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Study On The Nutrient Release Kinetics And Thermodynamic Characteristics Of Vegetable Oil Coated Controlled Release Fertilizer

Posted on:2017-09-24Degree:MasterType:Thesis
Country:ChinaCandidate:Y HuangFull Text:PDF
GTID:2323330536950444Subject:Fertilizer learn
Abstract/Summary:PDF Full Text Request
In order to ascertain the supplying capability of vegetable oil coated controlled release fertilizer,this paper studied systemly the nutrient release kinetics?thermodynamic characteristics of the coated controlled release fertilizer with different longevity?NPK ratio of at normal temperature?high temperature,the influence of the stability of coating technology,coating thickness,ambient temperature,core fertilizer NPK ratio and other factors on nutrient release characteristics of controlled release fertilizer was studied deeply,the research results will help explain the mechanism of the fertilizer nutrient release coated controlled release?prodict the longevity and determine the fertility of coated controlled release.The main results and conclusions are as follows:1)The three kinds of controlled release fertilizer CRFA?CRFB?CRFC under 25? and 40? nutrient release were in "S" type with coating thickness 110 g / m~2 and catalytic amount respectively 1.5 ‰?2 ‰?2.5 ‰,the increasing amount of catalyst could improve the integrity of coated fertilizers when coated process was stable,25? the longevity of the three controlled release fertilizer are 142d?133 d?133 d?40? were 55 d.Each batch of interspecific nutrient release patterns of the three fertilizer under the same coating process was very similar,25 ? the fitting correlation coefficients range between batches of CRFA?CRFB?CRFC are respectively 0.989 ~ 1.000?0.983 ~ 1.000?0.999 ~ 1.000?40? were higher.2)25 ? Three different NPK ratio coated controlled release fertilizer of hefei HN?HK?HPK nutrient release characteristic curve are in "S" type;under the conditions of high temperature(60?~ 90 ?)and different coating thickness HN almost all for parabolic,HK envelope thickness of 110 g / m~2 for the "S" shape and other for parabolic,HPK are all in "S" type;the increase of Coating thickness can improve the integrity of the envelope and longevity extension,such as 25? coating thickness increased from 70 g / m~2 to 110 g / m~2 the longevity of HN?HK?HPK respectively extend 100d?130d?70d,under normal temperature conditions and the same coating thickness the core of the fertilizer had no significant impact 0n the longvity,while the trend was HN <HK <HPK under high temperature.3)The nutrient release rate versus time curve of HN?HK?HPK was "two peak-valley" pattern conformed to the typical " diffusion mechanism ",under normal temperature and low coating thickness the second peak of nutrient release rate will be less than the first peak,under high temperature the second peak were significantly higher than those of the first peak;Average nutrient release rate changing with temperature(25? ~ 90?)HN presenter "S" type trend,while HK?HPK for exponential growth.4)Withith coated thickness increase every 5? addition of nutrient release rate of HN?HK?HPK under high and low temperature range(60?/25??75?/25??90?/25?)and high temperature range(75?/60??90?/60??90?/75?)all showed a trend of decline,such as thickness of coated from 70 g/m~2 to 130 g/m~2 HN60/25 and 90/75 increase respectively by 0.33% / 5??4.61% / 5?,in addition to high temperature range 90/75 every 5? addition of nutrient release rate of the core exhibit HK> HN> HPK,others showed HN> HK> HPK.5)Richard equation was the best in HN?HK?HPK nutrient release kinetics equation followed by the first order kinetic equation?parabolic equation?Elovich equation,the temperature?coating thickness and the core did not affect the Richard equation fitting.The maximum cumulative release rate N0 in Richard equation was less than 100%,N0 between cores showed HN>HK>HPK,The nutrient accumulated release parabola when shape parameter d was less than or equal to-1,the curve was "s" type when d >-1,the d value increases when coating thickness increases,d value decreased when the temperature increase,compared with HK?HN d values of HPK was more than-1 easily,curve inflection point ti get larger when coating thickness increased and the temperature rised,the rate constant k increased when coating thickness decreased and the temperature rised,k value between cores exhibited HPK <HK <HN.The efficiency difference and relative difference of maximum between the calculated the fertilizer efficiency longevity by Richard equation and the actual longevity amplituded range 0.03 ~ 9.0d?0.30 ~ 5.23% respectively,the calculated longevity and the actual longevity of fertilizer is very close,so Richard equation can forecast controlled release fertilizer nutrient release well.6)The dependency degree Q value and the sensitivity to temperature would decreased when coated thickness increased,in the range of 25 ~ 75?,HN is the most sensitive to change of temperature,while HN?HK?HPK were gradually less sensitive to temperature When the membrane material was damaged by the high temperature.7)Tn the range of 25 ~ 75? the nutrient release Arrhenius plot of three kinds of cores fitted a higher coefficient r and the activation energy Ea could be obtained,high coating thickness would increased activation energy Ea such as coating thickness from 70 g/m~2 to 110 g/m~2 HN?HK?HPK increased by 17.16?16.15?19.42 KJ mol-1 respectively,between the cores Ea showed HN <HK <HPK,25 ~ 75? the gibbs free energy ? G < 0? the enthalpy ?H<0? the entropy change ?S <0,with the coated thickness increase ? G? ? H?? S increased,between the cores ?G??H??S showed HN> HK> HPK,the controlled release fertilizer nutrient release process can be spontaneous.
Keywords/Search Tags:Botanical oil, Control realease fitilizer, Nutrient release characteristic Nutrient release kinetics, Nutrient release thermodynamics
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