Abstract

This study presents a green approach for urea synthesis using plasma–ice interaction with N₂ + CO₂ and NH₃ + CO₂ gas mixtures. Plasma characterization via electrical and optical emission spectroscopy revealed that urea formation involves complex reactions driven by high-energy species, producing reactive nitrogen and carbon intermediates. Plasma-treated ice exhibited increased pH, electrical conductivity (EC), and reduced oxidation–reduction potential (ORP). Optimization of parameters, especially treatment time, significantly influenced urea formation. The NH₃ + CO₂ plasma produced a higher urea concentration (7.7 mg L⁻¹) compared to the N₂ + CO₂ plasma (0.55 mg L⁻¹) due to ammonia's greater reactivity. This method offers a sustainable, energy-efficient alternative to traditional urea synthesis processes.