Preparation And Property Of Desiccants Which Are Made From Natural Material

The desiccants in common use have some shortcoming of themselves, in order to find substitutes and find a new way of processing the agriculture byproduct, in this paper, we prepared desiccant from corn hull. Corn hull has a great deal of surface hydroxyl that can form hydrogen bond with water molecule. According with experiments, we projected some methods as hydrolyzation, derivation and heat treatment to prepare desiccant from corn hull. The raw material was partially hydrolyzed by acid, α-amylase and cellulose, and holes appeared on the sample grain surface, thereby, the surface area of sample was augmented, the amount of surface hydroxyl was increased too. So the moisture adsorption capability of sample was enhanced. For derivation method, we used CH₃COONa to react with the raw material, and -CH₂OONa connected with the sample surface. -CH₂OONa has more moisture adsorption capability than hydroxyl. For heat treatment method, the raw material was heated in 120℃, and then, the sample was washed by hot water. This way can enlarge surface area and improve moisture adsorption capability of the sample. In this paper, we tested moisture adsorption capability of desiccants that were made from corn hull in different humidity and different temperature;we tested reversible adsorption of these desiccants too. The change of appearance of sample grain was validated by SEM and the augment of surface area was validated by mensuration. By contrasted with silica gel, the corn hull desiccants by hydrolyzation method and heat treatment method have advantages as stabilization on moisture adsorption, less water of reversible adsorption and high moisture adsorption ratio in high humidity. These desiccants have disadvantages as lower moisture ratio than silica gel in low humidity and slower moisture adsorption speed than silica gel. The corn hull desiccant by derivation method has advantages as high moisture adsorption ratio, high moisture adsorption speed, stabilization on moisture adsorption and hardly any water of reversible adsorption. This desiccant has a disadvantage as being agglomeration after regeneration.In addition, mechanism of moisture adsorption of corn hull desiccants. By the phenomena of adsorption and calculative activation energy, the mechanism of moisture adsorption was validated. The experiment results showed that the adsorption process of hydrolyzation and heated treatment production is chemisorption processgoing with physisorption process, the adsorption process of derivation production is chemisorption process.