagulant which coagulated the floc.

The main experiment compared the mass of salt in a solution and the mass of salt coagulated by aluminium sulphate. The result for the NaCl solution was used as the reference point as the solution was made purely of salt and no organic substances. Three types of water were coagulated: grey water, seawater and NaCl solution. The percent yield for all the three

±

were 76.1%±0.10%, 90.3%±0.08% and 95.5% 0.10% respectively. Hence this result concluded that aluminium sulphate is an effective coagulant for the flocculation process in the treatment of seawater. Page | 2



Abstract

I am exploring treatment of seawater by coagulation, using the question: How efficient is flocculation of ions i ons using the coagulant aluminium sulphate (Al 2(SO4 )3.16H2O) for the treatment of seawater ? To carry out this investigation, I compared the efficiency, in terms of

the comparative result of the highest percent yield, using aluminium sulphate as a coagulant for three different types of water and then evaluated its practicality as a coagulant for large-scale water treatment.

A coagulant was dissolved in the water to neutralize the ions i ons carried by the colloidal particles suspended in the water and precipitate them. But for effective coagulation, there were many variables to keep in mind such as concentration of coagulant and the type of coagulant. To determine these controls, a preliminary experiment was conducted where the trial and error method was used to determine the masses of coagulant and coagulant aid that were to be used. It was found that

≈7.930×10− Al (SO ) .16H O was the only 2

4 3

2

concentration of the coagulant which coagulated the floc.

The main experiment compared the mass of salt in a solution and the mass of salt coagulated by aluminium sulphate. The result for the NaCl solution was used as the reference point as the solution was made purely of salt and no organic substances. Three types of water were coagulated: grey water, seawater and NaCl solution. The percent yield for all the three

±

were 76.1%±0.10%, 90.3%±0.08% and 95.5% 0.10% respectively. Hence this result concluded that aluminium sulphate is an effective coagulant for the flocculation process in the treatment of seawater. Page | 2



Contents Section

Title

Page

Abstract

2

1

Introduction

4

2

Background Information

6

2.1

Colloidal Chemistry

6

2.2

Coagulation

8

2.3

Aluminium Sulphate

9

3

Investigation

11

3.1

Aim

11

3.2

Hypothesis

11

3.3

Coagulation Process

11

3.4

Method

12

4

Data Analysis

15

4.1

Experiment 1

15

4.2

Experiment 2

16

5

Conclusion & Evaluation

18

6

Discussion

20

Bibliography

24

Appendix A – Jar Test

25

Appendix B – Raw Data & Calculations

26

Appendix C – Apparatus & Chemicals List

30

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Research Question

How effective is flocculation of metal ions using the coagulant aluminium sulphate (Al 2(SO4 )3.16H2O) for the treatment of seawater?

1. Introduction

Dr. Adel Sharif of the Qatar Environment and Energy Research Institute mentioned in his speech at Qatar Foundation Annual Research Forum that overconsumption of water remains a key problem for the country as it develops. One of his visions is to use seawater and reuse water as a source of domestic supply in an economic and ecological way. But for both of these ideas, an efficient method to harvest these waters needs to be found.

Whilst researching into this topic, I found that an important process in water treatment is flocculation which makes use of coagulating chemicals to extract unnecessary metal ions and other microbes from water. A common coagulant used for this process is potassium aluminium sulphate for the minor flocculation of water which is later sent for further treatment. A cheaper coagulant which could work in the same way is hydrated aluminium sulphate. On further research, I defined a clear question: Can aluminium sulphate efficiently coagulate colloids present in seawater? For this investigation, I decided to equate efficiency to percent yield. In literature, I could not find reference to the actual efficiency of aluminium sulphate in any type of water, so I decided to conduct an experiment comparing the efficiency of the coagulant in different types of water; grey water, standard saline solution and seawater.

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My investigation is specifically focused on the quantity of colloids coagulated from the different sources of water. Grey water was obtained from the household draining system, which contains high concentrations of organic materials from the waste filtered from everyday uses. This should result in lower masses of salt measured than in seawater and sodium chloride solution as coagulants do not coagulate all organic materials. The seawater was collected from Al Wakra beach. As for the sodium chloride solution, the yield of the coagulation of this water should be the highest as the solution itself is only distilled water and a weighed mass of salt.

