致孔剂对植物油包膜尿素养分释放特性的影响

摘要

Adding porogen is often used as one of the key technologies regulating nutrient release from fertilizers. Adding porogen can artificially changes the coating porosity、pore diameter size、structure close degree, then adjusting the permeability of coating and controlling the nutrient release rate. , In this paper, we studied the effect of porogens on nutrient release of vegetable oil coated urea and potentials for applying this technology for the development of controlled release fertilizer. The vegetable oil coated urea was prepared using the best surface reaction coating technology of manufacturing controlled release fertilizer in China. The mixed vegetable oil consisted of tung oil、castor oil、peanut oil、soybean oil、cottonseed oil, the coating materials were then mixed with vegetable oil and curing agent through. lateral or base jet vortex fluidized bed., resulting six percent of urea. ST and SB were used as porogens in this experiment, ST is water soluble starch, SB is easy to swell in water. The experiments were performed under the still pure water dissolving incubation. We set up three temperature gradients with 25℃、30℃ and 35℃, respectively. The refractive index method was used for analyzing the urea content in the coated urea incubation solution, the nutrient release rate and longevity of vegetable oil coated urea were computed. The effects of adding porogen on nutrient release curves、temperature dependence and nutrient release activation energy of vegetable oil coated urea were analyzed, the relationship between nutrient release from vegetable oil coated urea and the amount of porogens was developed. The results showed that adding either ST or SB accelerated the nutrient release from vegetable oil coated urea, and shorted the longevity. If the amount of ST was added as 1%、3%、5%, the longevity of vegetable oil coated urea was shorten to 29.78、60.78、67.44 days, respectively. The longevity of vegetable oil coated urea was reduced with the increased proportion of ST. The nutrient release curves of coated urea with different proportion of SB was almost identical. The temperature dependence Q10 was reduced with increased ST. However, the temperature dependence Q10 was increased with increase of SB. In addition, nutrient release activation energy of vegetable oil coated urea was decreased by adding porogen.%为了探讨致孔剂对植物油包膜尿养分释放特性的影响，该研究通过25、30、35℃恒温静水培养方法对植物油包膜尿素养分释放特征曲线、肥效期、温度依存性以及养分释放活化能等进行了研究。结果表明：添加致孔剂ST（淀粉）和致孔剂SB（黏土矿物）均能加快植物油包膜尿素养分释放，均能缩短肥效期，当致孔剂ST用量从0增加至5%时，肥效期从122.20 d缩短为54.76 d，而添加不同用量致孔剂SB的植物油包膜尿素养分释放特征曲线基本重合；添加致孔剂ST植物油包膜尿素温度依存性Q10随用量增加而减小，而添加致孔剂SB则随着用量增加而增大；添加致孔剂会减小植物油包膜尿素养分释放活化能，当致孔剂ST和致孔剂SB用量分别为3%、4%时，养分释放活化能分别较不添加处理减少了40.20、23.28 kJ/mol。该文可为今后致孔技术在控释肥料研制中的应用提供参考。