Polyoxometalates and Catalysis Laboratory, Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India.
Centre for Nano and Material Sciences, Jain University, Jain Global Campus, Bengaluru, Karnataka, 562112, India.
Environ Sci Pollut Res Int. 2021 Mar;28(9):10633-10641. doi: 10.1007/s11356-020-11340-8. Epub 2020 Oct 24.
A heterogeneous catalyst comprising Keggin type polyoxometalate, silicotungstic acid (SiW), and MCM-22 was synthesized using wet impregnation method and characterized by acidity measurement, BET, FT-IR, XRD, and SEM. Their catalytic activity was evaluated for the degradation of cationic organic dyes like methylene blue (MB), crystal violet (CV), and an azo dye Chryosidine Y (CY) in an aqueous solution. The experimental parameters such as catalyst amount, initial dye concentration, and contact time were studied for the degradation of dyes, and it was found that the cationic dyes like methylene blue and crystal violet show better activity as compared to azo dye Chryosidine Y. This may be attributed to better electrostatic interaction of these cationic dyes with the residual negative surface charge of the catalyst, due to presence of SiW ion as it is rich in surface oxygens and surface hydroxyl groups. The control experimental results showed that the presence of SiW at the surface of MCM-22 promoted the degradation reactions, and presence of multiple W-O bonds in polyoxometalate also played a key role in this reaction. The catalyst exhibits recycling ability without any significant loss in activity up to four cycles.
采用浸渍法合成了 Keggin 型多金属氧酸盐、硅钨酸（SiW）和 MCM-22 的负载型催化剂，并通过酸度测定、BET、FT-IR、XRD 和 SEM 进行了表征。考察了催化剂用量、染料初始浓度和接触时间等实验参数对染料降解性能的影响，结果表明，与偶氮染料金橙 Y（CY）相比，阳离子染料亚甲基蓝（MB）和结晶紫（CV）的降解活性更好。这可能归因于这些阳离子染料与催化剂表面残留的负电荷之间具有更好的静电相互作用，这是由于 SiW 离子的存在，因为它富含表面氧和表面羟基。对照实验结果表明，SiW 位于 MCM-22 表面促进了降解反应，而多金属氧酸盐中存在的多个 W-O 键在反应中也发挥了关键作用。该催化剂在四循环内表现出良好的循环稳定性，活性无明显损失。
