Textile-based indicator for acid-base titration

In the present work, textile halochromic materials were obtained, which were tested as indicators of acid-base titration. Textile materials were obtained by functionalization of cotton fabric with halochromic disazo derivatives of 4,4’-diaminostilbene-2,2’-disulfonic acid using direct dyeing technology. Rectangular fragments of halochromic textile material, 20 by 20 mm in size, were placed directly into the titrated solution. The range of color change and the rate of its change were studied in the process of potentiometric titration of sodium hydroxide, sodium bicarbonate and tap water. Testing of halochromic textile material as an indicator of acid-base titration was carried out using the example of determining the acidity of water. The correctness of the results was determined using the added-found method. The halochromic sensor material is characterized by a high rate of color change. The color change of the material is visually observed in all cases within the jump on the titration curve. The data obtained when determining the alkalinity of water with various indicators are in good agreement with each other. When assessing the correctness of the results using the recovery test, the degree of discovery close to 100 % was obtained. When using such an indicator, the halochromic dye is localized within the tissue fragment, which significantly facilitates the fixation of the end point of titration. The use of the developed material can be relevant in contactless control systems for the acidity of the medium through a transparent wall as an alternative to fluorescent sensors.