REVERSIBLE INDICATOR (OPTIONS) Russian patent published in 2022 - IPC G01N31/22 B01J20/12 B01D53/28 

FIELD: chemistry.

SUBSTANCE: invention relates to a reversible indicator characterized by the fact that it is manufactured by continuous stirring under normal conditions until the formation of a sorbent having a uniform color, followed by its drying at a temperature of 95-105°C for 23-25 hours, 85-90, wt. %, natural-sodium bentonite clay with a content of at least 80% montmorillonite with a dispersion of no more than 7.5 mm, pre-saturated with moisture up to 50-60% of its maximum moisture capacity at a relative humidity of at least 80%, and 10-15 wt. % of indicator solution, which is pre-prepared by sequential mixing under normal conditions of 19.0-20.0 wt. % 6-aqueous cobalt chloride, 0.7-1 wt. % ammonium chloride, 1,7-2,2 wt. % copper sulfate and 78.6-76.8 wt. % distilled water, brought to a boil, boiled for 50-70 seconds and cooled under normal conditions to a temperature of no more than 30°C. The invention also relates to a reversible indicator characterized by the fact that it is manufactured by applying medium or slow filtration to filter laboratory paper for quantitative analyses with a mass fraction of ash up to 0.03%, a filtering capacity of no more than 100 s and a wet pressure resistance of at least 6 kPa, preferably medium filtration for quantitative analyses with a mass fraction ash up to 0.01%, filtration capacity of no more than 45 s and resistance to pressure in the wet state of at least 6 kPa, pre-aged for at least 300 s at a relative humidity of at least 80%, with a time gap of no more than 30 s of 0.02-0.05 ml of the indicator solution, which is pre-prepared by sequential mixing under normal conditions of 19.0-20.0 wt. % 6-aqueous cobalt chloride, 0.7-1 wt. % ammonium chloride, 1,7-2,2 wt. % of copper sulfate and 78.6-76.8 wt. % distilled water, brought to a boil, boiled for 50-70 seconds and cooled under normal conditions to a temperature of no more than 30°C.

EFFECT: expansion of the range of reversible indicators.

2 cl, 22 ex, 3 dwg