Super-absorbent polymer prepared from orange peels

[lakshu_s]

Hi Mr.Sybee,
Yes I was having lot of tests . Due date for the project is Feb end. I have concentrate more during December holidays. I was doing some research on the background information and why we are pursuing this experiment to put into my log book. I am attaching herewith what I found so far. I am struck in finding the details for:
Why avocado peels are mixed with orange peels during the process of preparing orange peel powder super absorbent polymer?
I see Kiara mentioned the reason as Emulsion polymerization.
I googled to learn the types of polymerization as they are not still covered in school syllabus. Please find below what I found so far:
- For polymerization it is required that the monomer molecule is capable of being linked to two (or more) other molecules of monomer by chemical reaction (functionality).
- Classification of polymerization are based on comparison of the molecular formed of a polymer with that of the monomer from which it was formed.
- Emulsion polymerization is a form of heterogeneous free radical chain polymerization, where hydrophobic polymer particles are formed in an aqueous dispersion medium
- Method of Emulsion polymerization:
Monomer molecules and free-radical initiators are added to a water-based emulsion bath along with soap like materials known as surfactants, or surface-acting agents. The surfactant molecules, composed of a hydrophilic (water-attracting) and hydrophobic (water-repelling) end, form a stabilizing emulsion before polymerization by coating the monomer droplets. Other surfactant molecules clump together into smaller aggregates called micelles, which also absorb monomer molecules. Polymerization occurs when initiators migrate into the micelles, inducing the monomer molecules to form large molecules that make up the latex particle.
I am also attaching the diagram herewith.

My clarification is : Why avocado peels are mixed with orange peels during the process of preparing orange peel powder super absorbent polymer?
Avacado peels release oil. We extract Pectin from orange peels. So is it oil in water emulsion polymerization. I think Pectin acts as emulsifier. Can you please clarify in depth how pectin with oil emulsion polymerization occurs? I am confused of what acts as surfactants and the method.
I am trying to think how this polymerization works while preparing our orange peel powder SAP.
Thanks for all your help and time.
Lakshita

[SciB]

Those are all tough questions, Lakshita, and I don't have good answers for you (yet). I think you are basically correct in reasoning that the process must be one of emulsion polymerization, but you will not be able to claim anything positively because you don't have any data to prove it. Speculation on a possible mechanism is what leads scientists to formulate more hypotheses to test. Each one builds on the previous ones and you hope that eventually you will hit on something close to the truth.

Citrus peels contain 30% pectin (https://en.wikipedia.org/wiki/Pectin) and are the major commercial source of pectin. Pectin is a polysaccharide consisting of a chain of sugar units (monomers) of various types. The dried orange peels would be the source of the polymer in your experiment, but as you said, pectin can also act as an emulsifier. Normally oils like avocado will stay separate from water because the two are chemically different. But, if you include a chemical that has one end hydrophobic (likes oil) and the other end hydrophilic (likes water) in the mixture, it will hold onto the oil and keep it emulsified in water.

OK, but what does the avocado oil do in the scheme of making a super-absorbent polymer? The short answer is--I don't know! But, based on the information you found, I could speculate that the avocado oil together with pectin forms what are called micelles (https://en.wikipedia.org/wiki/Micelle)--very small molecular containers that are hydrophilic on the outside and hydrophobic on the inside. Somehow these micelles act as sites for emulsion polymerization (https://en.wikipedia.org/wiki/Emulsion_polymerization) that may create super-long pectin polymers that are able to absorb a lot of water.

All this speculation is based on evidence from the literature and so is legitimate to use in building hypotheses, but remember that is only suggestive. You can't say that for sure this is the purpose of adding the dried avocado, but it is the best guess based on the facts as published by other scientists. Testing these hypotheses would take a long time and some creative experiment design. A judge might ask you how you would prove that your speculations are correct as to the purpose of the components of your formula, and you can just say that you would have to test each part individually to measure its effect on a particular step. The details can be worked out later.

I hope I have helped you to better understand the chemistry involved here. You are not expected to have a college-level understanding of this experiment but the more you know the easier it is to answer questions--and I can help you with that. So keep posting!

Good luck!

Sybee

[lakshu_s]

Thanks so much Mr.Sybee. Without your guidance I would have gone this much in this project. I will go over your explanation in detail and put everything together so it is easy for me to understand.