Prior to the experiment, the mass of the various compounds used as the coagulant and coagulant aid, a compound which increases the rate of coagulation, had to be quantified. Due to the paucity of data available, I conducted an experiment to determine the approximate concentration of aqueous aluminium sulphate required to flocculate ions from water. For this, I

≈

used a constant concentration of NaCl solution ( 0.8557M NaCl, which is

≈ 5.000  in

100ml of water) and varied the strength of aqueous Al 2(SO4)3. Ca(OH)2, which was used as procoagulant and its quantity required to aid the coagulation process the best was determined in another experiment but it is not presented in the body of this research. These experiments were conducted to determine the conditions under which the coagulation would work at its peak efficiency. As this was the most important aspect, a larger number of trials were conducted to provide a more accurate result. Although these were not relevant to my original research focus, they helped me understand more about the hydrated aluminium sulphate as a coagulant and the process of coagulation and flocculation.

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2. Background Information

2.1 Colloidal Chemistry

Colloidal chemistry is closely associated with various parts of water purification as the processes of coagulation, flocculation and filtration involve colloidal phenomena. Colloids, which are non-crystalline substances consisting of molecules of one substance dispersed through a second substance, carry positive or negative charge. These charges are important as they are present in all liquid mediums.

Frictional electrification potentially explains the dispersal of colloidal particles in a medium as friction between each them result in charge. The dissociation of surface molecules is another cause that leads to electric charge on colloidal particles, for example:

Figure 1: Dissociation of surface molecules (Oakley, H.B.)

In this example, the cation (Na +) passes in the solvent while the anion (C 15H31 COO-) has a tendency to form negative charges aggregated by itself due to weak attractive forces present in the long hydrocarbon chains.

Another explanation is the presence of acidic or alkaline groups in the solution. As an example, protein molecules give rise to either positive or negative charges depending on the pH, the H+ concentration, of the medium.

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Figure 2: Proteins create negative or positive charges (Oakley, H.B.)

They form a positively charged particle in low pH mediums and a negatively charged particle in high pH mediums as illustrated above.

When more than one ions are present in a medium, the selective accumulation of ions common to the colloidal particles takes place, resulting in the formation of positively charged or negatively charged particles. This is called ‘creation of charges due to the selective adsorption of molecules’.

Figure 3: Positively charged silver chloride (Oakley, H.B.)

This plays an important role during the flocculation as this phenomena aids complete flocculation of the ions. As the experiment will test three different types of water, it is

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important to keep in mind the type and number of these colloidal ions will be different for every trial.

2.2 Coagulation

Sols, which are fluid suspensions of colloidal solids in a liquid, are stable after precipitation due to the presence of electric charges on the particles. Due to electric repulsion, the particles do not come close to one another and hence do not aggregate. The removal of charge or attraction due to another charge by any means will lead to the aggregation of particles and hence cause immediate precipitation. This process of precipitation is known as coagulation or flocculation. Chemical precipitation is considered to be one of the most effective methods of removing colloids due to the coagulating effect of the precipitate formed as shown above. (Stein, Milton F.)

Coagulation, as a phenomenon, can be cause by different methods. A simple and basic method is heating or cooling which can be seen when the albumin in a boiled egg gets coagulated. In other cases, as different colloids have opposing charges, when these are mixed, they neutralise themselves and this results in the precipitation of both the sols simultaneously.

When large quantities of electrolytes are added to the solution, the electrolyte oppositely charged to the ions in the water neutralize each other due to which they aggregate and coagulated. This process will be used in the following investigation.

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2.3 Aluminum Sulphate

Aluminium sulphate (as anhydrous dialuminium;trisulphate Al2(SO4)3) is a clear salt. Hexadecahydrated aluminium sulphate, which is a while crystalline salt, is used in the experiment. Among its uses, it’s most common use is for

wastewater treatment and seawater treatment as both absorbents and Figure 4: 16-Hydrated Aluminium Sulphate

adsorbents.

(Pubchem) Aluminium sulphate reacts with the hydroxide and carbonates of the alkali and alkaline earth metals according to the already well-known equations (Stein, Milton F):

 +3 →  +3  +3 + 2 →  +3 +   +3 +  + 2 →  +3 + 4 These reactions are relevant in this investigation as the salts mentioned above are commonly present in the different kinds of water and the first equation refers to the coagulant and coagulant aid used in the experiment.

