Electrospun fiber mats as optical gas sensor for formaldehyde

Abstract

The developed sensor for detecting a formaldehyde gas by visual detection using a mixture of polymer solution/Schiff’s reagent/Milli-Q water was prepared by the electrospinning and film casting techniques. When Schiff’s reagent was exposed to formaldehyde gas, its color changed from yellow to violet and appeared absorbance λmax at 580 nm. Morphology of electrospun fibers was characterized by Optical Microscope (OM) and Scanning Electron Microscope (SEM). In this experiment, two types of studied polymer sensor: polyethylene oxide (PEO) and polyvinyl alcohol (PVA) were investigated. The optimized condition of electrospinning process were the 10:90:0 mass ratio of PVA/Schiff’s reagent/Milli-Q water, flow rate of syringe pump was 0.1 mL/hr, electric field of 20 kV, and distance between needle and collector of 25 cm. It was found that the obtained size of PVA/Schiff’s reagent/Milli-Q water electrospun fibers appeared to be well-distributed, and its diameter is in a range of 342 ± 41 nm. In this study, the formaldehyde gas was generated using temperature and agitation as well as bubbling with nitrogen gas in to the formalin solution. First, the condition of generating formaldehyde gas system is optimized. The optimized temperature and stirring rate are 50 ºC and 100 rpm, respectively. The electrospun sensor and film sensor were used to detect the generated formaldehyde gas concentration in a range of 61-122 µg/L. The relative standard deviation (%RSD) of the absorbance at 580 nm of both electrospun sensor and film sensor are 1.22% and 2.66%, respectively.