Research On The Characteristics Of Coal Humic Acid From Different Sources And Its Fertilizer Applicatio

Peat,lignite and leonardite are the main sources of humic acids（HAs）,which are abundant in my country.HAs are widely used in agriculture and other fields,and the composition and properties of HAs affect its application.Therefore,the comparative analysis of HAs extracted from different sources is of great significance.In this paper,five different coal samples were used as raw materials,and HAs from different sources was compared and analyzed by various analysis methods.Single factor optimization experiment was conducted to explore the optimal conditions for preparing HAs fertilizer from three kinds of raw materials through two process routes.The HAs fertilizers under the optimal preparation conditions were studied by systematic analysis methods,and their biological activities were tested through potted plant experiments.The main research contents and results were as follows:（1）The HAs from five different sources was extracted by the alkali-dissolving acid precipitation method,and the HAs was systematically analyzed by various analytical methods.The results showed that the content of aromatic structure,the f_ar/aland the content of total acidic groups satisfied HAs of leonardite>HAs of lignite>HAs of peat.The relationship of flocculation limit was HAs of peat and lignite>HAs of leonardite,and the relative content of aliphatic carbon was HAs of peat>HAs of lignite>HAs of leonardite.The maximum excitation wavelength of the five HAs was about 270 nm,and the range of Ex/Em was 268～272 nm/440～464 nm,the fluorophores in the five HAs are similar.There were four stages of thermal decomposition process for the five HAs,and the HAs of lignite and leonardite had higher thermo-gravimetric index（TGI）,indicating the existence of polycyclic aromatic cores with greater heat resistance.Five kinds of HAs from different sources were all amorphous,with amorphous cracks on the surface,high level of microporosity and high density,and irregular appearance.（2）Single factor experiments were used to explore the effect of nitrification process on the content of HAs in coals.The results showed that the optimal nitrification conditions for Xinbin peat were:nitric acid concentration was 15%,room temperature nitrification time was 1.5 h,and liquid-solid ratio was 4 m L/g,under the optimal single factor condition,the content of HAs was 43.75%.The optimal nitrification conditions of Jinsuo lignite were as follows:nitric acid concentration was25%,room temperature nitrification time was 2.5 h,liquid-solid ratio was 3 m L/g,and content of HAs was 73.34%under the best single factor condition.The optimum nitrification conditions for Xinjiang leonardite were:nitric acid concentration was20%,room temperature nitrification time was 2 h,liquid-solid ratio was 3 m L/g,and content of HAs was 71.52%under the best single factor condition.（3）Single factor experiments were used to explore the effect of different experimental conditions on the yield of potassium humate fertilizer when KOH was used as an extractant.The results showed that the optimal single-factor preparation conditions for potassium humate of Xinbin peat were as follows:KOH solution concentration was 0.3 mol/L,reaction time at room temperature was 6 h,liquid-solid ratio was 20 m L/g,and the average yield was 69.32%under the optimal single-factor condition.The optimal single-factor preparation conditions for potassium humate of Jinsuo lignite were as follows:KOH solution concentration was 0.4 mol/L,reaction time at room temperature was 4 h,liquid-solid ratio was 25 m L/g,and the average yield under the optimal single-factor conditions was 74.89%.The optimal single-factor preparation conditions for potassium humate of Xinjiang leonardite were as follows:KOH solution concentration was 0.5 mol/L,reaction time at room temperature was 5 h,liquid-solid ratio was 20 m L/g,and the average yield under the optimal single-factor condition was 83.16%.（4）Single factor experiments were used to explore the effect of different experimental conditions on the yield of ammonium humate fertilizer when ammonia was used as an extractant.The results showed that the optimal single factor preparation conditions for ammonium humate of Xinbin peat were as follows:ammonia solution concentration was 3%,reaction time at room temperature was 4 h,liquid-solid ratio was 25 m L/g,and the average yield under the optimal single factor conditions was 50.26%;The optimal single-factor preparation conditions for ammonium humate of Jinsuo lignite were as follows:ammonia solution concentration was 8%,reaction time at room temperature was 4 h,liquid-solid ratio was 25 m L/g,and the average yield under the optimal single-factor conditions was 54.41%;The single-factor preparation conditions for ammonium humate of Xinjiang leonardite were as follows:ammonia solution concentration was 8%,reaction time at room temperature was 5 h,liquid-solid ratio was 25 m L/g,and the average yield under the optimal single factor conditions was 88.05%.（5）Six kinds of HAs fertilizers under the optimum preparation conditions were systematically analyzed and applied.The results showed that compared with the corresponding raw coal HAs,the contents of total acid group,H/C,E₄/E₆,Δlog K value,hydrogen and nitrogen content all increased,while the content of aromatic structure,condensation limit value,TGI value and thermal stability all decreased.The N and P₂O₅ contents of nitrohumate nitrogen fertilizer were generally higher than those of nitrohumate potassium fertilizer,while the K₂O content was opposite.The six kinds of HAs fertilizers from different sources were all amorphous,and the carbon content was basically the same as that of raw coal HAs,and the solid surface had an amorphous crack.The three kinds of nitrohumic potassium fertilizers were all large aggregates with low surface void ratio,while the surface of the three nitrohumic ammonium fertilizers was fluffy and high porosity.Two different HAs fertilizers from the same source showed similar thermal stability and synchronous fluorescence curves.The application of XBNHA and JSKHA promoted the growth of Perilla,and the application of XBNHA and JSNHA promoted the growth of Cabbage.