Safa Sorur, Mirzaei Majid, Kazemi Foad, Ghaneian Mohammad Taghi, Kaboudin Babak
1Department of Environmental Health Engineering, International Campus of Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
2Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 49195-1159 Iran.
J Environ Health Sci Eng. 2019 Mar 13;17(1):233-245. doi: 10.1007/s40201-019-00343-4. eCollection 2019 Jun.
The consumption of pesticides and chemical fertilizers is one of the major environmental and health problems. In this report, 2,4-dichlorophenoxyacetic acid (2,4-D) was chosen to evaluate the impact of photodegradation using LED (Light-emitting diode) (400 and 365 nm) sources in batch and programmable circulated-mode photoreactors respectively.
A β-cyclodextrin (β-CD) grafted titanium dioxide P25 (P25/β-CD) and complexation of 2,4-D and β-CD were synthesized via photoinduced and spray-drying methods, respectively. The structures were characterized. Moreover, we investigated the effects of the amount of catalyst, the β-CD amount on bed catalyst, irradiation time, kind of photoreactor on the photocatalytic degradation efficiency.
Based on the results of experiments in batch reactor, the optimum amount of TiO, β-CD grafted by catalyst were 1 and 0.1 g/L, respectively. In batch-mode the photodegradation efficiency of 2,4-D after 5 h with P25, P25/β-CD as a photocatalyst and 2,4-D/β-CD complex with P25 photocatalyst were approximately 81, 85 and 95% respectively. After 8 h of irradiation in circulated-mode reactor, degradation yields with P25, P25/β-CD and 2,4-D/β-CD complex along with P25 were 89, 91 and 96% respectively. On the other hand, the circulated-mode photoreactor with high efficiency was appropriate to degradation of the high concentration of 2,4-D solution (200 mg/L). After 5 successive cycles with 25 h of irradiation, P25 and P25/β-CD maintained as high 2,4-D removal efficiency as 82.6, 84% respectively, with excellent stability and reusability.
The photodegradation method can be used as an effective and environmental friendly process in the degradation of organic compound.
农药和化肥的使用是主要的环境与健康问题之一。在本报告中，选用2,4-二氯苯氧乙酸（2,4-D）分别在间歇式和可编程循环模式光反应器中，评估使用发光二极管（LED）（400和365纳米）光源进行光降解的效果。
分别通过光诱导法和喷雾干燥法合成了β-环糊精（β-CD）接枝二氧化钛P25（P25/β-CD）以及2,4-D与β-CD的络合物。对其结构进行了表征。此外，研究了催化剂用量、床层催化剂上β-CD的用量、辐照时间、光反应器类型对光催化降解效率的影响。
基于间歇式反应器的实验结果，催化剂接枝的TiO₂、β-CD的最佳用量分别为1和0.1克/升。在间歇模式下，以P25、P25/β-CD作为光催化剂以及2,4-D/β-CD络合物与P25光催化剂作用5小时后，2,4-D的光降解效率分别约为81%、85%和95%。在循环模式反应器中辐照8小时后，P25、P25/β-CD以及2,4-D/β-CD络合物与P25的降解率分别为89%、91%和96%。另一方面，高效的循环模式光反应器适用于高浓度2,4-D溶液（200毫克/升）的降解。在进行5次连续循环、每次辐照25小时后，P25和P25/β-CD对2,4-D的去除效率分别高达82.6%、84%，具有出色的稳定性和可重复使用性。
光降解方法可作为降解有机化合物的一种有效且环保的工艺。
