Optimization of Synthesis Conditions for Urea-Formaldehyde Slow-Release Fertilizer Using Response Surface Methodology

In this study, we optimized the preparation of urea-formaldehyde fertilizer using response surface methodology with a Box-Behnken experimental design. The aim was to maximize the difference between CWIR and HWIR to maximize the content of slow-release insoluble nitrogen. In this work, a model of the impact of reaction factors on CWIR and HWIR was established. Through analysis of variance, the final model was significant. According to this model, the optimal reaction conditions were: a reaction temperature of 42.5 °C, a reaction time of 66.2 min, a U/F of 1.68, and a pH 3.3. Under these optimal conditions, the CWIR and HWIR reached 55.65 and 33.92%, respectively. In addition, the samples were characterized by scanning electron microscopy and thermal stability analysis. This study accurately synthesized urea-formaldehyde products with specific release periods according to production needs in order to improve the efficiency of fertilizer utilization.