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When aluminium sulphate is added to solutions of sodium carbonate, hydroxide, calcium hydroxide or calcium bicarbonate of equivalent strength in distilled water , the reaction is very slow. As mentioned by Milton F Stein in his notes on colloidal chemistry, “With a

temperature of 20°C, and with 10 grains per gallon of aluminium sulphate, coagulation becomes visible in one hour, and the reaction completes itself in two hours.” (Stein, Milton F.) But the coagulation process is more efficient in terms of the end yield in turbid water; this is why during coagulation for this experiment, the turbidity of the water has been increased as much as possible by using a magnetic stirrer.

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3. Investigation

3.1 Aim

Referring to the research question, the main focus of this essay is to calculate the efficiency of the compound aluminium sulphate as a coagulant in three different types of water (grey water, seawater and a prepared

≈ 0.8557  ) and evaluate its potential as

a seawater treatment coagulant.

3.2 Hypothesis

The investigation looks at coagulation in three different types of water: grey water, seawater and NaCl solution. Based on pilot testing, the highest yield would be of the NaCl solution, the second for the seawater and the lowest wastewater. This is due to limited or abundant presence of salt in the water for the given coagulant dose.

3.3 Coagulation Process

Ideally, the coagulation process is done using the jar test method as to be able to keep in control all the necessary variables. The jar testing apparatus consists of six paddles which stir the contents of six 1 liter containers. Different settings can be set for each of the paddles using the rpm gauge at the top-center of the device. Through this, comparisons can be made over the range of the six containers. (Christophersen, Dave)

During coagulation-flocculation, there are many variables which have to be taken into account such as the type of coagulant use which varies in yield based on molecular structure, Page | 11



coagulant dose, the pH of the water, the type of additional chemical dosages apart from the primary coagulant, the sequence of chemical addition, the intensity and duration of mixing during the process, the type of rapid mix and stirring device and the floc retention time.

If all the variables are carefully controlled, a simple experiment in stoichiometry and calculating the limiting reagent should provide a reliable model to investigate the efficiency of aluminium sulphate as a viable coagulant.

3.4 Method

The aim of the first experiment was to find the exact mass of aluminium sulphate required, under the conditions of the working space, to coagulate the salt from solutions. The controlled variables were the concentration of the NaCl solution, the volume of main medium, and the concentration of Ca(OH) 2, the coagulant aid. The pressure, temperature, and pH were not controlled but the latter two were recorded.

To make the NaCl solution, I added 5.000g of NaCl salt to 100ml of unionised water which made 0.8557M liquid NaCl.

1   )=0.08857  5.000  (58.43  ) × 1000 =0.8557   = 0.8557   (0.08857 100 1  To make the Ca(OH)2 solution: Add 0.200g of Ca(OH)2 salt to 10ml of unionised water which made a

2.699×10−  . To make the hydrated Al (SO ) solutions: Add a 2

4 3

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∙16 salt to a 20ml solution which creates the range of 3.966×10−      ∙16  ,7.930 × 10−      ∙ 16 ,11.89 × 10−  ∙16  23.79×10−  ∙ 16 solutions respectively. range of 0.500g, 1.000g, 1.500g, 2.000g of Al 2(SO4)3

To carry out the coagulation, fill a beaker with 100ml of the

≈0.8557 NaCL solution to be

the primary medium and place the beaker on a magnetic stirrer stand. Measure the pH of the solution using a pH paper. Add 10ml of the

2.699×10−  solution to the same

beaker. Place the magnetic stirrer in the solution and mix at 50% of its capacity for a minute. Measure the pH again. Then add a 100ml of

3.966×10− of Al (SO ) solution to the primary 2

4 3

medium. Cover this beaker and switch on the magnetic stirrer to 100% of it’s capacity for 30

minutes. After this rapid mix stage, let the solution rest for 60 minutes. Remove the magnetic stirrer from the solution. Check the pH of this solution using pH paper. Repeat the procedure 8 times for the same concentration. Repeat the steps by changing the concentration of the

∙16 solution to 7.930×10−,11.89×10−  23.79×10−.

