Preparation And Properties Of Kitchen Waste Oil Modified Polyvinyl Alcohol Slow-release Fertilizer

The preparation of traditional fertilizers into slow-release fertilizers can effectively reduce nutrient loss,reduce environmental damage and promote plant growth.Coated slow-release fertilizer(CSRF)is currently the most widely used slow-release fertilizer,but its coating material is difficult to degrade and the process is complicated.The process of chemically cross-linked slow-release fertilizer is relatively simple and usually has a longer slow-release period,but the problem of difficult degradation still exists.Based on the shortcomings of the above two fertilizers,the environmentally friendly polymer material polyvinyl alcohol(PVA)is selected as the main raw material.On the one hand,it is modified by kitchen waste oil(KWO)to prepare CSRF,and on the other hand,it is modified by grafting urea.Improving the compatibility of urea and PVA to prepare chemically grafted slow-release fertilizer(MSRF).Then through a series of test methods,the preparation mechanism,structure and performance of the two fertilizers were studied,and the performance influencing factors and laws were explored through experiments such as slow release,degradation and planting experiments.The main contents and results of this study are as follows:(1)PVA was blended/chemically modified with kitchen waste oil-based polyols(OP)to prepare slow-release fertilizers,and the preparation mechanism was discussed through experimental analysis.The results show that after OP modification,the swelling resistance,water repellency,plasticity and thermal stability of the PVA film material have been improved,while partially retaining its degradability and hydrophilicity.However,the urea recrystallization phenomenon destroys the membrane material,resulting in a shorter sustained-release period,which is only 120 mins at the longest.(2)On the basis of blending,urea was added to graft modified PVA to prepare MSRF,and the preparation mechanism was obtained;the cold water insoluble nitrogen content of all samples was measured,and MSRF1,MSRF2 and MSRF3 were selected as the research objects.It shows that OP-modified PVA solution(OPMPVA)has good compatibility with urea-modified compound hydroxyurea,and the prepared MSRF has good water repellency,degradability and slow release,and its nutrient release cycle can reach 20 days Above;30-day degradation rate can reach 10.2%.In addition,planting experiments showed that the MSRF application effect is better,and the nitrogen nutrient utilization rate has been improved.