Fabrication of mixed matrix nanofibers with electrospraying and electrospinning techniques and their application to gas toluene removal

This study describes the fabrication and characterization of mixed matrix nanofiber air filters having adsorptive and photocatalytic properties. Two fabrication techniques were applied as (i) single electrospinning (SE) and (ii) successive electrospinning and electrospraying (SEE) for doping of photocatalyst (TiO2) in nanofiber structure. Polyacrylonitrile (PAN) was used as main polymer, the nanoclay (NC) was used with ratios of 0.5%, 1.0% and 2.0% (w/w) as nanoadsorbent and TiO2 was used as photocatalytic oxidation agent. TiO2 was integrated to the nanofiber structure with two doping methods (blended in solution and sprayed) providing as same TiO2 mass (0.2 g TiO2/g PAN) in unit area of final nanofiber structure. The water vapor transmission rate (WVTR) values showed a decreasing trend with the addition of NC and varies between 80 and 150 g/m2h. The presence of NC played a critical role in increasing of toluene adsorption capacity of nanofiber from 15% to 40% with increasing of NC amount. The maximum toluene degradation rates of mixed matrix nanofiber were found as 0.09 ppm/min for the NC2.0-TiO2-S coded nanofiber and 0.05 ppm/min for the NC2.0-TiO2 coded nanofiber. The integration of TiO2 to nanofibers with SEE was found as more effective for toluene oxidation than SE. With the electrosprayed TiO2, the contact area of nanofiber is further increased and the UVA light more easily activates TiO2 onto nanofiber. Among all nanofibers, NC2.0-TiO2-S coded nanofiber (doped TiO2 with SEE) is promising for air filter considering its filtration properties in general, as it has high toluene adsorption and oxidation efficiency, good air permeability, 93% particulate matter filtration efficiency and low pressure drop.