| Recently, polyaluminium compounds have been more increasedly used in many disciplines such as environmental chemistry, geochemistry and biochemistry, thus caused great importance and research to polyaluminium compounds. The distribution and transformation of polyaluminium species in aqueous solution and the hydrolytic polymerization mechanism of trivalent aluminum ion are relatively hot ares of research.Amphoteric properties of aluminum provides us the favorable conditions to research the hydrolysis mechanism of Al3+ ion, but the variety and the complexity of aluminum hydrolysis reaction process have seriously restricted the preparation of pure polyaluminium compounds so as to influenced the development of its hydrolysis mechanism research. Our group has found out a simple and effective method to prepare pure polyaluminium compounds through years of exploration and attemption, that is phase diagram plotting method.This paper adopts the method of "top-down" wet slag and draws the AlCl3-H2O-Al2O3 ternary equilibrium system phase diagram. In the process of drawing, we regulated the basity of the aluminum chloride solution of different concentrati ons by using aluminum and made a slow evaporation with the obtained solution under 100℃ constant temperature, after waiting for enough solid precipitation, se parated solid and liquid, dissolved for chemical analysis for different solid-liquid ratio of wet slag point, and connected these points in line consists of the connec tion line in the phase diagram. By plotting a lot of different connection lines an d combining with X-ray powder differaction analysis validation can draw 100℃ of AICl3-H2O-Al2O3 ternary equilibrium system phase diagram.In addition, on the basis of 75℃ AlCl3-H2O-Al2O3 ternary equilibrium syste m phase diagram we have plotted, we selscted suitable feeding point to do reacti on and captured the obtained polyaluminium chloride solution with a certain conc entration of 2,6-naphthalene disulfonic acid disodium salt under 75℃, placed a fe w days to get [Al2O8Al28（OH）56（H2O）26]（2,6-NDS）6C16·66H2O (Al30) and [Al30.5O8（ OH）61.5（H2O）22][2,6-NDS]4[Cl]6`36H2O (Al30.5) crystal at room temperature, and by X-ray single crystal differaction data solving its structure, so as to enrich the fo rms of polyaluminium compounds and facilitate the fuether study on the hydrolys is mechanism. |
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