Study On Co-pyrolysis And Oxidation Of Waste Agracultural Plastic And Nitric Acid To Produce Fertilizer

Mulch film is widely used in agriculture,because of it‘s suppress weed growth and the effect of heat preservation,the using of mulch increase crop yields,leading to the increasing usage of agricultural film,due to the characteristics of plastic refractory,and the lack of effective means of recycling,the accumulation of film makes serious white pollution in the fields.The main constituents of mulching film is polyethylene.Therefore,this paper makes a depth analysis of the reasons why polyethylene is difficult to degrade,and uses the co-pyrolysis of oxidizing acid and polyethylene mulching film to generate organic compounds containing nutritional elements,so as to explore the feasibility of polyethylene into fertilizer.The main conclusions are as follows:1.After the reaction of polyethylene and nitric acid under heating conditions,the molecular weight of the polyethylene will decrease,and the THF soluble product with small molecular weight will be formed.The molecular weight of the THF soluble product will change with the reaction time,the concentration of the added acid,added absolute amount of nitric acid and the reaction temperature.The content of N element in the products also changed with the change of the initial reaction conditions.2.After the co-pyrolysis reaction polyethylene with nitric acid,film will generate functional groups including nitro,alcohol hydroxyl,carbonyl and carboxyl;Due to the heat decomposition of nitric acid itself,at the end of the reaction,up to 50 % of nitric acid will decompose into nitrogen oxides.3,Under heating conditions,polyethylene will be oxidized by sulfuric acid and phosphoric acid.So,the total mass of water insoluble solid increases,and the reaction process with sulfuric acid can generate compounds containing S element.The oxidation of polyethylene by sulfuric acid and phosphoric acid is slower than that by nitric acid,and only a small amount of tetrahydrofuran soluble substance is formed.4.The mixed acid of sulfuric acid and nitric acid can increase the total yield of the product and the soluble yield of THF soluble,reduce the molecular weight of the product and reduce the effective utilization rate of N element.5.Polyethylene can be degraded in a short time after the copyrolysis reaction with nitric acid.In the experiment period of 4 months,40% of the water insoluble solid is degraded,and the degraded components are mainly THF soluble product,accounting for 93.25 % of the total degradation mass,and THF insoluble component accounts for6.75 %.