Efficient removal of gaseous toluene by the photoreduction of Cu/ Zn-BTC metal-organic framework under visible-light

The available evidence on the functions of metal-organic frameworks (MOFs) in photocatalytic oxidation continuous airstream systems is scarce yet. Therefore, in this study, the effective and economical Zn-BTC, Cu-BTC and Cu/Zn-BTC MOFs were synthesized via a facile and simple solvothermal method and applied as LED-exited photocatalyst for toluene removal from air streams. Central Composite Design (CCD) and Response Surface Methodology (RSM) were used to optimize and evaluate the effects of flow rate, influent toluene vapor concentration and relative humidity on the photocatalytic degradation efficiency. The results of FT-IR, FE-SEM, EDAX, DRS and PXRD analyses indicated the successful preparation of nano-photocatalysts. The Cu/Zn-BTC MOF had higher removal efficiency compared with the Cu-BTC and Zn-BTC. The relative humidity had the highest effect on the toluene removal efficiency over the MOFs. Moreover, When Zn-BTC, Cu-BTC and Cu/Zn-BTC MOFs were under visible light in the optimum conditions (0.015 L/min, 30% RH (%) and 40 ppm), the removal process efficiency improved from 33% to 71.55% and 74.77%, respectively. We have also investigated that Cu/Zn-BTC MOFs are highly stable during long-term photocatalytic removal of toluene. Besides, no by-products were detected at the reactor output by GC-MS. Overall, our results suggested that the LED-based photocatalytic system with Cu/Zn-BTC MOFs offered a suitable performance at low relative humidities to remove VOCs from air.

Automated summary

In this study, Zn-BTC, Cu-BTC, and Cu/Zn-BTC MOFs were successfully synthesized and applied as nano-photocatalysts for toluene removal under LED illumination. Cu/Zn-BTC MOFs showed higher removal efficiency at low relative humidities according to optimization results.