Screening And Evaluation Of Processing Technology Of The Biochar From Caragana Korshinskii Based On High Nutrient Conservation

The study on adsorption of nitrate nitrogen（NO₃^--N）and ammonium nitrogen（NH₄⁺-N）by Caragana korshinskii derived biochar is the key to the application of biochar in the conservation of soil nutrients.In this paper,talking high soil nutrient absorbing efficiency as the aim,selected the best processing technology of Caragana korshinskii biochar,supplemented by liquid phase adsorption experiment,discussed the change of environmental factors in the adsorption system（mainly adsorbate concentration,reaction time,initial pH,biological carbon dosage,other coexisting ions etc.）,influence due to the adsorption of biochar on NO₃^--N and NH₄⁺-N of Caragana korshinskii biochar.The main results of this experiment are as follows:（1）with the increase of pyrolysis temperature and residence time,the yield of Caragana korshinskii biochar decreased,and the pH of Caragana korshinskii biochar increased.With the increase of pyrolysis temperature,the carbon content of Caragana korshinskii biochar increased,the oxygen content decreased,and the nitrogen content was stable.The CEC of Caragana korshinskii biochar showed a general downward trend,and was positively correlated with the corresponding O/C ratio.The specific surface area and total pore volume of Caragana korshinskii biochar increased at first and then decreased with the increase of pyrolysis temperature and residence time,.According to the analysis results of SEM,lower pyrolysis temperature and shorter residence time of the heating surface is smooth,layered structure is not obvious;extend the time and stay increased with the pyrolysis temperature,carbon frame structure,a large number of small holes in the surface of biochar began making a honeycomb,the specific surface area and total pore surface area the volume began to increase;the pyrolysis temperature and residence time continue to increase,the edge part of the layered structure collapse,hole wall erosion by increasing the degree of surface roughness,increasingly,the corresponding specific surface area and total pore volume decreased than before.（2）Caragana korshinskii biochar prepared under different pyrolysis conditions has goodadsorption effect on NO₃^--N.With the adsorption amount of NO₃^--N as the optimum condition,the Caragana korshinskii biochar prepared under the pyrolysis temperature of 650 degrees and the residence time of 3H was determined as the best Caragana korshinskii biochar based on NO₃^--N adsorption.（3）NO₃^--N to screening out the best adsorption of Caragana korshinskii biochar based on the pyrolysis temperature is 650,the residence time of 3H prepared under Caragana korshinskii biochar as the research object,the change of liquid phase adsorption in the system of environmental factors caused the following effects on adsorption of biochar NO₃^--N biochar: Caragana korshinskii on the removal rate of NO₃^--N increases with the addition the amount of Caragana korshinskii biochar.With the increase of pH,the amount of biochar adsorbed by Caragana korshinskii NO₃^--N decreased.When the adsorption time is 10 min,the adsorption capacity of Caragana korshinskii biochar to NO₃^--N has reached a balance state,and the adsorption rate is very fast.With the introduction of NH₄⁺as a competitive ion,the adsorption capacity of Caragana korshinskii biochar to NO₃^--N gradually decreases with the increase of NH₄⁺ ion strength.The best fitting effect on the adsorption of NO₃^--N Langmuir and biochar C.Freundlich adsorption equation,the theoretical maximum adsorption capacity of Langmuir adsorption equation that is 120.64mg/g.by D-R equation,the adsorption process was mainly chemical adsorption.Caragana korshinskii biochar as NO₃^--N adsorbent,recommended conditions NO₃^--N adsorption in solution is: the pyrolysis temperature is 650 degrees centigrade,the residence time of 3H,the adsorption time is 10-30 min,the adsorption environment pH is 3-5,the concentration of NO₃^--N containing solution is 70-100mg/L,and Caragana korshinskii biochar addition was controlled at 0.4g-0.5g.（4）Caragana korshinskii biochar prepared under different pyrolysis conditions has a certain adsorption effect on NH₄⁺-N.With the adsorption amount of NH₄⁺-N as the optimum condition,the Caragana korshinskii biochar prepared under the pyrolysis temperature of 500 degrees and the residence time of 3H was determined as the best Caragana korshinskii biochar based on NH₄⁺-N adsorption.（5）NH₄⁺-N to screening out the best adsorption of Caragana korshinskii biochar based on the pyrolysis temperature is 500,the residence time of 3H prepared under Caragana korshinskii biochar as the research object,the change of liquid phase adsorption in the system of environmental factors caused the following effects on adsorption of biochar NH₄⁺-N biochar: Caragana korshinskii on the removal rate of NH₄⁺-N increased with the increase of Caragana korshinskii the dosage of biochar.With the increase of pH,the adsorption rate of Caragana korshinskii biochar to NH₄⁺-N showed a continuous growth trend.When the adsorption time is 10 min,the adsorption capacity of Caragana korshinskii biochar to NH₄⁺-Nhas reached a balance state,and the adsorption rate is very fast.With the introduction of NO₃^-as competitive ion,with the increase of NO₃^-ion strength,the adsorption capacity of Caragana korshinskii biochar to NH₄⁺-N increased first,then decreased,and finally stabilized.The Freundlich adsorption equation has the best fitting effect on the adsorption of biochar by Caragana korshinskii NH₄⁺-N,and the maximum adsorption capacity is 21.38mg/g by Langmuir adsorption equation.As a NH₄⁺-N adsorbent,the recommended conditions for the adsorption of NH₄⁺-N in solution were: adsorption time was 10 min,adsorption environment pH was 7-9,solution containing NH₄⁺-N concentration was 70-90mg/L,and Caragana korshinskii biochar addition was controlled at 0.4g-0.5g.（6）in view of the experimental results of adsorption of NO₃^--N and NH₄⁺-N by Caragana korshinskii biochar,it is recommended that the pyrolysis temperature of 450-500 degrees and residence time of 2-3H are the ideal process for the preparation of biochar from Caragana korshinskii microphylla.In practical application,the improvement effect of Caragana korshinskii biochar on soil is related to the adsorption of NO₃^--N and NH₄⁺-N in soil.Therefore,whether the Caragana korshinskii biochar prepared under this process can achieve the best effect on the soil needs to be verified by subsequent studies.