Al2(SO4)3

The mass of the floc was quantified by measuring the weight of the filter paper before and after the floc was placed on it. Only after making sure that the filter papers has dried and only contains the floc on it, measure the weight of the floc+fliter paper. Assure that the filtered water does not show any signs of floc floating in the cylinder, then measure the volume of distilled water.

Mass of floc = Mass of floc + filter paper Mass of filter paper Page | 13



The pH of the distilled water was also measured for further analysis.

The same procedure of the above stated experiment was used for the main experiment in which the independent variable was the three different types of water. Repeat the procedure 8 times for the same concentration.

For coagulation of wastewater and sea water, there was an adjustment in the first step; the wastewater was filtered to remove physical impurities. For reference purposes, 100ml of

±

wastewater was previous heated (with five trials) and 4.620g( 0.001g) of salt was extracted. This experiment has been conducted assuming that the salt is evenly spread in the water.

±

100ml of seawater was previous heated (with five trials) and 5.139g( 0.001g) of salt was extracted. This experiment has been conducted assuming that the salt is evenly spread in the water.

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4. Data Analysis

4. 1: Experiment 1 : Obtaining the mass of (Al 2SO4)3 to be used Table 1: Obtaining the mass of (Al 2SO4)3 to be used Trial Set

Weight of Al 2(SO4 )3.16 H2O (g) 0.001g

Weight of NaCl (g) 0.001g

1

0.510

6.053

0.212

No floc

2

1.080

5.084

0.213

3

1.524

5.082

0.211

4

2.064

5.114

0.210

Floc 5.766 0.369 formed Floc was feathery in nature and dissolved when attempts were made to measure it Some of the floc passed through the filter paper and tinted filtered water white and yellow (for the trials with resultant the yellow tint)

±

±

Weight of Ca(OH)2 (g) 0.001g

±

Resultant floc

Weight Weight of floc + of filter filter paper (g) paper (g) 0.001g 0.001g

±

±

Analysis and Result

The relevance of this experiment is to identify the right concentration of aluminium sulphate required for the coagulation of 100ml water. As shown in the table, trial 2 was successful as floc, which could be measured, was formed. The rest of the trials were unsuccessful and hence have minimal relevance to the rest of the investigation.

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4.2: Experiment 2: Checking the efficiency of (Al 2SO4)3 as a coagulant

Graph 1: Mass of Coagulated Salt 5.4 5.2 5 4.8 4.6 4.4 4.2 4 3.8 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0

) g ( t l a s f o t h g i e W

Expected Average (g) Actual Average (g)

Grey Water

Seawater

NaCl solution

Expected Average (g)

4.62

5.139

5.08

Actual Average (g)

3.517

4.639

4.851

Different types of water

Table 2: Average percent yield of the three types of water Trials

No

Weight of floc –

Original weight

Difference in

Per cent yield

weight of

of salt (g)

weight of the

(%)

Al 2(SO4 )3.16H2O

0.001g

added (g)

Grey Water

Average

3.517

±0.003g

±

salt (g) 0.004g

Expected

±

0.961

79.1%

0.770

90.3%

0.227

95.5%

average:

±

4.620g( 0.001g) Seawater

Average

4.639

Expected average:

±

5.139g( 0.001g) NaCl

Average

4.851

5.080

Solution Table A.4: Comparison of averages of mass of salt Page | 16



As summarised in the graph and table above, the experiment showed different degrees of success in the different types of water. For grey water, the yield was the lowest, being

±

±

76.1% 0.10% and the highest being for the NaCl solution being 95.5% 0.10%. The seawater

±

had a 90.3% 0.08% yield, which is a fairly significant result, considering the variable nature of the experiment, as discussed below. The NaCl solution will be used as a standard as the solution was made of only salt without any possible interference from organic matter.

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5. Evaluation

∙

The results of the experiment support my hypothesis that the coagulant Al 2(SO4)3

16 would be most effective on the NaCl solution, less so on the seawater and least on the grey water. The error in all the measurements were 0.08% and 0.10% in the processed data. The pH paper used to determine the acidity or alkalinity of the solution had a large error of ±1pH which could have been decreased by the titration of the solution. As the main aim of this experiment was to compare the percent yield, the following errors did not affect my conclusion as the three types of water were all subjected to the same conditions. If a more accurate result were to be needed, the jar test method outlined in the appendix could be undertaken.

