摘要
【目的】尿素表面改性是提高包膜质量和养分控释能力的关键措施之一。我们研究了不同磨料对肥料核芯表面的改性效果,以及改性提高肥料养分控释的效果。【方法】供试肥芯为大颗粒尿素(直径3~5 mm,N46%),供试磨料包括白刚玉、棕刚玉、高铝瓷球、高铝瓷柱和氧化锆球。经测量不同磨料研磨后尿素的休止角,证明采用堆密度1.336 g/cm~3、直径6 mm的球形高铝瓷在10 min内对尿素表面改性效率最高,故用作后期的试验磨料。将1.5 kg的高铝瓷球与1 kg大颗粒尿素加入转鼓中,采用离散元仿真软件(EDEM)模拟磨料摩擦与尿素颗粒自摩擦的粒子运动、碰撞、受力和分布特征;使用扫描电子显微镜分析磨料、表面改性尿素和包膜尿素的表面和切面结构特性,采用原子力显微镜测试包膜尿素膜表面结构微观特征与粗糙度;采用静水溶出率法测定纳米SiO2改性蓖麻油基聚氨酯包膜的表面改性尿素的养分释放特征。【结果】EDEM仿真结果表明,转鼓底部颗粒运动快(1.125 m/s),边缘运动慢(0.00309 m/s),转动过程中,小颗粒物聚集在转鼓底部产生偏析。尿素自摩擦力约0.035 N,加入密度大于尿素的球形高铝瓷磨料后,混合体系的摩擦力变大(约0.042 N),尿素颗粒间的碰撞次数较自摩擦体系高出13.0%,因此改性效率得以提高。表面改性显著降低了颗粒表面粗糙度,在1μm^(2)检测范围内,粗糙度(Ra)平均降低了79.2%。由扫描电镜图可以看出,普通尿素表面粗糙,膜材料填充在凹陷部位,包膜耗费的膜材料较多,且膜与尿素贴合不紧密,在运输或长期储存过程中易发生膜破损,失去养分控释能力;改性后的尿素表面光滑,减少了无功能的膜材浪费,且膜厚均匀,膜层与核芯结合紧密,膜切面结构均匀,不易破损。养分释放结果表明,以5%包膜率的纳米SiO_(2)改性蓖麻油基聚氨酯对尿素包膜,表面改性尿素相较普通尿素可�
【Objectives】Surface modification is a key step towards realization of nutrient-release control of coated urea production.We tested several abrasives,and studied the basis for modification in improving the coating property.【Methods】In this study,large granular urea(3–5 mm,N 46%)was used as the fertilizer core,while the tested abrasives included brown-fused alumina,white-fused alumina,zirconia beads,alumina porcelain beads,and aluminum porcelain column.By measuring the repose angle of polished urea after polishing with the abrasives,alumina porcelain beads with a bulk density of 1.336 g/cm3 and a diameter of 6 mm were chosen as the abrasive in the later research stage.1 kg urea and 1.5 kg alumina porcelain beads were loaded into a drum granulator,discrete element software(EDEM)was used to simulate the motion,collision,force and distribution of particles in system of abrasive friction and urea particle self-friction.The surface and sectional structure and the roughness of modified urea were scanned using electron microscopy.The microstructure of the coating was observed using atomic force microscopy(AFM).The nutrient release characteristics of polished and ordinary urea,coated with 3%,5%and 7%of nano-SiO_(2) modified castor oil-based polyurethane,were determined by static water dissolution method.【Results】According to the simulation of EDEM,the urea particles near the bottom moved fast(1.125 m/s),and those at the edge moved slowly(0.00309 m/s),causing the segregation of small pAccording to the simulation of EDEM,the urea particles near the bottom moved fast(1.125 m/s),and those at the edge moved slowly(0.00309 m/s),causing the segregation of small particles at the bottom of the drum during the mixing process.The self-friction force of pure urea was about 0.035N,while the total friction force when mixed with the abrasive increased to about 0.042 N.This enlarged force increased the collision number of urea-abrasive mix system by 13.0%than that of the self-friction system,thus creating more efficient modi
作者
田虹雨
董晶晶
解臣硕
崔静
段建杭
张天骄
代佳颖
王硕
张丽莉
魏占波
武良
郭武松
刘之广
张民
TIAN Hong-yu;DONG Jing-jing;XIE Chen-shuo;CUI Jing;DUAN Jian-hang;ZHANG Tian-jiao;DAI Jia-ying;WANG Shuo;ZHANG Li-li;WEI Zhan-bo;WU Liang;GUO Wu-song;LIU Zhi-guang;ZHANG Min(National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources,Shandong Agricultural University,Tai’an,Shandong 271018,China;Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang,Liaoning 110016,China;Key Laboratory of Crop Specific Fertilizer,Ministry of Agriculture and Rural Affairs/Xinyangfeng Agricultural Technology Co Ltd.,Jingmen,Hubei 448000,China)
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2023年第5期900-911,共12页
Journal of Plant Nutrition and Fertilizers
基金
辽宁省揭榜挂帅项目(2021JH1/10400039-2)。
关键词
尿素
磨料
表面改性
离散元仿真
膜结构特征
养分控释性能
urea
abrasives
surface modification
discrete element simulation
coating structure characteristics
nutrient controlled release performance
