| Many areas have soil problems, such as soil depletion, drought and overusing chemicals in our country, which lead to many problems about pollution and involution,and the arable land has been reduced year by year. Besides, the quality and the amount of agricultural products cannot be guaranteed. As a result, it is extremely meaningful to research and produce the fertilizer with the ability of water-remaining and slow-releasing property for increasing the use rate of soil, preventing water from losing and improving productivity in agriculture.This article will use blueberries as a sample by using lignite as the source of humic acid(HA), poly(acrylic acid,PAA) and chitosan(CTS) as the main composition of coating materials and extracting HA through Oxidation degradation,then HA, CTS and AA polymerization reaction to increase the kinds and the amount of active groups in polymers and improve its salt tolerance and hydrophilic properties. This research will also produce the coating materials CTS-g-PAA/HA. Besides, it will produce a kind of coated fertilizer which has the function of water-remaining and slow-releasing.This function will be investigated in this research to improve the use of water and nutrient, reduce the cost of artificial irrigation and the use of chemicals and protect the environment.Lignite was oxidized by using H2O2 to extracting humic acid of it, and the effect of oxidized conditions to the content of humic acid was investigated. Boehm titration and Fourier transform infrared spectroscopy(FTIR) were used to analyze the effect of oxidized conditions to the content and the structure of Oxygen-containing functional groups. The changes in NH4+, PO43-, K+ adsorption amount of oxidization lignite and lignite were studied.The results demonstrated an intimate link between H2O2 and the content of humic acid from lignite, as well as the Oxygen-containing functional groups and the activity ones. The content of humic acid from the lignite was increased by 12.53% after a 24-hour oxidization and by using 20%(wt%.) H2O2, and soaked in the liquid-solid system with a L/P(liquid-to-powder ratio) 0.8. The oxidation degradation reaction only enhanced the content of the Oxygen-containing functional groups and humic acid increase without side effects.With H2O2 Oxidative degradation it can increase the absorption properties of NH4+,K+,whereas the PO43-can be reduced.Using HA, CTS and AA polymerization, The salt resistance of polymers can be effectively improved in the compound. SEM and FTIR were used to analyze the microstructure and functional groups of polymers.When the addition amount of HA increases by 15%,m(AA):m(CTS)is 8.0,KPS amount plus 2.5%,MBA 2.0%, 70%AA neutralization degree, reaction temperature 80?, the reaction time of 4.5h,CTS-g-PAA/HA absorb distilled water and salt solution respectively is 230.78g·g- 1and 55.53g·g-1. The water absorption rate of CTS-g-PAA/HA coating fertilizer are higher than PAA coating fertilizer,coated fertilizer nutrient elements release less than20% within 24 hours,the accumulative release is less than 80% beyond 28 days,as will as improve soil water retention. |
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