Photocatalytic Degradation of Ethylene by TiO2/WO3 on Electrospun Silk Nanofiber

Abstract

Anthropogenic ethylene at high concentrations in air is considered to be one of pollutant sources while the low concentration of ethylene naturally releasing from respiration in fruit could play an important role in the repining. Controlling ethylene concentration in active packaging by photocatalytic reactions is an alternative way to prolong shelf-life after harvesting. This research aims to develop the electrospun nanofiber from silk fibroin as a support. Several electrospinning parameters were controlled by applied high voltage of 30 kV, the distance between the needle and the collector of 8 cm and the flow rate of fibroin solution at 4 ml/h. The as-prepared electrospun fiber were coated with TiO2 and WO3 with 2 different patterns; TiO2 coated on WO3 immobilized on fiber (TiO2/WO3) and vice versa (WO3/TiO2). Moreover, the effect of TiO2:WO3 mole ratios (1:0.4 to 1:1.1) on ethylene removal from humid air with the initial ethylene concentration of 40 ppm were also investigated. The results show that TiO2/WO3 exhibited ethylene removal 1-1.5 times higher than WO3/TiO2 at mole ratios of 1:0.7 and 1:1.1. This higher efficiency may attribute to the charge separation effect resulting from synergetic effect of TiO2 and WO3, which can cause photo-excited holes to transfer to the surface of TiO2 and further reacted with water to form hydroxyl radical. The radicals initially induced decomposition of ethylene to CO2 and water. Furthermore, TiO2/WO3 at mole ratio of 1:0.7 showed the excellent ability to remove ethylene of 22.13 mmolC2H4/molTiO2 which is 1.4-times higher than that of TiO2 while WO3 could not remove ethylene. This emphasized the charge separation could be enhanced the photocatalytic efficiency.