ABSTRACT
All of the following materials were produced in Sinopharm Group Chemical Reagent Co. Ltd. and were 99.7% pure:
Al2(SO4)3⋅18H2O, Na2SO4, K2SO4, SnSO4, Na2CO3, ZnSO4⋅7H2O, TiOSO4, and Na3PO4.
2.2 Preparation process
The molar ratio of the molten salt and Al3+ is 4:1. The concentration of 0.5295 mol/L Al2(SO4)3⋅18H2O, 0.8469 mol/L K2SO4, and 1.2787 mol/L Na2SO4 are prepared respectively, thereby composing solution 1. And then, a certain percentage of SnSO4, TiOSO4, and ZnSO4⋅7H2O are added to solution 1. Next, 0.3396 mol/L Na2CO3 and 0.0018 mol/L Na3PO4 are prepared as the second solution, namely 2. The solution 2 is dropped at a speed of 5 ml/min into solution 1 at 65°C and is kept under continuous stirred at a rate of 400 r/min for 15 min by using a peristaltic pump until the reaction is completed to obtain a gel mixture of the two solutions. The temperature of the reaction container is raised to 90°C and aged for 24 h. The gel is evaporated to dryness. And then, the dried precursor powder is placed in a corundum crucible and compacted and placed in a muffle furnace. The dried precursor powder is heated respectively to 1000°C, 1100°C, 1200°C and 1300°C at the rate of 9°C/min. The solid agglomerate obtained after calcination is dispersed with concentrated sulfuric acid and then repeatedly washed with a large amount of distilled water and alcohol to remove impurities and finally dried to obtain a test sample.
