Permeation of fertilizer nutrients through polymer membrane: part I. Effect of P, K, and micronutrient fertilizer on permeability of urea

The study aimed at investigating the addition effects of P, K, and micronutrient fertilizers on the permeability of N-nutrient fertilizer urea through a representative polymer membrane, which is of great importance in polymer-coated compound fertilizer. Specifically, the permeability of urea through polystyrene membrane was determined experimentally at the nominal temperature of 298 K using the Ussing chamber method for fertilizer solutions of urea–water, urea–NaH2PO4–water, urea–Ca(H2PO4)2–water, urea–KCl–water, and urea–NaCl–water. The experimental data showed that the addition effects of NaH2PO4, KCl, and NaCl on urea permeability were pronounced and could be promotion or suppression depending on the amounts added. The variation of urea permeability with additive concentration could be explained by the ‘solution–diffusion’ model, suggesting that the specific intermolecular and interionic interactions in the permeation solution were an important factor determining the permeability. Using the saturated urea–water solution as basis, the addition of saturated KCl increased the urea permeability by 2.5 times, while the addition of saturated Ca(H2PO4)2 and NaH2PO4 decreased the permeability by 41% and 76%, respectively. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.