Study On The Preparation Of Environment-friendly Polysulfone Coated Fertilizer And Its Slow-release Performance

With the rapid growth of the world’s population,the demand for food is growing,and fertilizers play a vital role in the growth of crops.However,the current common fertilizers have the disadvantages of low utilization rate and environmental pollution,which limit its use.Coated fertilizers have effectively solved this problem.However,there are some problems in the use of coated fertilizers,when the nutrient is released,if the residual film left in the soil is non-degradable material,a large amount of accumulation will have a greater negative impact on the environment and agriculture.On the other hand,due to limited petrochemical reserves and environmental problems,the research on the use of renewable materials for the synthesis of polymer materials has attracted much attention in recent years,and they have better biodegradability than most petroleum-based polymers.Among the renewable materials,hydrocarbon-rich terpenoids have become a research hotspot and have become potential resources to replace petrochemical products.In order to solve these problems,in this paper,the degradable polysulfone material was prepared by copolymerization of natural products monoterpenes（eugenol and myrcene）and SO ₂,and it was used to prepare coated fertilizers.The following experimental studies were carried out:（1）In this paper,two kinds of monoterpenes（eugenol and myrcene）were copolymerized with SO₂ and a series of different molecular weight degradable products（poly（eugenol sulfone）and poly（myrcene sulfone））were prepared by controlling the reaction conditions,and the structure and properties of products were analyzed by FTIR,TG,GPC.According to the above results,the optimal preparation conditions of the poly（eugenol sulfone）with higher-molecular weight could be prepared under the condition of initiator dosage with 1%at 85°C for 36 h,and the optimal preparation conditions of the poly（myrcene sulfone）with higher-molecular weight could be prepared under the condition of initiator dosage with 1%at 80℃for30 h.（2）Using urea granules as the core,preparing coated fertilizer,optimizing the coating process,obtaining the best process parameters,and then preparing the outer cladding layer with different molecular weight poly（eugenol sulfone）and poly（myrcene sulfone）respectively.A series of coated fertilizers were investigated and their slow release properties were investigated.Combined with SEM analysis of the surface of the film,the results showed that the higher the molecular weight of the coated material,the smoother and denser the film surface of the prepared coated fertilizer.It helps prevent the intrusion of moisture and the better the s low release performance.（3）The degradation properties of poly（eugenol sulfone）and poly（myrcene sulfone）were investigated by soil burial method.The results showed that the film gradually degraded with time.The pH of the solution before and after the coating of the coated fertilizer was measured,and the pH did not change.It indicated that the chemical composition of the coated fertilizer did not affect the pH of the soil and did not cause acidification and alkalinity.It was an environmentally friendly coating material..（4）Simulating the slow release properties of poly（eugenol sulfone）and poly（myrcene sulfone）coated fertilizers using first-order kinetic equation,parabolic equation,Elovich equation,Ritger-Peppas equation and zero-order kinetic equation.Both materials show that the Ritger-Peppas equation has the best fitting effect and can be used to fit the sustained release period of the coated fertilizer.