The methodology of the experiment itself resulted in multiple inaccuracies and errors. For one, it was difficult to determine exactly when the flocculation was complete. There was no predetermined end point so it was assumed that it should be complete over a time period of 60 minutes (Stein, Milton F). Another experiment could be conducted to find the exact length of time the solutions would take to wholly coagulate.

Another major drawback of the experiment was the nature of the experiment itself. There were various variables to take into account as mentioned under section 3.3. Not all of these factors could be measured due to the limitations posed by available apparatus. Whether different concentrations of calcium hydroxide would have been more effective or better coagulant aids could have been used was not evaluated in this methodology but should be considered for further evaluation. Similarly, although prior testing was conducted to find the

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most efficient mass of all the chemicals required, only certain values were tested. It is possible that there is another value, which could result in higher yield and accuracy.

A variable which I attempted to take into consideration was the pH of the solution. Both the coagulant aid and the coagulant have alkaline and acidic effects on the solution respectively. Although it is known that aluminium sulphate works best under alkaline conditions (Stein, Milton F), the exact pH of the solution could not be controlled. However, it has been reported in the Appendix to be used as justification of the data.

As the stirrer was not an ideal rapid mixer but a magnetic stirrer, the turbidity of the entire solution could have been affected and so would have the effectiveness of the coagulation. The apparatus for stirring and rapid mixing does not provide us a quantitative value to designate to the speed of mixing, so the rate used by the magnetic stirrer could have varied. As mentioned in section 3.3, the ideal set up would have been the jar test method but, due to lack of the apparatus, it was not used.

One problem with the wastewater was the water source. The grey water used in the experiment was obtained from different local households. The wastewater did not coagulate as efficiently as the other two solutions; this could have been due to influence of the organic compounds in the water. As the specific compounds were not identified, the exact influence cannot be determined. Also, as the average quantity of salts present in the water was found to be slightly lower than the quantity tested for optimum coagulant, the dose may have been higher or lower than the optimum dose required for the specific type and volume of water. Page | 19



6. Discussion

The aim of the experiment was to determine the efficiency of aluminium sulphate as a coagulant for three different types of water. A potential practical application of the results could be the coagulation of sols present in seawater, rendering it suitable for domestic use. According to the results of the experiment, aluminium sulphate was successful in coagulating the metal ions, such as chloride, sodium, magnesium, strontium, silicate, iodide and others, which are commonly present in the seawater (W. Johnson, Martin). This is an effect method of coagulation as it was not only the ions that were successfully flocculated, but also microbes and other small particles (LeChevallier, Mark W.) However, due to the increasing rate of pollution of seawater it is difficult to determine all of its specific components.

Whilst testing the efficiency of aluminium sulphate as a coagulant in wastewater, the results were not as successful. They demonstrated an average percent yield of only 76.1%±0.10% as opposed to the 90.3%±0.08% yield of coagulation of seawater and

±

95.5% 0.10% yield of the NaCl solution. This implies that it is possible for the coagulation to be less effective in certain types of water with different constituents. The different components of seawater can vary with the origin of the water and therefore depending on this process without previous testing would be unwise. But for the seawater present in Qatar this result is suitable as the abundant seawater can be practically used as a public water source.

Another major factor that affects yield of coagulation is the pH of the water. Different coagulants work better in different levels of pH. The optimum pH of the final distilled solution required is 7 as it should be pure water. As aluminium sulphate works better in alkaline Page | 20



solutions, a coagulant aid was added to increase the pH and add more ions to aid the flocculation. Taking into consideration the fact that the original pH of the water varies as well, for different pHs, different masses of coagulant aids and other pH adjusting substances would be needed. This would be a difficult task to carry out frequently on a large scale such as for public water supply. Attempts to average out the pH could prove to be slightly useful.

The steady but very gradual decrease in pH of the world’s oceans due to the increase of dissolved carbonate ions would affect this calculation. This could also be a positive effect, as some of the pH levels would not need a coagulant aid as the pH of the water itself would be the optimum pH level for the coagulant.