Thanks,
Lakshita

[SciB]

You are so welcome, Lakshita. I am very happy to be able to help you understand the science and methods of your project. If you have any questions, make a note of them and post them so I can senound d you a reply.

The global warming trend is continuing and the UN report just published showed that the developed countries are not doing enough to curb CO2 and other emissions as temperatures keep rising. As glaciers disappear and rain patterns change, water shortages are bound to occur in farming areas with potentially disastrous results. Your cheap, natural water-absorbent material could help a farmer keep his crops growing well even in a drought by holding water in the soil.

I have a lot of hope that the youth of the world, like the 16 year-old Swedish student, Greta Thunberg, will join together to push for more rapid and comprehensive changes in carbon emissions. It will be their world and I am cheered by their serious interest in reversing the looming catastrophe. Your science project could be a game-changer for people in water-poor areas.

Best wishes,
Sybee

[lakshu_s]

Hi Mr.Sybee,

Thanks again for your compliments. I have been doing Environmental projects starting from my 4th grade and I love that subject. I am glad each time I am selecting something new, for me to learn as well. I started preparing orange peel SAP this Thanks giving holidays. Still in the process of drying. I will keep you posted with my findings and further clarifications.

I am planning to write the rough draft of the procedure (first 2 experiments – water retention experiment and effect of soil moisture) this week. I will post it to you so you can verify and let me know if the steps are correct. Once you validate I will proceed with that experiments after orange peel SAP is ready.

Thanks,
Lakshita

[SciB]

That sounds like a good plan, Lakshita. Just make sure that you order whatever you need now to avoid delays later.

Also, take pictures of your orange peel and avocado preparations as you go along. You could print the photos and show them on your display board and in the report.

Any questions--ask away.

Sybee

[lakshu_s]

Hi Mr.Sybee,
Thanks for all your wishes. Project is coming good. I did the first step and took step by step photos as you mentioned. Peels are almost dry. I am planning to give another 1 week to start my next step. We bought all the materials needed included greenhouse. Thanks for all your help.
I have a clarification on water retention experiment.
- Potassium polyacrylate I got, absorbs 500 times its original weight. I am planning to take 2 grams of each SAP and add water to it and see how much water is absorbed. Correct me if any further suggestions here
- I am confused on this formula: ((gs – gi)/gi)
Gs is the weight of the swollen variable
Gi is the weight of the variable before water is absorbed

Let us take initial weight of SAP is 2 grams. So gi is 2 grams
After adding water let us say it absorbs 400 times the original weight. So Gs will be 800 grams
Percentage of total water absorbed will be ((800-2)/2)*100
(798/2)*100 = 39900
I am seriously confused on this. I guess something is wrong here. How did Kiara get 70%? Is
formula wrong?
Can you please help me understand this.
- Hope I cannot show control variable (without SAP) for this experiment.

Thanks,
Lakshita

[SciB]

Hi Lakshita,

Glad to hear that you have all the material and your project is underway--good job!

About that calculation...the problem is what you are comparing. If I remember correctly, Kiara's % was derived from a comparison of the water absorbing abilities of her orancado compound to those of the standard SPA. Sure, if you are comparing the dry compound with the same after water absorption, it will give a number like 40,000%, but that is not the comparison you want. It is OK to measure the amount of water absorbed by a specific weight of SPA and by orancado but don't give it as a %--just as fold change. If 2g of SPA absorbs enough water to weigh 800 g, then it has undergone a 400-fold increase.

But do use % when you are comparing SPA to orancado after water absorption. The formula then will be:
(g OC - g SPA)/g SPA x 100 = % difference relative to SPA.
For example, if 2 g of OC weighs 750 g after water absorption and SPA weighs only 650, then the OC has absorbed 100/650 x 100 = about 15% more water than SPA.

Keep asking questions and send me whatever you have written up so far so I can give you suggestions on how to make it clearer and what to include or not include.

Good luck!

Sybee

[lakshu_s]

Hi Mr. Sybee,
Thanks for clarifying. I am confused still. Because the graph she has is Various SAPs vs water absorption ability.
In her analysis, she mentioned orange peel mixture absorbed 76.1%, Acrylic SAP 74.7%, orange peel powder 64% and so on.
My question is how she can have Acrylic SAP as 74.7%? As you mentioned, if she would have done comparison against relative SAP, then her percentage of 74.7% is wrong for Acrylic SAP since this the SAP against which she should be comparing other SAP’s right?
I am confused. Can you please help me understand better and how to graphically represent the water absorbing abilities.
Thanks,
Lakshita

[SciB]

Hi Lakshita,

You are correct. Something is wrong either with the calculation or the statement about what was measured and how it was done.

