Rapid Detection Study On Sulfur Dioxide

Sulfur dioxide is an unwanted byproduct of some industrial process with strong excitant odour and acidity.It causes serious damage to atmosphere and ecological system.It is very necessary to propose a gas detection method to realize real-time detection with easy operation and rapid response.Herein,we developed two methods based on photonic crystal(PC)technology and chemical identification,respectively.At the beginning,a three-dimensional opal Carboxymethyl Cellulose photonic crystal(3D-OCCPC)was prepared for the detection of sulfur dioxide.With the increasing concentration of sulfur dioxide,the diffraction peak of 3D-OPC red-shifted while its maximum amount of redshift is 7 nm,moreover,the minimum detectable concentration is 1×10~5ppm.Afterwards,3D inverse opal photonic crystal was prepared as well.Along with the increase of sulfur dioxide concentration,the diffraction peak blue-shifted while its maximum amount is 33 nm,moreover,the minimum detectable concentration is 5×10~5 ppm.Dimethyl sulfoxide(DMSO)was applied to the systemin order to specifically recognize sulfur dioxide gas.When the film was exposed to sulfur dioxide gas,the reflection peaks and structural color disappeared.The corresponding limitation of detection was 1000 ppm which is lower than the National Respiratory Protection Standard as 2800 ppm and the response time was around 30 min.Furthermore,α-cellulose was used to prepare the PC film instead of Carboxymethyl Cellulose.Its structural color was clear and spectral peak was symmetric,although its application in sulfur dioxide detection was failed due to the chemical modification by Phenyl Vinyl Sulfoxide.The mesoporous materials including MCM-41 and SBA-15 were treated with colorants and also employed to detect sulfur dioxide gas.When exposed to the 8000 ppm concentration of sulfur dioxide,the indicator with MCM-41 showed more rapidly response changing from white to red in one second while the traditional silica gel indicator changing from white to pale pink in one minute.The limit detection of sulfur dioxide was confirmed as 250 ppm.