Study on Biochar Coated Urea Fertilizer with Lignin Adhesive Modified by Different Solvents

Abstract:

Many straws and wastes should be treated effectively every year in China. The improper treatments of these wastes have caused severe environmental pollutions. At the same time, with the growing energy demand of the word, biomass conversion technologies have attracted considerable attention because they effectively convert biomass into renewable energy products. It’s found that the biochar, as the main product of pyrolysis technology, could improve the properties of the soil and stay for a long time in the soil. The biochar has a good prospect working as the soil amendment, but difficult to transport, storage and use directly. Therefore, molded biochar was necessary and it could be used as the fertilizer carrier. The biocharbased urea fertilizer can reduce nutrient release rate and improve efficiency of fertilizers, as well as environmental benefits of soil. Thus, the ethanol and wood vinegar were chosen to dissolve the lignin which were used as adhesive during preparing the biochar coated urea fertilizer. The properties of biochar coated urea with different lignin adhesive were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), viscometer and differential scanning calorimety (DSC) methods. The universal testing machine and homemade leaching equipment were used to analyze the biochar coated urea’s mechanics and slowrelease property. The experimental results showed that there is no obvious chemical reaction in the two solutions, and the ligninwood vinegar adhesive had a better surface properties and the viscosity value is 300% higher than ligninethanol adhesive. Comparing with the biochar coated urea of different adhesives, it is found that the ligninwood vinegar adhesive biochar coated urea has a higher coated and granulation rates which are up to 269.4% and 94.83% respectively; the particle size distribute uniform and qualified rate is almost up to 80%; the mechanics and slow release properties are superior too. Hence the ligninwood vinegar adhesive had a better performance on the viscosity and surface properties than ligninethanol adhesive, which is more suitable for the preparation of biomass carbon coated urea.