Whichever way the data are reported, you still have to measure the capacity of the polymer to absorb and retain water. This can be graphed as fold change. For example, if you add water to 2 g of SPA and afterwards it weighs 200 g, that's a 100-fold difference.

The second number that you want is the water absorption of OC relative to SPA as a %. So, starting with 2 g of SPA and 2 g of OC, you end up with 200 g of SPA+water and 300 g of OC+water then according to the formula:
(300 - 200)/200 x 100 = 50%
the OC absorbed 50% more water than the SPA.

At this point I would tell you to do some practice runs with SPA since you have a lot of that. The most important measurement you have to make is the amount of water that is absorbed by the polymers. Water has to be added to a weighed amount of polymer until it can hold no more. Then, the swelled polymer needs to be weighed, but to do that accurately, you need to separate it from the excess water. What I want you to do is weigh six 2 g portions of SPA into plastic or paper cups (weigh the cups first) add water and allow the cups to stand until the gel can't hold any more then pour off the excess (without pouring out any of the gel!) and weigh the cups with the gel. Subtract the weight of the cup and you have the weight of the polymer plus water.

Average the six weights and use an online program to calculate standard deviation and standard error of the mean. This statistical analysis will give you an idea how accurate your weighing method is. After you have done this calculation for both the SPA and the OC I can tell you how to compare the two readings and test them statistically to find out if they are truly different.

Remember, you are doing an experiment to find out YOUR results. Your hypothesis can be: OC can absorb more water per unit weight than SPA. Your water absorption experiments will give you the answer, but you have to compare them statistically in order to be able to say with 95% confidence that the two values are different. If the tests show this to be true then you have proven the hypothesis.

Try the practice experiment and let me know how it comes out and if you have more questions.

Good luck!

Sybee

[lakshu_s]

Thanks so much Mr.Sybee. This is much clear. Sure I will do the trial experiment and let you know for any clarifications. Thanks again for your time to explain me in detail.

Thanks,
Lakshita

[SciB]

You are very welcome, Lakshita. I'm happy to help. If you have any questions at all, don't hesitate to ask. that is what we are here for.

Sybee

[lakshu_s]

Hi Mr. Sybee,
Wishing you a very Happy New Year 2020!!
I am almost done with my Christmas holidays and school reopens on 7th. Thanks again for all your guidance.

- I am done with preparing Orange/Avocado SAP's (both sun dried and oven dried)

- I captured all the step by step photos and also started writing.

- I completed water retention experiment. I compared 3 SAP's (Potassium polyacrylate SAP vs Orange/Avocado peel powder SAP vs Orange/Avocado peel mixture SAP). I did 3 trials.
Orange/Avocado peel powder SAP is sun dried orange/avocado peel crushed to powder in mixer.
Orange/Avocado peel mixture SAP is sun dried orange/avocado peel mixed with strained liquid , placed in conventional oven , dried and crushed to powder.
The average of fold change for Potassium polyacrylate came to 399, Orange/Avocado peel powder came to 265 and Orange/Avocado peel mixture came to 460.
Please let me know if this is fine and your thoughts.

- I am planning to do the next experiment. These are the steps I am planning in my mind for the second experiment (soil moisture testing)
1. 3 biodegradable cups are filled with 3/4 top soil and 1/4 with each of the SAP. 1 cup is filled fully with top soil (for control testing).
2. Saturate each of the 4 cups with 50 ml of distilled water
3. After 21 days test the soil moisture in each of the 4 cups with soil moisture tester.

Is top soil ok to use since I thought normal potting soil will have other fertilizers needed for growth that would change the readings.

Thanks so much for your time.
Mrudula

[SciB]

Hi Lakshita,
Congratulations on accomplishing a major part of your project successfully. The orange/avocado mixture seems to be the most water-absorbent, but in order to prove it you need to calculate the standard error. Here's a good video that explains how to calculate both standard deviation and standard error and what they mean: https://www.youtube.com/watch?v=BwYj69LAQOI

Standard deviation shows you how close (or far) your individual values are from the average value and that indicates how accurate your water-absorption results are. The standard error takes into account the number of readings, which in your case was three.

