The potential application modified lignin sulfonate matrix to controlled-release urea and predict the release profile

The main aim of this paper is to investigate the potential usage of acetylated Lignin sulfonate for controlling urea fertilizer release. Initially, lignin sulfonate was isolated from black liquor, based on precipitation calcium hydroxide. FTIR spectrum of this material showed that it is high soluble in water, due to the large number of hydroxyl groups in its structure. Oxalic acid was used to reduce this biopolymer solubility in water. Different weight ratios of acetylated Lignin sulfonate and urea were melted. After complete mixing, they were poured in the spherical template, to produce spherical granules. In this study, time-release urea increased from about 2 min to 48 hr, for equal weight ratio of acetylated Lignin sulfonate to urea. One analytical model was used to predict the release profile. The results showed that the model could predict the release profile accurately.