The Development Of Acid Activated Bentonite For Edible Oil Bleaching And Investigation Of Its Adsorption Property

The characterization of bentonites from Wulanlinge ore of Xiazijie in Xinjiang, the development of its acid activated bentonite products, and the application in oils bleaching and bleaching performance were investigated. The results were obtained as follows:First, the mineralogical and physicochemical properties of WZB, WSB and WXB bentonite samples from Wulanlinge ore were characterized. It was proved that all the three samples belonged to low-medium-grade sodium-type bentonite, which possess of good physico- chemical properties and compose of about 60% montmorillonite. In addition, wet process of purification on WZB sample was carried out, and the optimum conditions followed as particle size of 80-100 mesh, solid-liquid ratio of 1:10, centrifugation speed of 2000 r·min-1 and centrifugation time of 10 min. The content of montmorillonite reached over 80% with recovery rate exceeding 75% under the best operation conditions.Second, the key effect factors of preparing acid activated bentonite were discussed, the optimal conditions for preparing the products were followed, 25% sulfuric acid strength, reaction time of 4h, reaction temperature of 95℃and the solid-liquid ratios of 1:2. On this basis the three bentonites were activated to investigate. It showed that WZB sample was activated with the most effectively, where there were good linearity relativity between properties of the products and physicochemical properties of raw bentonite. Furthermore, activation efficiency of WZB sample treated with phosphoric acid, sulfuric acid and hydrochloric acid were studied, respectively. It could be seen clearly that activation efficiency treated with phosphoric acid was poor as a whole, namely, free acid was higher and bleaching rate was lower. Whereas, activation efficiency with treated sulfuric acid and hydrochloric acid is better, and both the products prepared with 25% sulfuric acid and 30% hydrochloric acid, possessed the highest bleaching capability and others indexes met all requirements of vegetable oil bleaching. Then sulfuric acid was more suitable for activated reagent.Activity degree and free acid of acid products were varied similarly with increasing acid strengths, and acid strength corresponding to maximum of activity degree of acid products was less than that of bleaching rate of acid products. There were reversely changing trends between bulk density and bleaching rate.Chemical components analysis and structure characterization on acid activated bentonites, which, prepared with various acid strengths, were done. Ions of Na+, Ca2+ in montmorillonite interlayer released fast into solution, while octahedrally coordinated Mg2+, Al3+ and Fe3+ released slowly during acidification, and Mg2+ of them was most readily. The total pore volume, average pore diameter and special surface area of the products were varied regularly with the increasing of amounts of acids.Third, bleaching efficiency of cottonseed oil and sunflower oil using activated products...