| 摘要: |
| 【目的】探究金属离子改性生物炭对黑土氮素吸附和迁移特性的影响。【方法】以玉米秸秆为原材料，在450 ℃煅烧1.5 h条件下制备生物炭(BC)，分别用KCl、ZnCl2、FeCl3溶液对其进行金属离子负载改性(分别命名为K-BC、Zn-BC和Fe-BC)，并进行表征分析和氮素吸附试验，筛选出最佳改性生物炭；然后在黑土中添加质量分数0.3%的最佳改性生物炭(TB)，以黑土作为对照(CK)，探究这2个吸附体系的氮素吸附和迁移特性。【结果】Fe-BC对NO-3N和NH+4-N的吸附量分别为24 632.79和5 253.68 mg/kg，确定Fe-BC为最佳金属离子改性生物炭。Fe-BC的比表面积和平均孔径较BC提升了9.35和6.67倍。CK和TB在pH为3时对NO-3-N的吸附量最大，CK在pH为9时对NH+4-N的吸附量最大，TB在pH为5时对NH+4-N的吸附量最大。相较于准二级动力学方程，Elovich方程均能更好地描述CK、TB对NO-3-N和NH+4-N的吸附动力学特征；相较于Freundlich方程，Langmuir方程均能更好地描述CK、TB对NO-3-N和NH+4-N的吸附等温线；CK、TB对NO-3-N的吸附反应是自发、放热且无序的，对NH+4-N的吸附反应是自发、吸热且无序的。在氮素迁移试验中，TB对NO-3-N和NH+4-N的累积淋失量分别比CK减少53.19%和30.54%。【结论】黑土中添加Fe-BC可以有效增加对NO-3-N和NH+4-N的吸附量，降低黑土中NO-3-N和NH+4-N的淋失量，从而有效减少黑土中氮素的流失。 |
| 关键词: 金属改性生物炭 黑土 氮素吸附特性；氮素淋溶特性 |
| DOI： |
| 分类号: |
| 基金项目:国家重点研发计划项目 (2021YFD1500805) |
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| Effect of metal ion-modified biochar on nitrogen adsorption and migration features of black soil |
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GU Fangning,HAN Shouxin,WANG Hanbiao,et al
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| Abstract: |
| 【Objective】This study investigated the effect of metal ion modified biochar (BC) on nitrogen adsorption and transport in black soil.【Method】The corn stalk was taken as raw material to prepare BC by calcining at 450 ℃ for 1.5 h.KCl,ZnCl2 and FeCl3 solutions were used to conduct the metal ion loading modification (named K-BC,Zn-BC and Fe-BC,respectively).The characterization analysis and nitrogen adsorption test were conducted to determine optimum conditions.Then,0.3%（mass fraction） optimal BC (TB) was added to black soil to investigate nitrogen adsorption and migration characteristics using the black soil as control (CK).【Result】With the highest adsorption capacity of 24 632.79 and 5 253.68 mg/kg for NO-3-N and NH+4-N,Fe-BC was determined as the optimal metal ion-modified biochar.The specific surface area and average pore diameter of Fe-BC were 9.35 and 6.67 times higher than those of BC.CK and TB had the largest adsorption capacity for NO-3-N at pH of 3,CK had the largest adsorption capacity for NH+4-N at pH of 9,and TB had the largest adsorption capacity for NH+4-N at pH of 5. Compared with the pseudo-second-order kinetic model,Elovich model better described the adsorption kinetic characteristics of CK and TB for NO-3-N and NH+4-N.Compared with Freundlich function,Langmuir function better described the adsorption isotherms of CK and TB for NO-3-N and NH+4-N.The adsorption reaction of CK and TB to NO-3-N was spontaneous,exothermic and disordered,and the adsorption reaction of CK and TB to NH+4-N was spontaneous,endothermic and disordered.In the nitrogen migration test,the total cumulative amounts of NO-3-N and NH+4-N leaching by TB were reduced by 53.19% and 30.54%,respectively.【Conclusion】The addition of Fe-BC to black soil effectively reduced the loss of nitrogen in black soil by enhancing the nitrogen adsorption capacity of black soil and reducing the leaching loss of NO-3-N and NH+4-N. |
| Key words: metal modified biochar black soil nitrogen adsorption feature nitrogen migration feature |