A drawback of coagulation of seawater is the colour of the water. Seawater usually has a clear yellow or brownish tint, which cannot be removed by passing it through filter paper. The colour of the water is enhanced in turbid state, which i s predominantly seen during the later stages of the rapid mixing process. Water generally acquires colour through contact with decaying vegetation in swamps, as a result of underwater life. When aluminium sulphate is added to these, a coloured precipitate is formed but, depending on the cause of the colour, there is a possibility that aluminium sulphate may not be as efficient. Although coloured water would be a disadvantage, if the cause of the colour is an alkaline agent, coagulant aid would not be needed. This again depends on the possibility of being able to measure the quantities of these constituents in the water. Also, as this precipitation of ions is only one of the methods involved in the long process of water treatment which includes reverse osmosis, this weakness can be easily overcome.

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One of the most important factors to consider is the cost. The cost of the whole process is extremely relevant as the public need to be able to afford the water supply. As outlined in ‘The Manufacture Of Sulphate O f Alumina At The Colombus Water Softening And Purification Works’ by Charles P. Hoover, in the manufacturing of aluminium sulphate, the important

features are bauxite and sulphuric acid; including the costs of setting up the plant, an overall estimate would be $10,493.50. This is for the production of 1000 tonnes of 17% alum solution. According to him, a minimum of $12,000 original investment and a minimum annual expenditure of $6,000 would be needed. For a higher concentration and for further development, more costs would be incurred.

Although the majority of the costs are spent in one-time investments in the plant, more costs would be incurred for repair and maintenance of the plant, along with the hi gh costs of constantly obtaining the bauxite and sulphuric acid, which are the reagents which make aluminium sulphate. These costs only include the manufacture of alum but further expense would be required for building and usage of the actual water treatment plant. However, this method can be very useful for the public, as a large supply of drinkable water can be easily delivered to them with just these costs.

Another aspect to keep in mind is that although the majority of the salt coagulated, in most of the trials some ions remained suspended in the water. This could raise ethical issues concerning the health of the people who consume this water, considering the possibility that ingesting these ions could affect their heath.

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If this idea were to be implemented on a larger scale, more research should be conducted. Further exploration should include; testing for other coagulants which could be more effective for the coagulation of seawater; testing of other coagulant aids and its different concentrations which could result in a higher percent yield for seawater; and perhaps testing whether there is a different concentration of aluminium sulphate which was not tested in this experiment and could be more suited for the coagulation. The two major variables which were hard to control and manipulate were the pH and the colour of the solutions. It is possible that a different level of pH would create a better environment for the coagulation. Dilution of the water for a lower colour could be effective but this could also increase the costs due to greater use of coagulant aids and coagulants for the larger quantity of water. If all the variables are carefully controlled, a simple experiment in stoichiometry and calculating the limiting reagent should provide a reliable model to investigate the efficiency of aluminium sulphate as a viable coagulant for the large scale.

In conclusion, the process of coagulation of seawater can be a useful method for tapping the large seawater resource as public use for the residents of Qatar. The method itself can be improved and, with further exploration, it can be developed into a working model.

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Bibliography

1. Hoover, Charles P. "THE MANUFACTURE OF SULPHATE OF ALUMINA AT THE COLUMBUS WATER SOFTENING AND PURIFICATION WORKS [with DISCUSSION]." Journal (American Water Works Association) 2.4 (1915): 693-702. JSTOR. Web. 18 Dec. 2015.

2. Johnson, Martin W., and Fleming H. Richard. "Biological Chemistry and Physics of Sea Water." Nature 123.3106 (1929): 709-10. Web. 20 Jan. 2016.

3. Lechevallier, Mark W. "Water Treatment and Pathogen Control: Process Efficiency in Achieving Safe Drinking-water." Water Intelligence Online Wio 12 (2013): n. pag. Web. 18 Dec. 2015.

4. Mohlman, F. W. "COLLOID CHEMISTRY AND ITS RELATION TO TANK TREATMENT OF SEWAGE." Journal (American Water Works Association) 9.2 (1922): 311-18. JSTOR. Web. 16 Dec. 2015.

5. National Center for Biotechnology Information. PubChem Compound Database; CID=23065692, https://pubchem.ncbi.nlm.nih.gov/compound/23065692 (accessed Jan. 20, 2016). 6. Oakley, H. B. "The Origin of the Charge on Colloidal Particles." The Origin of the Charge on Colloidal Particles (1925): 902-16. - The Journal of Physical Chemistry (ACS Publications). Web. 20

Jan. 2016. .

