Preparation Of Hydrophobic Porous Starch And Application In Oil Absorbency

Because of the characteristics of renewable, reuse and biodegradation, the hydrophobic porous starch is environmentally friendly as oil absorption material. In order to prepare the hydrophobic porous starch, cornstarch was pretreated by enzymatic hydrolysis enzymatic hydrolysis and then modified with octenyl succinic anhydride(OSA) and Al3+ cross-linking. In this thesis, the effect of enzymatic hydrolysis on the structure and physicochemical properties of hydrophobic porous starch was investigated. OS substituent distribution in granular and molecular levels was studied by confocal laser scanning microscopy(CLSM), Fourier transform infrared spectroscopy(FT-IR). The application of the hydrophobic porous starch in oil absorbency was also investigated, showing potential application prospect in oil waste water management. The main results were as follows:1. Corn starch pretreated with enzymatic hydrolysis was modified with OSA and Al3+. The enzyme reaction mostly occurred in the amorphous lamellae of the starch granules and reaction rate was faster than in the crystalline region. The degree of oil absorption increased with the extension of hydrolysis. The oil absorption of the hydrophobic porous starch was up to 52.3%. The substitution degree and activation index of the hydrophobic porous starch were decreased due to destruction of the surface structure of starch granules.2. The structural analysis of the hydrophobic porous starch showed that enzyme treatment did not change the crystalline structure of starch granules, but formed different sizes of holes on the granule surface. OS groups were distributed throughout the hydrophobic porous starch, mostly in the periphery of the particles. And with the increase of hydrolysis rate, OS groups were distributed more in the interior of the hydrophobic porous starch granules. The Al3+ content on the surface of different hydrophobic porous starch was analyzed and found that Al3+ content increased with an increase of the hydrolysis rate.3. After static separation, degree of substitution and oil absorption of the hydrophobic porous starch were determined. It was found that the reaction of OSA was not uniform among starch granules, some of starch granules did not react with OSA. Degree of OS group substitution was the key factor that influenced the oil absorption properties for the hydrophobic porous starch. Oil adsorption ratio of the floating on the water of hydrophobic porous starch was higher than that of the settling down at the bottom of hydrophobic porous starch, as the OS groups distribution was more concentrated on the surface of the floating on the water of hydrophobic porous starch granules, but mainly inside of the settling down at the bottom of hydrophobic porous starch granules.4. The application of the hydrophobic porous starch on the oil absorption performance was also investigated, including the oil absorption, oil-water selectivity, oil resistance, etc. Effects of different thickness of oil film on the oil absorption were also investigated. The oil absorption of corn oil, engine oil and diesel oil were 80.4%, 52.3% and 41.9%, respectively,. In oil-water system, the water absorption rate of the hydrophobic porous starch was very low(about 6%), indicating a good oil-water selection performance. Under lower centrifuge speed condition, the hydrophobic porous starch showed a good oil-keeping performance.