In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according to contact various gas samples (as strong acid and base, chloroform, ammonia and HF) of this dye-coated nonwoven film was examined for the application of chemically toxic materials detecting tools in the actual site of working place without aid of any kinds of detecting devices. By the addition of electron transfer agent (quinone derivatives), quick color change behaviors were observed within 10 seconds under the contact of various toxic gases in general condition(room temperature, 50% humidity).
For the assuring of worker’s safety in actual work place in industry or factory handling various toxic gases, quick alarm devices without aid of any electronic tools is passionately required from the field. Colorimetric sensor is one of the powerful candidates about such requirements, but commercialized colorimetric sensors have weak points as relatively high price and late response time [
For the colorimetric dye, we selected several pH indicator as bromophenolblue (BPB), boromocresol green (BCG), m-cresol purple (MCP), chlorophenol red (CPR), hydroquinone, benzoquinone and CaCl2 were purchased from Sigma-Aldrich Co. Ltd. (St. Louis, MO, USA). Sodium alginate (SA) was purchased from Yakuri Pure Chem. Co. (Kyoto, Japan) (
All reagents were used without any other purification. 8 kinds of toxic gase s(HCl, Cl2, CH3NH2, NO2, HF, NH3, (CH3) 3N, SO2) were obtained from MG Tech. Co. (Hwasung, Korea).
The pH indicating and water soluble dyes p indicatingdyes were mixed with hydrophilic binder(Sodium Alginate, SA) to 0.1 wt% of dye in 1 w% of SA aqueous solution with or without benzoquinone (0.5 wt%), then this solution was coated on the nonwoven fabric sheet and cured with calcium chloride solution (10 wt%) (
The coated nonwoven fabric sheet was dried under room temperature and exposed to the vaporized toxic gas for the confirmation of time dependent color change in these coating layers using following MFC apparatus (Model 247C, MG Tech Co., Hwasung, Korea) (
toxic gases exposure through mass flow controller equipped gas supplier (8 kinds of toxic gases). In very short time (within 10 seconds) after gas exposure, all of the film type colorimetric sensors were changed their own color as blue to yellow or its reverse.
The color changing behaviors of the film type colorimetric sensors (BPB dye coated) with (+/−) benzoquinone were shown in
But, for the (+) benzoquinone, color changes owing to same condition was observed after 10 seconds from initial state (
This means that electron transfer reagents which were worked in biochemical reactions of the living cell func-
tion are also available in oxidation-reduction reaction of dyes in our system for colorimetric gas detection tool in working place.
In most of working places treating toxic gases, working condition was exposed to very humid and high temperature. So water soluble dye component contained in coating layer of film type colorimetric sensor can be extracted out from the coating layer when exposed to the wet environment. And it will be also existed with high possibility that the coating layer can be dissolved under the same condition. Therefore, the water resistivity of coating layer containing water soluble dyes is essential characteristics of this colorimetric sensor.
From the results of non-crosslinked film in
The International Commission on Illumination (CIE) first recommended the CIELAB color scale as a standard approximately, uniform color scale in 1976 [