7. Pirnie, Malcolm. "APPLICATION OF COLLOID CHEMISTRY TO STUDY OF FILTER EFFLUENTS." Journal (American Water Works Association) 9.2 (1922): 247-73. JSTOR. Web. 18 Dec. 2015.

8. Stein, Milton F. "SOME NOTES ON COLLOIDAL CHEMISTRY AND WATER PURIFICATION." Journal (American Water Works Association) 8.6 (1921): 571-82. JSTOR. Web. 18 Dec. 2015.

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Appendix A: Jar Test Jar Test Ideal aluminum sulphate coagulation follows the following basic steps: 1 1. Fill the jar testing apparatus containers with sample water. One container will be used as a control while the other containers can be adjusted depending on the variable constant. Different variables could be the pH of the jars, variations in coagulant doses, variations in coagulant aid doses, etc. 2. Add the coagulant to each container and stir at approximately 100 rpm for 1 minute. The rapid mix stage helps to disperse the coagulant throughout each container. 3. Turn off the mixers and allow the containers to settle for 30 to 45 minutes. Then measure the final turbidity in each container. 4. Reduce the stirring speed to 25 to 35 rpm and continue mixing for 15 to 20 minutes. This slower mixing speed helps promote floc formation by enhancing particle collisions which lead to larger floc.

Hawley's Condensed Chemical Dictionary (2007): n. pag. The National Environmental Services Centre. Web.

1

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Appendix B: Raw Data Experiment 1 : Obtaining the correct mass of (Al 2SO4)3 to be used

Trial No. of Weight of s Repeat Al 2( SO4 )3.16 s H 2O (g) 0.001g

Weight of NaCl (g) 0.001g

Weight of Ca(OH)2 (g) 0.001g

Resultant floc

1

5.017 5.081 5.048 5.089 5.011 5.029 5.143 5.007 6.053 5.160 4.989 5.107 5.003 5.090 5.011 5.102 5.211 5.084 5.110 5.013 5.065 5.041 5.094 5.090 5.147 5.093

0.210 0.221 0.207 0.218 0.202 0.212 0.215 0.209 0.212 0.200 0.211 0.218 0.221 0.206 0.219 0.220 0.211 0.213 0.210 0.200 0.219 0.205 0.214 0.219 0.213 0.204

No floc 2

±

1 2 3 4 5 6 7 8 Average 2 9 10 11 12 13 14 15 16 Average 3 17 18 19 20 21 22 23 24

0.515 0.521 0.504 0.512 0.508 0.509 0.511 0.502 0.510 1.027 1.121 1.111 1.038 1.056 1.076 1.114 1.098 1.080 1.531 1.510 1.493 1.523 1.564 1.521 1.503 1.548

±

±

Weight of floc + filter paper (g) 0.001g

±

Weight of filter paper (g) 0.001g

±

Floc formed

5.733 0.373 5.621 0.339 5.898 0.367 5.601 0.366 5.884 0.382 5.911 0.374 5.798 0.381 5.689 0.369 5.766 0.369 Feathery floc- unable to measure accurately as a minimal mass of it dissolved in the water while filtering

2

Floc did not form even after longer detention time periods (2 hours)

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Average 4 25 26 27 28 29 30 31


1.524 2.137 2.007 1.999 2.101 2.118 2.046 2.099

5.082 5.156 5.076 5.084 5.163 5.123 5.010 5.114

0.211 0.217 0.210 0.199 0.203 0.221 0.215 0.203

Flaky floc Some of the floc with passed through yellow tint the filter paper Flaky floc and tinted filtered water white and yellow Flaky floc (for the three trials with with yellow tint resultant the Flaky floc yellow tint)

32 2.003 5.187 0.214 Average 2.064 5.114 0.210 Table 4.1: Quantitative data and qualitative data of the first experiment

Experiment 2: Checking the efficiency of (Al2SO4)3 as a coagulant

Trials

No Weight of Weight Weight . Al 2( SO4 )3.16H 2O of of NaCl Ca(OH)2 (g) 0.001g salt (g) (g) 0.001g 0.001g

