Keggin型磷钨杂多酸功能化离子盐在模拟太阳光辐照下光催化降解DNT废水

Photocatalytic Degradation of DNT Wastewater by Keggin-Type Phosphor-Tungsten Heteropolyacid Functionalized Ionic Salts under Simulated Sunlight

通过离子液体与Keggin型磷钨杂多酸(H3PW12O40)离子交换形成非水溶性有机阳离子盐,实现Keggin型磷钨杂多酸离子的固定化,探究其光催化降解2,4-二硝基甲苯(DNT)废水的性能。以N-甲基咪唑为起始原料,经过二步合成1-甲基-3-乙酸甲酯基咪唑磷钨酸盐(MEImPWO)和1-甲基-3-烯丙基咪唑磷钨酸盐(MAImPWO),利用红外光谱仪和扫描电镜对其结构和形貌进行表征;考察了不同光照时间、催化剂用量、H2O2用量条件下,所合成离子盐在氙灯光源辐照下光催化降解DNT的性能。结果表明:所合成两种离子盐具有Keggin型磷钨杂多酸特征结构和咪唑结构;MEImPWO呈纳米棒状堆积,MAImPWO呈微米片状和纳米类球状颗粒堆积;两种盐都显示出具有在H2O2参与下、自然PH值条件下光催化降解DNT的良好性能。所得最佳的光催化条件和结果为:DNT水溶液(100 mg/L) 50 mL,MEImPWO 0.10 g + H2O2 0.48 g/L,光照1 h,DNT降解54%,光照4 h可使DNT完全降解;MAImPWO 0.10 g + H2O2 0.60 g/L,光照1 h,DNT降解62%,光照3 h可使DNT完全降解。两种催化剂在最佳条件下重复使用5次后,其光催化活性基本保持不变。

Non-water-soluble organic cationic salt of Keggin-type phosphorus tungsten polyacid was formed through the ion exchange reaction with an ionic liquid to realize the immobilization of Keggin-type phosphorus tungsten polyacid ion, and the photocatalytic performance of the ionic salts as obtained on the degradation of 2,4-dinitro toluene(DNT) wastewater was explored. With N-methylimidazole as the starting material, 1-methyl-3-methyl acetate-imidazole phosphotungstate (MEImPWO) and 1- methyl-3-allyl-imidazole phosphotungstate (MAImPWO) were synthesized through two steps respectively. Their structure and morphology were characterized by infrared spectrometer and SEM;and their performance on the photocatalytic degradation of DNT under xenon lamp light irradiation was investigated under the conditions of different light time, catalyst amount and H2O2 amount. The results show that the two synthesized salts have Keggin characteristic structure and imidazole structure;the morphology of MEImPWO is nanorod accumulation, and MAImPWO is micron sheet and nano spherical particles accumulation;both salts show good performance on the photocatalytic degradation of DNT with the participation of H2O2 and natural PH. The better photocatalytic conditions and results are: for MEImPWO, with the amount of catalyst 0.10 g, H2O2 0.48 g/L, light irradiation 1 h, the rate of DNT degradation was 54%, and DNT was completely converted within 4 h;for MAImPWO, with the amount of catalyst 0.10 g, hydrogen peroxide 0.60 g/L, there was 62% of total DNT degraded after 1 h light irradiation, and DNT was completely degraded within 3 h. The photocatalytic activity of the catalysts was basically kept unchanged after 5 cycles under the same conditions.