| Exchange-absorption behavior of ami no nitrogen on four kinds of cation exchange resins is investigated in the work; The optimum kind of cation resins is selected; the absorption and desorption of LSI-1010 cation exchange resin to amino nitrogen are researched ; and the ideal exchange-absorption and desorption conditions are established ; The work puts forword a new method to solve the question of browning in apple juice .The paper also deals with four kinds of anion exchange resins,and the ideal anion exchange resin is found; the static and dynastic kinetics of LSI-1031 anion exchange resin is determined and analyzed; The optimum parameters of exchange-absorption and desorption of fruit acid are procured.The work supplys theories and data for the fruit sugar of apple and a new way to resolve the problem of the high ratio of sugar to acid. The results of the paper are listed as follows.1. LSI-1000.LSI-1001,LSI-1010,LSI-1011 cation exchange resins differently improve the mechanism of apple juice , but LSI-1010 has an obvious enhance to the mechanism of apple juice.more importantly, the capacity of LSI-1010 cation exchange resin to amino nitrogen is larger.Its capacity is 2.Img/ml wet resin.2. The exchange-absorpt ioncapacityofLIS-lOlOcation exchange res in wi 11 increase with the lengthening of time , but its capacity does not change after 3.5 hours. The exchange-absorption equilibrium time is 3. 5h. The exchange-absorption isotherm of amino nitrogen on LSI-1010 cation exchange resin is determined at 20癈.The isotherm can be described by Freundlich equation. The equation is q = 0.0832C'2527 (r=0. 9952)3. The flow rate, concentration of amino nitrogen in apple juice and temperature influnce the curves of dynamic kinetics, but there is little affection of the juice pH to the curves . The optimum condi t ions are 4BV/hand 50. Besides, higher concentration of amino ni trogen can improve the performance of LSI-1010 cation exchange resin much more at lower flow rates.4. The eluant , i ts concent rat ion , flow rate and temperature are the factors which influnce the elution curves of amino nitrogen. The ideal conditions are: 4% HCl,2BV/h and 20癈. The aim of saving the eluant can be achieved when it is replaced after 4 circles. The efficiency of reclaim is above 80%. 18BV of the eluant can be reserved.5. All of LSI-1021,LSI-1022, LSI-1031, LSI-1032 anion exchange resins can variously exchange and absorb fruit acid , but LSI-1031 anion exchange resin has the largest capacity .Its capacity is 43. 4mg/ml wet res in. Besides, the resin can improve the mechanism of apple juice. The capacity of LSI-1031 anion exchange resin will rise as time gone,but it remains stable after 5 hours.The equilibrium time of LSI-1031 anion exchange resin to fruit acid is 5h.The exchange-absorption isotherm of LSI-1031 anion exchange resin at 20癈 can be described by Langmuir isotherm .The exchange-absorption of fruit acid on LSI-1031 anion exchange resin belongs to mono-molecule layor absorption.The isotherm equation of LSI-1031 anion exchange resin is:6. The flow rate, concentration of fruit acid in apple juice and temperture affect the dynamic kinetic curves of LSI-1031 anion exchange resin to fruit acid ; The ideal conditions are : 3BV/h and 50癈. Moreover,lower concentration of fruit acid can improve the capacity of LSI-1031 anion exchange resin.7. The elutant, its concentration, flow rate and temperture influnce the elution curves of fruit acid on LSI-1031 anion exchange resin. The optimum parameters are: 2%NaOH,2BV/h and 20癈 . Futhermore, gradient elution (2%-4%-2%NaOH) can raise the reclaim efficiency of fruit acid.
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