The influence of the structural features of lignin-based polyurethane coatings on ammonium sulfate release: kinetics and thermodynamics of the process

• Published in: JCT research Vol. 16; no. 2; pp. 449 - 463
• Main Authors: Avelino, Francisco, Miranda, Isabela Pires, Moreira, Tainá Dantas, Becker, Helena, Romero, Francisco Belmino, Taniguchi, Carlos Alberto Kenji, Mazzetto, Selma Elaine, de Sá Moreira de Souza Filho, Men
• Format: Journal Article
• Language: English
• Published: New York Springer US 15.03.2019; Springer Nature B.V
• Subjects: Agricultural practices; Ammonium sulfate; Biodegradability; Chemistry and Materials Science; Coatings; Corrosion and Coatings; Crosslinking; Formulations; Hydrophobicity; Industrial Chemistry/Chemical Engineering; Lignin; Materials Science; Morphology; Polymer Sciences; Polyurethane resins; Rate constants; Structural analysis; Surfaces and Interfaces; Thin Films; Tribology; Biodegradable materials; Coconut shell; Unmodified lignin; Solvent-free polymerization; Fertilizer
• ISSN: 1547-0091; 1935-3804; 2168-8028
• DOI: 10.1007/s11998-018-0123-y

The influence of the properties of lignin-based polyurethane (PU) coatings on the release behavior of ammonium sulfate was assessed through complete physicochemical, structural, and morphological characterization. The influence of the release medium was evaluated as well. The higher the amount of lignin in the coatings was, the lower the pore diameter and swelling degree and the higher crosslinking were. The hydrophobicity of coatings was not significantly changed by increasing the lignin content. However, the opposite behavior was observed for their biodegradability. The results of the nutrient release experiments showed that the two formulations of lignin-based PUs had very similar behavior in terms of release rates of NH 4 + and SO 4 2− in both release media, despite their different properties. However, there was a difference between their release rate constants obtained by using three different kinetic models. In addition, both PU coatings released a higher amount of SO 4 2− than NH 4 + in both media. The thermodynamic data suggest that dissolution and release processes for SO 4 2− are more spontaneous than that for NH 4 + . Nevertheless, both coatings behaved in accordance with CEN standards for CRF systems, representing a potential technique for agricultural applications.