Development of New Water-Based Anticaking Agents for NPK Fertilizers Using Response Surface Methodology

Caking remains a problem for the fertilizer industry in Thailand, especially for NPK fertilizers (15-7-18 and 18-4-5), leading to difficulty in application. In this work, we developed new water-based anticaking agents to obtain high anticaking performance using response surface methodology (RSM) with Box-Behnken Design (BBD). Nineteen chemical substances were screened and effects of three independent variables (polymer, surfactant, and solvent contents) were investigated. The practicability of the model validated through analysis of variance (ANOVA) and experiments were compared. Anticaking performance of the coatings was validated using our designed-accelerated caking method, expressed as the percentage of decrease in caking (%DC). Crushing strength and SEM/EDS analysis were used to evaluate the mechanical property and elemental composition of the coated fertilizers, respectively. The results suggested that different optimal compositions were required for different fertilizer formulas. In addition, only surfactant had a positive effect on caking prevention. The optimized anticaking coatings for 15-7-18 and 18-4-5 showed excellent performance with 92.0 %DC and 98.8 %DC, respectively.