Simple method to obtaining a prolonged-release system of urea based on wheat gluten: development and characterization

Urea is one of the most widely used nitrogen fertilizers. However, it is lost to the environment via processes such as denitrification, surface runoff, volatilization, and leaching. In this paper, a novel material is reported on, with low production cost and avoiding the use of harmful solvents, with a pastille morphology developed by a simple method from a mixture of wheat gluten and urea, with potential use as a prolonged-release system of urea (PRSU). The PRSU obtained was characterized by scanning electron microscopy, kinetics of water absorption, equilibrium water content (EWC), Fourier-transform infrared (FT-IR) spectroscopy analysis, and release kinetics. The PRSU diameter was 2.46 cm, and its thickness was 0.17 cm. The PRSU showed physical and structural characteristics such as micropores and hollow fractions in its structure. In addition, the wheat gluten pastille is classified as a swelling material and demonstrated an EWC of 58.47 ± 1.50%. FT-IR analysis of the samples showed hydrogen-bond interactions between the amino and carbonyl groups in the urea and the wheat gluten proteins. Laboratory tests showed that the system can release 97% of the urea within 8–10 h. These results showed that the PRSU presents suitable characteristics for its application as a fertilization alternative for carrying out better agronomic practices.