Study On The Influence Factors Of Sodium Chlorite Retention Rate And Chlorine Dioxide Release Laws Of Preservative Paper

Chlorine dioxide preservative agent has been widely used because of its high efficiency and safety.In this work,the chlorine dioxide preservative paper with slow release effect was prepared by the A and the B paper used as carrier and sodium chlorite used as the precursor of chlorine dioxide.The chlorine dioxide preservative paper was made up of the A and the B paper,in which the surface of the A paper was coated with sodium chlorite solution,and the surface of the B paper was coated with tartaric acid.During the preservation process of fruits and vegetables,it would release chlorine dioxide gas when fitting the A,B paper.Both chlorine dioxide and sodium chlorite were strong oxidizing substances,and also easy soluble in water.The main components of the preservative paper base were cellulose,hemicellulose and lignin,which contained active functional groups,such as benzene ring,double bond,aldehyde,phenol and so on.These functional groups would consume sodium chlorite and chlorine dioxide,and the porous structure which caused the adsorption of gas and liquid would also reduce the release of chlorine dioxide.This work investigated the effect on sodium chlorite retention rate and chlorine dioxide release rate in preservation through three methods,they were adjusting the pH of sodium chlorite coating liquid,applying different adhesive layers on the surface of the paper base and changing the content of adhesive layer.The coating machine was used to prepare the fresh-keeping paper.The sodium chlorite retention rate and chlorine dioxide release rate in preservative paper were calculated by the iodometric titration method.The preservative paper were analyzed by total reflection infrared spectroscopy and scanning electron micrograph.The retention mechanism of sodium chlorite and the influence of chlorine dioxide release on the preservation paper were analyzed.The conclusions on the sodium chlorite retention rate and chlorine dioxide release rate were obtained as follows:(1)The pH value of the A paper coating solution had a significant effect on the retention rate of sodium chlorite and the release of chlorine dioxide in the preservative paper.With the increase of the pH,the sodium chlorite retention rate in the A paper and the reaction amount of chlorine dioxide and the composition of paper increased significantly.On the contrary,the total amount of chlorine dioxide release in the preservation system decreased.When pH=14,the sodium chlorite retention rate was the fastest,and the retention time was the longest.With the increase of pH,the reaction amount of chlorine dioxide and the composition of paper increased,and the total amount of chlorine dioxide release in the preservation system decreased.Besides,the release time increased and then decreased,and the release rate sped up and then slowed down.According to the release and release time of chlorine dioxide,the optimal pH value is 10.(2)The porous structure of the preservative paper reduced the retention rate of sodium chlorite,and changed the release of chlorine dioxide.But the adhesive layer reduced the influence of the structure of the paper.The influence of four kinds of coating on the retention rate of sodium chlorite in the A paper was:PVA/starch adhesive>PVA>starch stearate>oxidized starch adhesive>matched group.In all cases,the sodium chlorite retention rate all decreased over time.It was beneficial to the early preservation of fruits and vegetables when coated with oxidized starch adhesive on the surface of fresh paper.The total mass was 75%higher than that of the control group.On the contrary,it was beneficial to the late preservation of fruits and vegetables when coated with PVA/starch adhesive.The total mass was 130%higher than that of the control group.(3)In relation of coating PVA,starch stearate and oxidized starch adhesive on the basis of fresh paper,when applying PVA/starch adhesive on paper base,the retention rate of sodium chlorite was the largest,the retention time was the longest.Chlorine dioxide had the largest release rate,and played the role of rapid preservation,at the same time,chlorine dioxide had the largest release.With the increase of PVA/starch content,the retention rate of sodium chlorite increased,the total release of chlorine dioxide increased,the maximum release amount and the maximum release rate of chlorine dioxide moved toward later stage,it was beneficial to the preservation of fruits and vegetables.Besides,the surface morphology of the paper changed,the porosity decreasesd,and the surface of the paper became more smooth.When the PVA/starch was 15.9 g/m2,the increase of the retention rate of sodium chlorite was not very significant on the A paper.Chlorine dioxide had the largest amount of release which was 4.6 mg,increased by 130%compared with the control group.(4)The composition and structure of fresh paper were the main factors that affect the retention rate of sodium chlorite and the release of chlorine dioxide.Sodium chlorite and chlorine dioxide reacted with glycosidic bond,aldehyde group,phenolic,non phenolic lignin and conjugated structure.Alkali treatment increased the reaction degree of sodium chlorite and chlorine dioxide with paper base and made the paper fibers more loose.The surface activity of fiber and the adsorption ability of paper base were enhanced,thus the release amount of sodium chlorite and chlorine dioxide retention rate were affected.