Study On The Preparation And Application Of Lignin In Biochar Urea

As an agricultural country, there are many straw and waste which can’t be treated effectively every year. It is difficult to convert straw to high-quality biochar due to its high ash content. Despite the use as energy, the straw is better to work as resource for returning to agriculture. Many studies have found that the biochar can stay for a long time and can improve the properties of the soil by adding it. The biocar has a good prospect working as the soil amendent. The biochar are most produced by pyrolysis technology, which is diffcult to transport, storage and use directly for the powder form. Molded biochar was necessary to use as the fertilizer carrier, this paper used the lignin as binder, the biochar based urea and the biochar coated ured were produced respectively, and made the research on the preparation technology, stuied the process conditions, the mechanics and slow-release properties, the specific work was as follows:(1)Make the industrial analysis, element analysis and the thermodynamic properties of lignib, and after the different solvents treatment. The dryed material were characterized by SEM, FTIR and different thermal analysis, then can fing out the effects on the lignin structure. At the same time the lignin content, heating temperature and urea content were studied on the influence of solution viscosity under different solvent system, the result showed that under different solvent, the factors influence on the solution viscosity is different.(2) The biochar based urea were produced by the means of hot press molding according to the lignin thermodynamic property. The ratio of biochar and urea was 1:1, and the study on the mechanics and slow-release property showed that the binder can prevent the biochar based urea burst, and can enhance the mechanical and slow release property. And then the binders on the effects of fertilizer property were studied, SEM and universal testing machine were used to measure the structure and mechanical properties, and the home-made sand pillar leaching device was used to test the slow-release property. Lignin content, forming pressure and heating temperature were studied on the effects of properties of urea based on biochar. The results showed that compared to the mixture of urea and biochar, the shaped urea based on biochar could significantly delay nutrient release of fertilizer. With the increase of lignin content and molding pressure, the mechanical strength and the slow-release property had improved; With the heating temperature’s increase, the same content of urea based on biochar’s mechanical strength and slow-release property firstly increased and then decreased, and at the temperature of 70℃, urea based on biochar’s properties were best. At the same time, with the increase of lignin content, soil urease activity decreased, therefore the urea based on biochar has inhibitory effect on soil urease.(3) The lignin has good solubility in alcohol and wood vinegar, then two types of adhesive was prepared. The biochar coated urea was prepared by the granulating disc machine, granulation performance, mechanics and slow release property were tested. The results showed that: the biochar coated urea binded by lignin-vinegar’s granulation rate was 12~24% and biochar coating rate was 34~42% higher than the biochar coated urea binded by Lignin-ethanol. And the biochar coated urea binded by lignin-vinegar’s particle size distribution was uniform, the mechanics and slow release property is better.(4) The study of biochar coated urea banded by bignin-wood vinegar showed that with the heating temperature increase, the granulating ratio and the envelope rate slightly increased, the biochar coated urea’s nitrogen content reduced, and the mechanics and slow-release property firstly increased and then decreased, and at the temperature of 65 ℃, biochar coated urea’s properties were best; With the binder content increase, the granulating ratio and the envelope rate increased, the biochar coated urea’s nitrogen content reduced, and the mechanics and slow-release property increased; With the rise of solid-liquid ratio, the granulating ratio and the envelope rate firstly increased then decreased, the biochar coated urea’s nitrogen content increased, and the mechanics and slow-release property firstly increased then decreased.