Turning Urine into a Sustainable Plant Fuel

Sub : Sci

Sec: Msc

Why in News

A new electrochemical process, recently published in Nature Catalysis, has demonstrated an innovative method to extract urea from urine and convert it into per carbamide, a crystalline peroxide derivative. This breakthrough not only enhances wastewater treatment but also transforms urine into a valuable agricultural resource, aligning with sustainability goals.

Details:

Urine is often referred to as “liquid gold” because it is rich in essential plant nutrients—phosphorus, potassium, and nitrogen.
Researchers have developed an innovative electrochemical technique to extract urea from urine in solid form using a low-energy, environmentally friendly process.
This method converts urea into per carbamide, a crystalline peroxide derivative with high purity.

Pee-Cycling: A Sustainable Solution

An adult produces around 450-680 litres of urine annually, containing approximately 4 kg of nitrogen and 0.3 kg of phosphorus—sufficient to grow wheat for daily bread consumption for a year.
The challenge in utilizing urine as a fertilizer lies in its complex composition, especially due to salts that interfere with urea extraction.

Urea Extraction:

Urea consists of nitrogen, oxygen, and hydrogen and tends to form hydrogen bonds with other molecules.
When urea interacts with hydrogen peroxide, it forms per carbamide, a solid crystalline compound.
Per carbamide Properties:
- Steadily releases active oxygen, making it useful for oxidation reactions.
- Enhances the recovery of urea from urine, making it more accessible for agricultural use.
When used as a fertilizer, per carbamide releases nitrogen slowly, promoting root respiration and crop growth.
This innovation provides a missing link in the nitrogen cycle, efficiently recycling human-generated nitrogen back into the ecosystem.

Electrochemical Technique:

Researchers developed an in-situ electrochemical process using graphitic carbon-based catalysts to convert urine-derived urea into per carbamide.
This process achieved almost 100% purity, effectively extracting per carbamide from both human and animal urine.
Initially, researchers aimed to stabilize hydrogen peroxide in liquid form. They realized that using urea from urine as a binding agent could serve dual purposes—stabilizing hydrogen peroxide while also addressing urine treatment and nitrogen cycling.
This led to the development of activated graphitic carbon catalysts that enhance chemical reactions leading to per carbamide formation.

Chemical Pathways for Urea Conversion:

Pathway I: Urea reacts directly with hydrogen peroxide in the presence of a catalyst, promoting effective bonding.
Pathway II: Urea binds with hydroperoxyl (-OOH) intermediates, facilitating a reaction that forms per carbamide.
The activated graphitic carbon catalyst was optimized to enhance both pathways, ensuring maximum yield.
The extracted per carbamide combines urea’s nitrogen-rich benefits with the oxidative properties of hydrogen peroxide, making it a promising sustainable resource.