Weight of Filter Paper (g) 0.001g

Weight of floc+filter paper (g) 0.001g

1 2 3 4 5

0.367 0.366 0.382 0.364 0.379 0.371 0.370 0.380 0.369 0.373 0.339 0.366 0.375 0.368 0.389

5.098 4.989 4.880 5.176 4.878 5.004 5.889 6.270 5.699 6.424 5.745 5.785 5.384 6.598 6.198

±

±

1* (grey water)

Average 2 (seawater )

Average 3 (NaCl Solution)

1 2 3 4 5 1 2 3

1.072 1.102 1.221 1.033 1.098 1.105 1.034 1.003 1.165 1.210 1.087 1.099 1.156 1.128 1.054

N/A

N/A N/A

N/A 5.093 5.143 4.997

±

0.203 0.212 0.211 0.206 0.200 0.212 0.202 0.203 0.205 0.210 0.213 0.214 0.207 0.209 0.201

±

±

Total mass of distilled water (ml) 1ml 125 119 129 123 126 124 115 112 112 115 114 114 113 112 115

±

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4 5

1.128 5.160 0.211 0.378 1.007 5.009 0.213 0.367 Average 1.095 5.080 0.208 0.375 Table A.1: Quantitative data from the second experiment

Trials

No.

First pH pH Before pH (ph) (ph) During(ph) 1pH 1pH 1pH 1* 1 6 7 7 (grey water) 2 6 8 7 3 7 8 7 4 5 8 6 5 6 8 7 2 1 7 8 7 (seawater) 2 8 8 7 3 8 9 7 4 7 9 7 5 7 8 7 3 1 6 8 7 (NaCl 2 7 9 7 Solution) 3 7 8 7 4 7 9 7 5 7 9 7 Table A.2: Measured pH of the solutions

±

Trials

±

2

114 112 113

pH After (ph) 1pH

±

6 7 6 7 7 7 8 8 8 8 7 8 7 7 8

of Weight of Weight of Weight of flocNo Weight floc+ filter Filter Paper floc (g) weight of Al 2( SO4 )3.16H 2O paper (g) (g) 0.001g 0.002g added (g) 0.001g 0.003g 1 5.098 0.367 4.731 3.659 2 4.989 0.366 4.623 3.521 3 4.880 0.382 4.498 3.227 4 5.176 0.364 4.812 3.779 5 4.878 0.379 4.499 3.401 1 5.889 0.370 5.519 4.485

±

1* (grey water)

±

5.989 6.437 5.661

±

±

±

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(seawater)

2 6.270 0.380 3 6.199 0.369 4 6.424 0.373 5 5.745 0.339 3 1 6.384 0.375 (NaCl 2 6.598 0.368 Solution) 3 6.198 0.389 4 5.989 0.378 5 6.437 0.367 Table A.3: Weight of floc and possible salts

5.890 5.830 6.051 5.406 6.009 6.230 5.809 5.611 6.070

Trials

No Weight of floc – Original weight weight of of salt (g) Al 2( SO4 )3.16H 2O 0.001g added (g) 0.003g 1* 1 3.659 Expected (grey average: 2 3.521 water) 4.620g( 0.001g) 3 3.227 4 3.779 5 3.401 Average 3.517 2 1 4.485 Expected (seawater) 2 average: 4.887 5.139g( 0.001g) 3 4.665 4 4.841 5 4.319 Average 4.639 3 1 4.853 5.093 (NaCl 2 5.102 5.143 Solution) 3 4.755 4.997 4 4.483 5.160 5 5.063 5.009 Average 4.851 5.080 Table A.4: Comparison of mass of salt

±

±

±

±

4.887 4.665 4.841 4.319 4.853 5.102 4.755 4.483 5.063

Difference in weight of the salt (g) 0.004g

Per cent yield (%)

0.961 1.099 1.393 0.841 1.219 1.103 0.654 0.252 0.474 0.298 0.820 0.770 0.240 0.041 0.242 0.667 -0.054 0.227

79.2% 76.21% 69.84% 81.8% 73.61% 76.12% 87.2% 95.1% 90.8% 94.2% 84.0% 90.27% 95.3% 99.2% 95.2% 86.9% 101% 95.49%

±

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IB Chemistry Extended Essay

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