Research On Ethylene Adsorption Mechanism And Preservation Effect Of Oyster Shell Powder

Oyster is a common kind of bivalve mollusks which is widely grew and bred in coastal area of China.Oyster is also the first edible and pharmaceutical resources,which is issued by Ministry of Health.After the consumption of oyster,a large amount of oyster shell is abandoned occupying beaches and land resources and having impact on ecological environment.Prismatic layer which is the main portion of the oyster shell has a large number of 2-10?m micro holes.This lamellar structured layer provides favorable material foundation for its adsorption effect.Peach is a typical kind of climacteric fruit.Reducing the concentration of exogenous ethylene could weaken the ethylene sensitivity of the honey peaches in order to delay the endogenous enthylene production peak and respiratory climacteric,which could delay fruit senescence.To reduce the pollution of the oyster shell and make a better use of its adsorption capacity,in this research,we use ostrea rivularis as raw material to discuss the ethylene adsorption efficacy and its runnig parameters after grinding processing.On the basis of those discussions,the adsorption mechanism of oyster shell powder and its application to the Okubo peach preservation could be preliminarily studied.The main research results are as follows:1.In constant atmospheric pressure conditions,the ethylene adsorption rate of oyster shell powder is very high during former 2h and the adsorption reaction will achieve dynamic balance after a certain time.The higher temperature leads higher ethylene equilibrium concentration.Increasing oyster shell powder dosage could improve the adsorption effect in a specific range.With the powder particle size decreasing,the ethylene equilibrium concentration tends to firstly descend then ascend.2.In volume 0.5L,ethylene intial concentration 270ppm conditions,the adsorption temperature and the powder particle size interaction significantly.Using response surface analysis,we drew the the conclusion that the optimal adsorption conditions for oyster shell powder is powder dosage 2.00g,temperature 273.00K,powder particle size 200M and ethylene equilibrium concentration predicted value is 71.2549ppm in those conditions.3.The oyster shell powder-ethylene adsorption isotherm has been drawn based on the optimal adsorption conditions.After linear and nonlinear fitting for Langmuir and Freunlich isothermal adsorption equation,the results show that the Langmuir model fitting is more accuracy,the adsorption process tends to be monolayer.Through Langmuir and Freundlich adsorption isotherm equation,we know that in 273K,298K and 313K,the theoretic maximum adsorption capacity of the oyster shell powder are 132.22?g/g?136.32?g/g and 174.92?g/g.The change rules of k and kf value indicate that decreasing tempreture is helpful for enhancing the powder's adsorption capacity.n value is greater than 1 shows that it is an optimal adsorption.4.The adsorption isostere linear regression equation is worked out after calculating Clausius-Clapeyron equation,which shows that the ethylene adsorption reaction of oyster shell powder is an exothermic process.The adsorption heat is less than 40kJ/mol and around 10-20kJ/mol indicates that the adsorption reaction needs low heat,the process belongs to physical adsorption.The Bangham adsorption rate equation through linear fitting is q = qe[1-exp(-0.9755t0.60323)].5.200M oyster shell powder functions similiarly to KMnO4 ethylene adsorbent.They can both reduce Okubo peaches' decay rate,weight loss rate and delay their climacteric.As PG and CX activities of the Okubo peach ranging gently,PPO and POD activities reducing,the senescence and browning process of Okubo peach delay effectively,extending its storage period 2-5 days to 6-8 days.