Now, in order to prove that the OA mix was really superior to the polyacrylate, you need to do a statistical test. If I remember right, I think you said that you have not had lessons in statistics yet, correct? Well, you don't need to wait for your teacher to tell you how to do these tests because there are many videos in which teachers will explain how to do the tests simply and understandably.

In statistics there is a term called the 'null' hypothesis. This is the hypothesis that states that there is NO difference between two values--that the apparent difference is caused by chance. That will be what you are testing when you compare the water absorption of the polyacrylate, 399, to that of OA mix, 460. It looks like the OA is higher, but without testing for the null hypothesis, you cannot say for sure. That is the purpose of these statistical tests.

One is called the Student's t test:
https://www.youtube.com/watch?v=pTmLQvMM-1M&t=40s

and the other is the Chi-squared test:
https://www.youtube.com/watch?v=WXPBoFDqNVk

If you are familiar with using an Excel spreadsheet for doing calculations, you can do that. The video shows you how. Otherwise, you can do all the calculations by hand using a calculator.

I'm sure you will have some questions, but watch the videos first. You can also watch other videos about the test as there are several. I just happen to like the way statistics is taught on the recommended videos.

Learning to use these tests is challenging at first but they are really important in science and if you decide to go into a career in science, you will surely use both the t test and Chi-squared frequently when comparing the means of data sets.

For the second part of your project I had hoped you would also grow some plants in the soil with the different water absorbers to see if there was a noticeable difference in growth rate between the PA and the OA. This would complete your project and make it more interesting to the viewer, but if you don't have time, the moisture retention test will be fine. There does not seem to be a large difference in water absorbance between PA and OA, so you might not see a difference in growth rate. I expect that you would see a significant effect if you compared plant growth in soil with and without PA or OA mix.

Post again with your questions and I will be ready to help.

Good luck!
Sybee

[SciB]

Hi Lakshita,
Congratulations on accomplishing a major part of your project successfully. The orange/avocado mixture seems to be the most water-absorbent, but in order to prove it you need to calculate the standard error. Here's a good video that explains how to calculate both standard deviation and standard error and what they mean: https://www.youtube.com/watch?v=BwYj69LAQOI

Standard deviation shows you how close (or far) your individual values are from the average value and that indicates how accurate your water-absorption results are. The standard error takes into account the number of readings, which in your case was three.

Now, in order to prove that the OA mix was really superior to the polyacrylate, you need to do a statistical test. If I remember right, I think you said that you have not had lessons in statistics yet, correct? Well, you don't need to wait for your teacher to tell you how to do these tests because there are many videos in which teachers will explain how to do the tests simply and understandably.

In statistics there is a term called the 'null' hypothesis. This is the hypothesis that states that there is NO difference between two values--that any apparent difference is caused by chance. That will be what you are testing when you compare the water absorption of the polyacrylate, 399, to that of OA mix, 460. It looks like the OA is higher, but without testing for the null hypothesis, you cannot say for sure. That is the purpose of these statistical tests.

One is called the Student's t test:
https://www.youtube.com/watch?v=pTmLQvMM-1M&t=40s

and the other is the Chi-squared test:
https://www.youtube.com/watch?v=WXPBoFDqNVk

If you are familiar with using an Excel spreadsheet for doing calculations, you can do that. The video shows you how. Otherwise, you can do all the calculations by hand using a calculator.

I'm sure you will have some questions, but watch the videos first. You can also watch other videos about the test as there are several. I just happen to like the way statistics is taught on the recommended videos.

Learning to use these tests is challenging at first but they are really important in science and if you decide to go into a career in science, you will surely use both the t test and Chi-squared frequently when comparing the means of data sets.

For the second part of your project I had hoped you would also grow some plants in the soil with the different water absorbers to see if there was a noticeable difference in growth rate between the PA and the OA. This would complete your project and make it more interesting to the viewer, but if you don't have time, the moisture retention test will be fine. There does not seem to be a large difference in water absorbance between PA and OA, so you might not see a difference in growth rate. I expect that you would see a significant effect if you compared plant growth in soil with and without PA or OA mix.

Post again with your questions and I will be ready to help.

Good luck!
Sybee