فهرست نشریات علمی دسترسی آزاد ایران

Soil alone cannot provide plants with all the vital nutrients they need. Chemical fertilizers are often used to supplement these nutrients but can introduce harmful contaminants. Fertilizers are coated to prevent wastage, cut costs, and minimize environmental pollution. Utilizing natural and biodegradable polymers is a highly viable option for coating fertilizers and producing slow-release fertilizers. These polymers, such as acetylated lignin sulfonate, offer an ideal solution owing to their natural abundance and efficient utilization. The system's behavior is comprehensively studied by modeling the nitrogen penetration process into the coating. The diffusion coefficient (D), concentration profile, and release rate are generally determined through modeling. Due to the thinness of the membrane, it is impossible to determine the concentration profile experimentally. Therefore, the total mass transferred through the membrane (Mt) is typically measured at specific intervals. The D, a parameter influencing Mt at specific times, is determined differently. This article aims to determine the concentration profile numerically using the Crank–Nicolson method for urea fertilizer coated with acetylated lignin sulfonate. Release charts are generated at various time points by solving Mt. Investigations indicate that at around 3000 seconds, the concentration profile becomes entirely linear and aligns with the concentration profile at 12000 seconds. Furthermore, beyond 3000 seconds, the stability of the concentration profile about time signifies a steady-state system. A comparative analysis between the experimental data and the numerical solution results demonstrates the high accuracy of the numerical solution, with the maximum relative error occurring at 7895 seconds.