Preparation of ZrO2 aerogels by L-malic acid and L-tartaric acid assistant sol-gel method

In our previous work, we adopted the organic acids assisted sol-gel method to prepare ZrO2 aerogels. In preparation process, we found the organic acids with two carboxyl groups and one side group including -OH, -NH2, and -SH were prerequisite to form wet gels. Furthermore, the citric acid with three carboxyl groups and one hydroxyl group was also successfully to form wet gels. Therefore, we speculated that the organic acids required to possess at least two carboxyl groups and one side group to form wet gels. In this work, different organic reagents including acetic acid (AA), oxalic acid (OA), lactic acid (LA), edetic acid (EDTA), butanediol (BD), glycerol (GA), citric acid (CA), L-malic acid (LMA) and L-tartaric acid (LTA) were adopted as gel accelerators to verify our assumption. A series of ZrO2 aerogels were successfully synthesized using ZrOCl2 center dot 8H(2)O as zirconium precursor, and LMA or LTA as the gel initiators by the sol-gel method. It was found that the gelation time of LTA as gelator was shorted than that of LMA in the same condition. When LTA as an gelator, the tetragonal phase can keep until 1000 degrees C, while for LMA, the tetragonal phase can keep at 800 & DEG;C. After supercritical fluid drying (SCFD), ZrO2 aerogel with high surface area of over 339 m(2)center dot g(-1) and large pore volume of over 0.92 cm(3)center dot g(-1) can be obtained.