A Potential Sustainable Urea-Releasing Device Produced by a Solid-State Reaction

This work produced chemically activated sugarcane bagasse-based activated carbon (AC) for the controlled release of urea. Fourier transform infrared (FTIR) and Raman analysis confirmed the presence of graphitic structures and multiple oxygen-containing functional groups. After the solid-state reaction that formed the material, their surface area reached 1401 m² g^-1 for the sample prepared with a pyrolysis temperature of 400 °C, a concentration of sodium hydroxide equivalent to 11 mol L^-1, and an activation temperature of 900 °C (AC 400-11-900). Zeta potential measures indicated negative charges at pH > 4, reaching almost (–50 mV) at pH 9. The adsorptive capacity of the AC with the highest surface area was equal to (758.7 ± 263.8) mg g^-1. Nevertheless, the matrix did not release the urea molecules previously adsorbed into it, which is appealing for fertilizer-releasing purposes because the activated carbon would be able to re-adsorb the non-absorbed urea molecules, sustaining nutrient availability for longer periods.

Keywords:
agricultural application; biomass waste; statistical approach; design of experiments; urea