Local student Kiara Nirghin has developed a low-cost, biodegradable, superabsorbent polymer which could prove useful in fighting South Africa’s drought.

Sixteen-year-old Nirghin who attends St Martin’s High School in Johannesburg recently won a Google Science Fair Community Impact Award for the Middle East and Africa with her submission ‘No more thirsty crops’.

South Africa is presently experiencing one of the worst droughts in 45 years, with the lowest ever rainfall since 1904 threatening food security.

Nirghin saw Superabsorbent Polymers (SAPs) as a clear solution. SAPs absorb and carry about 300 times their weight in liquid relative to their own mass. When a SAP is cross-linked with polymerisation, 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. Nirghin developed a biodegradable version using orange and avocado peels.

Nirghin explains her process:

“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 polymerisation 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, utilising photo polymerisation. 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.”

Agri SA requested over $1 billion in government subsidies to help farmers through the crisis. This innovative product could prove useful in assisting farmers at a relatively low cost.