Experimental Study On Colloidal Properties Of Palygorskite Clays

Palygorskite is a mineral typified by layer-chained and hydrous magnesium aluminum silicate. It is widely applied in industrial field for these features in unique crystal structure and fine colloidal properties as well. Among them, the viscosity is frequently used as a key indicator for the evaluation of colloid properties. A high viscosity at relatively low solid concentration is an important characteristic of palygorskite. However, it largely varies in different mine regions, and even in same mineral layer. The pre-treatment methods selected for industrial applications are also factors accounted for changes in colloidal viscosity of the palygorskite products. Therefore, investigating the influence factors of its colloidal viscosity, is of essential significance to comprehensive utilizations and further processing of palygorskite.Samples of clay palygorskite, collected from Jiangsu and Anhui provinces, are the main targets for the investigation on colloidal viscosity. Methods selected here, including the XRD, SEM, and TEM and others, are all applied to evaluate changes in colloidal viscosity. Mineral features for this evaluation are on mineral compositions of the clay, chemical composition, impurity content, and morphological structures in fibers. The results showed that the key factors to contribute the colloidal viscosity are mainly associating with the features of mineral compositions and morphological structures. As for the morphological structures, it is great to effect the colloidal viscosity with relative changes in its length. The ratio of length to width of palygorskite fibers is suggested here as the best morphology feature for evaluation on the colloidal viscosity.Through TG-DSC, AFM and Zeta potential methods, other influence factors that related more mechanism in colloidal chemistry, including status of water in palygorskite, contacting features among fibers of palygorskite, the relevant Zeta potential and heating temperature to the specimen, were also concerned in this thesis. The results showed that:with temperature increasing on the mineral palygorskite, relative changes occur in ways of reducing in colloidal viscosity and the Zeta potentials as well, but greatly with agglomerating trend for the palygorskite fibers.An by product of this thesis was also achieved. Under appropriate controls on its molecular weight, it is evident to disperse efficiently the mineral particles but improve significantly the stability of palygorskite colloid; and also effective to purify by removing the impurities like as quarts and dolomites. But, meanwhile, it is possible to face the risks of separation of solid-liquid to get the powder of palygorskite and low recycling ratio of palygorskite. To better resolve the relative problems, ozonization that can break chain-linked carbons of polymer by intensive oxidations has been considered. This method can effectively reduce the stability of palygorskite colloid, which is helpful to high the recycling ratio of palygorskite powder from its colloid.