Measurement and correlation for the solubility of 2-chloro-5-nitrotoluene-4-sulfonic acid and 2-amino-5-chloro-4-methylbenzenesulfonic acid in aqueous sulfuric acid solutions

The solubility of 2-chloro-5-nitrotoluene-4-sulfonic acid (CNT acid) and 2-amino-5-chloro-4-methylbenzenesulfonic acid (CLT acid) in aqueous sulfuric acid solutions was measured over the temperatures range from 276.91 to 345.42 K at atmospheric pressure by a dynamic method. The solubility of CNT acid and CLT acid in aqueous sulfuric acid solutions increased with temperature. In the experiment, the highest solubility of CNT acid and CLT acid was both obtained in pure water, and the lowest solubility was exhibited at solute-free mass fraction of aqueous sulfuric acid solutions w30 = 0.50 and w30 = 0.20, respectively. The experimental data were correlated with the modified Apelblat model, and the root-mean-square deviations ranged from 0.76 to 1.28 K. According to the solubility data, the improvement of separation process of CNT acid and CLT acid was recommended.