生物炭的制备及其对氮肥吸附效果的研究

Study on the preparation of biochar and its effect on nitrogen fertilizer retention

以玉米秸秆为原材料,分别在350、400、450℃下炭化3 h制备玉米秸秆生物炭(分别命名为B350、B400、B450),利用X射线衍射仪、扫描电镜仪、比表面积及孔径分布仪、红外光谱仪等对材料进行表征,确定材料的相关性能,并探讨其与氮肥吸附的相关性。以平衡实验法研究了溶液pH对生物炭吸附氨氮的影响。实验结果表明:玉米秸秆生物炭B350、B400、B450对氨氮的吸附过程均遵循二级吸附动力学模型,且采用Langmuir方程能更好地描述吸附等温线模型;玉米秸秆生物炭对氨氮的饱和吸附量按从大到小依次为B400、B350、B450,且均为有利吸附;玉米秸秆生物炭对氨氮吸附的最佳pH为8~12。

The corn stalk derived-biochar was prepared by carbonization at 350,400,and 450℃for 3 h and was named as B350,B400,B450.They were characterized by X-ray diffraction,scanning electron microscopy,N2 adsorption apparatus,infrared spectrometry to determine their properties and to explore their correlation with nitrogen fertilizer adsorption.In addition,the effect of pH on the ammonia nitrogen adsorption by biochar was studied using equilibrium test.The experimental results showed that the adsorption process of ammonia nitrogen by B350,B400 and B450 followed the secondary adsorption kinetics model.The adsorption isotherm model of ammonia nitrogen could be better described by Langmuir equation.The saturated adsorption amount of ammonia nitrogen followed the downward order of B400>B350>B450.All prepared biochars were favorable to the adsorption of ammonia nitrogen.The best pH values for ammonia nitrogen adsorption by biochars were 8~12.