Abstract:

The color response of brilliant blue to the acidity of solutions(H⁺ concentration >0.1 mol/L) and the mechanism were studied using a prepared high acidity test paper. The results show that the colors of dissolved or fixed brilliant blue vary with the change of the acidity of solutions. It turns regularly from blue, green, kelly to yellow with the increase of H⁺ equilibrium concentration from 0.1 to 9.0 mol/L in the solution. The color transition only depends on the acidity of the solution and is unaffected by the acid type or its oxidation. The absorption phenomena between the color variation of brilliant blue and solution acidity were investigated by spectrophotometry, and the mechanism was also proposed. The high acidity paper was prepared based on the color response of brilliant blue to the acidity. It can be used to directly detect the H⁺ concentration of the solution in the range of 0.1~9.0 mol/L with the accuracy of ±1 mol/L.

Key words: brilliant blue, acidity response, high acidity test paper, mechanism of color variation