Development of methods for controlling organic impurities in wastewater treatment

Electrical conductivity was studied aqueous solutions of surface-active substances (surfactants) different nature depending on the concentration of electrolytes in solution, in order to control the content of harmful impurities of organic nature in mineralized waters conductometric method. It has been established that the specific electric conductivity decreased with increasing surfactant concentration, however, the nature of the changes in solutions of low-molecular and colloidal surfactants is different. In the case of low-molecular surfactants, the dependence has a linear form, for example, for a solution of butanol with an ionic potassium chloride force of 2 mol / m3, according to the equation: y = -0,0604x + 0,5085, and for solutions of colloidal surfactants – extremal, passing through a minimum. An increase in the ionic strength of the medium for solutions of surfactant ionogenic (sodium oleate) and nonionic type (neonol AF 9–10) leads to a decrease in the minimum on the concentration curve of electrical conductivity. A decrease in the value of the critical micelle concentration (CMC) for sodium oleate from 1.1 10-3 mol / dm3, up to 0.4 · 10-3 mol / dm3 at a concentration of potassium chloride in a solution of 2 mol / m3, and CMC = 0, 1 10-3 mol / dm3 at an ionic strength of the solution of 10 mol / m3. In the case of neonol AF 9–10 (CMC = 1.24 ? 10-4 mol / dm3), an increase in the electrolyte concentration, for example KCl from 2 to 75 mol / m3 in the solution, does not shift the CMC point in the entire ionic strength range of the medium. Thus, the extreme character of the dependence of the conductivity isotherms of colloidal surfactants in the region of low ionic strengths of the solution, can serve as an analytical signal for the detection of impurities of the amphiphilic nature and the possibility of predicting the overall mineralization of complex water.