The synthesis and application of titanium dioxide coated silk fibroin filters

The purpose of this research is to synthesize silk fibroin filters and investigate volatile organic compounds removal efficiency in indoor air using the synthesized SF filters. The catalyst and mechanical properties of SF filters were studied. In addition the studied of VOCs removal efficiency was included. He experiments were conducted at two scales; a small reactor and a large modeling room. Small reactor experiments were performed to study the impacts of catalyst dosage, initial concentration, and air flow rate. While large modeling room experiments were conducted to study the effects of initial concentration and catalyst dosage.
SEM micrographs revealed the fibrous morphology of the SF fiber. It was found that at different catalyst dosages, TiO2 was moderately distributed onto the surface of SF filter. An average diameter of the SF fiber was approximate 10 µm. The thickness of the SF filters and SF filters coated with TiO2 were approximately 4.10 and 4.75 mm, respectively. The spectral data showed the strong cut off at 390 nm. The band gap energy was approximately 3.2 eV. The highest differential pressure (P) of 3,331±13 Pa was obtained for the SF filter coated with 7.5% wt. TiO2/vol.sol. The mechanical properties of SF filters coated with 7.5% wt.TiO2/vol.sol. were numbers of 1622 cm-1 (amide I), 1533 cm-1 (amide II), and 1225 cm-1 (amide III), which regard to the crystalline structure.
For the VOCs treatment in a small reactor, the highest VOCs removal efficiency of 26±0.06% was obtained when using the SF filter and air flow rate of 5 L/min. The highest VOCs removal efficiency via Photocatalytic oxidation process was 67.6±0.53% for the SF filter coated with 5.0% wt.TiO2/vol.sol. at the air flow rate of 5 L/min and light intensity of 0.125 mW/cm2. While, the highest removal efficiency of the commercial air filter was about 25.0±1.43%. For experiments in a large modeling room, the highest VOCs removal efficiency of 48.9±0.15% was achieved for the SF filter coated with 5.0% wt.TiO2/vol.sol. when using the air flow rate of 2.39 m3/min and light intensity of 0.85 mW/cm2. Therefore, the SF filter coated with TiO2 can potentially be applied as an alternative material for treatment of indoor air pollution.