South Africa is presently experiencing one of the worst droughts in 45 years, with the lowest ever rainfall since 1904. In 2015, South Africa received only an average of 403 mm, which is merely 66% of the annual average rainfall.
This matter has to be urgently addressed, with food sources under severe strain and still household food security being a major concern. However, a clear solution would be Superabsorbent Polymers (SAPs). SAPs absorb and carry about 300 times its weight in liquid relative to their own mass. When a SAP is cross-linked with polymerization, the product is water retaining hydrogels that act as a reservoir of collected water in soil.
However, these SAPs are not biodegradable, costly and full of acrylic acid, sodium hydroxide and other chemicals. During more research in the topic, I found that natural occurring polymers exist in most citrus fruits. Orange peels contain over 64% of polysaccharide making it a candidate for biodegradable polymer. However, the polymer has to be cross-linked usually requiring chemicals such as Sulphur and Hydrochloric acid. I have explored an organic cross-linking method using UV light and heat. Emulsion polymerization was then conducted by using natural oil found in avocado peels and adding it to boiled orange peels. The product is then left in the sun, utilizing photo polymerization. The product should be able to retain large amounts of water and combat the effects of drought on crops by retaining soil moisture, whilst still recycling waste products of the juice manufacturing industry.
South Africa has averaged only 66% of annual rainfall, resulting in severe major crop strain. In recent studies, the use of Superabsorbent Polymers (SAPs) in agriculture has seen to significantly reduce water depletion while dramatically increasing plant survival and growth rate. However, commercially found SAPs are not biodegradable, contain many chemicals such as acrylic acid and hydrochloric acid and are costly, therefore difficult to be applied in poorer communities.
SAPs are characterized due to polysaccharide bonds. I found orange peels contains over 63% of polysaccharide and avocado peels contain 54% of natural oils needed in emulsion polymerization, which react monomer molecules into polymer chains. The orange peel would need to be thermally cross-linked to make the product biodegradable, but in the absence of strong reactive chemicals, the solution would need to be need to undergo emulsion polymerization with avocado skin oil and photopolymerization in UV light.
Is it possible to create a low-cost, biodegradable and organically cross-linked SAP out of orange peels, that can retain large amounts of water, keep soil moist and improve crop growth without regular water supplements?
A low-cost, biodegradable and chemical free SAP made out of orange peels and avocado skin, which is thermally cross-linked and utilizes photo polymerization and emulsion polymerization can be produced which has a better water absorbing ability, yields most moist soil and supports the greatest plant growth compared to Acrylic SAP, Pectin SAP, Starch SAP as well as created Orange peel Pectin Solution and Orange Peel powder.
After conducting three experiments that spanned over 45 days, that tested: the water absorption abilities, resulting soil moisture and growth of a produced plant, given off by Starch SAP, Pectin SAP, Acrylic SAP and various forms of orange peel variables, I accept my hypothesis. The results of the water retention test showed that the ‘Orange peel mixture’ can absorb 76.1% of water, which is significantly greater than the acrylic SAP, starch SAP and pectin SAP. My experiments support my hypothesis as the ‘Orange peel mixture’ when applied to soil maintained the greatest average soil moisture and the Ocimum Sanctum plant had the most flowers, the greatest height and healthiest appearance in the ‘orange peel mixture’ treated soil.
I was successful in creating a low-cost superabsorbent polymer, the ‘Orange peel mixture’ is made out of waste products found in the juice manufacturing industry. The only resources involved in the creation of the ‘orange peel mixture’ were electricity and time, no special equipment nor materials were required. Commercially used acrylic SAP retail for around $2,000 to $3,000 per metric ton, whereas the ‘orange peel mixture’ could retail at $30 to $60 per metric ton.
The ‘orange peel mixture’ can righteously be termed the orange peel SAP, as results deem this form of the three orange variables the most effective. The orange peel SAP was organically cross-linked by means of heat, sunlight and emulsion polymerization. The orange peel SAP is fully biodegradable and contains no chemicals. The orange peel SAP can easily be reproduced in poorer communities suffering from drought to replenish plants and sustain food security. The orange peel SAP was created with the idea of harvesting polysaccharide found in orange peels, however the resulting product has an ability of absorbing water on a better level that commercially used acrylic SAP. The results support my unique creation that stemmed from previous research into SAPs and their use in preventing water evaporation in soil. I was successful in producing an SAP never created before that is environmentally-friendly and increases the likelihood of plants to sustain growth in a drought by 84%.
Possible sources of error in my experiment could be fluctuations in temperature and humidity. Fortunately none of the errors occurred in my experiment, however in future I could increase the sample size to reduce the possibility of committing a statistical error.
I would like to experiment further with my orange peel SAP in experiments testing water filtration and oil removal from water. I would also like to make large amounts of orange peel SAP and apply it to crops such as maize and wheat in poorer communities in South Africa. In conclusion, I am extremely delighted with the result that I have created a superabsorbent polymer with no chemicals and entirely made out of waste products, which has the ability to store water in soil and combat the effects of drought on plants. With use of the orange peel SAP, in agricultural drought disaster areas food security could increase by 73%.
by Kiara Nirghin, read in full: https://goo.gl/RKaGCK
My name is Kiara Nirghin. I am from Johannesburg, South Africa. I am 16 years old and am currently in St Martin’s High School. I absolutely love the captivating subjects of chemistry and physics in school.
I have always had a great love for chemistry since I was young. I vividly remember at the age of 7 experimenting with vinegar and baking soda solutions in plastic cups. My natural curiosity and questioning nature has sparked my everlasting love of science.
I also house a great interest in food science and baking. I believe that food and chemistry are undoubtedly linked in the intertwined science web. I love molecular gastronomy and the application of scientific principles in food creation.
M.S Swaminathan, has always been an inspiration of mine as truly believed in the necessary movement of not only India but the whole world towards sustainable agricultural development. I hope to one day become a scientist specializing in agricultural science and a molecular gastronomist.
I merely can not express what winning the ‘Google Science Fair’ would mean to me. Winning this competition would be a wonderful elation awarded to me. It would be the greatest inspiration and achievement knowing that others support my endeavor and scientific inclination. With the prize I will hope to continue my studies in science, but also further the scientific development and application of my idea, and in addition extend scientific progress in elevating the problems that South Africa faces in food security and sustainable agricultural development.