Degradation of methyl orange and congo red by using chitosan/polyvinyl alcohol/TiO₂ electrospun nanofibrous membrane

In this study, chitosan/polyvinyl alcohol/TiO₂ nanofiber was fabricated via electrospinning at a pump rate of 1.5 mL/h and voltage 6 kV. Field-emission scanning electron microscopic images showed bead free finer nanofiber. Fourier transform infrared spectra proved the formation of strong bond among chitosan, polyvinyl alcohol and TiO₂. X-ray powder diffraction showed that TiO₂ became amorphous in the composite nanofiber. Toughness and thermal stability of the chitosan/PVA nanofibrous membrane was increased with addition TiO₂. The chitosan/PVA/TiO₂ nanofibrous membrane was stable at basic medium. But degraded in acidic and water medium after 93 and 162 h, respectively. The adsorption mechanism of congo red obeyed the Langmuir isotherm model. On the other hand, adsorption characteristic of methyl orange fitted well with both Langmuir and Freundlich isotherm models. The maximum adsorption capacity of the resulting membrane for congo red and methyl orange is 131 and 314 mg/g, respectively. However, a high dose of adsorbent was required for congo red.