Abstract: This work was conceived to investigate the effect of pH on NaClO2 retention rate and ClO2 release rate in preservative paper through adjusting the pH of NaClO2 coating solution. The NaClO2 retention rate from paper A coated with sodium chlorite and the ClO2 release rate from the preservation system were calculated by iodometric titration method. In addition, the surface of paper A and paper B coated with tartaric acid was analyzed by attenuated total reflection infrared (ATR-IR) spectroscopy. The results showed that with the increase of pH, the NaClO2 retention rate from paper A and the amount of ClO2 reacting with preservative components increased significantly. On the contrary, the total amount of ClO2 release from the preservation system decreased. At pH 14, the NaClO2 retention rate was the highest, and the retention time was the longest. Besides, the release time initially increased and afterwards decreased, and the release rate was initially high and then decreased. At pH 10, ClO2 was released for the longest time, and the release rate and amount could guarantee ClO2 concentration for the preservation of fruits and vegetables.

Key words: preservative paper, pH value, attenuated total reflection infrared spectroscopy, sodium chlorite, ClO2