| The growth of crops needs long-term and sustained nitrogen nutrition.Polyurethane coated urea controlled release fertilizer is one of the most widely used urea fertilizers,which can slow down and control the release rate of urea and improve the utilization rate of urea.The most important property of controlled release fertilizer is the release effect of nutrients,and the nature of coating is the key to the controlled release effect of nutrients.The study of controlled release effect of controlled release fertilizer often requires long-term nutrient release test,which slows down the research process of controlled release fertilizer.At the same time,polyols,one of the raw materials for polyurethane coating,will fluctuate in different batches of raw materials,and the influence on the final products also needs to be studied.This paper discusses the relationship between the controlled release effect of coated controlled release fertilizer and the properties of polyurethane membrane materials.The influence of the change of hydroxyl value of polyether polyol on the final product parameters is discussed.In addition to the loss of urea in agricultural production,there are also a lot of urea in the sewage of industrial and agricultural production,which will cause pollution to the environment and also be unfavorable for the growth of plants.Black liquor is the main pollutant in paper industry,and its main components are lignin,hemicellulose,xylose and other biomass materials,which has great application value in agricultural production.In this paper,the modified biocarbon adsorbent was prepared from the dry powder of black liquor of paper making.The adsorption effect and mechanism of the adsorbent were studied.The pollution of black liquor was reduced,and the new ideas and materials were provided for reducing the pollution and new urea fertilizer.The details are as follows:（1）Five kinds of polyurethane coated urea controlled release fertilizer and polyurethane membrane materials were prepared with polyether polyols with different hydroxyl value.The properties of polyurethane coating and polyurethane film were studied by infrared,thermogravimetry,contact angle,water vapor transmittance and elongation at break,and the nutrient release behavior of controlled release fertilizer at different temperatures was studied.The results showed that the nutrient release effect of polyurethane coated controlled release fertilizer with the same coating rate prepared from polyether polyol with the same coating rate was small at 25°C,and other parameters were not different.Therefore,in actual production,the fluctuation of hydroxyl value of polyol in a certain range had little effect on the final controlled release fertilizer products;the controlled release fertilizer had little effect on the final controlled release fertilizer products;the controlled release fertilizer had little effect on the final controlled release fertilizer products in a certain range;the controlled release fertilizer had little effect on the final controlled release fertilizer products in a certain range;the controlled release fertilizer had little The nutrient release behavior of polyurethane film was different and the law was not consistent,and the contact angle and water vapor permeability of polyurethane membrane were related to the final fertilizer release effect.（2）Activated biocarbon was prepared by urea and potassium carbonate activation with paper black liquor dry powder as raw material,and then oxidized to prepare oxidized biocarbon.The adsorption effect of the prepared biocarbon on urea was studied.The results show that the adsorbent has excellent adsorption effect on urea.When the initial concentration of urea is 1000mg·L-1,the adsorption capacity can reach 570 mg·g-1;the adsorption process conforms to pseudo secondary kinetic model and Langmuir adsorption isothermal model;the thermodynamic data show that the adsorption process is spontaneous heat absorption process.This shows that the oxidation biochar has a good potential in the application of urea adsorption. |
